Antibiotic resistance in Lactobacillus sp. isolated from probiotic yogurts

Background and Aim : Recently The use of probiotic products has increased, due to their beneficial effect on human health. The overuse of antibiotics has led to increasing resistant bacteria. Lactobacillus(L.b) may act as reservoirs of antibiotic resistance genes and transfer to pathogen bacteria or microflora. This study aimed to assess the antibiotic resistance among Iranian commercially available probiotic yogurts. Methods : Thirty Iranian probiotic yogurt samples were selected, then de Man Rogosa and Sharpe (MRS) media were used for isolating Lactobacillus Sp. After purification of colonies by Streak plate method, L.b colonies were identified for morphology, gram staining, and biochemical tests (catalase, oxidase, fermentation of various sugars, methyl red, motility test, indole test). The disk diffusion method was used to detect the resistance of strains to erythromycin, tetracycline, chloramphenicol, vancomycin, gentamycin, ciprofloxacin, streptomycin, ceftriaxone according to the CLSI method. Results : Resistant bacteria were determined based on the inhibition zone diameter, using flowing breakpoints: for vancomycin and tetracycline less than ۱۴ mm, for ceftriaxone, chloramphenicol, streptomycin, and erythromycin less than ۱۳ mm, for gentamycin less than ۱۲ mm and streptomycin less than ۱۱ mm inhibition zone diameter was categorized as a resistant. The isolates showed a high level of resistance toward vancomycin (۲۶/۳۰), gentamycin (۲۷/۳۰), ciprofloxacin (۲۷/۳۰), and streptomycin (۲۹/۳۰). None of the strains showed resistance to erythromycin, tetracycline (۴/۳۰ intermediate), chloramphenicol, ceftriaxone (۹/۳۰ intermediate).Conclusion : Due to the observed antibiotic resistance, it is highly recommended to evaluated antibiotic resistance Lactobacillus strains before using in yogurt preparation.

کلیدواژه ها:

probiotic ، Lactobacillus ، antibiotic resistance