Risk factors and skin colonization/recolonization – a matter in the development of sternal wound infection after cardiac surgery

Cardiac surgeries are classified as “clean procedures” as they do not involve access to any space populated by the patient’s microbiota. Nevertheless, the development of sternal wound infection (SWI) can sometimes occur. The aim of the study was to analyze risk factors of SWI, efficacy of antiseptics procedures, skin microbiota colonization/recolonization, and their impact on infection development in patients undergoing cardiac surgery.

Of 500 patients who had undergone cardiac surgery through a median sternotomy, perioperative swabs of standardized surgical cut area were taken at three-time points: ‘1’-after admission to treatment rooms, ‘2’-before incision; ‘3’-before chest reconstruction. Material was cultured and grown bacterial colonies were counted.

Out of the total population, 23 patients developed SWI and 11 had suspicion of SWI while 466 were without SWI. Risk factors which had statistically significant impact of infection development were high body mass index (BMI) and use of cardiopulmonary bypass (CPB) during operation. The most common SWI-pathogens were coagulase-negative staphylococci (CoNS) and Gram-negative bacilli. From the perioperative period, CoNS and Staphylococcus aureus were isolated. When simultaneous positive cultures in ‘swab-1 and -3’ were observed (respectively, ≥87 and ≥17 bacterial colonies), the risk of complications was higher (patients with SWI – 69.57%; without SWI – 6.71%). Regarding point ‘3’, significant differences were noted in the general level of grown colonies. About 3 times more bacterial colonies were grown in the group with healing problems and SWI. SWI development is multifactorial. The rate of skin microbiota recolonization during surgery may suggests that being more colonized in the surgical incision area was more susceptible to local complications.