3.23 Yersinia Species

Microbiology review for the USMLE Step 1 Exam

• Yersinia are gram-negative, non-motile bacteria that cause zoonotic diseases.
• Yersinia produce urease enzyme to survive in the stomach and are facultative intracellular bugs.
• Three species of yersinia causing disease in humans are Yersinia pestis, Yersinia enterocolitica, and Yersinia pseudotuberculosis.
• The Yersinia species inhibit phagocytosis, the capsule contains F1 and V proteins and the injectosome injects Yersinia outer proteins.
• Yersinia pestis spreads through fleas, causing bubonic, pneumonic, or septicemic plague with symptoms like fever, chills, and swollen lymph nodes.
• Yersinia enterocolitica is spread through contaminated food or dog feces, causing enteric infection, and symptoms like diarrhea, abdominal pain, and vomiting.
• Yersinia pseudotuberculosis causes enteric disease, similar to Y. enterocolitica, and granulomatous lesions that look like tuberculosis.
• Yersinia pestis is rare with 500 cases reported since 1970, compared to Y. enterocolitica, which causes 100,000 cases each year