Laboratory Results for Case Classification - Confirmed

Confirmation of Y. pestis at a Reference Laboratory level can be accomplished by one of the following sets of procedures:

• Positive DFA or DNA detection and bacteriophage lysis of a recovered isolate.
• Appropriate titer change in paired serum sample testing.

Without an isolated culture (or 4-fold increase in titer), confirmation cannot be verified and can only be considered as presumptive.

• Testing
• Biochemical tests and the Antimicrobial Susceptibility Test (E test) are also used at CDC to characterize the bacterium, but are not considered to be confirmatory.
• Bacteriophage lysis
• Serology assays
• Immunohistochemistry