Rapid Spread of Methicillin-resistant Staphylococcus Aureus in a New Hospital in the Broad-spectrum Antibiotic Era

Objectives: It has been known that it takes a long time for methicillin-resistant Staphylococcus aureus (MRSA) to introduce and become endemic within a hospital. During the last decade, widespread use of broad-spectrum antibiotics might have affected the time required for MRSA to spread and become endemic in hospitals. However, there has been no report on this issue. We investigated how fast MRSA has spread and become endemic in a hospital opened in the broad-spectrum antibiotic era.

Methods: The study was performed at a Korean hospital, which opened in 1999. We examined the change of antimicrobial susceptibility and antimicrobial use density (AUD) for 6 years since hospital opening.

Results: S. aureus susceptibility to oxacillin decreased from 64% in the first month to 33% in the second month (P=.05), and then has maintained around 30%. AUD was remarkably high from the first year, in which total AUD and those of aminopenicillins, second-generation cephalosporins, fluoroquinolones, and macrolides were 4674.6, 1444.6, 1700.9, 421.3, and 520.0 DDD/1000 patient-days, respectively.

Conclusions: MRSA has spread within a few months in a hospital opened in the broad-spectrum antibiotic era. Excessively high use of broad-spectrum antibiotics seems to be responsible for rapid spread of MRSA in the hospital.