——————————————————— Spirochetes ——————————————————— >Leptospira species (includes pathogenic and saprophytic species) >Borrelia species (36 known strains). Most common strains associated with Lyme disease: 1] Borrelia burgdorferi 2] Borrelia afzelii 3] Borrelia garinii >Treponema pallidum
Spirochaete bacterium with subspecies that cause treponemal diseases such as syphilis, bejel, pinta and yaws.
Treponemes have a cytoplasmic and outer membrane.
Using light microscopy treponemes are only visible using Dark field illumination.
T. pallidum causes syphilis and is a motile spirochaete that is generally acquired by close sexual contact, entering the host via breaches in squamous or columnar epithelium.
The helical structure of T. pallidum pallidum allows it to move in a corkscrew motion through a viscous medium such as mucus. It gains access to host’s blood and lymph systems through tissue and mucous membranes.
Important considerations: The choice of an agent should be based on local antimicrobial sensitivities, site of infection, cost, and comorbid conditions. Generally, the most common agents/regimens are listed first.
Syphilis (primary, early latent): Less than one year. Primary: ulcer or chancre at site of infection. Secondary: rash, mucocutaneous lesions, adenopathy
Benzathine Penicillin G (Bicillin L-A) 2.4 million units IM as a single dose
PCN-allergic patients / alternatives: Ceftriaxone 1 gram IV/IM q24h x 10 – 14 days OR Doxycycline 100mg twice daily for 2 weeks OR Azithromycin 2000mg x 1 OR Tetracycline 500mg four times daily for 2 weeks. Note: pregnant women should be treated with pcn (desensitize patient if necessary).
Syphilis (late, or greater than one year duration):
Benzathine Penicillin G 2.4 million units IM weekly x 3 doses
PCN-allergic patients / alternatives: Doxycycline 100mg twice daily for 28 days OR tetracycline 500mg orally four times daily for 28 days. Note: pregnant women should be treated with pcn (desensitize patient if necessary).