Occurrence of and microbiological findings in postoperative infections following open-heart surgery. Effect on mortality and hospital stay.

A prospective study of postoperative infectious complications after open-heart surgery was carried out in 885 patients. A total 200 postoperative infections occurred in 173 patients, an overall incidence was 19.5%. The mortality rate was 0.8%. The incidence of sternal wound infections was 7.7% (superficial 6.3% and deep 1.4%) and of leg wound infections 11.4%. Superficial sternal wound infections were associated with septicaemia in 10.7% and deep sternal wound infections in 33.3%. The leg wound infections caused no blood culture positive septicaemia. The incidence of urinary tract infections was 4.6% while respiratory tract infections occurred in only 2.5%. Early prosthetic valve endocarditis occurred in only one patient (0.3%). Staphylococcus aureus and epidermidis were the two bacteria most frequently cultured from sternal wound infections (82.4%), while gram-negative bacteria alone were seldom found (5.9%). In leg wound infections the incidence of gram-negative bacteria was greater (17.3%). Although E. coli was the causative agent in 37% of postoperative urinary tract infections the incidence of infection by the classical hospital-acquired organisms (klebsiella and pseudomonas) was also high (32%). Postoperative infections caused an average prolongation of hospital stay of 8 days. The increase was shortest for urinary tract infections (5 days) and longest in patients with postoperative mediastinitis (28 days).