Abstract:

Objective: The antibiotic susceptibility of 39 lactic acid bacterial strains isolated from yak milk cheese was
evaluated in this study. Methods: Disc diffusion method was employed to test antibiotic susceptibility of these isolates
to eight most widely used antibiotics, including ampicillin, chloramphenicol, erythromycin, neomycin, nalidixic acid,
streptomycin, tetracycline and vancomycin. Results: These strains primarily presented resistance to four antimicrobial
agents: vancomycin, neomycin, streptomycin and nalidixic acid. The number of resistant strains was 36 (92.3%), 32 (82.1%),
38 (97.4%) and 39 (100%), respectively. There was variation in susceptibility between the species. Multidrug resistance
was identified in most isolates. Conclusion: This study provides valuable data on these isolates for the consideration of
application as probiotic bacteria or fermentation starters.

Key words: yak milk cheese, lactic acid bacteria, antibiotics, resistance