Prevalence, antimicrobial resistance and biofilm formation in Enterococcus species from Bacteremia and Urinary tract infections cases in Lagos

Authors: Wasiu Olawale Salami, Kehinde Olugbenga Amisu, Aminat Olajumoke Lawal-sanni, Samuel Oluwasegun Ajoseh, and Kabiru Olusegun Akinyemi

Ger. J. Microbiol. 2026. vol. 6, Iss. 2 pp:30-46
Doi: https://doi.org/10.51585/gjm.2026.2.0063

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Abstract:

Enterococcus spp. are resilient, opportunistic Gram-positive pathogens increasingly associated with catheter-related urinary tract infections and bloodstream infections, in which biofilm formation and antimicrobial resistance (AMR) contribute to persistence and treatment failure. This study investigated the prevalence, risk factors, multidrug resistance (MDR), biofilm formation, and the presence of resistance and virulence genes among Enterococcus isolates. A total of 835 clinical samples (285 blood, 280 urine, 50 sputum, and 75 each of wound and oral swabs) were collected from inpatients at three tertiary hospitals in Lagos between November 2024 and December 2025. Enterococcus isolates were identified using standard methods. Antimicrobial susceptibility testing (AST), biofilm formation assays by established protocol, and detection of resistance and virulence genes by real-time PCR were performed. Enterococcus spp. Overall prevalence was 3.9% (33/835), with E. faecalis and E. faecium accounting for 81.8% and 18.2%, respectively. Isolation rates were higher for blood samples (6.7%, 19/285) than for urine samples (5.0%, 14/280).  Enterococcus spp. occurred more in males (4.3%) than in females (3.7%), with the 19–37 age group mostly affected. Indwelling catheters were identified as a major risk factor. Enterococcus isolates exhibited 100% resistance to chloramphenicol and imipenem, and 97% resistance to vancomycin, ciprofloxacin, meropenem, and trimethoprim-sulfamethoxazole. High susceptibility was recorded for tigecycline (98.1%) and gentamicin (90.9%). All isolates were MDR with a mean Multiple Antibiotic Resistance index of 0.70. Eight resistotypes were identified, with the following patterns: CHL, TMP/SMX, IMI, MEM, DOR, CIP, VAN, ERY; more frequent. Biofilm production was detected in 57% of isolates. The resistance gene vanA was found in 12% of isolates, and ermA in 6%, while the virulence gene SagA (9.1%) was detected only in blood isolates. These findings revealed intense local selective pressure and a high-risk device-linked reservoir of MDR enterococci, underscoring the urgent need for antimicrobial stewardship and device-focused infection prevention and control.

Keywords:

Prevalence, Enterococcus, Resistance, Biofilm. Virulence, Susceptibility

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