ABSTRACT
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.
Limitation of the study
The yogurt samples were analyzed mainly for bacterial isolation, identification, and antimicrobial properties. Therefore, only a limited number of samples (≤4 repetitions of each brand of yogurt) were analyzed. This is not enough to account for intersample variability.
Declaration of interest
The authors declare no conflicts of interest. The authors alone are responsible for the content and writing of the article.
Additional information
Notes on contributors
Anthony Opeyemi Ayeni
Anthony Opeyemi Ayeni, MSc, Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria. Beneficial microbes.
Werner Ruppitsch
Werner Ruppitsch, PhD, Division of Human Medicine, Institute of Medical Microbiology and Hygiene, Austrian Agency for Health and Food Safety, Vienna, Austria. Molecular Bacteriology.
Funmilola Abidemi Ayeni
Funmilola Abidemi Ayeni, PhD, Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria. Beneficial Microbes, Bacterial Resistance.