Isolation of Mycobacterium avium subsp. Paratuberculosis from bovine feces of infected dairy herds by the Cornell’s Method modified

Abstract

In order to improve the isolation rate of Mycobacterium avium subsp. paratuberculosis (Map) from bovine feces a new bacteriological procedure for decontamination and cultivation of fecal samples was evaluated in 250 samples collected from asymptomatic animals in 14 infected dairy herds in southern Chile. Before culture all samples were treated with a decontaminant solution containing 0.9% hexadecylpiridinium chloride and an antibiotic solution containing amphotericin B, vancomycin and nalidixic acid. Herrold Egg Yolk Medium (HEYM) and mycobactin J supplemented with the same antibiotics mentioned above was used for the isolation of the agent. Map was isolated from 40 (16%) fecal samples and fungi contamination was observed only in 7.6% of cultures after the eighth week of incubation. The identification of the isolated strains was confirmed in all cases by PCR technology using specific primers for this pathogen (P90 and P91). The high rate of isolation and low rate of contamination as well as the specificity of the culture medium makes this procedure a good diagnostic tool of bovine Paratuberculosis.