Coagulase-negative staphylococci and sternal infections after cardiac operation

BACKGROUND: Coagulase negative staphylococci (CoNS) have been recognized as important pathogens in nosocomial infections, especially in connection with implanted foreign materials. In cardiac operation they are among the most common pathogens isolated from infected sternal wounds. The definition of the infection is very important. In this study we focus on deep postoperative chest infections. METHODS: By studying 33 infected patients retrospectively and comparing them to 33 matched uninfected controls, we studied the characteristics and costs of the infections. RESULTS: Typical for these infections is the late and insidious onset, and that the infections initially give only minor symptoms such as pain, redness, and serous secretion. We found the following risk factors for infection: number of preoperative days in a hospital, the total length of the operation, and if the patient had undergone an early reoperation due to causes other than infection. This kind of infection more than doubled the hospital costs for the patients affected. CONCLUSIONS: Coagulase negative staphylococci are the most important pathogens in deep postoperative infections in this material. They cause infections that are difficult to recognize since they give only discrete symptoms and start well after the patients leave the hospital. The risk factors for patients with CoNS infections are mostly associated with a long exposure to the hospital environment. The treatment is often difficult and costly because of multiresistant bacteria and frequent need for repeated surgical revisions.