The change of antibiotic resistance rates over the years in Enterococcus spp. isolated from clinical specimens

Abstract

Aims: The aim of this study was to retrospectively evaluate the change in antibiotic resistance rates of Enterococcus species isolated from various clinical samples of outpatients and inpatients in our hospital over the years. Methods: Between January 2018 and December 2021, various clinical samples sent to Tekirdağ Namık Kemal University Hospital Microbiology Laboratory from outpatients, inpatients and intensive care patients were retrospectively examined. The samples were inoculated on 5% sheep blood agar, chocolate agar and EMB agar media according to their types and incubated at 37°C. The blood cultures were performed by BACTEC 1280 System (Becton Dickinson, MA, USA). Bacterial identification and antimicrobial sensitivity tests were made using conventional methods and automated systems. Results: A total of 417 Enterococcus strains were isolated in our laboratory at four years and included in the study. Of the 417 isolates, 204 (48.9%) were isolated from male patients and 213 (51.1%) from female patients. The mean age of the patients was 57.79±22.9 years (0-96 years). It was determined that 36.9% of the isolates belonged to outpatients, 33.4% to inpatients and 29.7% to intensive care unit patients. Of the 122 enterococci isolates identified as species, 49.2% were typed as Enterococcus faecalis (E. faecalis) and 40.2% as Enterococcus faecium (E. faecium). Of the 417 isolates, 60.4% were isolated from urine samples, 24.2% from blood samples, and 8.9% from wound samples. Considering the total antibiotic resistance rates; ampicillin was 34.9%, ciprofloxacin was 46.4%, vancomycin was 8.4%, tigecline was 3.2%, high-level gentamicin was 49.0%. Linezolid and nitrofurantoin resistance were not detected. Ampicillin and vancomycin resistance rates were determined to have a statistically significant increase within four years. Ampicillin, ciprofloxacin, vancomycin and high-level gentamicin resistance rates were found to be significantly higher in isolates obtained from inpatients and intensive care patients compared to enterococcal isolates obtained from outpatients. Conclusion: In our study, it was determined that antibiotic resistance in enterococcal isolates, which are the causative agents of infection in our hospital, increased over the years. In this way, determining the change in antibiotic resistance rates is beneficial in determining appropriate antibiotic use policies. It is thought that conducting surveillance studies on antibiotic resistance periodically and taking new measures according to changing antibiotic resistance rates will be beneficial in terms of treatment.