Leptospira
| Leptospira | |
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| Family: | Leptospiraceae
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| Genus: | Leptospira
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Leptospira is a genus of spirochaete bacteria, including a small number of pathogenic and saprophytic microorganisms. The first Leptospira to be described was L. interrogans (1907) as Spirochaeta Interrogans) was isolated from kidney tissue slices of a Leptospirosis victim. For quite a time, the genus only had two members - the pathogenic L. interrogans and saprophytic L. biflexia.
The current (2004) classification of Leptospira is as follows:
- Leptospira interrogans
- aka L. icteroides, Spirochaeta interrogans, S. icterohaemorrhagiae, or S. icterogenes
- Leptospira biflexa
- Leptospira alexanderi
- Leptospira borgpetersenii
- Leptospira fainei
- Leptospira inadai
- Leptospira kirschneri
- Leptospira meyeri
- Leptospira noguchii
- Leptospira parva
- Leptospira santarosai
- Leptospira weilii
- Leptospira wolbachii
It is placed in the family Leptospiraceae, together with the species Leptonema illini. The IUMS (2002) confirmed nomenclature for leptospira is as follows:
Genus species serovar Serovar_name : i.e. genus and species italicised, serovar name in plain text, genus and serovar capitalised and species lowercase. Examples include:
Leptospira interrogans serovar Ballum
Leptospira biflexa serovar Codice
Description
The leptospira are an extremaly varied (over 200 serovars known) group of helix-shaped motile gram-negative bacteria; if straightened, they'd measure 6-20 μm long and 0.1-0.15μm in diameter. The number of curls depends on the straightened length and varius up to as much as 20.
The bacteria have a number of freedom degrees; when ready to proliferate via binary fision, the bacterium noticeably bends in the place of the future split.
Pathogenic leptospira have hook-like ends and extensively use axial flagella (one on each end) for penetration into host organism tissue; human infection may occur through even slightly damaged skin, mucouse membranes or eyes.
Leptospira, both pathogenic and saprophytic, can occupy diverse environments, habitats and life cycles; it generally recognized these bacteria are virtually ubiquitous in terms of geographic distribution (present everywhere except Antarctica).
Most of Leptospira, however, are hydrophilic - high humidity and neutral (6.9-7.4) pH are essential for their survival in the environment, with stagnant water reservoirs - bogs, shallow lakes, ponds, puddles, etc - being natural placeholder for the bacteria.
Proliferation rate is typically slow; growth in an artificial nutrient environment (for L. interrogans, one typicaly contains human blood serum) becomes noticeable in around 5-7 days.
Parasitic species' optimal growth temperature is 28-32 degrees Celsius, while saprophytic one can grow at as low as 13 degrees Celsius.
Due to high variance of the pathogens, leptospira-caused diseases leave immunity only to a particular serovar that actually caused the infection.
This circumstance prevents creation of effective vaccines against Leptospirosis.