infection control and hospital epidemiology september 2006, vol. 27, no. 9 original article Analysis of Risk Factors for Sternal Surgical Site Infection: Emphasizing the Appropriate Ventilation of the Operating Theaters Serap Simsek Yavuz, MD; Yesim Bicer, MD; Nihan Yapici, MD; Sibel Kalaca, MD; Osman Ozcan Aydin, MD; Gercek Camur, MD; Funda Kocak, MD; Zuhal Aykac, MD objective. To determine the incidence of and identify risk factors for sternal surgical site infection (SSI). design. Prospective cohort study. Data on potential risk factors, including the type of operating theater and infection data, were collected prospectively and analyzed by multivariate analysis. setting. Siyami Ersek Thoracic and Cardiovascular Surgery Hospital, a 700-bed teaching hospital and the largest center for cardiac surgery in Turkey. The cardiothoracic unit performs approximately 3,000 cardiac operations per year. patients. All adult patients who underwent cardiac surgery with sternotomy between January 14, 2002, and July 1, 2002, and who survived at least 4 days after surgery were included in the study. results. Potential risk factor data were complete for 991 patients. There was sternal SSI in 41 patients (4.1%). Female sex, diabetes mellitus, operation performed in the older operating theaters, and duration of procedure exceeding 5 hours were identified as independent risk factors for sternal SSI. conclusions. Female and diabetic patients are at higher risk for sternal SSI and should be followed up carefully after cardiac surgery to prevent the development of sternal SSI. Reducing the duration of surgery could reduce the rate of postoperative sternal SSI. The operating theater environment may have an important role in the pathogenesis of sternal SSI, and appropriate ventilation of the operating theaters would be critical in the prevention of sternal SSI. Infect Control Hosp Epidemiol 2006; 27:958-963 From the Departments of Infectious Disease and Clinical Microbiology, (S.S.Y., F.K.), Anesthesiology and Reanimation (Y.B., N.Y., O.O.A., Z.A.), and Cardiovascular Surgery (G.C.), Siyami Ersek Thoracic and Cardiovascular Surgery Hospital, Uskudar, and the Department of Public Health, School of Medicine, Marmara University, Haydarpasa (S.K.), Istanbul, Turkey. Received March 31, 2005; accepted June 14, 2005; electronically published August 14, 2006.  2006 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2006/2709-0013$15.00. Sternal SSI has been reported in 2%–10% of patients who undergo cardiac surgery with sternotomy. 1,2 To avoid sternal SSI after cardiac surgery, risk factors should be identified and eliminated if possible. Although numerous studies investi- gated the risk factors of sternal SSI, there is no universal agreement regarding any of the reported risk factors. In this study, risk factors for sternal SSI were investigated prospec- tively; standard definitions of sternal SSI were used. The type of operating theater was also investigated as a possible risk factor for sternal SSI. methods Patients and Setting All adult patients (age, 118 years) who underwent cardiac surgery with sternotomy at Siyami Ersek Thoracic and Car- diovascular Surgery Hospital (Uskudar, Turkey) between Jan- uary 1, 2002, and June 1, 2002, and who survived at least 4 days after surgery were included in the study. Siyami Ersek Thoracic and Cardiovascular Surgery Hos- pital is a 700-bed teaching hospital and the largest center for cardiac surgery in Turkey. The hospital has 2 buildings; the older one has been in use since 1968, and the new one was constructed at the beginning of this study. In each of the buildings, there are 6 operating theaters. Differences between the old and the new operating theaters were in the ventilation systems and the inner doors. Older operating theaters were equipped with plenum ventilation (which includes a positive pressure air supply from clean to less clean areas, with a total of 27 changes of high-efficiency filtered air per hour), whereas the newer ones were equipped with laminar-flow ventilation systems. The doors of the newer operating theaters were au- tomatic and were always kept closed except, occasionally, when there was movement through them. Although the doors of the older operating theaters were also automatic previously, they did not function properly any more and were generally left open. Surgical teams used each operating theater with equal frequency. Sterilization and disinfection of surgical in- struments was done in the same sterilization room. Infection