Spirochetes (Family Spirochaeteae)
Morphology and Motility:
- Unique morphology & cork screw motility
- Aerobic, microaerophilic or anaerobic
- Some culturable, some pathogenis others saprophytic
- Some ferment or oxidise sugars or fatty acids
- RNApolymerase insensitive to rifampin & incorporated in growth culture
medium for selection.
Taxonomy and importance (5 species):
- Helical cells (protoplasmic cylinders, PC)
- Trilayered membrane outer sheath (OS)
- Axial filaments or periplasmic fibrils (PF)
- Structure (rings, hook & basal body) and chemistry similar to
- PF wound between OS & PC two-thirds of PC on either ends
- 2-100 PF depending on spirochete species
- PF on either ends rotate in opposite directions--cork screw motility
- Cristispira: Giant spirochetes (10um width); symbiotic in clams & oysters;
- Free-living anaerobes; ferement sugars to acetate, ethanol, CO2 and H2
- Free-living aerobes; oxidise sugars to acetate and CO2; Aquatic habitat.
- Treponema: Host associated commensals or parasites of humans & animals;
- T. pallidum-- STD syphilis; infects male genital organs; cooling of
infected region decreases infection (heat sensitive, 41 C); treatment
antibiotics; remains uncultured; identified in patient exudates by
special silver staining (thin cells).
- Borrelia: Host assosiated parasite; Anaerobic to microaerophilic; culturable
on complex artificial medium; Thick cells & identified by normal staining
- B. recurrentis-- relapsing fever in humans; 2 or 3 cycles of 3 - 7
d high fever & muscular pain and recovery for 7 - 9; treatment
Tetracycline; Transmission by human body louse (vector transmission)
- B. Burgdorferi-- (identified in 1975, named after an American town);
Lyme disease; transmited by deer ticks to humans; rapid spread due to
deer farming; treated by antibiotics; if untreated than arthritis, damage
to CNS and cardia failure can occur.
- Leptospira: Obligate aerobes; Simple growth requirements (fatty acids
- L. biflexa-- aquatic & free-living
- L.interrogans human & animal parasite; host specific eg L.
canicola-- dogs; L. interrogans serovar icteroharrhagiae-- rodents
(kideny infected); transmitted to humans via contaminated urine;
leptospirosis-- importane cattle disease.
Author: Dr Bharat Patel
HTML'd by Troy Baalham
[Created 11 Sept 1995]
[Modified 11 Sept 1995]