1586. A Comparative Analysis of In Vitro Susceptibilities of Vancomycin-Resistant Enterococci Against Doxycycline, Minocycline, Tigecycline, Eravacycline and Omadacycline

Abstract

BackgroundVancomycin-resistant Enterococci (VRE) are nosocomial pathogens that cause significant morbidity and mortality especially among patients with chronic medical conditions, critical illness and prolonged hospitalizations. Majority of human infections are caused by two species— E. faecium and E. faecalis, and which can acquire resistance to ampicillin, aminoglycosides, and vancomycin. Our aim was to study the susceptibility profile of the VRE strains to the tetracycline group of antibiotics on isolates collected from our local hospital. Older tetracyclines and their novel derivatives are included in this study.MethodsEighty preserved isolates of VRE were tested against five tetracyclines, i.e. doxycycline, minocycline, tigecycline, eravacycline and omadacycline. Antimicrobial susceptibility testing was performed using the E-test method in accordance to CLSI guidelines. Isolates were then classified as either susceptible, intermediately susceptible or resistant based on established breakpoints.ResultsEighty isolates (54 VRE. faecium and 26 VRE. faecalis) were included in the study. Out of 54 E. faecium isolates, 52 (96.3%) were susceptible to tigecycline, 15 (27.8%) were susceptible to minocycline, 14 (25.9%) were susceptible to doxycycline, 42 (77.8 %) were susceptible to omadacycline, and 52 (96.3%) were susceptible to eravacycline. Out of 26 E. faecalis isolates, 26 (100%) were susceptible to tigecycline, 2 (7.6%) were susceptible to minocycline, 2 (7.6%) were susceptible to doxycycline, 2 (7.6%) were susceptible to omadacycline, and 25 (96.15%) were susceptible to eravacycline.ConclusionTigecycline and eravacycline exhibited better in vitro antimicrobial activity against vancomycin-resistant E. faecium and E. faecalis when compared to doxycycline and minocycline. Omadacycline showed a relatively favorable susceptibility profile for E. faecium, but less favorable for E. faecalis. Results of this study will be useful to incorporate in the local antibiogram and will guide antimicrobial stewardship efforts. These findings will not only add to existing knowledge on susceptibility profiles of the novel tetracyclines, i.e. eravacycline and omadacycline, but also on their applicability in the clinical setting.Disclosures All Authors: No reported disclosures