Culture-dependent and molecular characterization of Vancomycin-Resistant Enterococci from clinical, food, and water samples across Osun State, Southwest Nigeria

Abstract

The emergence and continuous rise in the prevalence of vancomycin-resistant Enterococci (VRE) are alarming and pose a public health threat. The factors responsible for this include intrinsic resistance, acquired resistance, and horizontal gene transfer among Enterococci. This study aimed to evaluate the current prevalence rate, phenotypic and genotypic identification of VRE strains isolated from clinical (in and out-patients), ready-to-eat (RTE) food, and water samples across three geopolitical regions of Osun State in southwestern Nigeria. A total of 466 clinical, RTE food and water samples were analyzed using conventional microbiological techniques, molecular identification of isolates, and detection of van genes using specific primers by polymerase chain reaction (PCR). Phenotypic identification revealed 69 VRE isolates; 64 of which were confirmed VRE with molecular techniques. The overall VRE prevalence rate was 13.7% (64/466), while the proportion of Enterococci that was VRE was 34.6% (64/185). The prevalence of clinical, food, and water samples from the individual sample types was 15.7% (26/166); 14.0% (21/150,) and 11.3% (17/150) respectively.The occurrence of VRE species was 45.3% for E. faecalis, 12.5% for E. hirae, 4.7% each for E. gallinarum, and E. durans; 3.1% each for E. faecium and E. casseliflavus and 1.6% for E. avium. Other unidentified species were 16 (25.0%). Additionally, 47 (73.4%) had either the vanA, vanB, or vanC genes; as detected in 10 (15.6%), 8 (12.5%), and 29 (45.3%) isolates respectively across the different sample types and species respectively. Hence, a high occurrence of vanC carriage in the recovered VRE isolates was recorded. This information is vital as continued monitoring and surveillance is crucial to provide data to clinicians and public health workers. It could serve as a key factor in managing and curtailing the spread of VRE strains, to control its growth and infections caused in hospital and community settings.