A protracted outbreak of Staphylococcus epidermidis infections among patients undergoing valve replacement.

OBJECTIVE: To investigate a Staphylococcus epidermidis outbreak among patients undergoing cardiac surgery. DESIGN: Retrospective cohort study. SETTING: A 260-bed community referral center. PATIENTS: Case-patients were patients with S. epidermidis mediastinitis, endocarditis, or both after valve implantation at Hospital de La Ribera from January to June 2002. The study population included patients undergoing valve surgery at Hospital de La Ribera from January 2000 to June 2002. RESULTS: From January to June 2002, 8 cases of mediastinitis, endocarditis, or both occurred among 53 patients undergoing cardiac surgery. In the same months of 2000, there had been no cases among 22 patients, and in 2001, only 1 case among 47 patients (P = .095 and P = .034, respectively). In 2002, there were 4 cases of mediastinitis and endocarditis, 3 cases of mediastinitis, and 1 case of endocarditis, all following aortic valve replacement. The epidemic curve suggested a protracted outbreak. Patients with chronic obstructive lung disease were six-fold more likely to be case-patients (95% confidence interval, 1.6-23.8). The mean duration of surgery tended to be longer in non-case-patients (161.4 +/- 57.9 minutes) than in case-patients (123.7 +/- 23.7 minutes) (P = .06). CONCLUSION: The cause of this protracted outbreak was likely multifactorial. Reemphasis of existing policies was associated with resolution of the outbreak.