3.07 Listeria Monocytogenes

Microbiology review for the USMLE Step 1 exam

• Listeria monocytogenes is an intracellular, aerobic, gram-positive rod that can cause foodborne illness
• It can live inside various types of cells, including epithelial cells, macrophages, and monocytes, and spreads from cell to cell through actin polymerization
• It is most commonly found in refrigerated deli meats and unpasteurized dairy products, and can cause gastroenteritis, meningitis, and premature labor/spontaneous abortion in immunocompromised individuals, pregnant women, and older or young individuals
• It is usually treated with ampicillin, but bactrim (trimethoprim and sulfamethoxazole) can be used in cases of ampicillin allergy