Micro| Spirochetes

3.30 Spirochetes Microbiology review for the USMLE Step 1 Exam Spirochetes are spiral or corkscrew-shaped bacteria that stain gram negative. They have a unique endoflagella that distinguishes them from other species of bacteria. The endoflagella rotates within the periplasmic space and causes the bacteria to move, acting as its own propeller. Borrelia burgdorferi, Treponema pallidum, and Leptospira interrogans are the three important species of spirochetes to know. Borrelia burgdorferi causes Lyme disease, which is spread from wildlife to ticks and then to humans. The deer tick, also known as ixodes scapularis, is associated with Borrelia burgdorferi, but deer are not the reservoir for the bacteria. Lyme disease presents in three stages: erythema migrans (bulls-eye rash), flu-like symptoms, Bell's palsy, myocarditis, transient myalgias, arthritis, and neurological symptoms like encephalopathy and peripheral neuropathy. Treponema pallidum causes syphilis, which presents in stages: primary (chancre), secondary (rash), latent, and tertiary (gummas, neurological symptoms). Leptospira interrogans causes leptospirosis (Weil's disease), which is spread from infected animal urine to humans through broken skin, mucous membranes, or ingestion. Leptospirosis presents with flu-like symptoms, jaundice, renal failure, and meningitis.