RESEARCH ARTICLE Vancomycin Tolerant, Methicillin-Resistant Staphylococcus aureus Reveals the Effects of

Methicillin-resistant Staphylococcus aureus (MRSA) is an important opportunistic pathogen that causes both healthcare- and community-acquired infections. An increase in the inci-dence of these infections may lead to a substantial change in the rate of vancomycin usage. Incidence of reduced susceptibility to vancomycin has been increasing worldwide for the last few years, conferring different levels of resistance to vancomycin as well as producing changes in the cell wall structure. The aim of the present study was to determine the effect of vancomycin on cell wall thickening in clinical isolates of vancomycin-tolerant (VT) MRSA obtained from pediatric patients. From a collection of 100 MRSA clinical isolates from pedi-atric patients, 12 % (12/100) were characterized as VT-MRSA, and from them, 41.66 % (5/ 12) exhibited the heterogeneous vancomycin-intermediate S. aureus (hVISA) phenotype. Multiplex-PCR assays revealed 66.66 % (8/12), 25 % (3/12), and 8.33 % (1/12) of the VT-MRSA isolates were associated with agr group II, I, and III polymorphisms, respectively; the II-mec gene was amplified from 83.3 % (10/12) of the isolates, and themecIVa gene was amplified from 16.66 % (2/12) of the isolates. Pulsed field electrophoresis (PFGE) fingerprin