Bacterium
Yersinia pestis
Flea-borne plague, safety-pin bipolar rod
yer-SIN-ee-uh PES-tis
High-yield clue
Bipolar 'safety-pin' staining coccobacillus spread by rat fleas, causing swollen tender lymph node (bubo) vocabulary.
Overview
A Gram-negative coccobacillus that causes plague, transmitted by rodent fleas; a high-yield zoonotic and select-agent study organism with a classic bipolar staining look.
Classification
- Gram-negative
- Coccobacillus
- Enterobacterales
- Facultative anaerobe
- Non-motile
Lab & identification clues
- Bipolar 'safety-pin' staining with Giemsa/Wayson vocabulary
- F1 capsular antigen concept
- Slow-growing on standard media note
- Yop virulence protein vocabulary
Associations
- Oriental rat flea (Xenopsylla) vector vocabulary
- Bubonic, septicemic, and pneumonic form vocabulary
- Rodent reservoir and Category A agent framing
Commonly confused with
- Yersinia enterocolitica
- Francisella tularensis
Frequently asked questions
What is Yersinia pestis?
A Gram-negative coccobacillus that causes plague, transmitted by rodent fleas; a high-yield zoonotic and select-agent study organism with a classic bipolar staining look.
What is the Gram stain of Yersinia pestis?
Yersinia pestis is Gram negative.
What are the lab clues for Yersinia pestis?
Lab clues for Yersinia pestis include Bipolar 'safety-pin' staining with Giemsa/Wayson vocabulary, F1 capsular antigen concept, Slow-growing on standard media note, and Yop virulence protein vocabulary.
What is Yersinia pestis commonly confused with?
Yersinia pestis is commonly confused with Yersinia enterocolitica and Francisella tularensis.
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.