Fundamentals of Microbiology

1.2.4.1 Spirochaetes

Spirochaetes (also Spirochetes) belong to a phylum of distinctive Gram-negative bacteria, which have long, helically coiled (spiral-shaped) cells. Spirochetes are chemoheterotrophic in nature, with lengths between 5 and 250 µm and diameters around 0.1-0.6 µm. Spirochaetes are distinguished from other bacterial phyla by the location of their flagella, sometimes called axial filaments which run lengthwise. These cause a twisting motion which allows the spirochaete to move about. When reproducing, a spirochaete will undergo asexual transverse binary fission. Most spirochaetes are free-living and anaerobic, but there are numerous exceptions.

The spirochetes are divided into three families: (Brachyspiraceae, Leptospiraceae, and Spirochaetaceae), all placed within a single order (Spirochaetales). Some of the disease-causing members include the following:

1. Leptospira sp., which causes leptospirosis;

2. Borrelia recurrentis, which causes relapsing fever;

3. Treponema pallidum - causes syphilis;

4. Treponema pertenue, which causes yaws.