Bacterial mediastinitis after heart transplantation: clinical presentation, risk factors and treatment.

Background: The incidence of mediastinitis after heart transplantation has been reported to be between 2.5% and 7.5%. Most previous reports from the transplant literature have assessed patients who had not received induction therapy.

Methods: From December 1996 to January 2002, a total of 230 heart transplants were performed using induction therapy with rabbit anti-thymocyte globulin at La Pitié Salpêtrière Hospital (Paris, France). Mediastinitis developed in 15 patients (6.5%). A case-control study was performed to characterize the clinical presentation, microbiology, risk factors and therapy of mediastinitis after heart transplantation.

Results: Only 4 patients (26%) had a temperature of >38 degrees C and 6 patients (40%) had a white blood cell count of >10,000 cells/mm(3). Septicemia (46%) and positive temporary epicardial pacing wires culture (60%) were frequently observed. Staphylococcus aureus (5 of 15), Staphylococcus epidermidis (5 of 15) and gram-negative bacteria (5 of 15) were the causative organisms cultured intra-operatively. Mean duration of mechanical ventilation (2.4 vs 1.6 days; p < 0.03) and use of ventricular assistance (20% vs 0%; p < 0.04) were different between cases and controls. The mortality rate at hospital discharge was 6.7% (1 of 15).

Conclusions: In the context of immunosuppression after heart transplantation, a high degree of suspicion is necessary to make the diagnosis of mediastinitis. Positive blood and temporary epicardial pacing wires cultures can be helpful in suggesting the presence of mediastinitis. Using vancomycin and an aminoglycoside as prophylaxis has to be considered because of the high prevalence of methilcilin-resistant S epidermidis and gram-negative bacteria. Conservative therapy (sternal debridement without muscle flap closure, and closed-chest drainage) showed excellent results in this series.