Feline mycobacterial disease in northern California: Epidemiology, clinical features, and antimicrobial susceptibility

Matthew J.L. Munro, Barbara A. Byrne, Jane E. Sykes

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Background: Mycobacterial infections in cats are challenging to treat and incompletely described. Hypothesis/objectives: To describe the features of mycobacterial infections in cats from northern California. Animals: Nineteen cats, all with nontuberculous mycobacterial (NTM) infections; 4 with Mycobacterium avium infection, 15 with rapid-growing mycobacterial (RGM) infection. Methods: Retrospective study. Cases with positive mycobacterial culture, species identification, and susceptibility testing were included. Descriptive statistics were used. Fisher's exact test and Mann-Whitney U test were used for comparisons between M avium and RGM infections (P ≤.05). Results: Rapid-growing mycobacterial cases included Mycobacterium smegmatis (9), Mycobacterium fortuitum (4), Mycobacterium abscessus (1), and Mycobacterium thermoresistibile (1). Mycobacterium avium infections were more likely than RGM infections to be disseminated (3/4 vs 0/15; P =.004). Disease of the skin/subcutis (15/15 vs 0/4; P <.001) and outdoor access (14/15 vs 0/4; P =.001) were primary features of RGM infections. Resistance to fluoroquinolones and aminoglycosides was common among M avium isolates. A high prevalence of resistance to third- and fourth-generation cephalosporins was noted in RGM species. Death/euthanasia was noted only in M avium cases (3/4). Twelve of 15 cats with RGM infection had available follow-up; 4 of these cats achieved remission. Conclusions and Clinical Importance: The most prevalent RGM species isolated from cats from northern California are M smegmatis and M fortuitum. Susceptibility to prescribed antimicrobials does not appear to guarantee treatment success. Combination drug treatment is recommended. Repeat culture and susceptibility testing should be performed when disease is persistent/relapsing.

Original languageEnglish (US)
JournalJournal of Veterinary Internal Medicine
StateAccepted/In press - 2020


  • antimicrobial
  • atypical bacteria
  • cutaneous
  • panniculitis
  • systemic
  • treatment

ASJC Scopus subject areas

  • veterinary(all)


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