Principles of Leptospira classification

The genus Leptospira belongs to the family leptospiraceae, order Spirochateales. Two types of classification coexist, one based on genetic and one based on antigenic determinants. Both recognize patogenic and saprophytic species, but serologically indistiguishable strains may belong to totaly different species according to genetic classification. |

Classification sheme used on theese pages is based on both genetic classification (to species level) and serologic classification (subspecies level).
Table: Difference of leptospira and related species**

. | Leptospira | Leptonema | Treponema | Serpulina | Borrelia
Obligate aerobes | + | + | - | - | -
Obligate anaerobes | - | - | S | + | -
Facultative aerobes | - | - | - | - | -
Microaerophiles | + | - | - | - | S
Cell dia. um | 0.1 | 0.1 | 0.1-0.4 | 0.3-0.4 | 0.2-0.5
Cell length um | 6-24 | 6-20 | 5-20 | 7-9 | 3-20
Energy and carbon sources
Carbohydrates | - | - | S | + | +
Long-chain fatty acids | + | + | - | - | +
Growth on Tryptose blood agar |  | + |  | + |
Presence of intracytoplasmic tubules | - | + | + | + | -
Chromosomal G+C content mol%* | 35-41 | 51-53 |  |  |

Legend:
(+) present in >90 % strains (-) present in less than 10 % strains (S) present in 11-89% strains

(*) Hovind-Hougen K.; Leptospiraceae, a new family to include Leptospira Noguchi 1917 and Leptonema ge. nov.; Int. J. of Sys. Bacteriol. 29:245-251, 1979.
(**) Bergey Manual of Determinative Bacteriology - Ninth Edition - Williams and Wilkins, 1994.

Table: Difference of pathogenic and saprophytic leptospira***

Characteristic | Pathogenic | Saprophytic
Patogenicity | + | -
Growth at 13 C | - | +
Inhibition of growth with 8'azaguanine | + | -
Conversion to spherical phorms by 1M NaCl | + | -
Lipase | S | +
Mol% G+C of DNA | 35.3-39.9 | 38-41

***Marina Cinco; Identification to species level and the differentiation of saprophytic and pathogenicc leptospira; in The Present State of Leptospirosis Diagnosis And Control, Martinus Nijhoff Publishers, 1986.