COAGULASE-NEGATIVE STAPHYLOCOCCAL STERNAL WOUND INFECTIONS AFTER OPEN-HEART OPERATIONS

Background. Coagulase-negative staphylococci are commonly isolated fro m wounds of patients after median sternotomy; however, the epidemiolog y of these infections is poorly described and the morbidity, mortality , and cost of care remain undefined. Methods. Retrospectively, we stud ied all patients with sternal wound infections attributable to coagula se-negative staphylococci after 22,180 open heart procedures performed at the Cleveland Clinic between January 1, 1988, and December 31, 199 4 (84 months). In an assessment of potential risk factors for sternal wound infections caused by coagulase-negative staphylococci, 17 patien ts with coagulase-negative staphylococcal sternal wound infections wer e compared with 29 patients who underwent open heart operations withou t subsequent sternal wound infections, as well as with another 22 pati ents in whom sternal wound infections attributable to other pathogens developed. Results. A total of 436 sternal wound infections were ident ified (19 per 1,000 procedures), of which 100 (23%) were attributable to coagulase-negative staphylococci (4.5 per 1,000). Fifty-six percent of coagulase-negative staphylococcal sternal wound infections were su perficial, 27% were deep, and 17% represented mediastinitis; 14% of pa tients had a concomitant secondary bloodstream infection. Ninety-two p ercent of coagulase-negative staphylococcal isolates were methicillin resistant. The mean interval from operation to onset of infection was 24 days (range, 4 to 388 days), and most patients had purulent dischar ge from the chest wound, fever, and leukocytosis. Adverse outcomes inc luded reexploration (39%), flap operation (12%), and sternectomy (5%); 89% required parenteral antibiotics for a mean of 22 days. This resul ted in 2,600 additional hospital days, with an average additional dire ct cost per case of $20,000. In both case-control studies, insulin-dep endent diabetes mellitus was the only risk factor significantly associ ated with sternal wound infections attributable to coagulase-negative staphylococci (p value = 0.02 by two-tailed Fisher's exact test). Conc lusions. Sternal wound infections attributable to coagulase-negative s taphylococci had a substantial impact on cardiothoracic surgery-relate d morbidity. (C) 1997 by The Society of Thoracic Surgeons.