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Gastrointestinal infections are endemic in Nigeria and several factors contribute to their continual survival, including bacterial resistance to commonly used antibiotics. Nigerian yogurts do not include probiotics, and limited information is available about the antimicrobial properties of the fermenters in the yogurt against gastrointestinal pathogens. Therefore, the antimicrobial potentials of bacteria in Nigeria-produced yogurts against intestinal pathogens were investigated in this study. Viable counts of lactic acid bacteria (LAB) in 15 brands of yogurt were enumerated and the bacteria identified by partial sequencing of 16S rRNA gene. Susceptibility of the gastrointestinal pathogens (Salmonella, Shigella and E. coli ) to antibiotics by disc diffusion method, to viable LAB by the agar overlay method, and to the cell-free culture supernatant (CFCS) of the LAB were investigated. Co-culture analysis of LAB and pathogens were also done. Viable counts of 1.5 × 1011 cfu/ml were observed in some yogurt samples. Two genera were identified: Lactobacillus (70.7%) and Acetobacter (29.3%). The Lactobacillus species reduced multidrug-resistant gastrointestinal pathogens by 4 to 5 log while the zones of inhibition ranged between 11 and 23. The Lactobacillus and Acetobacter strains examined displayed good activities against the multidrug-resistant tested pathogens. This is the first report of antimicrobial activities of acetic acid bacteria isolated from yogurt in Nigeria. [ABSTRACT FROM AUTHOR]

Introduction: Recent upsurge in bacterial resistance has led to search for alternative to antibiotics in treatment of infectious diseases including diarrhea. One of the common causative agent of diarrhea is Shigella sp. Lactic acid bacteria has been used in probiotic formulation for prevention of various form of diarrhea. This study investigates possible antagonistic effects of lactic and acetic bacteria on Shigella sp in co culture. Material-methods: Antibiotic susceptibility of Shigella spp. SS10 to ofloxacin, gentamycin, cefuroxime, ceftazidine, lincomycin, oxacillin, cloxacillin, cefotaxime, ciprofloxacin and nitrofurantoin was tested by disc diffusion method. Shigella spp. SS10 was co-incubated in two different experiment with 3 Lactobacillus species (Lactobacillus plantarum QN01, Lactobacillus parabuchneri SM03 and Lactobacillus fermetum SH01) and 1 Acetobacter pasteurianus RV04 which has been previously isolated from Nigeria-produced yogurts. An 8h old Shigella spp. SS10 was introduced into an overnight culture of LAB and a fresh Shigella spp. SS10 was inoculated into overnight culture of LAB. Viable counts of pathogens at 0h and after 24h co-incubation at 37 °C were observed. Results: Shigella spp. SS10 was resistant to 50% of the tested pathogens. The tested LAB effected an average of 4 log reduction in viable counts of the Shigella strain. The Acetobacter strain displayed very good inhibitory activity with a 4 log reduction in microbial load. Conclusion: Lactic and Acetic acid bacteria isolated from Nigerian yoghurt has considerable activity against Shigella sp. in co culture experiment. [ABSTRACT FROM AUTHOR]