Which of the following infections is caused by a spirochete?

Spirochetes are a unique group of bacteria characterized by their spiral shape and motility. Among the listed infections, syphilis is caused by the spirochete Treponema pallidum. This organism is known for its corkscrew-like movement, which enables it to navigate through viscous environments, such as the human body’s tissues.

In the case of syphilis, the infection is primarily transmitted through sexual contact, leading to a range of clinical manifestations such as sores, rashes, and potentially serious systemic complications if left untreated. The diagnosis is often made through serological testing, which detects antibodies generated in response to this spirochete.

The other infections mentioned are caused by different types of bacteria: tuberculosis is caused by Mycobacterium tuberculosis, a fastidious organism that has a waxy cell wall; strep throat is caused by Streptococcus pyogenes, a Gram-positive cocci; and gonorrhea is caused by Neisseria gonorrhoeae, a Gram-negative diplococcus. Each of these pathogens has distinct paths of transmission, virulence factors, and clinical presentations, firmly placing syphilis as the only spirochetal infection in the list provided.