Abstract

Bloodstream infections resulting from Enterococcus faecalis pose significant therapeutic challenges due to emerging antimicrobial resistance. This study examines the characteristics profile and resistance patterns of Enterococcus faecalis from blood samples obtained from patients in a tertiary hospital in Lagos State, Nigeria. A total of 103 blood samples were aseptically collected and processed using standard microbiological techniques. The isolates were characterized presumptively identified based on cultural, morphological, and biochemical properties, while species confirmation was done using the API 20 Strep system and PCR amplification of the 16S rRNA gene. Antibiotic susceptibility testing was determined via the Kirby-Bauer disc diffusion method, and all isolates were screened for resistance genes. Sixteen Enterococcus faecalis isolates (15.5%) were recovered from the samples. Among these, four isolates (25%) exhibited resistance to all antibiotics tested. High levels of resistance were observed to vancomycin (100%), cefotaxime, tigecycline, norfloxacin, azithromycin, and cefoxitin (62.5% each), while the highest susceptibilities were recorded for ertapenem (75%), meropenem, and chloramphenicol (62.5% each). Multiplex PCR analysis detected sul2 and sul1 genes responsible for sulphonamide resistance in 81.3% and 31.3% of the isolates, respectively, and one isolate tested positive for the blaZ gene, which encodes β-lactamase, conferring resistance to penicillins. Sequence analysis confirmed bacterial identities, and phylogenetic analysis revealed the evolutionary relationships among the strains. The detection of multidrug-resistant E. faecalis in bloodstream infections is alarming, as it limits therapeutic opinions, increases the risk of treatment failure and adverse outcomes. It highlights urgent need for antibiotic stewardship/effective infection control measures.