The quest to identify heterogeneously resistant vancomycin-intermediate Staphylococcus aureus strains

Definitive identification of heterogeneously resistant vancomycin-intermediate Staphylococcus aureus (hVISA) strains in the clinical microbiology laboratory has been an elusive goal for over a decade. Clinical data continue to affirm the importance of identifying hVISA strains in order to optimise antistaphylococcal therapy, especially for patients with infective endocarditis and other infections with high bacterial loads. Whilst the population analysis profile–area under the curve method can identify hVISA isolates with a high degree of accuracy, this method is not amenable to routine use in a clinical microbiology laboratory. Other methods to identify hVISA isolates lack sensitivity and/or specificity. Thus, the quest continues.