Comprehensive Comparative Analysis of Enterococcus faecalis versus Enterococcus faecium Strains Isolated from Clinical Samples: A Retrospective Observational Study

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Bulut D., Karakoç H. n., Sencan İ.

Flora İnfeksiyon Hastalıkları ve Klinik Mikrobiyoloji Dergisi, vol.29, no.2, pp.280-288, 2024 (ESCI) identifier


Introduction: Enterococci, common human pathogens, are widespread in the body and environment. Indeed, Enterococcus faecalis and Enterococcus faecium are significant human pathogens, contributing to the rising incidence of nosocomial infections. This study aims to compare their occurrence and mortality in diagnosed infections, demonstrating predictive value when strain typing is not feasible, and contributing to empirical treatment literature. Materials and Methods: This study was conducted retrospectively on cases diagnosed and treated with healthcare-associated infections between 2015 and 2022 at a tertiary healthcare institution. The cases were categorized into bacteremia, urinary tract infections, pneumonia, and surgical site infections groups. Demographic, clinical, and laboratory characteristics of the cases, as well as the development/follow-up periods of the infections and mortality rates, were compared among the groups. Species identification was confirmed using conventional methods, VITEK® 2 Compact (bioMérieux, Marcy l’Etoile, France), and matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF MS) (Bruker Daltonics, Bremen, Germany). Data analysis was performed using SPSS Software Version 23, and p< 0.05 was considered significant. Results: Based on the data from the infectious diseases committee, a total of 4713 cases were followed up with a diagnosis of healthcare-associated infections. Among these cases, 528 (11.2%) were infected with Enterococcus spp. In Enterococcus infections, the causative agent was identified as E. faecalis in 290 cases (54.9%), E. faecium in 210 cases (39.8%), and other Enterococcus spp. in 28 cases (5.3%). Vancomycin resistance was assessed in 523 Enterococcus isolates, and resistance was detected in 26 cases (5%). The average age of the cases is 65.5 ± 17.8 years, with 49.1% of the included samples belonging to females. The prevalence of E. faecalis and E. faecium did not differ significantly based on gender and age (p= 0.709, p= 0.683). Around 54.5% of Enterococcus infections occurred before 2019 (p= 0.29), with the most common infections observed in the intensive care unit (ICU) (64.4%) and presenting as bloodstream infections (61.6%). The mean onset of infection was 25.3 ± 31.7 days. Upon analyzing the responsible microorganisms, no significant difference was found between E. faecalis and E. faecium (p> 0.05). Examining the risk factors for Enterococcus infections, it was observed that E. faecium was more frequently found in patients undergoing hemodialysis (p= 0.031). Conclusion: In our study, we analyzed E. faecalis and E. faecium isolates, finding shared characteristics. Enterococcus is linked to extended hospital stays and bloodstream infections. Hemodialysis patients face higher E. faecalis infection rates. Treating both pathogens empirically is crucial, considering the low vancomycin resistance.