Safety of targeted perioperative mupirocin treatment for preventing infections after cardiac surgery.

BACKGROUND: Indiscriminate antibiotic use may lead to development of antibiotic resistance. Preoperative mupirocin treatment decreases Staphylococcus aureus carriage and may reduce subsequent surgical site infection, but is unlikely to benefit noncarriers. This study was undertaken to evaluate whether avoiding mupirocin in noncarriers places them at increased risk for subsequent postoperative infection. METHODS: We conducted a retrospective cohort study examining incidence of postoperative infection in patients undergoing cardiac surgery at the Cleveland Clinic after introduction of a protocol of polymerase chain reaction screening for nasal S aureus carriage, and avoiding mupirocin treatment of noncarriers. RESULTS: Between August 1, 2002, and May 31, 2004, 6,334 patients were screened for nasal carriage of S aureus before undergoing cardiac surgery. There was no significant difference in infection rates between carriers and noncarriers when examining the incidence of all infections (5.6% and 5.0%; relative risk [RR] 1.11 [95% confidence interval (CI): 0.86 to 1.43]), infections caused specifically by S aureus (1.04% and 0.80%; RR 1.30 [95% CI: 0.71 to 2.39]), any surgical site infection (3.1% and 3.2%; RR 0.97 [95% CI: 0.69 to 1.36]), S aureus surgical site infection (0.82% and 0.58%; RR 1.41 [95% CI: 0.71 to 2.82]), any bloodstream infection (3.1% and 2.5%; RR 1.21 [95% CI: 0.86 to 1.71]), and S aureus bloodstream infection (0.37% and 0.48%; RR 0.77 [95% CI: 0.30 to 2.03]). Mupirocin use declined substantially after introduction of the protocol. CONCLUSIONS: A strategy of targeting perioperative mupirocin treatment to carriers leads to significant reduction in mupirocin use without increasing early postoperative infectious complications in noncarriers.

Predictive value and cost-effectiveness analysis of a rapid polymerase chain reaction for preoperative detection of nasal carriage of Staphylococcus aureus.

OBJECTIVE: To determine the accuracy and cost-effectiveness of a polymerase chain reaction (PCR) for detecting nasal carriage of Staphylococcus aureus directly from clinical specimens. CROSS-SECTIONAL STUDY: This occurred in a tertiary-care hospital in Cleveland, Ohio, and included 239 consecutive patients who were scheduled for a cardiothoracic surgical procedure. Conventional cultures and a PCR for S. aureus from nasal swabs were used as measurements. COST-EFFECTIVENESS ANALYSIS: Data sources were market prices and Bureau of Labor Statistics. The time horizon was the maximum period for availability of culture results (3 days). Interventions included universal mupirocin therapy without testing; initial therapy, with termination if PCR negative (treat-PCR); initial therapy, with termination if culture negative (treat-culture); treat PCR-positive carriers (PCR-guided treatment); and treat culture-positive carriers (culture-guided treatment). The perspective was institutional and costs and the length of time to treatment were outcome measures. RESULTS: Sixty-seven (28%) of the 239 swabs grew S. aureus. Rapid PCR was 97.0% sensitive and 97.1% specific for the detection of S. aureus. For populations with prevalences of nasal S. aureus carriage of up to 50%, the PCR assay had negative predictive values of greater than 97%. PCR-guided treatment had the lowest incremental cost-effectiveness ratio (1.93 dollars per additional day compared with the culture strategy). Among immediate treatment strategies, treat-PCR was most cost-effective. The universal therapy strategy cost 38.19 dollars more per additional day gained with carrier identification compared with the PCR strategy. CONCLUSION: Rapid real-time PCR is an accurate, rapid, and cost-effective method for identifying S. aureus carriers for preoperative intervention.