Microbiological Quality Assessment of Dairy Product: Detection of Extended Spectrum Beta Lactamase Genes in Bacterial Isolates from Yoghurt Sold in Sagamu Metropolis, Ogun State, Nigeria

Abstract

The presence of pathogenic microorganisms in dairy products including yoghurt is undesirable because of the risk of infectious diseases. This study  assessed the microbiological quality of some yoghurt samples in Sagamu metropolis, Ogun State, Nigeria with respect to pH, microbial types and counts  and detection of extended spectrum beta lactamase (ESBL) genes. The pH readings ranged between 4.05 and 5.81 while minimum total viable bacterial  and minimum total coliform counts ranged from 1.1 x 101 to 2.0 x 10⁶ CFU/mL and 3.0 X 100 to 2.3 x 10⁴ CFU/mL, respectively. The samples yielded a  total of 40 bacterial isolates including 15 Gram-positive and 25 Gram-negative isolates belonging to eight Genera among which Staphylococcus aureus  and Pseudomonas aeruginosa were the most prevalent 10 (25%). Escherichia coli showed the highest resistance to levofloxacin (100%). Gram-negative  isolates had higher number of multidrug resistant isolates (92%). ESBL was detected phenotypically in 4 (16%) of Gram-negative bacteria. Only SHV gene  was detected in two P. aeruginosa while CTX-M and TEM genes were not detected in any of isolates. The yoghurt samples contained pathogenic  microorganisms that are capable of causing health complications. Therefore, rigorous inspection and quality standards are required to ensure Good  Manufacturing Practice.