Abstract

Background: Enterococci are considered as important causative pathogens of a variety of community and hospital-acquired infections. Due to the development of multidrug resistant (MDR) enterococci and the emergence of strains possessing high-level resistance to antimicrobial agents, treatment of their infections has been more complicated. In addition to more prevalent species of the Enterococcus genus, non-faecalisInonfaecium species are also responsible for severe healthcare-associated infections. Therefore, this study was designed to investigate high-level gentamicin resistance among the clinical isolates of non-faecalis and non-faecium enterococci in Shiraz, in the southwest of Iran. Methods: A total of 28 non-faecalislnon-faecium spp. were isolated from various infections. They were identified by the conventional methods. Antimicrobial resistance patterns, multidrug resistance, and high-level gentamicin resistance were determined, according to CLSI guidelines and related definitions. Detection of aminoglycoside resistance genes was also performed using standard procedures. Results: All of the isolates were MDR (100), and 75 of them were high-level gentamicin resistant (HLGR) (MIC >= 500 similar to mu g/mL). The distributions of aac(6')-Ie-aph(2 '')-Ia and aph(3)-IIIa resistance genes were 82.1 and 75, respectively. The aph (2 '')-Ib , aph (2 '')-Ic, aph (2 '')-Id, and ant(4)-Ia genes were not found in any isolate. Although vancomycin resistance was observed in 19 (67.8) isolates, all of the isolates were susceptible to linezolid and fosfomycin. Conclusions: Our data indicate a high rate of MDR non-faecalislnon-faecium isolates. Furthermore, high-level gentamicin resistance was notable and all of the HLGR isolates harbored at least one of aac(6)-Ie-aph(2')-Ia or aph (3 )-IHa resistance gene.