Vancomycin intermediate-resistant Staphylococcus aureus

OBJECTIVE: To describe further details about the third reported case of vancomycin intermediate-resistant Staphylococcus aureus (VISA). CASE SUMMARY: A patient with a history of recurrent methicillin-resistant S. aureus (MRSA) bacteremia was treated with several courses of vancomycin for 18 of 23 possible weeks on an inpatient/outpatient basis. After 6 months of repeated courses, an isolate of MRSA showed a minimum inhibitory concentration of 8 micrograms/mL, indicating intermediate resistance to vancomycin. The patient continued to receive a vancomycin/aminoglycoside/rifampin regimen and, when he was hospitalized several weeks later, no further MRSA or VISA was detected. DISCUSSION: Prolonged, intermittent vancomycin use (18 of 23 possible weeks) for MRSA bacteremia on an inpatient/outpatient basis most likely contributed to the development of VISA. Infection control measures prevented the spread of VISA among patients and healthcare workers. CONCLUSIONS: Infection control measures and evaluation of antimicrobial prescribing need to be strongly enforced to further prevent the spread and development of resistant organisms.