[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$ftXxNsPIb3GRltpZwNyjJIHepwEYjOQyG6L17ajyPci4":32,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":47},[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":36,"seoTitle":37,"seoDescription":37,"author":38,"createdDate":39,"lastUpdatedDate":40,"draft":41,"category":42,"image":37,"body":43,"faq":44,"tags":45,"related":46},"spirochetes-morphology-classification-disease","Spirochetes: Morphology, Classification, Disease",null,"Acharya Tankeshwar","2021-06-08","2025-12-29",false,"bacteriology","Spirochetes are long, thin, flexible, spirally coiled helical bacilli. These motile, gram-negative bacilli are classified into eight genera primarily on the basis of habitat, pathogenicity, phylogeny, morphological and physiological characteristics.\n\nThese long slender bacteria are only a fraction of a micron in diameter but 5 to 250 microns long. They are tightly coiled, and so look like miniature springs or telephone cords. Spirochetes do not take up ordinary stains but can be stained only by **silver impregnation stains**, except *Borrelia*which is poorly gram stained.\n\nMost of the genera of spirochetes are saprophytes and are widespread in aquatic environments and in animals. Only three genera *Treponema, Borrelia,* and *Leptospira* contain organisms pathogenic for humans. Spirochetes cause several diseases, notably syphilis, [Lyme disease](\u002Fborrrelia-burgdorferi-lyme-disease\u002F), relapsing fever, [leptospirosis](\u002Flab-diagnosis-leptospirosis\u002F), yaws, pinta, etc.\n\nThe order Spirochaetales includes two families of spiral bacteria, *Spirochaetaceae* and *Leptospiraceae.*\n\n- Order **Spirochaetales**\n\nFamily *Spirochaetaceae*: Four genera *Treponema, Borrelia, Spirocheta, Cristispira*Family *Leptospiraceae*: Two genera *Leptospira*, *Leptonema*\n\nDifferentiation of the genera within the family is based on the number of axial fibrils, the number of insertion disks present and biochemical and metabolic features.\n\n## Structure\n\nSpirochete motility is conferred by flagella that emerge from each pole. However, unlike typical [bacterial flagella](\u002Fbacterial-flagella-structure-importance-and-examples-of-flagellated-bacteria\u002F), spirochete flagella fold back from each pole onto the protoplasmic cylinder itself and remain in the periplasm of the cell; because of this, they have been called endoflagella. In addition, both **endoflagella** and the protoplasmic cylinder are surrounded by a flexible membrane called the **outer sheath.**\n\n![Endoflagella of spirochetes - Endoflagella of spirochetes (Image source:crondon)](https:\u002F\u002Fassets.microbeonline.com\u002Fblogs\u002Fendoflagella-of-spirochetes.jpg)Figure: Endoflagella of spirochetes (Image source:crondon)\n\n### Cell wall\n\nCell wall of spirochetes is similar to that of gram-negative bacteria but differs by **bearing endoflagella**. It is more complex, consisting of:\n\n- Outer membrane\n- Periplasmic space containing flagella\n- Peptidoglycan layer\n- Inner (cytoplasmic) membrane\n\n### Endoflagella\n\nEndoflagella are present in the periplasmic space between the outer membrane and the peptidoglycan layer. They attach to the membrane only at the pole. The number of periplasmic flagella varies from species to species.\n\nEndoflagella are responsible for the motility of spirochetes. Motility may be of various types, such as:\n\n- Flexion-extension type\n- Corkscrew type rotatory movement\n- Translatory type\n\n## Spirochetes vs. Spirilla\n\nThough spirochetes and spirilla differ phylogenetically, spirilla with many turns can superficially resemble spirochetes. In addition, spirilla do not have spirochetes’ outer sheath and endoflagella but instead contain typical bacterial flagella.\n\n## Morphological differences between Treponema, Borrelia and Leptospira\n\n| Feature | Treponema | Borrelia | Leptospira |\n| --- | --- | --- | --- |\n| Size | 6-14 μm \\*0.2μm | 10-30 μm \\* 0.2-0.5 μm | 6-20 μm \\* 0.1 μm |\n| Spirals (in number) | 6-12 | 3-10 | Numerous and tightly coiled with hooked ends |\n| Wavelength | 1 μm | 3 μm | 0.5 μm |\n| Amplitude of spiral | 1-1.5 μm | Up to 2 μm | 0.1 μm |\n| Endoflagella of each pole | 3-4 | 7-11 | 1 |\n\n## Diseases caused by various genus of Spirochetes\n\n| Spirochetes | Disease | Transmission |\n| --- | --- | --- |\n| Treponema |  |  |\n| T. pallidum subsp. pallidum | Syphilis | Sexual contact |\n| T. pertenue | Yaws | Direct contact |\n| T. carateum | Pinta | Direct contact |\n| Borrelia |  |  |\n| B. burgodorferi | Lyme disease | Tick-borne |\n| B. recurrentis | Relapsing fever (epidemic) | Louse-borne |\n| B. vincentii | Vincent’s angina | Direct contact |\n| Leptospira |  |  |\n| L. interrogans | Leptospirosis Severe form (Weil’s disease) | Contact with rodent urine |\n\n**References and further readings**\n\n1. Bacterial Motility, *Spirochaetes*. Retrieved June 8, 2021, from \u003Chttps:\u002F\u002Fcronodon.com\u002FBioTech\u002FBacteria_motility3.html>\n2. [Bailey & Scott’s Diagnostic Microbiology](https:\u002F\u002Famzn.to\u002F2WZxPHL), Forbes, 11th edition",[],[],[],[48,54,61,66,70,74,79,84,88,92],{"slug":49,"name":38,"description":50,"image":51,"body":52,"postCount":53},"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":55,"name":56,"description":57,"image":58,"body":59,"postCount":60},"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":62,"name":63,"description":64,"image":37,"body":37,"postCount":65},"sushmita-baniya","Sushmita Baniya","Author \u002F Contributor",32,{"slug":67,"name":68,"description":64,"image":37,"body":37,"postCount":69},"samikshya-acharya","Samikshya Acharya",20,{"slug":71,"name":72,"description":64,"image":37,"body":37,"postCount":73},"alisha-tripathi","Alisha Tripathi",6,{"slug":75,"name":76,"description":77,"image":37,"body":37,"postCount":78},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor",10,{"slug":80,"name":81,"description":82,"image":37,"body":37,"postCount":83},"guest-author","Guest Author","Guest Author \u002F Contributor",2,{"slug":85,"name":86,"description":64,"image":37,"body":37,"postCount":87},"srijana-khanal","Srijana Khanal",18,{"slug":89,"name":90,"description":82,"image":37,"body":37,"postCount":91},"dr-poonam-acharya","Dr. Poonam Acharya",1,{"slug":93,"name":94,"description":64,"image":37,"body":95,"postCount":96},"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]