Microbiology Practice Exam 2026 - Free Microbiology Practice Questions and Study Guide

Treponema pallidum is the bacterium responsible for causing syphilis. This organism is a spirochete, which means it has a spiral shape that enables it to move with a corkscrew motion, facilitating its penetration through host tissues. Syphilis is primarily transmitted through sexual contact, and once in the body, the bacterium can evade the immune system, allowing it to persist and potentially lead to serious complications if left untreated. The infection typically progresses through distinct stages: primary, secondary, latent, and tertiary syphilis, each characterized by different symptoms and clinical manifestations.

The other options listed are associated with different diseases. Mycobacterium tuberculosis is known for causing tuberculosis, a respiratory disease. Staphylococcus aureus is a common cause of skin infections, food poisoning, and is also associated with various systemic infections. Salmonella enterica is primarily known for causing foodborne illnesses and gastroenteritis. Understanding the unique characteristics of Treponema pallidum helps in recognizing its role in the pathology of syphilis, distinguishing it from other bacteria that cause different infections.