Surveillance of high-priority enterococci and factors associated with clinical enterococcal infections in a Reference Hospital in northern Nigeria

Vancomycin-resistant enterococci (VRE) are high-priority pathogens; however, most healthcare providers in resource-limited settings do not consider enterococci in the differential diagnosis of clinical bacterial infections. This cross-sectional surveillance study determined the antimicrobial resistance (AMR) profile of Enterococcus and factors associated with their presence in patients attending the Ahmadu Bello University Teaching Hospital (ABUTH), Zaria, Nigeria. Non-repetitive clinical samples from 180 patients were processed for the isolation, identification, and antimicrobial susceptibility testing of enterococci in Slanetz-Bartley agar and the Vitek® 2 Compact system. Structured questionnaires were used to collect participants' sociodemographic and risk factor data. The prevalence of enterococcal infection was 23.3% (42/180), comprising 57.1% Enterococcus faecalis and 42.9% Enterococcus faecium. Subgroup analysis showed no significant association between the isolation rates and sample type (p=0.379). The frequency of enterococcal infection was significantly highest among patients aged 31-40 years (p<0.05), with a higher frequency among older patients. Moreover, unemployed patients (OR=1.8, p=0.0195) and those using pit latrines (OR=2.1, p=0.034) had significantly increased the odds of enterococcal infection. Enterococci resistance was highest against ampicillin (100%), tetracycline (90.5%), and ciprofloxacin (69%), with 83.3% exhibiting a multidrug-resistant (MDR) phenotype. Remarkably, 7.1% of all isolates were VR-E. faecium. Moreover, enterococci with a multiple antimicrobial resistance (MAR) index of 0.3 (45.2%) were predominant. A high level of MDR enterococci (including VRE) was identified in the clinical samples from patients initially managed for non-enterococcal infections, underscoring the need to use a selective bacteriological medium to minimize microbiological misdiagnosis in resource-limited healthcare settings. This study provides valuable local surveillance data indicating gaps in the integration of appropriate diagnostic bacteriology into clinical infectious disease practice.