Journal of Pure and Applied MicrobiologyVol. 8 No. Special Edition Nov. 2014

Effects of Linezolid on Suppressing Heteroresistant Vancomycin Subpopulations among Heteroresistant Vancomycin Intermediate Staphylococcus aureus (hVISA)

Issam Alshami1, Ahmed Eid Alharbi1, Nada Abdelmohsen Abdel-Aziz1,2, Kawther Mohammed Ibrahim1,3 and Rehab Abdallah Eltahlawi4

1Department of Medical Microbiology and Immunology, College of Medicine, Taibah University, Saudi Arabia. 2Department of Medical Microbiology and Immunology, Sohag Faculty of Medicine, Sohag University, Egypt. 3Department of Medical Microbiology and Immunology, Ain Shams Faculty of Medicine, Ain Shams University, Egypt. 4Department of Medical Microbiology and Immunology, Faculty of Medicine, Zagazig University, Egypt.

Received on 29 August 2014 and accepted on 21 October 2014

 

ABSTRACT

Infections due to heterogeneous Vancomycin Intermediate Staphylococcus aureus (hVISA) are associated with vancomycin treatment failure, in which they raise a great concern for treatment options for hVISA infections. Earlier studies indicate that the combination of vancomycin and linezolid should be avoided. The aim of this study was to compare the in vitro activities of vancomycin and linezolid against hVISA in a setup, to help formulate a better treatment and reduce the emergence of hVISA. In this particular study, 8 hVISA were studied. Different methods were applied to all the isolates in order to assess their tolerance to vancomycin and to detect the presence of heterogeneous subpopulations within strains, in the presence of different concentrations of linezolid. The methods included minimum inhibitory concentration, Time-Kill experiments and Population Analysis Profiling. When linezolid was combined with vancomycin, slight or no antagonism was observed. Despite this, we find that the combination with linezolid reduces the emergence of heteroresistant vancomycin resistant among hVISA. Despite previous studies indicating that vancomycin and linezolid in combination should be avoided, Sub MIC of Linezolid could be used to reduce vancomycin treatment failures among hVISA infections.

Keywords : Linezolid, Vancomycin MRSA, VISA, hVISA.