Linezolid Activity Against Clinical Gram-Positive Cocci With Advanced Antimicrobial Drug Resistance in Iran Publisher Pubmed



Houri H¹ ; Kazemian H^{2, 3} ; Sedigh Ebrahimsaraie H⁴ ; Taji A⁴ ; Tayebi Z⁵ ; Heidari H⁴ Show Affiliations
Source: Journal of Global Antimicrobial Resistance Published:2017

Abstract

Objectives The aim of the study was to investigate the linezolid activity against clinical Gram-positive cocci with advanced antimicrobial drug resistance. Methods A collection of methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant enterococci (VRE), penicillin non-susceptible Streptococcus pneumoniae (PNSP), and group B streptococci (GBS) were isolated from various clinical samples. Antimicrobial susceptibility tests were done using standard methods Subsequently, we investigated linezolid antibacterial activities, the first approved oxazolidinone against isolates by the standard broth microdilution method. Results According to our results, MRSA and PNSP isolates were multidrug resistant, and almost half of the VRE isolates were high level gentamicin resistant (HLGR). Furthermore, resistance to linezolid was not seen among the isolates. The MIC90 values for MRSA, VRE, PNSP and GBS isolates were 4 μg/ml, 2 μg/ml, 1 μg/ml, and 0.5 μg/ml, respectively. Only 6.25% of vancomycin resistant enterococci showed intermediate susceptibility to this antibiotic. Conclusions These findings indicate that linezolid has an excellent activity against clinical drug resistant Gram-positive isolates in Iran. Constant monitoring and surveillance of linezolid MIC distribution allows the researchers to assess and detect gradual upward MIC drifts. © 2017 International Society for Chemotherapy of Infection and Cancer