Mycobacteria resources for referring vets

If you think you may have seen a case but aren’t sure, you may also find our background and clinical presentation resource useful.

There are there three tests we use to try to identify the species of mycobacteria present in a patient; the IGRA blood test, PCR and specialist culture. Please read about these different tests, how they are most usefully used and ideas of costs: Testing for Feline (or Canine) Mycobacterial Infections.

• The IGRA is offered by Easter Bush Pathology here in Edinburgh and the test sample requirements and submission form can be found on their website: https://vet.ed.ac.uk/clinical/pathology/diagnostic-services/mycobacteria-testing. This assay is very good at detecting an immune response to mycobacteria that cause TB; these are responsible for ~50% of all mycobacterial disease in cats in the UK. Results are normally issued within seven days of sample submission.
• The PCR test is run by Leeds University Teaching Hospital. It takes 1-2 weeks to get the result and gives you the exact species of mycobacteria involved. APHA off an alternative PCR that is designed to detect cases of M. bovis infection. If fresh tissue to submitted for this test and is positive by PCR, confirmatory culture (below) will be performed for no extra cost. 
• APHA also offer specialist culture, but it only detects ~50% of cases, and can take weeks to a few months to get an answer, especially with M. microti, which is the most common Mycobacteria found to cause disease in cats.

The presence of mycobacteria within a tissue sample is often flagged up on a histopathology report. They are seen as acid fast Ziehl Neelson (ZN) positive bacteria with the conformation of mycobacteria. If the pathologist finds these in a tissue biopsy you now need to know whether it is a tuberculous (TB) causing mycobacteria – Mycobacteria tuberculosis complex (MTBC) – or a non-tuberculous mycobacteria (NTM). 

If you have diagnosed a case of mycobacterial infection in a companion species, then a lot of questions can be answered by reading Companion Animal Mycobacterial Infections: Treatment and Zoonotic risks in addition to Treating Mycobacterial infections in Cats – Drugs, Doses & Costs. This contains useful background information on disease epidemiology, common clinical presentations and diagnostics. We have also prepared an owner information sheet.

If you are a veterinarian requiring further advice on a patient that is not answered in the documents on this page, the team at the University of Edinburgh can assist. For advice requests, complete a referral advice form and email it to companion.animalTB@ed.ac.uk. Please note that there is usually a charge for this service to cover the clinician time.

To refer a patient with suspected or confirmed mycobacterial infection to our team, please contact our Reception directly hfsareception@ed.ac.uk or complete an online referral request form. We have also prepared an owner information sheet.

When treating cases, please read our information sheet about treatment protocols and the potential side effects of these drugs. For cases of TB in cats, when caused by either M. bovis or M. microti, and presenting with cutaneous lesions and/or lung involvement we now have an estimated 80% success rate when treating these cases.

Mycobacterial Disease Advice Request Form

Companion Animal Mycobacterial Infections: Further Reading