Occurrence of Beta-Lactamases Genes in Beta-Lactam Resistant Bacteria Isolated from Milk of Goats with Sub-Clinical Mastitis in Thika Sub-County, Kenya

Abstract

For decades, beta-lactam antibiotics have played a critical role in the control of mastitis in animals. However, the emergence of beta-lactam-resistant bacteria poses a challenge to both human and veterinary medicine. In this regard, bacterial isolates from milk samples collected from dairy goats with sub-clinical mastitis from Thika Sub-county, Kenya, were used in the current study to interrogate the occurrence of beta-lactamases genes in bacterial isolates (Klebsiella pneumoniae, Staphylococcus aureus, and Acinetobacter spp., and Coagulase-negative Staphylococci) with known phenotypic resistance profiles to penicillin G, cephalexin, cefoxitin, and cefotaxime. Four target genes, blaTEM, blaSHV, blaCTX, blaOXA, and blaKPC were amplified using a polymerase chain reaction, and compared with Escherichia coli American Type Culture Collection 35218 and non-standard Klebsiella pneumonia positive controls. Out of the 46 samples, 44 samples (95.7%) harbored blaTEM with two samples of the 44 bacterial isolates, also possessing the blaSHV gene. Only one isolate of Klebsiella pneumonia and Acinetobacter spp had a combination of blaTEM and blaSHV. None of the bacteria had blaCTX, blaOXA, and blaKPC genes. The data indicated that sub-clinical mastitis in dairy goats in Thika Sub-county is associated with the bacteria carrying beta-lactamases genes, suggesting that the use of beta-lactam antibiotics for the treatment of sub-clinical mastitis may result in the treatment failure and potential transfer of the infectious bacteria to humans and other animals. The current study recommends the use of an alternative class of antibiotics for the management of beta-lactam-resistant bacteria.