Serum level of prophylactic antibiotics in cardiac surgery and its implication on surgical site infection (SSI).

Background: Surgical site infection in cardiac surgery is still common despite applying preoperative antibiotic prophylaxis as per guidelines. Therefore, the aim of our study was to assess the relationship between perioperative antibiotics serum levels and the incidence of surgical site infection.

Methods: This is a prospective study that included all adult patients who underwent elective coronary artery bypass grafting between June and December 2018. The serum antibiotics levels were measured at 4 different time points. The patients were divided into two groups: The group who developed surgical site infection and the group who did not develop surgical site infection. The serum antibiotics levels were compared between the two groups.

Results: Eighty-seven consecutive patients were enrolled in the study. The overall rate of infection was 17.95% (14/78 patients). High pre-operative HbA1C levels were associated with a higher rate of SSI (SSI 8.46 ± 2.23 vs no SSI 7.28 ± 1.82, P = 0.04). Patients who developed surgical site infection had longer intervals between administration of prophylactic antibiotics and different parts of the procedure than those who did not develop infection T2 (SSI 3.09 ± 1.12 vs no SSI 2.32 ± 0.98, P = 0.004), T3 (SSI 5.74 ± 1.69 vs no SSI 4.68 ± 1.83, P = 0.024) and T4 (SSI 7.35 ± 1.97 vs no SSI 6.01 ± 2.11, P = 0.015).

Conclusion: Prolonging different parts of cardiac surgery procedures could lead to higher risk of infection and better timing of intra-operative re-dosing of prophylactic antibiotics could be guided by measuring intra-operative serum concentrations of these antibiotics.