Antibiotic use linked to MRSA risk

Patients with Staphylococcus aureus who have been treated with antibiotics within the past three months may be at an increased risk for methicillin-resistant S. aureus, according to results of a three-year study examining predictors of MRSA.

The study, presented by Rosie Lyles, MD, examined 193 patients with serious S. aureus infections who were treated at John H. Stroger, Jr. Hospital in Chicago from 2004 to 2006. Forty percent of these patients had the methicillin-resistant form of S. aureus.

The results demonstrated that patients who had been treated with an antibiotic within the past three months were at an increased risk for MRSA. Treatment with beta-lactam antibiotics was associated with a 6.3% increased risk for MRSA; treatment with fluoroquinolones was associated with a 4.45% increased risk.

Higher mean arterial pressure – defined as 1.07 per 5 mm Hg increase – was also associated with an increased risk for MRSA. Hispanic ethnicity was associated with a decreased risk for MRSA.

Presented at: ICAAC/IDSA joint meeting. Oct. 25-28, 2008. Washington, DC.