Comparative Analysis of Prevalence and Antibiotic Resistance in Vancomycin-Resistant Enterococcus from Clinical Samples – Demographics and Phenotypes

Of all enterococci species, the most renowned clinically as multidrug-resistant pathogens are Enterococcus faecium and Enterococcus faecalis. Vancomycin-resistant Enterococcus (VRE) species are the principal cause of opportunistic hospital-acquired infections, due to numerous resistance mechanisms.

In this study, the prevalence and antibiotic resistance profiles of VRE according to clinical sources from three selected hospitals in Southwest-Nigeria were investigated. Altogether, 431 samples (urine, rectal, and wound swabs - caesarian section (CS), automobile accidents, and other skin lesions and abrasions) were collected from three selected hospitals in Osun State, Nigeria. Established techniques were employed for the recovery of enterococci and screening for VRE while antibiotic susceptibility tests were carried out by disc diffusion technique.

Altogether, 208 (48.3%) enterococci strains were recovered from which 85 (40.9%) were VRE. E. faecium predominated at 71.8% (61/85) and E. faecalis at 28.2% (24/85) as determined by phenotypic characterization. VRE isolates exhibited 100%, 97.6%, and 92.9% resistance to ampicillin, clindamycin, and quinupristin-dalfopristin (Q/D) respectively. The least resistance in-vitro was to tigecycline (27.1%). None of the antibiotics exhibited 100% activity against all the isolates. vanA resistant phenotype was prevalent at 65.9%. E. faecium from all study locations displayed higher levels of resistance than E. faecalis. Multiple antibiotic resistance (MAR) indices in all VRE isolates were ≥0.2, all being multidrug-resistant.

The high prevalence rate along with the high level of multidrug resistance observed in the present study is worrisome and poses a continuous threat in the therapy of illnesses triggered by VRE as vancomycin was perceived as a drug of choice to curb enterococcal infections.