Detection of Mycobacterium avium subspecies in the gut associated lymphoid tissue of slaughtered rabbits

Background

Rabbits are susceptible to infection by different species of the genus Mycobacterium. Particularly, development of specific lesions and isolation of Mycobacterium avium subsp. avium and Mycobacterium avium subsp. paratuberculosis, both subspecies of the M. avium complex, has been reported in wildlife conditions. Although, rabbit meat production worldwide is 200 million tons per year, microbiological data on this source of meat is lacking and more specifically reports of mycobacterial presence in industrially reared rabbit for human consumption have not been published. To this end, we sought mycobacteria by microbiological and histopathological methods paying special attention to Mycobacterium avium subsp. paratuberculosis in rabbits from commercial rabbitries from the North East of Spain.

Results

M. avium subsp. paratuberculosis was not detected either by culture or PCR. However, Mycobacterium avium subsp. avium was detected in 15.15 % (10/66) and Mycobacterium avium subsp. hominissuis was detected in 1.51 % (1/66) of gut associated lymphoid tissue of sampled animals by PCR, whereas caecal contents were negative. 9 % (6/66) of the animals presented gross lesions suggestive of lymphoid activation, 6 % (4/66) presented granulomatous lesions and 3 % (2/66) contained acid fast bacilli. Mycobacterial isolation from samples was not achieved, although colonies of Thermoactinomycetes sp. were identified by 16s rRNA sequencing in 6 % (4/66) of sampled animals.

Conclusions

Apparently healthy farmed rabbits that go to slaughter may carry M. avium subspecies in gut associated lymphoid tissue.