Clinical profile and antibiotic susceptibility pattern of Enterococcus faecalis and Enterococcus faecium with an emphasis on vancomycin resistance

Abstract

Background: Enterococci are recognized as an important nosocomial opportunistic pathogens in recent times and are difficult to treat due to their intrinsic and acquired resistance to many antibiotics. In this study, we analyzed the clinical profile and antibiotic susceptibility pattern with an emphasis on vancomycin resistance among Enterococcus faecalis and Enterococcus faecium isolated from various clinical samples. Methods: This retrospective study was carried out in Sohar Hospital, Oman, after obtaining an ethical approval from the Ministry of Health, Oman. Enterococci isolates identified as E. faecalis and E. faecium from the positive bacterial culture in patients' suspicion of bacterial infection during the study period from January 2017 to December 2021 were analyzed. Details of the study population such as demography, clinical samples, and antibiotic susceptibility pattern of the enterococci isolates were extracted from the hospital electronic health record system. The data were entered into Microsoft Excel sheet, cleaned for errors, and statistically analyzed using Statistical Package for the Social Sciences (SPSS) version 26. The quantitative variables were expressed as mean ± standard deviation while qualitative variables presented as frequencies. Results: In total, 132 nonduplicate E. faecalis and E. faecium were studied. E. faecalis (68.9%) was the predominantly isolated species followed by E. faecium (31.1%). The frequency of isolation was more among females (54.5%) and elderly (47.7%) aged more than 60 years. Majority of enterococci were isolated from urine (49.6%), followed by blood (29.1%) and pus/wound swab (11.8%). All isolates were susceptible to linezolid, while all isolates showed resistance to clindamycin. None of the E. faecalis isolates exhibited resistance to vancomycin, while 13.5% of E. faecium isolates were resistant to vancomycin. E. faecium showed higher resistance to beta lactams, ciprofloxacin, and nitrofurantoin (>80%), while E. faecalis demonstrated low resistance to beta-lactams and nitrofurantoin (<10%). Conclusions: Linezolid and vancomycin were effective against Enterococci causing nosocomial infection in our tertiary care hospital. However, continuous and frequent surveillance for resistance patterns is critical for judicious and evidence-based use of antibiotics.