Mediastinitis in cardiac surgery: A review of the literature

[Local infectious complications in cardiac surgery: etiology and the role of antimicrobial prophylaxis]

OBJECTIVE

To investigate the relationship between antimicrobial prophylaxis protocol, prevalence and etiology of local infectious complications after open cardiac surgery.

MATERIAL AND METHODS

A retrospective cohort observational study was performed between 2010 and 2019 at the Ural Institute of Cardiology. Antimicrobial prophylaxis was performed using the main (cefuroxime 1.5 g IV every 6 hours) and alternative protocols (vancomycin 15 mg/kg IV every 12 hours).

RESULTS

The prevalence of local infectious complications throughout the entire follow-up period was 4.5±0.3% [95% CI 4.45-4.54]. There were 42 cases of deep infection (0.9±0.13%). Coagulase-negative staphylococci prevailed (15.9±2.5% of cases, 35 cultures). Resistant flora included coagulase-negative methicillin-resistant staphylococci (13 cultures, 37.1±8.2%) and representatives of Enterobacteriaceae family, producers of extended-spectrum beta-lactamase (8 cultures, 50.0±18.2%). Antimicrobial prophylaxis with vancomycin increases the risk of local infectious complications (OR 1.75, 95% CI 1.20, 2.55, p=0.001). Both protocols of antimicrobial prophylaxis demonstrated comparable efficacy against gram-positive and gram-negative microorganisms.

CONCLUSION

Coagulase-negative staphylococci are the most common cause of local infectious complications in cardiac surgery. Modern antimicrobial prophylaxis regimens are relevant despite resistant flora.

Recent developments in controlling sternal wound infection after cardiac surgery and measures to enhance sternal healing

One of the major risks of cardiac surgery is the occurrence of infection at the sternal wound site. Sternal wound infections are primarily classified into superficial infection and deep sternal wound infection or mediastinitis. A patient is diagnosed with mediastinitis if microorganisms are present in their mediastinal tissue/fluid or with the observation of sternal wound infection during operation and with characteristic symptoms including chest pain, fever, and purulent drainage from the mediastinum. It is usually caused by Staphylococcal organisms in 75.8% of cases and the rest is caused by gram-negative bacteria. Currently, in cardiac surgery, hemostasis is achieved using electrocautery and bone wax, and the sternum is closed using wire cerclage. Several studies show that bone wax can act as a nidus for initiation of infection and the oozing blood and hematoma at the site can promote the growth of infectious organisms. Many research groups have developed different types of biomaterials and reported on the prevention of infection and healing of the sternum. These materials are reported to have both positive and negative effects. In this review, we highlight the current clinical practices undertaken to prevent infection and bleeding as well as research progress in this field and their outcomes in controlling bleeding, infection, and enhancing sternal healing.