[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$ftjl-H89xDQJMlcS7zXTL8wRNbH0aU2RpCRjWpUYXLhk":36,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":273,"$fucxFBm2ZjZfGSdmdRaSNGBI_F0jJme4f0GTvzUhQfL8":336},[4,8,12,16,20,24,28,32],{"title":5,"slug":6,"path":7},"About Microbeonline.com","about-microbeonline-com","\u002Fabout-microbeonline-com\u002F",{"title":9,"slug":10,"path":11},"About Me","about-me","\u002Fabout-microbeonline-com\u002Fabout-me\u002F",{"title":13,"slug":14,"path":15},"Advertise with Us","advertise-us","\u002Fadvertise-us\u002F",{"title":17,"slug":18,"path":19},"Privacy Policy","privacy-policy","\u002Fprivacy-policy\u002F",{"title":21,"slug":22,"path":23},"Authors","authors","\u002Fauthors\u002F",{"title":25,"slug":26,"path":27},"Microbes","microbes","\u002Fmicrobes\u002F",{"title":29,"slug":30,"path":31},"Books","recommended-books","\u002Frecommended-books\u002F",{"title":33,"slug":34,"path":35},"Tags","tags","\u002Ftags\u002F",{"type":37,"data":38},"blog",{"slug":39,"title":40,"description":41,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":44,"lastUpdatedDate":45,"draft":46,"category":47,"image":42,"body":48,"faq":49,"commentsClosed":46,"tags":68,"related":70,"comments":269},"pipette-tips-types-uses-and-criteria-to-choose-it","Pipette Tips: Types, Uses, and Criteria to Choose It","Pipette tips are the aseptic barrier between specimen and pipette. Learn tip types — filter, low-retention, wide-bore — and when each is clinically mandatory vs. optional.",null,"Ashma Shrestha","2022-07-15","2026-07-31",false,"lab-equipment","A student runs a PCR that keeps coming up positive in the no-template control, the well that should contain no DNA at all. The reagents are fine. The technique looks clean. The culprit is the pipette: aspirating a concentrated template a few wells earlier pushed a fine aerosol up into the pipette shaft, and it drifted back down into the next sample. A plain tip does nothing to stop this. A filter tip would have. This is the hidden logic of pipette tips: they look like disposable plastic, but the tip you choose decides whether tiny amounts of the last sample contaminate the next one, and whether the volume you think you dispensed is the volume you actually dispensed.\n\nPipette tips are the attachable part of pipettes that aid in aspirating and dispensing liquids. Most commonly used tips are disposable or autoclavable. These are also available in various types like non-sterile or one-time use (used for general laboratory procedure), pre-sterile (used for cell cultures), and filtered tips (used for handling RNA and DNA).\n\nPipettes are the [laboratory equipment](\u002Fequipment-essential-for-microbiology-laboratory\u002F) used for handling liquid samples. Almost all the pipettes require pipette tips for performing their intended work.\n\nTips made of virgin polypropylene are the most common and the most environmentally friendly. Sometimes the tips also contain plastics or metal additives (yellow and blue colored tip).\n\n![Pipette tips  - Different types of pipette tips](\u002Fblogs\u002FPipette-Tips.png)Figure: Different types of pipette tips\n\n## Why the Pipette Tip Is the Critical Component\n\nThe design of a micropipette is built around one principle: the liquid must never contact the pipette barrel. The barrel contains the piston, the spring mechanism, and the air column that drives aspiration and dispensation. If liquid or aerosol enters the barrel, the pipette becomes a contamination source — transferring material from one sample to the next through every subsequent pipetting step until the barrel is decontaminated.\n\nThe pipette tip makes this separation possible. Liquid enters the tip only. The air cushion between the liquid and the piston ensures the liquid goes no further. The tip is discarded after each use, taking any biological material with it.\n\nThis design works — unless the aerosol generated during rapid aspiration or dispensation travels upward past the air cushion and reaches the barrel. This is what filter tips prevent. The hydrophobic polyethylene filter inside the tip shaft physically blocks aerosols and liquid from travelling upward, regardless of pipetting speed or technique.\n\nUnderstanding this mechanism is what makes tip selection a clinical decision, not just a procedural one. The pipette tip is not a passive plastic attachment. It is the aseptic barrier between the specimen and the pipette, and choosing the wrong tip type does not just affect accuracy, it can invalidate an entire diagnostic run.\n\n## Types of Pipette Tips\n\nThe pipette tips are divided into several types based on their functions and properties. One basis for differentiating the types of tips is sterility. Some tips might be sterile and RNase-free (filter tip). In contrast, non-sterile tips are used for routine work such as serological tests, where sterility and nuclease-free certification are not required.\n\nAnother basis is their purpose; some require a more extended head to prevent contamination (long tip) or may require precise measurement (low retention tips). Finally, the last basis for differentiation is size; 0.1 to 1000 µl is available in universal (non-sterile) pipette tips.\n\nThe types of tips and their functions are as follows:\n\n### Based on sterility\n\nSterile or Pre-sterile Tips\n\nThese are one-time use tips that come in the pre-sterilized form. These tips are free of DNA, RNase, ATP, and pyrogens and suitable for experiments that require sterile conditions like cell cultures, PCR, etc. These are also helpful while handling volatile liquids and specimens that require testing in a contamination-free environment.\n\nNon-sterile Tips\n\nThese are the most commonly used tips, and also known as universal or general purpose pipette tips. These tips are not sterile because they are not certified as free of RNase, DNA, pyrogens, etc. These are applicable in simple laboratories for handling liquid specimens and reagents that are not volatile or do not have high contamination risk.\n\n### Based on purpose\n\nFilter Tips\n\nPipetting creates aerosols that carry the risk of cross-contamination. The filter tips are fitted with a filter to avoid the formation of aerosols. This type of tip is helpful in PCR[ (polymerase chain reaction)](\u002Freal-time-pcr-principles-and-applications\u002F), handling RNA\u002FDNA, radio-labeled, infectious, and volatile samples.\n\nLow-retention Tips\n\nThese tips withhold less liquid than generally used ones, which help preserve samples\u002Freagents. These tips are good for viscous and highly concentrated samples. However, these pipette tips are very costly. These are ideal for [electrophoresis](\u002Felectrophoresis-principles-types-and-uses\u002F) , protein analysis, sequencing, or any tests that use viscous and concentrated liquids.\n\nLong Tips\n\nSometimes the reagents or samples have a minimal volume and are at the bottom of the container. It means putting not only the pipette tip but also the shaft of the pipette inside the container. This increases the risk of contamination, so using a pipette tip that is longer than usual ones is the best substitute.\n\nShort Tips\n\nThe extended tips become inconvenient when the samples are drawn or placed into small wells. So, using short tips with a multichannel pipette is the perfect fit. Likewise, pipetting with long tips can strain the hands and require wider bench space. So, switching to shorter tips in order to avoid these conditions is the best option.\n\nWide Bore Tips\n\nSometimes the samples that a laboratory handles can be fragile and deteriorate while transferring from a narrow area of the standard tips. So, using tips with a wide orifice is the best option for handling samples involving cells or that are very dense.\n\n### Based on size\n\nThe pipette tips based on the size range from 0.1 to 1000 µl for non-sterile\u002Fgeneral purpose pipettes. 200 µl and 1000 µl tips are used in serological tests and school laboratory experiments.  Whereas for filter tips, these range from 0.1 to 1250 µl. These are available in bulk or a box.\n\n## Which Tip Type for Which Procedure?\n\n| Procedure | Recommended tip | Reason |\n| --- | --- | --- |\n| PCR setup (master mix + template) | Filter tip (mandatory) | Aerosol carry-over from PCR products invalidates reactions; filter blocks barrel contamination |\n| RNA extraction and handling | Filter tip (mandatory) | RNases are ubiquitous; any barrel contamination introduces RNase degradation of sample |\n| DNA sequencing setup | Filter tip (mandatory) | Carry-over contamination produces mixed sequencing signals |\n| ELISA (serum\u002Fplasma samples) | Standard sterile or non-sterile | No amplification step; low contamination risk; filter tips optional |\n| Routine serological dilutions | Standard non-sterile | General purpose; no nucleic acid amplification involved |\n| Cell culture work | Sterile (pre-sterile, pyrogen-free) | Cells are sensitive to endotoxins and microbial contamination |\n| Viscous samples (glycerol, serum concentrates, protein solutions) | Low-retention | Reduces sample left in tip; improves volume accuracy and sample recovery |\n| Blood, cell suspensions, viscous biological samples | Wide-bore | Prevents cell shearing or clogging through narrow standard tip orifice |\n| Samples at bottom of narrow containers | Long tips | Prevents shaft contamination when tip must be inserted deeply |\n| Multichannel pipette, plate transfers | Short tips | Shorter tips fit microtiter wells without hitting the plate bottom |\n| Infectious specimens (BSL-2\u002FBSL-3 work) | Filter tip | Protects pipette barrel and reduces aerosol exposure risk to operator |\n| Radioactive or volatile samples | Filter tip | Prevents volatile or radioactive material from entering the barrel |\n\n## Criteria for Choosing the Right Pipette Tip\n\nThe main criteria for choosing the right pipette tip is the experiment you conduct in your laboratory. Sterile filter tips are a must if you are attempting molecular tests in the laboratory. Along with the experiment, there are many more criteria to consider before buying the tips. They are as follows:\n\n### Volumes of Liquid Handled\n\nThe volume of liquid samples or reagents varies widely in the laboratories. In the laboratory, it is best to have tips of various sizes and purposes.\n\n### Pipette Used\n\nIf you are handling multiple samples in a limited time, you might use a multichannel pipette. Still, general laboratories use micropipettes, so buying the tips suitable for both types in bulk is more economical.\n\n### Preferred Company\n\nFor sterile tips, confirm the manufacturer provides a sterilization certificate specifying that tips are certified free of DNA, RNase, ATP, and endotoxins.\n\n### Budget\n\nBudget is another key criterion when choosing tips for your laboratory. The filter tips are costly as compared to general-purpose tips. So, if the budget is tight and you are not willing to perform any molecular tests, then buying just general-purpose tips is the best choice.\n\n## Handling of Pipette Tips\n\nHandling pipette tips is a crucial step in minimizing laboratory errors. Some points to consider while performing the laboratory work are as follows:\n\n- Maintain the right temperature during storage and while performing tests. Bring the tip and all the equipment to room temperature.\n- If you use general-purpose pipette tips, rinse it correctly with the sample\u002Fliquid you are aspirating to avoid delivering the incorrect volume of the liquid.\n- Do not use your hands while removing or placing the pipette tips in the pipette to avoid cross-contamination.\n- Pipetting technique should be standard. Press the plunger to the first stop and immerse it into the liquid to aspirate the sample. While dispensing, press the plunger up to the second stop (double press) to dispense all the liquid.\n- Immersing the pipette tip up to the correct depth is also important.\n- While aspirating the sample and pulling it out from the container, hold the pipette vertical.\n- Check the pipette tips before and after dispensing, to ensure the liquid is dispensed completely.\n- The force applied while pressing the plunger should be consistent.\n\n## Common Pipette Tip Errors and Their Consequences\n\n| Error | Consequence | Prevention |\n| --- | --- | --- |\n| Using standard tips for PCR | Aerosol contamination of barrel; PCR product carry-over; false positives in negative controls | Use filter tips for all PCR work (non-negotiable) |\n| Reusing tips between samples | Cross-contamination; organisms or nucleic acids from one sample enter the next | One tip per sample; use tip ejector, never hands |\n| Touching tip orifice with fingers | Skin microbiota introduced; RNases from skin degrade RNA samples | Always attach and remove tips using the ejector button and tip rack |\n| Tip not fully seated on cone | Air leak; inconsistent aspiration volume; tip falls off during transfer | Press firmly until tip seats with a slight click; check all channels in multichannel use |\n| Using wrong tip size for volume | Low-volume tips used for high-volume aspiration creates excessive suction; tip may crack or aspirate beyond capacity | Match tip size to pipette model and target volume |\n| Storing tips without cover | Dust and environmental RNases settle into tips; molecular work contaminated | Keep tip boxes closed; use individually wrapped sterile tips for PCR and RNA work |\n| Using autoclavable tips for RNA work | Autoclaving does not eliminate RNase activity unless DEPC-treated water is used | Use certified RNase-free pre-sterile tips for RNA handling |\n\n## How to Remember\n\n**\"The tip is the barrier: filter it when the stakes are high.\"** The tip separates the specimen from the pipette barrel. When the procedure involves nucleic acid amplification, infectious specimens, or RNA, that barrier must include a filter. For routine serological or culture work, a standard tip is sufficient. The question is always: what happens if barrel contamination occurs? If the answer is \"invalid PCR run\" or \"patient misdiagnosis,\" use a filter tip.\n\n**Filter tip = anytime amplification is involved.** PCR, RT-PCR, nested PCR, LAMP, sequencing: any procedure that amplifies nucleic acid is exquisitely sensitive to carry-over contamination. Filter tips are mandatory, not optional, for all of these.\n\n**Wide-bore for cells; low-retention for viscous.** Wide-bore tips prevent shearing, so cells, blood, and dense suspensions pass through without damage. Low-retention tips prevent sticking, so viscous or concentrated samples cling less to the inner surface, improving volume accuracy and sample recovery. Two different problems; two different tip solutions.\n\n**Tip color is size, not sterility.** Yellow tips = typically 200 µL range. Blue tips = typically 1000 µL range. White\u002Fclear tips = typically 10 µL range. Color coding varies slightly by manufacturer, but yellow and blue are the most standardized. Color tells you volume range, not sterility status. Check the packaging label for sterility information.\n\n## Key exam facts in one table\n\n| Topic | Key fact |\n| --- | --- |\n| Function of the tip | Aseptic barrier, liquid contacts only the tip, never the pipette barrel |\n| Most common tip material | Virgin polypropylene: inert, low protein-binding, withstands autoclaving |\n| Filter tip mechanism | Hydrophobic polyethylene filter inside tip shaft blocks aerosols and liquid from entering barrel |\n| Filter tip is mandatory for | PCR, RT-PCR, RNA handling, DNA sequencing, infectious specimens, volatile\u002Fradioactive samples |\n| Low-retention tips are used for | Viscous, concentrated, or expensive samples; reduces liquid adhesion to tip walls |\n| Wide-bore tips are used for | Cells, blood, dense suspensions; prevents shearing through narrow orifice |\n| Long tips are used for | Samples at the bottom of deep or narrow containers; prevents shaft contamination |\n| Short tips are used for | Multichannel pipetting into microtiter plate wells |\n| Sterile (pre-sterile) tips are certified free of | DNA, RNase, ATP, endotoxins, pyrogens |\n| Non-sterile tips | General purpose; not certified RNase\u002FDNA-free; single-use unless the manufacturer specifies autoclaving |\n| Color coding (general) | Yellow ≈ 200 µL; blue ≈ 1000 µL; white\u002Fclear ≈ 10 µL (varies by manufacturer) |\n| Tip reuse | Never between samples, one tip per sample is non-negotiable |\n| Autoclaving non-sterile tips for RNA work | Not sufficient. Autoclaving does not eliminate RNase; use certified RNase-free tips |\n\n**References**\n\n1. Leber, A. L. (Ed.). (2016). *Clinical Microbiology Procedures Handbook* (4th ed.). ASM Press. \u003Chttps:\u002F\u002Fdoi.org\u002F10.1128\u002F9781555818814>\n2. ISO 8655-1:2022. Piston-operated volumetric apparatus. Part 1: *Terminology, general requirements and user recommendations*. International Organization for Standardization.\n3. Harkins, J. (2021). The different types of pipette tips and when to use them. *INTEGRA Biosciences*. \u003Chttps:\u002F\u002Fwww.integra-biosciences.com\u002Fglobal\u002Fen\u002Fblog\u002Farticle\u002Fdifferent-types-pipette-tips-and-when-use-them>\n4. Mahon, C. R., Lehman, D. C., & Manuselis, G. (2018). *Textbook of Diagnostic Microbiology* (6th ed.). Elsevier.\n5. Cheesbrough, M. (2006). *District Laboratory Practice in Tropical Countries, Part 2* (2nd ed.). Cambridge University Press.",[50,53,56,59,62,65],{"question":51,"answer":52},"Why are filter tips mandatory for PCR work?","During pipetting, aerosols are generated — fine droplets that can travel upward through the tip and into the pipette barrel. In PCR, even nanogram quantities of contaminating DNA or PCR product entering the barrel are enough to cause false-positive results in subsequent runs. Filter tips contain a hydrophobic polyethylene filter inside the tip shaft that physically blocks aerosols and liquid from travelling beyond the tip. Filter tips are mandatory for all PCR setup, RT-PCR, sequencing, and RNA handling. Standard non-sterile tips are not acceptable substitutes for this work.",{"question":54,"answer":55},"What is the difference between low-retention tips and standard tips?","Standard polypropylene tips allow a thin film of liquid to adhere to the inner tip surface, which is not significant for most aqueous samples. Low-retention tips have a modified hydrophobic inner surface that minimises this adhesion, resulting in more complete liquid delivery and better volume accuracy. They are used for viscous samples, concentrated protein solutions, expensive or scarce reagents, and any situation where even a small residual volume left in the tip represents a meaningful loss or accuracy problem.",{"question":57,"answer":58},"When should wide-bore pipette tips be used?","Wide-bore tips have an enlarged orifice compared to standard tips. They are used when the sample contains intact cells, blood, dense cell suspensions, or any particulate material that would be sheared or clogged by the narrow opening of a standard tip. Shearing cells through a narrow tip orifice damages cell membranes, affects cell viability, and produces inaccurate counts in haemocytometer or flow cytometry applications. Wide-bore tips allow these samples to pass through without mechanical damage.",{"question":60,"answer":61},"Can non-sterile autoclavable tips be used for RNA work?","No. Autoclaving kills microorganisms but does not reliably eliminate RNase activity. RNases are extremely heat-stable enzymes that can survive autoclaving and degrade RNA samples on contact. For RNA extraction, RT-PCR, and any procedure involving RNA, only certified RNase-free pre-sterile tips should be used — these are manufactured and packaged under conditions that confirm absence of RNase, DNase, ATP, and endotoxins, and come with a sterilization certificate.",{"question":63,"answer":64},"What does tip colour indicate?","Tip colour is a size indicator, not a sterility indicator. Yellow tips typically correspond to the 200 µL volume range; blue tips to the 1000 µL range; white or clear tips to the 10 µL range. Colour coding is largely standardised across major manufacturers but can vary — always confirm the volume range on the packaging label. Sterility status is stated on the packaging, not indicated by colour.",{"question":66,"answer":67},"Why should tips never be touched by hand before use?","Human skin carries RNases, DNases, and microorganisms that transfer to the tip on contact. For molecular work, skin RNases degrade RNA samples; for microbiology culture work, skin commensals introduced on a tip can appear as contaminants in culture results. Tips should always be attached using the pipette's tip ejector mechanism pressing into the tip rack, and removed using the tip ejector button — hands should never contact the tip body or orifice.",[69],"pipette",[71,79,104,141,167,193,221,246],{"slug":72,"title":73,"description":74,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":75,"lastUpdatedDate":76,"draft":46,"category":47,"image":42,"faq":77,"tags":78},"equipment-essential-for-microbiology-laboratory","Microbiology Laboratory Equipment: List, Uses, and How They Work","A practical guide to essential microbiology laboratory equipment, what each instrument does, how it works, and when it is used, covering sterilizers, incubators, microscopes, centrifuges, and glassware.","2022-05-25","2026-07-28",[],[],{"slug":80,"title":81,"description":82,"seoTitle":42,"seoDescription":42,"author":83,"createdDate":84,"lastUpdatedDate":85,"draft":46,"category":47,"image":42,"faq":86,"tags":102},"real-time-pcr-principles-and-applications","Real-time PCR (qPCR): Principles and Applications","Real-time PCR (qPCR) amplifies and quantifies DNA simultaneously using fluorescent probes. Learn SYBR Green vs TaqMan, Ct values, and clinical uses in viral load testing.","Acharya Tankeshwar","2019-12-26","2026-07-05",[87,90,93,96,99],{"question":88,"answer":89},"What is the Ct value in real-time PCR and how is it interpreted?","The Ct value (cycle threshold) is the PCR cycle number at which the fluorescent signal from the reaction crosses a pre-set detection threshold. It is inversely proportional to the amount of starting template: a sample with high viral load reaches the threshold in fewer cycles (low Ct value), while a sample with low viral load requires more cycles (high Ct value). In HIV viral load monitoring, a Ct of approximately 20 corresponds to a high viral load, while a Ct above 34 indicates very low or undetectable levels. An important caveat: Ct values are not directly comparable between different assays, instruments, or laboratories.",{"question":91,"answer":92},"What is the difference between SYBR Green and TaqMan probes in real-time PCR?","SYBR Green is a fluorescent dye that binds to any double-stranded DNA and fluoresces — it is non-specific, detecting all amplification products including primer dimers and non-specific products. It is cheaper and simpler but requires melting curve analysis to confirm the correct product was amplified. TaqMan probes are sequence-specific — a labelled probe complementary to an internal target sequence is cleaved by Taq polymerase during extension, releasing a fluorescent reporter only when the correct sequence is amplified. TaqMan is more specific, suitable for multiplex detection, and is the standard for clinical diagnostic assays. SYBR Green is used in research settings where cost matters and melting curve verification is feasible.",{"question":94,"answer":95},"How does real-time PCR differ from conventional PCR?","In conventional PCR, amplification and detection are separate steps — the tube is opened after cycling and products are detected by gel electrophoresis. In real-time PCR, amplification and detection occur simultaneously in a closed tube — fluorescence is measured after each cycle as amplicon accumulates. The closed-tube design eliminates post-PCR handling and the carry-over contamination risk it creates. Real-time PCR is also quantitative, measuring the amount of starting template, while conventional PCR is qualitative (presence or absence only). Real-time PCR is faster because no gel electrophoresis step is required.",{"question":97,"answer":98},"What are the clinical applications of real-time PCR in microbiology?","Real-time PCR is used for viral load quantification — HIV, HCV, HBV, and CMV monitoring in transplant patients all rely on qPCR to measure virus copy numbers and guide treatment decisions. It is used for COVID-19 (SARS-CoV-2) detection, TB quantification, and diagnosis of infections where pathogen load correlates with disease severity or treatment response. It is also used for SNP detection, allelic discrimination, and — when combined with reverse transcription — for mRNA expression analysis and RNA virus detection.",{"question":100,"answer":101},"Why is real-time PCR preferred over conventional PCR in clinical diagnostic laboratories?","Real-time PCR is preferred for three reasons. First, the closed-tube format eliminates post-PCR amplicon manipulation, dramatically reducing the risk of carry-over contamination that causes false positives — a major problem in high-throughput diagnostic laboratories. Second, it is quantitative, providing viral load or copy number data that guides clinical decisions such as when to start or switch antiviral therapy. Third, it is faster — results are available in 1–3 hours compared to 4–6 hours for conventional PCR followed by gel electrophoresis.",[103],"pcr-techniques",{"slug":105,"title":106,"description":107,"seoTitle":42,"seoDescription":42,"author":108,"createdDate":109,"lastUpdatedDate":110,"draft":46,"category":47,"image":42,"faq":111,"tags":139},"electrophoresis-principles-types-and-uses","Electrophoresis: Principles, Types, and Uses","Electrophoresis separates charged molecules such as proteins and DNA by moving them through a gel in an electric field. Learn the principle, the factors that control mobility, the main types, and how serum protein electrophoresis detects multiple myeloma.","Srijana Khanal","2022-07-13","2026-09-01",[112,115,118,121,124,127,130,133,136],{"question":113,"answer":114},"What is the basic principle of electrophoresis?","Charged molecules placed in an electric field migrate toward the electrode of opposite charge. Negatively charged molecules (anions) move toward the positive anode, and positively charged molecules (cations) move toward the negative cathode. Each molecule travels at a speed set by its electrophoretic mobility, which depends on its net charge, its size and shape, and the viscosity and pore size of the medium. Molecules separate only if their mobilities differ.",{"question":116,"answer":117},"Why does DNA always move toward the anode?","DNA carries a phosphate backbone that remains negatively charged at any pH used in the laboratory. Because it is always an anion, it is always attracted to the positive anode. Its charge-to-mass ratio is also nearly constant regardless of fragment length, which is why DNA fragments separate essentially by size alone.",{"question":119,"answer":120},"Which way does a protein move in electrophoresis?","It depends on the buffer pH relative to the protein's isoelectric point (pI). Above its pI the protein is net negative and moves toward the anode. Below its pI it is net positive and moves toward the cathode. At exactly its pI, its net charge is zero and it does not migrate.",{"question":122,"answer":123},"Why is electrophoresis called an incomplete form of electrolysis?","In electrolysis, ions travel all the way to the electrode and undergo discharge there. In electrophoresis the electric field is switched off while the molecules are still in transit, so they never reach the electrode. What matters is not the reaction at the electrode but how far each molecule traveled, because that distance is the separation.",{"question":125,"answer":126},"What is the difference between zone and moving boundary electrophoresis?","In zone electrophoresis the sample is applied as a narrow zone on a supporting medium such as paper, cellulose acetate, or a gel, and components resolve into discrete bands. In moving boundary electrophoresis the separation occurs in free solution with no supporting medium, and the components appear as moving boundaries rather than distinct bands. The classical example of the latter is the Tiselius apparatus.",{"question":128,"answer":129},"What are the main factors affecting electrophoretic mobility?","Inherent factors include the net charge of the molecule, its charge density, its molecular weight, and its size and shape. External factors include the applied voltage, current and power, the pore size and viscosity of the supporting medium, the temperature, and the pH of the buffer, which determines the net charge on ampholytes such as proteins.",{"question":131,"answer":132},"How is electrophoresis used to diagnose multiple myeloma?","Serum protein electrophoresis separates serum proteins into albumin and the alpha, beta, and gamma globulin fractions. Normal gamma globulins are produced by thousands of plasma cell clones with slightly different mobilities, so they form a broad band. In multiple myeloma a single malignant clone produces one identical immunoglobulin, and these identical molecules migrate together to produce a sharp, narrow monoclonal (M) band in the gamma region.",{"question":134,"answer":135},"Does electrophoresis separate molecules by size or by charge?","By both, because mobility depends on the ratio of net charge to size. SDS-PAGE deliberately removes the charge variable by coating every protein with a uniform negative charge proportional to its length, so that separation depends on size alone. Native gels, in contrast, separate molecules on the basis of charge and size together.",{"question":137,"answer":138},"Why is a larger pore size not always better?","Larger pores impede migration less, so molecules travel faster, but small molecules pass through almost unhindered and are therefore poorly resolved. The gel concentration is chosen to match the size range of interest: a low-percentage gel resolves large fragments, and a high-percentage gel resolves small ones.",[140],"electrophoresis",{"slug":142,"title":143,"description":144,"seoTitle":145,"seoDescription":146,"author":43,"createdDate":147,"lastUpdatedDate":148,"draft":46,"category":47,"image":42,"faq":149,"tags":165},"glass-pipettes-types-handling-and-uses","Glass Pipette: Types, Mohr's vs. Serological, and How to Use One Correctly","Glass pipette types and how to use them safely: Mohr's vs. serological (drain-out vs. blow-out), reading the meniscus, why you never pipette by mouth, and when to use a glass pipette over a micropipette.","Glass Pipettes: Types, Meniscus Reading, Blow-Out Rules, and Uses","Compare Mohr, serological, volumetric, and Pasteur pipettes, read the meniscus correctly, and apply drain-out and blow-out rules for accurate transfers.","2022-07-29","2026-07-30",[150,153,156,159,162],{"question":151,"answer":152},"What is the difference between a Mohr's pipette and a serological pipette?","\u003Cp>A Mohr's pipette is a drain-out type: the graduation marks stop above the tip, and the liquid in the ungraduated section below the last mark is not delivered. Never blow out a Mohr's pipette. A serological pipette is a blow-out type: the graduation marks extend to the tip, and the last drop must be expelled by pressing the bulb at the end of dispensing. Serological pipettes are identified by a blow-out ring near the suction end at the top. Confusing the two introduces a systematic delivery error, as blowing out a Mohr's over-delivers, while failing to blow out a serological under-delivers.\u003C\u002Fp>",{"question":154,"answer":155},"How do you read the meniscus correctly in a glass pipette?","\u003Cp>For colorless and light-colored liquids, read from the bottom of the concave meniscus curve, with your eye exactly level with the graduation mark. Reading from the top of the curve over-reads the volume. For coloured or opaque liquids that form a convex meniscus, read from the top of the curve. Parallax error, which is caused by positioning your eye above or below the graduation mark, produces false high or false low readings and is eliminated by always levelling your eye with the mark before reading.\u003C\u002Fp>",{"question":157,"answer":158},"What is a volumetric pipette and when is it used?","A volumetric pipette (also called a bulb pipette or transfer pipette) is a non-graduated pipette designed to deliver one specific fixed volume with the highest accuracy of any glass pipette type. It has a single volume mark on the bulb section and no graduation marks along the stem. It is used when one exact volume is needed repeatedly — for example, in titrations, standard solution preparation, or media preparation steps requiring a precise defined volume. It is not suitable when partial volumes or flexible delivery amounts are needed.",{"question":160,"answer":161},"Why is mouth pipetting prohibited in the laboratory?","\u003Cp>Mouth pipetting creates a direct route for laboratory liquids, including infectious specimens, toxic chemicals, and corrosive reagents, to enter the mouth, be inhaled, or be swallowed. It has caused laboratory-acquired infections, chemical poisonings, and deaths. All aspirating in the laboratory must be done with a pipette bulb, three-valve filler, or mechanical pipetting aid. Mouth pipetting is prohibited by laboratory safety regulations in all clinical and research settings globally.\u003C\u002Fp>",{"question":163,"answer":164},"What are the different accuracy classes of glass pipettes?","\u003Cp>Graduated glass pipettes are classified as Class A, Class As, and Class B based on accuracy. Class A and Class As pipettes have tightly specified error tolerances and are suitable for analytical and clinical work requiring high accuracy. Class B pipettes have double the error limits of Class A and are used for general laboratory work where a lower level of precision is acceptable. For any work where volume accuracy affects clinical results, such as serological titrations and media preparation to precise concentrations, Class A pipettes should be used.\u003C\u002Fp>",[166,69],"laboratory-glassware",{"slug":168,"title":169,"description":170,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":171,"lastUpdatedDate":172,"draft":46,"category":47,"image":42,"faq":173,"tags":192},"micropipette-parts-types-and-uses","Micropipette: Parts, Types, and Uses","Learn the parts, types, and uses of micropipettes — including air vs. positive displacement, pre-wetting technique, reverse pipetting for viscous samples, and common errors that affect diagnostic accuracy.","2022-07-19","2026-07-19",[174,177,180,183,186,189],{"question":175,"answer":176},"What is the difference between air displacement and positive displacement micropipettes?","In air displacement micropipettes, a cushion of air separates the piston from the liquid inside the tip. The piston displaces air, which draws liquid into the tip. This method is accurate for standard aqueous samples but is affected by temperature, viscosity, and altitude. In positive displacement micropipettes, the piston contacts the liquid directly inside a specialised tip — there is no air cushion. This makes positive displacement pipettes accurate for viscous, volatile, and high-density samples that would compress or expand an air cushion and produce volume errors.",{"question":178,"answer":179},"How do I select the correct micropipette size for my volume?","Always select the smallest micropipette whose range covers the target volume. For example, to transfer 5 µL, use a P20 (range 2–20 µL) rather than a P200 or P1000. Using a pipette at the extreme low end of its range introduces proportionally large errors — a P1000 set to 5 µL operates at 0.5% of its working range, where small variations in technique produce large percentage errors in actual volume delivered.",{"question":181,"answer":182},"What is pre-wetting a micropipette tip and why is it necessary?","Pre-wetting involves aspirating the target liquid into a new tip and dispensing it back into the source container, repeating 2–3 times before the actual transfer. A dry tip surface absorbs a small amount of liquid on first contact, causing the first aspiration to deliver slightly less than the set volume. Pre-wetting saturates the tip surface, eliminating this short-delivery error. It is especially important for critical measurements in PCR setup, serial dilutions, and ELISA.",{"question":184,"answer":185},"When should reverse pipetting be used instead of forward pipetting?","Reverse pipetting is used for viscous samples (glycerol, serum, concentrated protein solutions) and volatile liquids (ethanol, chloroform). In forward pipetting, the air cushion compresses under the resistance of viscous flow, causing under-delivery. Reverse pipetting overcomes this by aspirating more than the target volume (press to stop 2), then dispensing only to stop 1 — the excess in the tip acts as a buffer that compensates for the resistance of viscous flow. Never press to the second stop when dispensing in reverse pipetting.",{"question":187,"answer":188},"What are the most common micropipette errors in the laboratory?","The most common errors are: using too large a pipette for the target volume (e.g., P1000 for 5 µL work); not pre-wetting the tip before critical first aspirations; pipetting at an angle greater than 20° during aspiration; immersing the tip too deeply into the liquid; and using standard tips for PCR work where filter tips are mandatory. Each error produces a different type of volume inaccuracy or contamination event.",{"question":190,"answer":191},"How often should micropipettes be calibrated?","Micropipettes should be calibrated every 3–6 months under normal laboratory use, or more frequently if used heavily or after being dropped or repaired. Calibration uses the gravimetric method — weighing dispensed distilled water at a known temperature and converting weight to volume using a density conversion factor. Accuracy should fall between 99% and 101% of the nominal volume. ISO 8655 is the governing standard for piston-operated volumetric apparatus.",[69],{"slug":194,"title":195,"description":196,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":197,"lastUpdatedDate":110,"draft":46,"category":47,"image":42,"faq":198,"tags":220},"automated-pipette-liquid-handling-system","Automatic Pipette and Liquid Handling System: Parts, Working, Uses","\u003Cp>Automated pipettes use software-controlled robotic arms for precise high-throughput liquid handling. Learn their working principles, parts, benefits, and limitations in microbiology.\u003C\u002Fp>","2022-07-10",[199,202,205,208,211,214,217],{"question":200,"answer":201},"What is an automated pipette and how does it differ from a manual micropipette?","An automated pipette (also called a liquid handling robot or automated liquid handling system) is a software-controlled instrument where robotic arms aspirate and dispense defined volumes without continuous human intervention. A manual micropipette requires the operator to perform every aspiration, dispensation, tip change, and plate movement individually. Automated systems process more than 100 samples per hour with coefficient of variation values typically below 1%, eliminating fatigue-related error and throughput limitations of manual pipetting.",{"question":203,"answer":204},"What is the difference between semi-automatic and fully automatic pipetting systems?","\u003Cp>Semi-automatic pipetting systems handle aspiration and dispensation mechanically but require human intervention for moving plates or tubes between steps and for changing tips. They process 10–100 samples at a time. \u003C\u002Fp>\u003Cp>\u003C\u002Fp>\u003Cp>Fully automatic (robotic) systems use robotic arms to move plates, change tips, and manage all physical steps. The only human input required is programming the run parameters at the start. Fully automatic systems provide a walk-away facility, allowing the technician to perform other tasks while the system processes samples.\u003C\u002Fp>",{"question":206,"answer":207},"What is acoustic droplet ejection (ADE) and how is it different from standard pipetting?","\u003Cp>Acoustic droplet ejection (ADE) is a contactless pipetting method that uses focused sound energy to eject precise droplets of liquid from a source well up into an inverted target plate, with no tip and no physical contact, and therefore no contamination risk from tip-to-liquid contact. Each acoustic pulse ejects a fixed, very small droplet, on the order of a few nanoliters, and larger volumes are built up by ejecting more droplets. The acoustic power is tuned to the fluid, because viscous or high-surface-tension liquids need more energy to eject a drop. ADE achieves the lowest contamination risk of any liquid transfer method but is also the most expensive, and it is used mainly in high-throughput drug discovery and genomics.\u003C\u002Fp>",{"question":209,"answer":210},"What are the main advantages of automated liquid handling in clinical microbiology?","The main advantages are: higher throughput (>100 samples per hour versus 48–96 by a manual technician), improved reproducibility (identical volume and timing across all samples), reduced fatigue-related error (no drift in technique over long processing sessions), reduced contamination risk (fewer human touchpoints during the run), and walk-away operation (technician time is freed for other tasks). These advantages were demonstrated clearly during the COVID-19 pandemic, when reference laboratories used robotic extraction systems to process hundreds of PCR samples per day.",{"question":212,"answer":213},"Why are automated pipetting systems not commonly used in district-level laboratories in low- and middle-income countries?","\u003Cp>The primary barriers are cost and maintenance. Entry-level automated liquid handling systems cost from approximately $10,000; fully integrated high-throughput platforms cost $150,000 or more. Ongoing maintenance requires trained service engineers, regular calibration, and replacement parts. \u003C\u002Fp>\u003Cp>\u003C\u002Fp>\u003Cp>Most district-level diagnostic laboratories in Nepal, Nigeria, the Philippines, and similar settings rely on manual micropipettes and glass pipettes for routine work, with automation limited to national reference laboratories or large urban hospital laboratories.\u003C\u002Fp>",{"question":215,"answer":216},"\u003Cp>What are the parts of an automatic pipette?\u003C\u002Fp>","\u003Cp>An automatic pipette, or automated liquid handling system, has two levels of parts. The pipetting head is a motorized version of a micropipette, with a piston, shaft, and tip cone, driven by a stepper motor instead of a thumb plunger; it can be single-channel or multichannel. Around it sits the robotic workstation: a robotic arm that moves the head across a deck of labware, a tip-loading and ejection station, liquid-level and tip-presence sensors, an optional wash station on fixed-tip systems, and the control software that stores the protocol and drives the run. During use the operator interacts only with the software.\u003C\u002Fp>",{"question":218,"answer":219},"\u003Cp>How does an automatic pipette work, and how is it different from a manual one?\u003C\u002Fp>","\u003Cp>An automatic pipette uses a motor-driven piston to aspirate and dispense set volumes, and a robotic arm to move plates and change tips, so it can run more than 100 samples per hour without continuous human input once programmed. A manual pipette requires the operator to perform every aspiration, dispensation, tip change, and plate move by hand, one sample at a time. The mechanism of liquid movement is the same in both (usually air displacement, sometimes positive displacement for viscous samples); the difference is that automation replaces the human thumb and hand with a motor and a robotic arm, which raises throughput and reproducibility at the cost of price and maintenance.\u003C\u002Fp>",[69],{"slug":222,"title":223,"description":224,"seoTitle":225,"seoDescription":226,"author":83,"createdDate":227,"lastUpdatedDate":76,"draft":46,"category":47,"image":228,"faq":229,"tags":245},"types-of-pipettes-used-in-the-microbiology-laboratory","Types of Pipettes Used in the Microbiology Laboratory","Learn the types of pipettes used in microbiology, such as glass, micropipette, multichannel, automated, and calibrated, complete with a guide on choosing the right pipette for your procedure.","Laboratory Pipettes: Choose the Right Type and Avoid Volume Errors","Choose among glass, micropipette, multichannel, and automated pipettes by volume and task, with calibration, handling, and error-prevention guidance.","2026-06-28","https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Fcolorful-pipette-for-microbeonline.png",[230,233,236,239,242],{"question":231,"answer":232},"What are the main types of pipettes used in a microbiology laboratory?","Five main types are used: glass pipettes (graduated, volumetric, and Pasteur) for mL-scale transfers; micropipettes for µL-scale precision work; multichannel pipettes for simultaneous transfer into multiple wells of a microtiter plate; automated liquid handling systems for high-throughput processing; and pipette tips, the disposable consumables that serve as the aseptic barrier in all micropipette-based work.",{"question":234,"answer":235},"What is the difference between a pipette and a micropipette?","A glass pipette measures and transfers volumes in the milliliter range (0.1 mL to 25 mL) and requires a pipette bulb or filler for aspiration. A micropipette measures and transfers volumes in the microliter range (0.2 µL to 10,000 µL) using an air displacement mechanism — liquid enters only the disposable tip and never contacts the pipette barrel. The key distinction is scale: glass pipettes work in mL, micropipettes work in µL.",{"question":237,"answer":238},"How do I choose the right pipette for a procedure?","Three questions guide selection. First, what volume do you need? If the volume is in mL, use a glass pipette; if in µL, use a micropipette — and select the smallest micropipette model whose range covers your target volume. Second, how many simultaneous transfers are needed? If filling a microtiter plate, use a multichannel pipette. Third, what is the contamination risk? For PCR, RNA work, or infectious specimens, use filter tips with any micropipette.",{"question":240,"answer":241},"When is a multichannel pipette used instead of a single-channel micropipette?","A multichannel pipette is used whenever the target container is a microtiter plate — 96-well or 384-well format. Clinical applications include ELISA, broth microdilution MIC testing, and serological titrations. The multichannel pipette delivers identical volumes into multiple wells simultaneously from a single plunger depression, improving reproducibility compared to repetitive single-channel pipetting.",{"question":243,"answer":244},"What is a calibrated loop and how does it differ from a pipette?","A calibrated inoculating loop delivers a defined volume (1 µL or 10 µL) of specimen onto a culture plate — functioning as a volume measurement device without needing a pipette or tip. It is used specifically for semi-quantitative urine culture in microbiology. A pipette, by contrast, aspirates and dispenses liquid between containers using a mechanical aspiration mechanism. The calibrated loop is a low-cost, practical alternative to pipettes for a specific clinical purpose in resource-limited settings.",[69],{"slug":247,"title":248,"description":249,"seoTitle":42,"seoDescription":42,"author":43,"createdDate":250,"lastUpdatedDate":251,"draft":46,"category":47,"image":42,"faq":252,"tags":268},"multichannel-pipettes-parts-and-calibration","Multichannel Pipettes: Parts and Calibration","Multichannel pipettes aspirate and dispense into multiple wells simultaneously. Learn their parts, forward and backward pipetting technique, calibration procedure, and when to use them in ELISA and MIC testing.","2022-07-23","2026-08-24",[253,256,259,262,265],{"question":254,"answer":255},"What is a multichannel pipette used for in clinical microbiology?","Multichannel pipettes are used for any procedure that uses a microtiter plate format — 96-well or 384-well. The most common clinical microbiology applications are ELISA (loading patient samples and reagents across the plate), broth microdilution MIC testing (preparing serial antibiotic dilutions across a row of wells), and serological titrations. The multichannel pipette delivers identical volumes into multiple wells simultaneously, improving reproducibility compared to repetitive single-channel pipetting.",{"question":257,"answer":258},"What is the difference between an 8-channel and a 12-channel multichannel pipette?","A standard 96-well microtiter plate has 8 rows (labelled A to H) and 12 columns (labelled 1 to 12). An 8-channel pipette fills one entire column at a time, requiring 12 pipetting steps to fill a full plate. A 12-channel pipette fills one entire row at a time, requiring 8 pipetting steps to fill a full plate. The choice between them depends on whether the procedure is organised by column or by row — for example, if each row contains one patient's serial dilutions, a 12-channel pipette processes one patient per step.",{"question":260,"answer":261},"What is the difference between forward and backward pipetting with a multichannel pipette?","Forward pipetting (also called exact pipetting) is the standard method: press the plunger to stop 1 before aspiration, release to fill, then press to stop 1 to dispense and stop 2 to blow out. It is used for standard aqueous liquids. Backward pipetting (overfilling technique) presses the plunger to stop 2 before aspiration, aspirating more than the target volume, then dispenses only to stop 1 — the excess remains in the tip and is discarded. Backward pipetting is used for foamy or viscous liquids where forward technique causes inconsistent fill across channels.",{"question":263,"answer":264},"Why must a trough (reagent reservoir) be used with a multichannel pipette?","A multichannel pipette has 8 or more tip cones spread across a fixed distance that matches the spacing of a microtiter plate. Individual test tubes are too narrow and spaced too far apart for all channels to reach the liquid simultaneously. A reagent trough provides a wide, shallow source of liquid where all channels can immerse to equal depth at the same time, ensuring each channel aspirates the same volume. Unequal immersion depth is one of the most common causes of inconsistent volume delivery across channels.",{"question":266,"answer":267},"How is a multichannel pipette calibrated?","Multichannel pipettes are calibrated using the gravimetric method: dispensed distilled water is weighed on an analytical balance, and volume is calculated using the formula V = w × Z, where w is the average weight of water dispensed and Z is a conversion factor based on water density at the measured temperature. Each channel must be calibrated individually, which makes multichannel calibration more time-consuming than single-channel calibration. Target accuracy is 99–101% of nominal volume. Because of the complexity, many laboratories use specialist calibration service providers for multichannel pipettes.",[69],{"enabled":270,"threads":271,"total":272},true,[],0,[274,280,286,293,299,304,310,315,320,323,330],{"slug":275,"name":83,"description":276,"image":277,"body":278,"postCount":279},"acharya-tankeshwar","Editor-in-chief","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Ftankeshwar-acharya-author-microbeonline.jpg","***Tankeshwar Acharya, MSc (Medical Microbiology)***\n\n*Tankeshwar Acharya is an Assistant Professor in the Department of Microbiology at Patan Academy of Health Sciences (PAHS), Nepal, where he has been teaching and practicing clinical microbiology for over 14 years. He is the founder of Microbe Online, one of the leading free microbiology education resources on the web, covering bacteriology, mycology, parasitology, immunology, and clinical laboratory diagnostics written from direct experience in both the classroom and the diagnostic laboratory.*",493,{"slug":281,"name":43,"description":282,"image":283,"body":284,"postCount":285},"ashma-shrestha","SEO Copywriter and Science Communicator\nKathmandu, Nepal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fashma-shrestha.png","Ashma Shrestha holds a Master of Science in Medical Microbiology from the Institute of Science and Technology (IOST), Tribhuvan University, Nepal, where she developed a strong foundation in virology, molecular biology, and diagnostic microbiology.\n\nShe now works as an SEO Copywriter at Resolution Digital, where she combines her scientific training with research-driven content strategy. She is certified in Google Analytics and Google Business Profile (GBP), and brings a data-informed approach to science communication writing content that is not only accurate but structured to reach and serve the students who need it most.\n\nAt microbeonline, Ashma contributes articles primarily in virology and molecular biology, areas she finds most compelling for their mechanistic depth and their growing clinical relevance. Her writing reflects the same standard the site is built on: factual rigor, clear explanation of the *why* behind microbiology concepts, and content that helps students move from memorization to genuine understanding.\n\nShe is passionate about making complex microbiological concepts accessible without sacrificing accuracy; a skill that sits at the intersection of her scientific training and her professional work in content and SEO.",79,{"slug":287,"name":288,"description":289,"image":290,"body":291,"postCount":292},"sushmita-baniya","Sushmita Baniya","Author \u002F Contributor","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fsushmita-baniya-1.png","Sushmita Baniya holds an M.Sc. in Medical Microbiology from Tribhuvan University (National College), with a research focus in Genetics and Molecular Biology. She is actively involved in teaching and research in the field of microbiology.",26,{"slug":294,"name":295,"description":289,"image":296,"body":297,"postCount":298},"samikshya-acharya","Samikshya Acharya","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fsamikshya-acharya.jpeg","Samikshya Sharma completed her postgraduate studies in Medical Microbiology at the Central Department of Microbiology, Tribhuvan University, Nepal. She contributes to Microbeonline with the goal of making foundational and clinical microbiology concepts clear and useful for students in medical, laboratory science, and allied health programs.",20,{"slug":300,"name":301,"description":289,"image":42,"body":302,"postCount":303},"alisha-tripathi","Alisha Tripathi","Alisha Tripathi holds an M.Sc. in Medical Microbiology from National College, Tribhuvan University. With over a year of teaching experience, her academic interests span Molecular Biology, Immunology, and Genetics.",6,{"slug":305,"name":306,"description":307,"image":42,"body":308,"postCount":309},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor","Aastha Shrestha is a Biotechnology graduate with an M.Sc. from National College, Tribhuvan University. Her academic interests center on Molecular Biology and Immunology; two fields that are increasingly converging in modern diagnostic and clinical microbiology. \n\nShe contributes to Microbeonline with the goal of making complex concepts in these areas approachable and exam-relevant for students across medical, biotechnology, and laboratory science programs.",9,{"slug":311,"name":312,"description":313,"image":42,"body":42,"postCount":314},"guest-author","Guest Author","Guest Author \u002F Contributor",1,{"slug":316,"name":108,"description":289,"image":317,"body":318,"postCount":319},"srijana-khanal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fsrijana-khanal-1.png","Srijana Khanal is a microbiology educator with nearly a decade of teaching experience, including her role as faculty in the Microbiology Department at National College, NIST. \n\nHer time in the classroom has given her a clear sense of where students struggle and what explanations actually work, a perspective that directly shapes how she writes.\n\nHer academic interests span Immunology, Genetics, Basic Sciences, and Research Methodology, and she brings the same rigor to her writing that she brought to teaching. Alongside academic writing, she has a passion for creative writing -- an instinct that shows in her ability to make dense scientific material readable without sacrificing accuracy.\n\nShe contributes to Microbeonline to extend her teaching reach beyond the classroom, helping medical and laboratory science students across the region build a stronger foundation in microbiology.",15,{"slug":321,"name":322,"description":313,"image":42,"body":42,"postCount":314},"dr-poonam-acharya","Dr. Poonam Acharya",{"slug":324,"name":325,"description":326,"image":327,"body":328,"postCount":329},"nisha-rijal","Nisha Rijal","Microbiologist and AMR Specialist Kathmandu, Nepal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fnisha-rijal-1.png","Nisha Rijal is a microbiologist with nearly 15 years of frontline diagnostic and surveillance experience at the National Public Health Laboratory (NPHL), national reference laboratory under the Department of Health Services, Nepal. She currently works as an AMR Support Officer at the World Health Organization (WHO), Nepal, where her work focuses on strengthening antimicrobial resistance surveillance systems and translating AMR data into actionable public health response.\n\nHer research, published in peer-reviewed journals and cited over 220 times, spans some of the most clinically significant infectious disease challenges in Nepal and South Asia: antimicrobial resistance trends in *Vibrio cholerae* across an 11-year national surveillance dataset, sero-epidemiology of scrub typhus in patients with acute febrile illness, lower respiratory tract infections in HIV-positive patients, and gonococcal resistance surveillance. She was a contributor to Nepal's National Antimicrobial Resistance Containment Action Plan, a foundational policy document for AMR governance in Nepal. You can find list of [Nisha Rijal's article here in Google Scholar.](https:\u002F\u002Fscholar.google.com\u002Fcitations?user=N-Ruq54AAAAJ&hl=en)\n\nThis depth of experience is visible in her writing at Microbeonline. Her 53 published articles cover bacteriology, parasitology, mycology, immunology, and laboratory techniques, and are consistently among the most detailed and clinically grounded content on the site. She brings to every article the same standard that national reference laboratory work demands: methodological precision, awareness of real diagnostic constraints, and an understanding of what results actually mean for patient care in resource-limited settings.\n\nHer areas of particular expertise include antimicrobial susceptibility testing and resistance mechanism detection, quality assurance in clinical microbiology, and laboratory-based infectious disease surveillance.\n\n---\n\n*Nisha Rijal contributes to Microbeonline in a personal capacity. Her views and writing do not represent the positions of the World Health Organization or any other institution.*",55,{"slug":331,"name":332,"description":333,"image":334,"body":335,"postCount":314},"padma-shrestha","Padma Shrestha","Author","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fpadma-shrestha.png","Padma Shrestha is from Kathmandu, Nepal. She has completed Masters degree in Medical microbiology from Tribhuvan University. She has great interest in Microbiology and Molecular Biology.",[337,344,350,355,360,365,369,373,377,382,386,391,395,400,405,410,414,418,422,426,430,434,438,442,446,450,453,457,462,467,472,476,480,485,489,493,497,501,505,509,513,517,521,524,528,532,536,540,545,548,552,556,560,564,568,572,576,580,584,588,592,596,600,604,608,612,616,620,623,627,630,633,636,639,642,645,648,651,654,657,660,663,666,669,672],{"slug":338,"name":339,"description":340,"image":341,"body":342,"postCount":343},"gram-negative-cocci","Gram-Negative Cocci and Coccobacilli","Neisseria, Moraxella, Haemophilus and related gram-negative coccal organisms","https:\u002F\u002Fassets.microbeonline.com\u002Ftags\u002Fgram-negative-cocci.png","# Gram Negative Cocci\n\nNeisseria gonorrhoeae, Neisseria meningitides, Moraxella catarrhalis, and other Neisseria spp. are clinically relevant gram-negative cocci.\n\nN. gonorrhoeae is the leading cause of sexually transmitted disease whereas N. meningitides is a leading cause of fatal bacterial meningitis.",14,{"slug":345,"name":346,"description":347,"image":42,"body":348,"postCount":349},"microscopy","Microscopy","Microscope types, components, and microscopy techniques","These are list of blog posts related to microscopy. ",12,{"slug":351,"name":352,"description":353,"image":42,"body":42,"postCount":354},"gram-positive-cocci","Gram-Positive Cocci","Staphylococcus, Streptococcus, Enterococcus, Micrococcus — organisms, diseases, and identification tests",11,{"slug":356,"name":357,"description":358,"image":42,"body":42,"postCount":359},"gram-negative-rods","Gram-Negative Rods (Other than Enterobacteriaceae)","\u003Cp>Gram negative rods other than members of Enterobacteriaceae family such as  Pseudomonas, Acinetobacter and related organisms\u003C\u002Fp>",5,{"slug":361,"name":362,"description":363,"image":42,"body":42,"postCount":364},"gram-positive-rods","Gram-Positive Rods","Bacillus, Clostridium, Listeria, Corynebacterium, Actinomyces and related organisms",8,{"slug":366,"name":367,"description":368,"image":42,"body":42,"postCount":349},"mycobacteria","Mycobacteria","Mycobacterium tuberculosis, leprosy, atypical mycobacteria, and acid-fast organism diagnosis",{"slug":370,"name":371,"description":372,"image":42,"body":42,"postCount":349},"anaerobic-bacteriology","Anaerobic Bacteriology","Anaerobic organisms, anaerobic culture methods, and anaerobic infection diagnosis",{"slug":374,"name":375,"description":376,"image":42,"body":42,"postCount":349},"enterobacteriaceae","Enterobacteriaceae","Identification, differentiation, and clinical significance of Enterobacteriaceae family members",{"slug":378,"name":379,"description":380,"image":42,"body":42,"postCount":381},"spirochetes","Spirochetes","Treponema, Leptospira, Borrelia and spirochetal infections",7,{"slug":383,"name":384,"description":385,"image":42,"body":42,"postCount":343},"food-microbiology","Food Microbiology","Food-borne pathogens, food safety, spoilage, and preservation",{"slug":387,"name":388,"description":389,"image":42,"body":42,"postCount":390},"antimicrobial-susceptibility-testing","Antimicrobial Susceptibility Testing","Methods for testing antibiotic susceptibility in clinical microbiology",22,{"slug":392,"name":393,"description":394,"image":42,"body":42,"postCount":343},"antimicrobials-moa-amr","Antimicrobials (MOA & AMR)","Mechanisms, detection, and clinical significance of antimicrobial resistance",{"slug":396,"name":397,"description":398,"image":42,"body":42,"postCount":399},"sterilization-disinfection","Sterilization and Disinfection","Methods of sterilization and disinfection in healthcare and laboratory settings",10,{"slug":401,"name":402,"description":403,"image":42,"body":42,"postCount":404},"specimen-collection-transport","Specimen Collection and Transport","Collection, handling, and transport of clinical specimens for microbiological testing",27,{"slug":406,"name":407,"description":408,"image":42,"body":42,"postCount":409},"bacterial-structure-physiology","Bacterial Structure and Physiology","Bacterial cell structure, growth, physiology, and environmental factors affecting growth",21,{"slug":411,"name":412,"description":42,"image":42,"body":413,"postCount":303},"horizontal-gene-transfer","Horizontal Gene Transfer","Articles related to **Horizontal Gene Transfer**",{"slug":415,"name":416,"description":42,"image":42,"body":417,"postCount":399},"chromatography","Chromatography","Information about chromatographic techniques.",{"slug":140,"name":419,"description":420,"image":42,"body":421,"postCount":381},"Electrophoresis","Information about Electrophoresis Techniques ","Detailed information  about Electrophoresis Techniques ",{"slug":103,"name":423,"description":424,"image":42,"body":425,"postCount":303},"PCR Techniques","Information about various types of Polymerase Chain Reaction Techniques ","More detailed information about various types of Polymerase Chain Reaction Techniques ",{"slug":427,"name":428,"description":429,"image":42,"body":42,"postCount":303},"bacteriophage","Bacteriophage","Description about Bacteriophage.",{"slug":431,"name":432,"description":433,"image":42,"body":42,"postCount":303},"malaria","Malaria","It is the collections of articles regarding malarial disease. ",{"slug":435,"name":436,"description":437,"image":42,"body":42,"postCount":303},"anaerobic-culture-techniques","Anaerobic Culture Techniques","Posts related with Anaerobic Culture Techniques.",{"slug":439,"name":440,"description":441,"image":42,"body":42,"postCount":409},"immunoassays","Immunoassays","You will get information about all the diagnostic tests that rely on the specific binding between an antigen and an antibody to detect or quantify a substance.",{"slug":443,"name":444,"description":445,"image":42,"body":42,"postCount":381},"biosafety-levels","Biosafety levels ","Articles related to Biosafety Levels",{"slug":447,"name":448,"description":449,"image":42,"body":42,"postCount":359},"environmental-factors","Environmental Factors ","In this case we are talking about growth requirements of microorganisms with deep dive in environmental factors that affect the growth. ",{"slug":69,"name":451,"description":452,"image":42,"body":42,"postCount":303},"Pipette","Posts related with Pipette. ",{"slug":454,"name":455,"description":456,"image":42,"body":42,"postCount":381},"bacteriology-mcqs","Bacteriology MCQs","This sections lists MCQs in Bacteriology.",{"slug":458,"name":459,"description":460,"image":42,"body":42,"postCount":461},"parasitology-mcqs","Parasitology MCQs","This section lists MCQs in Parasitology.",2,{"slug":463,"name":464,"description":465,"image":42,"body":42,"postCount":466},"virology-mcqs","Virology MCQs","This is the collections of Multiple Choice Questions in Virology.",4,{"slug":468,"name":469,"description":470,"image":42,"body":42,"postCount":471},"mcqs-in-microbiology","MCQs in Microbiology","This section lists the collections of Multiple Choice Questions in General Microbiology Topics. ",3,{"slug":473,"name":474,"description":475,"image":42,"body":42,"postCount":381},"immunology-mcqs","Immunology MCQs","In this section; we are posting collections of Multiple Choice Questions about Immunology. ",{"slug":477,"name":478,"description":479,"image":42,"body":42,"postCount":399},"microbial-curiosities","Microbial Curiosities","In this clusters, we are posting interesting and unique information about Microorganisms. ",{"slug":481,"name":482,"description":483,"image":42,"body":42,"postCount":484},"bacterial-culture-media","Bacterial Culture Media","Posts related to Bacterial Culture Media. ",23,{"slug":486,"name":487,"description":488,"image":42,"body":42,"postCount":303},"fungal-culture-media","Fungal Culture Media","Posts related to Fungal Culture Media.",{"slug":490,"name":491,"description":492,"image":42,"body":42,"postCount":359},"motility-test","Motility Test","This lists the procedure regarding various tests methods for bacterial motility.",{"slug":494,"name":495,"description":496,"image":42,"body":42,"postCount":399},"bacterial-enumeration","Bacterial enumeration","These posts are related to isolation and enumeration of bacteria. ",{"slug":498,"name":499,"description":500,"image":42,"body":42,"postCount":461},"gram-positive-coccobacillus","Gram-positive coccobacillus","List of Gram Positive Coccobacilli",{"slug":502,"name":503,"description":504,"image":42,"body":42,"postCount":466},"dimorphic-fungi","Dimorphic Fungi","This is about various dimorphic fungi. ",{"slug":506,"name":507,"description":508,"image":42,"body":42,"postCount":381},"bacterial-classification","Bacterial Classification","These posts are related with various approaches used for the classification of Bacteria. ",{"slug":510,"name":511,"description":512,"image":42,"body":42,"postCount":359},"immunofluorescence","Immunofluorescence ","Various Tests related to Immunofluorescence ",{"slug":514,"name":515,"description":516,"image":42,"body":42,"postCount":309},"antibody-mediated-immunity","Antibody-mediated Immunity","This clusters links the articles that are sharing insights about Antibody-mediated immunity. ",{"slug":518,"name":519,"description":520,"image":42,"body":42,"postCount":381},"hypersensitivity","Hypersensitivity","Articles related to Hypersensitivity.",{"slug":522,"name":523,"description":42,"image":42,"body":42,"postCount":471},"haemophilus","Haemophilus",{"slug":525,"name":526,"description":527,"image":42,"body":42,"postCount":466},"sexually-transmitted-infections-stis","Sexually transmitted infections (STIs)","This is the clusters of infections that are transmitted sexually. ",{"slug":529,"name":530,"description":531,"image":42,"body":42,"postCount":349},"adaptive-immunity","Adaptive Immunity","Blog posts related to B Cell Immunity and T Cell Immunity.",{"slug":533,"name":534,"description":535,"image":42,"body":42,"postCount":343},"fungal-diagnostics","Fungal Diagnostics","Various methods used for the Diagnosis of Fungal Infections. ",{"slug":537,"name":538,"description":539,"image":42,"body":42,"postCount":359},"laboratory-storage-and-preservation","Laboratory Storage and Preservation","Articles about Laboratory Storage of Antimicrobial Disk, Test organisms and Equipment used for this process. ",{"slug":541,"name":542,"description":543,"image":42,"body":544,"postCount":303},"laboratory-heating-equipment","Laboratory Heating Equipment","A guide to laboratory heating equipment, including hot plates, water baths, Bunsen burners, incubators, and dry baths, and how to choose the right one for each task.","Laboratory heating equipment covers the instruments that warm, melt, incubate, or sterilize samples and media in a microbiology laboratory. Each one delivers heat differently. \n\nA hot plate gives high, direct, dry heat; a water bath gives gentle, even, wet heat up to about 100°C; a Bunsen burner gives an open flame for rapid, very high heat; an incubator holds cultures at a steady temperature over hours or days; and a dry bath heats small tubes without water. Choosing the right one depends on the temperature you need, how precise it must be, and whether the sample can tolerate direct or open-flame heat.\n\nThe articles below cover each piece of heating equipment in detail, including its parts, working principle, uses, and the mistakes that most often go wrong at the bench.",{"slug":166,"name":546,"description":547,"image":42,"body":42,"postCount":309},"Laboratory Glassware","Posts about Laboratory Glassware. ",{"slug":549,"name":550,"description":551,"image":42,"body":42,"postCount":309},"helminths","Helminths","In this section, we are covering properties, life cycle, pathogenesis and laboratory diagnosis of Helminths\u002FHelminthic infestations. ",{"slug":553,"name":554,"description":555,"image":42,"body":42,"postCount":303},"protozoan-parasite","Protozoan Parasite","In this cluster, we are covering protozoan parasites. ",{"slug":557,"name":558,"description":559,"image":42,"body":42,"postCount":314},"tests-for-gram-positive-cocci","Biochemical Tests for Gram Positive Cocci","This is the lists of Biochemical Tests that are used for Gram Positive Cocci. ",{"slug":561,"name":562,"description":563,"image":42,"body":42,"postCount":399},"bacterial-staining-technique","Bacterial Staining Technique","Lists of various staining techniques that are used to stain bacteria. ",{"slug":565,"name":566,"description":567,"image":42,"body":42,"postCount":409},"enzyme-tests","Enzyme Tests","\u003Cp>Various Biochemical Test that are based on enzymatic activity of the microorganisms. \u003C\u002Fp>",{"slug":569,"name":570,"description":571,"image":42,"body":42,"postCount":354},"carbohydrate-utilization","Carbohydrate Utilization","\u003Cp>Various biochemical tests which are related to Carbohydrate fermentation or Utilization\u003C\u002Fp>",{"slug":573,"name":574,"description":575,"image":42,"body":42,"postCount":359},"susceptibility-based-id","Susceptibility-based ID","\u003Cp>These are susceptibility based identification test such as optochin sensitivity, bacitracin sensitivity etc. \u003C\u002Fp>",{"slug":577,"name":578,"description":579,"image":42,"body":42,"postCount":466},"microbial-metabolism","Microbial Metabolism","\u003Cp>Tests about Microbial Metabolism. \u003C\u002Fp>",{"slug":581,"name":582,"description":583,"image":42,"body":42,"postCount":364},"substrate-utilization","Substrate Utilization","\u003Cp>The test in which a non-sugar carbon\u002Fnitrogen source is used or degraded (citrate, malonate, decarboxylases, indole, PAD).\u003C\u002Fp>",{"slug":585,"name":586,"description":587,"image":42,"body":42,"postCount":471},"atypical-pneumonia","Atypical Pneumonia","\u003Cp>Organisms responsible for Atypical Pneumonia. \u003C\u002Fp>",{"slug":589,"name":590,"description":591,"image":42,"body":42,"postCount":359},"antigen","Antigen","\u003Cp>Various articles related to Antigens.\u003C\u002Fp>",{"slug":593,"name":594,"description":595,"image":42,"body":42,"postCount":381},"innate-immunity","Innate Immunity","\u003Cp>Articles related to Innate Immunity. \u003C\u002Fp>",{"slug":597,"name":598,"description":599,"image":42,"body":42,"postCount":466},"respiratory-tract-infection","Respiratory Tract Infection","\u003Cp>In this cluster, you can see various etiological agents that causes respiratory tract infection. \u003C\u002Fp>",{"slug":601,"name":602,"description":603,"image":42,"body":42,"postCount":359},"torch-infection","TORCH Infection","\u003Cp>In this section; you can find articles related with TOCH infection. \u003C\u002Fp>",{"slug":605,"name":606,"description":607,"image":42,"body":42,"postCount":364},"microbiology-for-beginners","Microbiology for Beginners","\u003Cp>These articles are very basic articles, which will share general concepts in Microbiology. \u003C\u002Fp>",{"slug":609,"name":610,"description":611,"image":42,"body":42,"postCount":303},"dna-replication","DNA Replication","\u003Cp>Articles related to DNA and Replication of DNA. \u003C\u002Fp>",{"slug":613,"name":614,"description":615,"image":42,"body":42,"postCount":381},"genetic-code","Genetic Code","\u003Cp>Articles related to Genetic Code.\u003C\u002Fp>",{"slug":617,"name":618,"description":619,"image":42,"body":42,"postCount":381},"molecular-technique","Molecular Technique","\u003Cp>Posts related to Molecular Techniques. \u003C\u002Fp>",{"slug":621,"name":622,"description":42,"image":42,"body":42,"postCount":314},"colorimetric-assay","Colorimetric Assay ",{"slug":624,"name":625,"description":626,"image":42,"body":42,"postCount":359},"pharmaceutical-microbiology","Pharmaceutical Microbiology","\u003Cp>Various articles related to Pharmaceutical Microbiology\u003C\u002Fp>",{"slug":628,"name":629,"description":42,"image":42,"body":42,"postCount":471},"blood-and-immune-cells","Blood and Immune Cells",{"slug":631,"name":632,"description":42,"image":42,"body":42,"postCount":359},"host-pathogen-interaction","Host Pathogen Interaction",{"slug":634,"name":635,"description":42,"image":42,"body":42,"postCount":466},"blood-culture","Blood Culture",{"slug":637,"name":638,"description":42,"image":42,"body":42,"postCount":466},"environmental-microbiology","Environmental microbiology ",{"slug":640,"name":641,"description":42,"image":42,"body":42,"postCount":381},"copromicroscopic-technique","Copromicroscopic Technique",{"slug":643,"name":644,"description":42,"image":42,"body":42,"postCount":471},"quality-control","Quality Control",{"slug":646,"name":647,"description":42,"image":42,"body":42,"postCount":381},"dermatophytes","Dermatophytes",{"slug":649,"name":650,"description":42,"image":42,"body":42,"postCount":471},"viral-hemorrhagic-fevers","Viral Hemorrhagic Fevers",{"slug":652,"name":653,"description":42,"image":42,"body":42,"postCount":466},"h2s-production","H2S Production",{"slug":655,"name":656,"description":42,"image":42,"body":42,"postCount":461},"water-quality-testing","Water Quality Testing",{"slug":658,"name":659,"description":42,"image":42,"body":42,"postCount":359},"virology-basics","Virology basics",{"slug":661,"name":662,"description":42,"image":42,"body":42,"postCount":466},"typing-methods","Typing Methods",{"slug":664,"name":665,"description":42,"image":42,"body":42,"postCount":471},"blotting-technique","Blotting Technique",{"slug":667,"name":668,"description":42,"image":42,"body":42,"postCount":466},"history-microbiology","History of Microbiology",{"slug":670,"name":671,"description":42,"image":42,"body":42,"postCount":466},"trematodes","Trematodes",{"slug":673,"name":674,"description":42,"image":42,"body":42,"postCount":461},"coccidian-parasites","Coccidian Parasites"]