High-level resistance to aminoglycoside, vancomycin, and linezolid in enterococci strains

Abstract

Objective: This study sought to identify antibiotic susceptibility rates of enterococcal strains, and to compare the high-level resistance to aminoglycosides (HLAR) in vancomycin-sensitive enterococcal species (VSE) and vancomycin-resistant enterococcal species (VRE). Materials and Methods: The study included 100 VRE and 100 VSE strains recovered from the samples sent to laboratory from various departments of Haydarpasa Numune Training and Research Hospital. Results: All VRE strains were defined as Enterococcus faecium, although of the VSE strains, 53% were identified to be as Enterococcus faecalis, 42% E. faecium, 3% Enterococcus durans, and 2% Enterococcus avium. High-level resistance to vancomycin (MIC, >256 mg/ml) was determined in all VRE strains and when analyzing MIC values for teicoplanin, five strains were found to be moderately susceptible (MIC, 16 mg/ml) and 95 strains were resistant (MIC, >32 mg/ml). Of the VRE strains, one was linezolid-resistant (MIC, 12 mg/ml) and the other was intermediately susceptible (MIC, 4 mg/ml) and remainders were evaluated to be susceptible (MIC, <2 mg/ml). In VRE strains, high-level gentamicin resistance (HLGR) was found to be 83% and high-level streptomycin resistance (HLSR) 89%, association of HLSR with HLGR was 78%. In VSE strains, HLGR was found to be 42% and, HLSR 48%, the association of HLSR with HLGR was found to be 36%. HLAR in VRE strains was found to be higher as compared with VSE strains (p <0.005). Conclusion: Antimicrobial resistance is increasing in enterococci strains. Therefore a follow-up is required resistance pattern including both vancomycin resistance and HLAR.