No abstract

We report the results of a case-control study of post-surgical mediastinitis, that we conducted for eighteen months. The aim of the study was to detect possible risk factors for mediastinal infection after cardiovascular surgery as well as to analyze related clinical features. Thirty episodes of mediastinal infections over 687 consecutive cardiovascular surgeries (4,4%) were registered during a control period of 18 month at Hospital Italiano of Buenos Aires, Argentina. Among all variables analyzed only the following were significantly associated to mediastinal infection in the postoperative period: time elapsed at the recovery unit (p < 0.01) total time with catheter placed in the pulmonary artery (p: 0.05) and the rate of postoperative complications (p < 0.01). Six patients with mediastinal infection (20%) had undergone reoperation shortly after main surgery compared to only 3 (5%) in the control group (p: 0.05). The association with surgical events may be related to post-surgical causation. The presence of fever, only after 72 hours from surgery, allowed discrimination between patients with and without mediastinal infection. All case patients showed abnormalities in surgical wound, and 28 of these patients (93%) had at least two local signs of infection. Among the 37 types of microorganisms isolated from sternal secretion, 22 (59%) were gram-positive cocci, with Staphylococcus as the predominant genus. While 40% of the recovered gram-positive bacteria were methicillin-resistant, only 50% of the gram-negative bacteria were sensitive to aminoglycosides and ceftazidime. The in-hospital time was significantly longer in patients with mediastinitis compared to control patients (p < 0.001). The mortality rate inpatients mediastinitis was 33%. In conclusion, mediastinal infection actually remains representing a severe and costly complication of cardiovascular surgery due to its high morbidity and mortality rates.