Comparison of methods for mycobacteria isolation from swine feces

Swine mycobacteriosis is an important cause of carcass condemnation at abattoirs. One of the best ways to recognize the etiologic agent involved, in live animals, is the fecal isolation, as 94% of the lesions are located in the digestive tract. Therefore, the goal of the present study was to compare the performance of four decontamination methods followed by inoculation in three different culture media, totalizing twelve procedures of mycobacteria search from swine fecal samples experimentally contaminated. The swine feces were artificially contaminated with 0.02 g of Mycobacterium avium, PIG-B strain, and subjected to mycobacteria isolation trial. The protocols used were: 1) modified Petroff or basic method; 2) modified Lowenstein-Jensen or acidic method; 3) modified Petroff or basic method with re-suspension in Amphotericin B; 4) modified Lowenstein-Jensen or acid method with re-suspension in Amphotericin B, followed by inoculation in Petragnani, Lowenstein-Jensen and Lowenstein-Jensen medium with antibiotics (Penicillin G and Nalidixic acid). There was a difference (p<0.05) between the mycobacterial recovery percentages from swine feces. The acid method with re-suspension in Amphotericin B solution and inoculation in Lowenstein-Jensen medium with antibiotics showed the best results (87% of mycobacteria recovery).