Serratia and Surgical Site Infections: Risk factors and Epidemiology

Abstract

Background. Serratia spp. have been associated with surgical site infection (SSI) outbreaks associated with specific providers, topical creams and contaminated saline products. Patient risk factors for developing infection with this organism have not been extensively studied. We sought to evaluate risk factors for Serratia SSI. Methods. Cases of Serratia SSI occurring between 2012 and 2016 were identified via an infection control surveillance program. SSI was defined by National Healthcare Safety Network (NHSN) criteria. Controls were randomly selected individuals undergoing similar procedures during the same time frame without identified Serratia SSI. Data was analyzed using partitioning, student T test and chi‐square analysis to identify risk factors for Serratia SSI. Results. During the study period, 17 cases and 34 controls were identified, all of whom were cardiac or vascular surgery patients. Males were afflicted far more often than females (Relative risk 4.9, 95% CI 0.72‐33.37, P = 0.04) Cases were older (mean age [standard error] 55.1[3.40] vs. 66.3[4.92] years, P = 0.04), had longer operative times (238.1[19.1] vs. 212.5[28.2] minutes, P = 0.04), and a similar American Society of Anesthesiologist preoperative risk score (3.8[0.07] vs. 3.1[0.1], P = 0.83). We did not observe significant differences in body mass index, cardiopulmonary comorbidities, preoperative catheterization, or malignancy. In partition analysis, gender, (incision time >180 minutes and age >62) was all highly predictive of Serratia SSI risk (receiver operator characteristic 0.81). Other risk factors screened, including types of vascular access, specific surgeon(s) performing procedures, reoperation, open chest procedures and antecedent cardiac catheterization, were not significantly associated with an increased risk of serratia SSI's. Serratia SSI's were associated with a 29% 30‐day mortality rate, compared with 5.8% seen in controls (P = 0.02). Conclusion. Gender, operative time and age are associated with an increase in Serratia SSI risk. Serratia SSI is associated with a high mortality rate. Providers should be vigilant for this organism, particularly in older male patients undergoing complex cardiovascular surgical procedures.