Emergence in Asian Countries of Staphylococcus aureus with Reduced Susceptibility to Vancomycin

Abstract

To investigate the prevalence of Staphylococcus aureus with reduced susceptibility to vancomycin among methicillin-resistant S. aureus (MRSA) strains in Asian countries, a total of 1,357 clinical isolates of MRSA collected from 12 Asian countries were screened by using brain heart infusion agar plates containing 4 mg of vancomycin per liter. The presence of strains that were heterointermediately resistant to vancomycin (hVISA) was confirmed by population analysis. Of 347 (25.6%) MRSA isolates that grew on the screening agar plates, 58 isolates (4.3%) were hVISA. hVISA strains were found in India, South Korea, Japan, the Philippines, Singapore, Thailand, and Vietnam. However, neither vancomycin-intermediate S. aureus nor vancomycinresistant S. aureus isolates were found among MRSA isolates from Asian countries in this survey.

Reduced Vancomycin Susceptibility inStaphylococcus aureus, Including Vancomycin-Intermediate and Heterogeneous Vancomycin-Intermediate Strains: Resistance Mechanisms, Laboratory Detection, and Clinical Implications

“…After the first reports of VISA and hVISA from Japan, it did not take long for this resistance phenotype to be recognized around the world. Strains of S. aureus (predominately MRSA) demonstrating the hVISA or VISA phenotype have now been reported for many countries including the United States, Japan, Australia, France, Scotland, Brazil, South Korea, Hong Kong, South Africa, Thailand, Israel, and others (22,67,69,77,79,82,94,158,167,194,195,206,258,284,300,326,327,331,352,354,366,373). A retrospective analysis of stored isolates detected previously unrecognized hVISA/VISA strains at least back to 1987 in the United States and back to a similar period in France, Spain, and Germany (11,22,39,276,288); however, there has been some concern about the potential loss of resistance during prolonged storage, which could impact results of such retrospective analyses.…”

Phagocytosis and intracellular killing of heterogeneous vancomycin-intermediate Staphylococcus aureus strains

“…However, due to selective pressure, S. aureus isolates with decreased susceptibility to vancomycin have emerged (Song et al, 2004). The Clinical and Laboratory Standards Institute (CLSI) designates staphylococci requiring concentrations of vancomycin ¡2 mg l 21 for growth inhibition as susceptible, those requiring 4-8 mg l 21 as intermediately sensitive and those requiring ¢16 mg l 21 as resistant (CLSI, 2009).…”

Increased Vancomycin MICs for Staphylococcus aureus Clinical Isolates from a University Hospital during a 5-Year Period

“…Since then, six confirmed vancomycin-resistant S. aureus (VRSA) (MIC Ն 32 g/ml) (3-5, 30, 32; L. M. Weigel, personal communication) and at least 21 vancomycin-intermediate S. aureus (VISA) (17,33) strains have been documented in the United States. A considerable prevalence of heterogeneous VISA (hVISA), in which only a subset of the bacterial population expresses the resistant phenotype, has been reported among S. aureus isolates from various geographic and patient populations of the world (9,12,27,32,33).…”