High Level Aminoglycoside Resistance and Distribution of Aminoglycoside Resistant Genes among Clinical Isolates ofEnterococcusSpecies in Chennai, India

Abstract

Enterococci are nosocomial pathogen with multiple-drug resistance by intrinsic and extrinsic mechanisms. Aminoglycosides along with cell wall inhibitors are given clinically for treating enterococcal infections. 178 enterococcal isolates were analyzed in this study.E. faecalisis identified to be the predominantEnterococcusspecies, along withE. faecium,E. avium,E. hirae,E. durans,E. disparandE. gallinarum. High level aminoglycoside resistance (HLAR) by MIC for gentamicin (GM), streptomycin (SM) and both (GM + SM) antibiotics was found to be 42.7%, 29.8%, and 21.9%, respectively. Detection of aminoglycoside modifying enzyme encoding genes (AME) in enterococci was identified by multiplex PCR foraac(6′)-Ie-aph(2′′)-Ia;aph(2′′)-Ib;aph(2′′)-Ic;aph(2′′)-Idandaph(3′)-IIIagenes. 38.2% isolates carriedaac(6′)-Ie-aph(2′′)-Iagene and 40.4% isolates carriedaph(3′)-IIIagene.aph(2′′)-Ib; aph(2′′)-Ic; aph(2′′)-Idwere not detected among our study isolates.aac(6′)-Ie-aph(2′′)-Iaandaph(3′)-IIIagenes were also observed in HLARE. durans,E. avium,E. hirae, andE. gallinarumisolates. This indicates that high level aminoglycoside resistance genes are widely disseminated among isolates of enterococci from Chennai.