[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$fzswm8zl71Sli8iHMYIr_tTpdm9dc9kKnfnuq66uy6i8":32,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":144},[4,8,12,16,20,24,28],{"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},"Abbreviations","abbreviations","\u002Fabbreviations\u002F",{"title":25,"slug":26,"path":27},"Microbes","microbes","\u002Fmicrobes\u002F",{"title":29,"slug":30,"path":31},"Books","recommended-books","\u002Frecommended-books\u002F",{"type":33,"data":34},"blog",{"slug":35,"title":36,"description":37,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":40,"lastUpdatedDate":41,"draft":42,"category":43,"image":38,"body":44,"faq":45,"tags":55,"related":57},"motility-patterns-of-bacteria","Motility Patterns of Bacteria: Tumbling, Darting, Swarming, and the Key Exceptions","Which bacteria show which motility pattern; tumbling (Listeria), darting (Vibrio), swarming (Proteus), corkscrew (Campylobacter, spirochetes) — plus the temperature and strain exceptions that trip up identification.",null,"Acharya Tankeshwar","2013-05-03","2026-07-15",false,"bacteriology","A wet mount from an overnight broth shows cells that roll end-over-end rather than swim in a straight line. That tumbling is not incidental; in the right clinical context (a neonatal sepsis or meningitis workup) it points straight at *Listeria monocytogenes*. Motility is not just present-or-absent; the *pattern* of movement, and the temperature at which it appears, can name the organism. This article maps those patterns and, just as importantly, the exceptions where a normally motile organism goes still.\n\nWhen you read about the [structure of bacterial cells,](\u002Fstructure-of-bacteria\u002F) you might have learned about flagella and the different types of flagellar arrangements found in gram-negative bacteria. Most Gram-positive bacteria are atrichous (without flagella), so they are non-motile (*Enterococcus gallinarum and E. casseliflavus\u002FE. flavescens*, the gram-positive, **catalase** negative cocci, generally are motile. )\n\n![Test for Bacterial Motility: Center (Non-motile); Corners (Motile) - Test for Bacterial Motility: Center (Non-motile); Corners (Motile)](\u002Fblogs\u002FTest-for-Bacterial-Motility-300x210.png)Figure: Test for Bacterial Motility: Center (Non-motile); Corners (Motile)\n\nSo when it’s about bacterial motility, we mostly discuss Gram-negative bacteria. Motility patterns of Gram-negative bacteria are also used for their identification.\n\nYou might have appreciated the colony of *Proteus spp* in blood agar and MacConkey agar and identified it with its characteristics swarming patterns.\n\nSo in this blog post, I am sharing information about the characteristic motility patterns of some bacteria. You will also find information about those bacteria which become non-motile in specific conditions and about some great exceptions to motility characteristics;\n\n## Characteristics types of  Bacterial Motility\n\n| Motility pattern | Organism(s) | Note |\n| --- | --- | --- |\n| Tumbling | *Listeria monocytogenes* | Motile 18–25°C, non\u002Fminimally motile 35–37°C; umbrella growth near top of semisolid tube at 25°C |\n| Darting (\"shooting star\") | *Vibrio cholerae*; *Campylobacter jejuni* | Single polar flagellum in *Vibrio*; abolished by O1\u002FO139 antiserum |\n| Corkscrew (flexion–extension) | Spirochetes (*Treponema*, *Borrelia*, *Leptospira*); *Campylobacter* | Move by bending\u002Frotating; axial filaments in spirochetes |\n| Swarming | *Proteus* spp.; *Clostridium tetani* | *Proteus* swarms on agar surface; more evident at RT than 35–37°C |\n| Gliding | *Mycoplasma* | No flagella |\n| Stately (slow, majestic) | *Clostridium* |  |\n| Peritrichous, straight-swimming | *E. coli* (most), *Salmonella* (most), *Enterobacter* | *E. coli* A-D group non-motile; *Salmonella* Gallinarum and Pullorum non-motile |\n\n**Key non-motility exceptions to memorize:** *Bacillus anthracis* (non-motile among otherwise-motile *Bacillus*); *Klebsiella pneumoniae*; *Shigella*; *Acinetobacter*; *Yersinia* (motile only at 20–28°C). **Motile cocci exception:** *Enterococcus gallinarum* and *E. casseliflavus* (most other Gram-positive cocci are non-motile\u002Fatrichous).\n\n## Characteristics Motility Patterns of Selected Organisms\n\n 1. Alcaligenes are motile by peritrichous flagella.\n 2. **Acinetobacter are non-motile.**\n 3. Bacillus spp. should be motile; non-motility is a clue to *Bacillus anthracis*.\n 4. [Campylobacters](\u002Fcampylobacter-jejuni-disease-properties-and-laboratory-diagnosis\u002F) are small delicate, spirally curved, motile Gram-negative bacteria.  They show characteristic rapid **corkscrew-like motility.**\n 5. **E. coli:** Most are motile by peritrichous flagella. Alkalescens-Dispar group i.e.**A-D** group is non-motile.\n 6. **Enterococcus casseliflavus and E. gallinarum are motile** (the motile-cocci exception); *E. faecium* and *E. faecalis* non-motile.\n 7. **Helicobacter:** [Helicobacter spp](\u002Fhelicobacter-pylori-tests-results\u002F) is motile by a tuft of flagella (up to 4-7 sheathed flagella are present at one end).\n 8. **Listeria spp:** It is motile with a characteristic **tumbling and rotating** motility in broth cultures when grown at 18- 25°C but not motile or minimally motile when grown at 35-37°C. Listeria gives \"umbrella\"-shaped growth near the top of a semisolid tube at 25°C.\n 9. **Proteus** spp: [P. mirabilis and P. vulgaris ](\u002Fproteus-species-properties-diseases-identification\u002F)are actively motile (swarming motility). [Motility](\u002Ftests-bacterial-motility-procedure-results\u002F) is not as easily observed at 35–37 ºC as at room temperature (20–28 ºC).\n10. **Pseudomonas spp**: Most species of [Pseudomonas ](\u002Fpseudomonas-aeruginosa-infection-mortality-pathogenesis-and-diagnosis\u002F)are motile except *Pseudomonas malli* using one or more flagella.\n11. **Salmonella spp:** Most strains are motile except *Salmonella* G*allinarum* and *Salmonella* Pullorum\n12. Spirilla are motile with groups of flagella at both ends.\n13. Spirochaetes (*Treponema, Borrelia, Leptospira*): Are **motile by bending and rotating body movements.**\n14. Trophozoites of protozoan parasites *Entamoeba histolytica and* [Giardia lamblia](\u002Fgiardia-lamblia-life-cycle-diseases-and-laboratory-diagnosis\u002F) *(move by flagella and an undulating membrane)* etc show motility in wet preparation.\n15. *Vibrio cholerae*: *Vibrio cholerae* are motile with the single polar flagellum and show rapid darting  (“Shooting Star”) motility.\n16. *Yersinia enterocolitica* is motile when grown at 20- 28°C but non-motile at 35-37°C.\n\n## How to Remember\n\n**Name the swim, name the bug.** Tumbling = *Listeria*. Darting shooting-star = *Vibrio*. Swarming sheets on agar = *Proteus*. Corkscrew = spirochetes and *Campylobacter*. The movement is often the fastest presumptive clue you have.\n\n**\"Cold swimmers\": Listeria and Yersinia.** Both swim at 20–25°C and stall at 37°C. Body temperature switches their flagella off.\n\n**The still ones that should surprise you.** Most *Bacillus* swim — a *non-motile* one raises *anthracis*. Most Gram-positive cocci sit still — a *motile* enterococcus points to *gallinarum*\u002F*casseliflavus*. The exception is the exam point.\n\n**References**\n\n1. Madigan MT, Bender KS, Buckley DH, Sattley WM, Stahl DA. *Brock Biology of Microorganisms*. 15th ed. Pearson; 2018.\n2. Procop GW, Church DL, Hall GS, Janda WM, Koneman EW, Schreckenberger PC, Woods GL. *Koneman's Color Atlas and Textbook of Diagnostic Microbiology*. 7th ed. Philadelphia: Wolters Kluwer; 2017.",[46,49,52],{"question":47,"answer":48},"What are the main types of bacterial motility patterns?","Common named patterns include tumbling motility (Listeria), darting or shooting-star motility (Vibrio cholerae and Campylobacter), swarming motility (Proteus), corkscrew or flexion-extension motility (spirochetes such as Treponema, Borrelia, and Leptospira), gliding motility (Mycoplasma), and stately slow motility (Clostridium). The pattern is often a fast presumptive clue to the organism's identity.",{"question":50,"answer":51},"Which bacteria are important non-motile exceptions?","Key non-motile organisms include Klebsiella pneumoniae, Shigella, and Acinetobacter. A high-yield exception is Bacillus anthracis, which is non-motile while most other Bacillus species are motile. On the Gram-positive side, most cocci are non-motile, so the motile enterococci (Enterococcus gallinarum and E. casseliflavus) are the notable exception.",{"question":53,"answer":54},"Why is Listeria motile at 25°C but not at 37°C?","Listeria monocytogenes produces the flagella responsible for its characteristic tumbling motility mainly at lower temperatures, around 18 to 25 degrees Celsius. At 35 to 37 degrees Celsius, flagellar expression is reduced, so the organism appears non-motile or only minimally motile. In a semisolid tube at 25 degrees it also produces a characteristic umbrella-shaped growth near the top.",[56],"motility-test",[58,76,95,111],{"slug":59,"title":60,"description":61,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":62,"lastUpdatedDate":63,"draft":42,"category":64,"image":38,"faq":65,"tags":75},"sulfide-indole-motility-sim-medium","Sulfide Indole Motility (SIM) Test: Principle, Procedure & Result Interpretation","SIM medium principle, procedure, and how to read sulfide, indole, and motility correct including why it catches weak H2S producers that TSI and KIA miss.","2022-10-10","2026-07-17","biochemical-tests",[66,69,72],{"question":67,"answer":68},"Why does SIM detect H2S that TSI\u002FKIA misses?","SIM is semisolid, which lets H2S gas diffuse through the whole tube rather than staying trapped at one interface like it does on a TSI or KIA slant. Weak producers like Salmonella Typhi can show clear diffuse blackening on SIM while barely registering on TSI.",{"question":70,"answer":71},"I can't tell if my tube is motile because the H2S blackening covers everything — what do I report?","If sulfide production is dense enough to obscure a clear read of the surrounding medium, the accepted convention is to record it as motility-positive rather than guessing negative from an unclear tube.",{"question":73,"answer":74},"Can I add Kovac's reagent first and read motility after?","No — always read motility and H2S first. Adding reagent is the last, irreversible step; doing it early can make the earlier readings unreliable.",[56],{"slug":77,"title":78,"description":79,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":80,"lastUpdatedDate":41,"draft":42,"category":64,"image":38,"faq":81,"tags":94},"tests-bacterial-motility-procedure-results","Tests for Bacterial Motility: Methods, How to Read Them, and Where They Fool You","A practical guide to testing bacterial motility: hanging drop, semisolid stab, and SIM\u002FMIU. When to use each, how to read a stab tube, and the false positives (mucoid Klebsiella) and false negatives (flagellar shock, strict aerobes) that catch people.","2015-10-19",[82,85,88,91],{"question":83,"answer":84},"How do you read a semisolid motility tube?","Stab the organism down the centre of a semisolid agar tube and incubate. Hold the tube to the light and look at the stab line. A motile organism spreads away from the stab and clouds the surrounding medium; a non-motile organism grows only along the stab line, leaving the medium clear. Adding triphenyltetrazolium chloride (TTC) makes this easier to read, because bacteria reduce the colourless TTC to a red compound, so growth and spread appear red.",{"question":86,"answer":87},"Why can a non-motile organism give a false-positive motility result?","Mucoid strains, especially of Klebsiella pneumoniae, can seep between the agar and the glass wall of the tube, producing a cloudy appearance that mimics motile spread. Using a tube with adequate depth and reading the density of growth in the central stab, rather than just overall cloudiness, helps avoid this error.",{"question":89,"answer":90},"Why might a motile organism like Pseudomonas look non-motile in a stab tube?","Pseudomonas and Vibrio are strict aerobes and do not grow well down the oxygen-poor depth of a stab tube. Their spread may be limited to the top few millimetres even though they are motile, so a clear deep stab can be misread as non-motile. For these organisms, confirm motility by microscopy such as a hanging drop preparation.",{"question":92,"answer":93},"Does temperature affect bacterial motility tests?","Yes. Some organisms only produce flagella at lower temperatures. Listeria monocytogenes and Yersinia enterocolitica are motile at around 20 to 25 degrees Celsius but non-motile at 35 to 37 degrees Celsius. Testing these at body temperature can give a false-negative motility result, so a parallel tube incubated at room temperature is used when these organisms are suspected.",[56],{"slug":96,"title":97,"description":98,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":99,"lastUpdatedDate":41,"draft":42,"category":43,"image":38,"faq":100,"tags":110},"procedure-hanging-drop-method-test-bacterial-motility","Hanging Drop Method: Principle, Procedure & How to Read True Motility","Step-by-step hanging drop technique — how to tell true motility from Brownian movement and passive drift, plus its real use in flagging cholera and ruling out Bacillus anthracis.","2014-08-03",[101,104,107],{"question":102,"answer":103},"How do I tell true motility from Brownian movement?","True motility means organisms change position relative to each other over time — purposeful, directional movement. Brownian movement is jiggling in place; the organisms stay in the same relative position to one another even though they appear to vibrate. Brownian movement appears on every slide regardless of whether the organism is motile.",{"question":105,"answer":106},"My drop dried out before I finished reading it — what went wrong?","Almost always an incomplete vaseline seal. If the drop looks like it's shrinking or the edges look ragged partway through observation, remake the prep with a more complete seal rather than trying to interpret a drying sample.",{"question":108,"answer":109},"Can hanging drop be used to help rule out anthrax?","Yes, as one early step. Bacillus anthracis is classically nonmotile, while closely related B. cereus group members are typically motile — so a quick motility check helps distinguish a concerning isolate before specialized confirmatory testing, per Luna et al. (2005), cited in the References.",[56],{"slug":112,"title":113,"description":114,"seoTitle":38,"seoDescription":38,"author":39,"createdDate":115,"lastUpdatedDate":41,"draft":42,"category":116,"image":38,"faq":117,"tags":142},"bacterial-flagella-structure-importance-and-examples-of-flagellated-bacteria","Flagella: Structure, Arrangement, Function","Bacterial flagella: structure (filament, hook, basal body), types of flagellar arrangement with mnemonics, how flagella rotate, clinical significance in pathogenesis, identification, and motility patterns. With memory aids and exam tips.","2013-04-28","general-microbiology",[118,121,124,127,130,133,136,139],{"question":119,"answer":120},"What is the difference between monotrichous, lophotrichous, amphitrichous, and peritrichous flagella?","Atrichous: no flagella (Klebsiella, Shigella). Monotrichous: single flagellum at one pole (Vibrio cholerae, Pseudomonas). Lophotrichous: tuft at one pole (Helicobacter pylori). Amphitrichous: flagella at both poles (Alcaligenes). Peritrichous: flagella distributed over entire cell surface (E. coli, Salmonella, Proteus). Mnemonic: 'A Monkey Lives Peacefully, Always' — Atrichous, Monotrichous, Lophotrichous, Peritrichous, Amphitrichous.",{"question":122,"answer":123},"What are the three structural components of a bacterial flagellum?","Filament — long helical extracellular portion composed of flagellin protein subunits. Hook — short flexible coupling between filament and basal body. Basal body — the motor embedded in the cell wall and membrane. Gram-negative bacteria have three ring systems (L, P, MS rings); gram-positive bacteria have only two rings (no outer membrane to anchor an L ring).",{"question":125,"answer":126},"Why do all motile Enterobacteriaceae have peritrichous flagella?","Peritrichous flagellation is phylogenetically conserved in Enterobacteriaceae — encoded in the core genome. Non-motile exceptions to memorise: Klebsiella, Shigella, and Yersinia pestis. Mnemonic: 'KSY — Keep Still, You!' All other motile Enterobacteriaceae are peritrichous.",{"question":128,"answer":129},"How do H antigens differ from O antigens in Salmonella serotyping?","O antigens are somatic LPS antigens — heat-stable, alcohol-resistant. H antigens are flagellar (flagellin protein) antigens — heat-labile, alcohol-labile. In the Widal test, anti-H antibodies appear later (day 10-12) and persist longer than anti-O antibodies (day 6-8), sometimes for years after infection or vaccination — making elevated H titers alone less specific for current active infection.",{"question":131,"answer":132},"What makes Helicobacter pylori flagella different from other bacteria?","H. pylori has lophotrichous flagella (4-7 at one pole) that are sheathed — covered by a membrane extension of the outer membrane. This sheathing: protects flagellin from acid degradation in the stomach (pH 1-2); masks flagellin from TLR5 recognition, reducing innate immune response and enabling chronic colonisation. Flagella-deficient H. pylori mutants cannot penetrate gastric mucus and cannot colonise the stomach.",{"question":134,"answer":135},"What is the difference between true bacterial motility and Brownian movement?","Brownian movement is random, non-directional vibration of all microscopic particles caused by water molecule bombardment — no net displacement. True bacterial motility is directional — the organism progressively moves from point A to point B. In wet preparations: observe whether the organism changes position relative to surrounding debris. Debris also shows Brownian movement but does not show directional travel.",{"question":137,"answer":138},"Why does Proteus mirabilis swarm on blood agar but not on MacConkey or CLED?","On blood agar, Proteus differentiates from swimmer cells to hyperflagellated swarm cells (up to 500 flagella per cell) that spread in concentric rings. MacConkey: bile salts inhibit flagellar function and swarming differentiation. CLED: low electrolyte concentration suppresses the proton-motive force driving the flagellar motor. Both media are preferred for urine cultures to prevent swarming from obscuring other organisms.",{"question":140,"answer":141},"What is chemotaxis and how do bacterial flagella enable it?","Chemotaxis is movement toward attractants and away from repellents via the run-and-tumble mechanism. Counterclockwise flagellar rotation = bundled flagella = smooth run. Clockwise rotation = bundle flies apart = tumble and reorientation. Chemoreceptors bias the ratio — detecting increasing attractant concentration decreases tumbling frequency and lengthens runs, producing net movement up the concentration gradient without any nervous system.",[143,56],"bacterial-structure-physiology",[145,151,158,163,167,171,176,181,185,189],{"slug":146,"name":39,"description":147,"image":148,"body":149,"postCount":150},"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.*",433,{"slug":152,"name":153,"description":154,"image":155,"body":156,"postCount":157},"ashma-shrestha","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.",81,{"slug":159,"name":160,"description":161,"image":38,"body":38,"postCount":162},"sushmita-baniya","Sushmita Baniya","Author \u002F Contributor",32,{"slug":164,"name":165,"description":161,"image":38,"body":38,"postCount":166},"samikshya-acharya","Samikshya Acharya",20,{"slug":168,"name":169,"description":161,"image":38,"body":38,"postCount":170},"alisha-tripathi","Alisha Tripathi",6,{"slug":172,"name":173,"description":174,"image":38,"body":38,"postCount":175},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor",10,{"slug":177,"name":178,"description":179,"image":38,"body":38,"postCount":180},"guest-author","Guest Author","Guest Author \u002F Contributor",2,{"slug":182,"name":183,"description":161,"image":38,"body":38,"postCount":184},"srijana-khanal","Srijana Khanal",18,{"slug":186,"name":187,"description":179,"image":38,"body":38,"postCount":188},"dr-poonam-acharya","Dr. Poonam Acharya",1,{"slug":190,"name":191,"description":161,"image":38,"body":192,"postCount":193},"nisha-rijal","Nisha Rijal","**Nisha Rijal** is a microbiologist and quality assurance specialist. She served for nearly 12 years as a microbiologist at the National Public Health Laboratory (NPHL), Nepal's national reference laboratory, and continues to work as a consultant microbiologist in international public health organization. ",51]