Antibiotic Resistance in Non-enterococcal Lactic Acid Bacteria Isolated from Yoghurt

Aims: To evaluate the antibiotic resistance in non- enterococcal lactic acid bacteria.

Study Design: Examination of commercially available yoghurts.

Place and Duration of Study: Department of Applied microbiology and Brewing, Nnamdi Azikiwe University, Awka, from June 2011 and May, 2012.

Methodology: Commercially available yoghurt (25 brands in all) purchased in Awka and Onitsha towns, Anambra State, Nigeria were evaluated for the lactic acid bacteria (LAB) strains present, their probiotic potentials and their antibiotic resistance/susceptibility. Out of this total, 8 isolates (6 Lactobacillus sp and 2 Streptococcus sp) were obtained for further studies. The probiotic characteristics of the 8 isolates were evaluated in vitro. The in vitro tests used to evaluate probiotic potentials were: tolerance to low pH and bovine bile, cell surface hydrophobicity, and antimicrobial activities.

Results: Generally, Lactobacillus E5 showed the best probiotic characteristics among the strains tested. This strain was able to survive at pH of 2.5 for 3 hours of exposure to fresh bovine bile and had low cell surface hydrophobicity. It was also resistant to some of the commonly used antibiotics and inhibited test pathogenic bacteria (Escherichia coli 1 and Staphylococcus aureus). The antimicrobial resistance patterns of the 8 isolates were tested against 12 antibiotic agents. All the isolates obtained in this study were found to be resistant to Gentamycin but sensitive to Clindamycin and Lincomycin.

Conclusion: Although the use of LAB has a long and safe history and has acquired the “generally regarded as safe” (GRAS) status, the safety of selected strains should be evaluated before use, not only for virulence factors and other disease-causing traits, but also for the presence of antibiotic resistance determinants and their capability of disseminating these determinants.