Plague Differential Diagnoses

Updated: Aug 13, 2021
  • Author: Venkat R Minnaganti, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
  • Print

Diagnostic Considerations

In 2014, an automated system in a Colorado hospital laboratory mistakenly identified a serum isolate as Pseudomonas luteola. Upon further examination, the organism was correctly identified as Y pestis. [10]

Diagnosis is made by detecting the organism from involved sites, but treatment should not be delayed pending a microbiologic diagnosis when plague is clinically suspected. The organism can be isolated from lymph node aspirates, blood, sputum, and other sites. Gram stain classically demonstrates gram negative organisms with a “safety pin” morphology. Diagnosis may also be supported by direct fluorescent antibody or PCR testing. Serologic testing may be done, but it requires both acute and convalescent antibody testing. 

An important clinical clue for diagnosing plague is a history of contact with animals from an endemic plague focus, especially dead rodents or other wild animals known to harbor the bacterium. [28]  

Differential Diagnoses