Sustained Combinatorial Antibiotic Delivery Against Gram Positive and Gram Negative Pathogens for Preventing Mediastinitis

Abstract

Open-heart surgery requires opening the sternum or the chest bone across the centre to access the heart and other vessels. This process is termed median sternotomy and is reported to cause complications like mediastinitis, sternal dehiscence, osteomyelitis, and soft tissue wound infection. Mediastinitis, or deep sternal wound infection, is the most frequent and expensive complication after cardiac surgery. Currently, sternal closure after cardiac surgery is done using wire cerclage, and hemostasis is attained using electrocautery and bone wax. Several studies have reported that bone wax can act as a source for initiating infection. Globally, it results in an infection level of 75.8% by Staphylococcal infections and 18.8% by Gram-negative rods. Considering the Indian scenario, Gram-negative infections caused by Escherichia coli and Klebsiella pneumoniae are more prevalent in mediastinitis. Even though the incidence is low, the possibility of mediastinitis is on the rise by 10-40%, resulting in a mortality rate of 15%. Bacterial contamination on the sternal wound site can affect the healing process. The patients undergoing cardiac surgery are at the risk of infections due to the impairment of the immune response and potential entry of bacterial pathogens. The infection is usually present with systemic or local signs. Inadequate control measures to manage infected sternal wounds will lead to inflammation, bacteremia, and septicemia, both of which can be fatal. A combination of antibiotics is prescribed before and after cardiac surgery to prevent infections from intra-operative technique contaminations. The clinical usage of vancomycin as a topical agent for hemostasis and mediastinitis is also reported, but it is not reported to be very effective in reducing infections, and it lacks activity against Gram-negative bacterial infection. Even though sufficient sterile steps are taken during pre-and post-operative conditions to prevent infections, there are certain cases where this causes dreadful complications. .