Study on Bacteria and Factors Involved in Wound Infections after Cardiac Surgery in Shahid Madani Hospital

Surgical wound infection is one of the important complications of cardiac surgery. Several risk factors including obesity and diabetes are associated with wound infection. The aim of the present study was to evaluate the wound infections after cardiac surgery, related risk factors and pattern of antibiotic resistance of the bacteria. Patients were divided into two groups; wound infection (case) group and without infection (control) group. Swabs from wound secretion and tissues of sternum were prepared for culture by standard methods. After obtaining colonies and Gram staining, using biochemical test and several differential tests, bacteria were identified. Sensitivity to antibiotics was examined by disk diffusion method (modified Kriby-Bauer). In this period, 2127 patients underwent cardiac surgery in Shahid Madani hospital. The incidence rate of wound infection was 1.17%. In the study period, 11 patients (44%) of case group died of mediastinitis. The only independent predicting factors for wound infection were long-time intubation and use of vasoconstrictors. Complications seen in the case group were mediastinitis (56%), wound infection (40%) and foot infection (4%). Organisms isolated from infection sites were mainly Staphylococcus aureus, Entrobacter spp., Pseudomonas aeroginosa and Staphylococcus epidermidis. Antibiogram results showed that bacteria had the most sensitivity to ciprofloxacin, cefotaxime, amicacine and cefteriaxone. In this study, long-time intubation and use of vasoconstrictors were predictors of wound infection in all cardiac surgery patients. The incidence of wound infection might be reduced by improving intubation time or quality of intubation period and use of vasoconstrictors as needed.