engleski

Mycobacterium sp. isolated from cattle in Croatia during the process of certification of herds free of bovine tuberculosis

In 2010, Croatia initiated the proceedure of verification of officially tuberculosis-free herds. Cattle older than 6 weeks were tested with tuberculin skin test (monotest) twice in period of at least 6 months between testings. Cattle with suspicious monotest reaction were re-tested using comparative method (bovine and avian tuberculin). Cattle with positive tuberculin skin test reactions (monotest or comparative method) were removed from breedings. Tissue and organ samples were taken during slaughter for bacteriological isolation of causative agent of bovine tuberculosis – Mycobacterium (M.) sp. Isolates were identified by microscopic examination, by molecular testing and by classical bacteriological methods. In 2010, 314 cattle samples from 100 breedings were examined. M. tuberculosis complex species were isolated from 117 cattle samples from 23 breedings. NTM were isolated from samples collected from 12 cattle belonging to 12 flocks. Mycobacteria were not isolated from 185 bovine samples taken from animals with positive tuberculin reaction. Bacterial infection with any kind of mycobacteria was not identified in 64 breedings. In 2011, until June 15th, 276 cattle samples from 126 breedings were bacteriologically tested. M. tuberculosis complex species were isolated from 19 cattle samples from 6 breedings and NTM were isolated from 4 cattle samples from 4 breedings. 97 tested samples were negative on Mycobacteria. Reoccuring infection with Mycobacterium caprae in 2011 was detected in 2 breedings. Bacteriological examination of 133 samples is still ongoing. Infection of cattle with numerous NTM could partially be the reason for lowered tuberculin skin test specificity and should be considered in planing programms like verification of cattle herds officially free of tuberculosis. Also, repeated detection of the same Mycobacterium sp. infection from year to year in cattle in the same breeding indicates need for more radical system of tuberculosis eradication in herd.

certification; tuberculosis; cattle; Croatia

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