Mycobacterium microti: Not Just a Coincidental Pathogen for Cats

Area of Science:

• Veterinary Medicine
• Microbiology
• Immunology

Background:

• Bovine tuberculosis is well-studied with established diagnostics.
• Feline tuberculosis is poorly understood, with limited diagnostic tools.
• Mycobacterium tuberculosis complex infections are a differential diagnosis for cats with specific lesions.

Purpose of the Study:

• To describe cases of Mycobacterium microti infection in domestic cats.
• To evaluate diagnostic approaches for feline tuberculosis.
• To investigate potential sources of M. microti infection in cats.

Main Methods:

• Case series reporting clinical, diagnostic, and pathological findings.
• Application of an adapted feline interferon gamma (IFN-γ) release assay.
• Bacteriological analysis and investigation of wild mice populations.

Main Results:

• Eleven cases of M. microti infection in cats were identified in Switzerland.
• The adapted feline IFN-γ assay was successfully used for ante mortem diagnosis in two cases.
• Direct contact with M. microti reservoir hosts was suspected, but not confirmed in wild mice.

Conclusions:

• Mycobacterium microti infection should be considered in cats with granulomatous disease.
• An adapted feline IFN-γ assay is a promising ante mortem diagnostic tool.
• The source and transmission routes of M. microti in cats remain unclear.