Vancomycin-intermediate and -resistant Staphylococcus aureus: What the infectious disease specialist needs to know

Ever since the first strain of Staphylococcus aureus with reduced susceptib ility to vancomycin and teicoplanin was reported from Japan, there has been a lot of confusion regarding the laboratory and clinical approach to patie nts with infections due to S. aureus with reduced susceptibility to vancomy cin. To date, 6 clinical infections with vancomycin-intermediate S. aureus (VISA) have been reported in the United States. Intermediate resistance app ears to develop from preexisting strains of methicillin-resistant S. aureus in the presence of vancomycin, and all but 1 infection occurred in patient s with exposure to dialysis for renal insufficiency. Detection of VISA is d ifficult in the laboratory, and special inquiries about susceptibility test ing methods may be needed. These VISA-infected patients had underlying illn esses, and their infections did not appear to respond well to conventional treatment. Prevention strategies have been outlined. Without continued vigi lance in enforcing infection-control measures, improved use of antimicrobia ls, and coordination of efforts among public health authorities, increasing levels of vancomycin resistance in S. aureus are likely to be encountered.