Antibiotic resistance, phylogenetic grouping and virulence potential of Escherichia coli isolated from clinical and environmental samples from the Cape Coast metropolis of the central region of Ghana

Abstract

The genetic diversity of Escherichia coli isolated from clinical and environmental samples from Cape Coast was studied. Bacterial isolation and identification was carried out using standard biochemical tests and confirmed using Analytical Profile Index (API) 20 E kits. All test E. coli isolates were screened for their susceptibility to 16 antibiotics, followed by a screening for extended spectrum ƒÀ-lactamase (ESBL) production. DNA was extracted from all tests E. coli isolates and PCR assays were performed to determine the prevalence of ESBL genes - blaTEM and blaSHV, the molecular phylogeny and the virulence potential of the E. coli isolates. In all 389 E. coli isolates were obtained comprising 261 from clinical and 128 from environmental samples. All 389 E. coli isolates were sensitive to imipenem whereas the least percentage sensitivity was recorded when all E. coli isolates were screened against ampicillin. The percentage sensitivity of the isolates recovered from environmental samples to the 16 antibiotics was higher than that of clinical isolates except for nalidixic acid, aztreonam and amikacin where isolates of environmental origin recorded lower percentages of sensitivity. Also 29.88 % of the test E. coli isolated from clinical samples and 12.50 % from environmental samples were phenotypically confirmed as ESBL producers. Furthermore, 42.91 % of clinical isolates and 11.72 % of the environmental isolates respectively belonged to group B2. Also 27.20 % and 26.05 % of clinical isolates belonged to group A and D respectively while the environmental isolates recorded 53.13 % and 35.16 % respectively belonging to group A and D. In addition, 3.83 % of the environmental isolates and none of the clinical isolates were found to belong to group B1. E. coli isolates recovered from stool samples recorded the highest percentages of enterotoxigenic E. coli, enteropathogenic E. coli, enteroaggregative E. coli and enterohaemorrhagic E. coli, while E. coli isolates recovered from urine recorded the highest percentage of uropathogenic E. coli.