Seasonal variation in incidence and causal organism of surgical site infection after PLIF/TLIF surgery: A multicenter study

Postoperative SSI is a common and potentially serious complication in spine surgery. Seasonal variation occurs in rates of nosocomial infection, with higher rates found in the summer, during which hot, humid conditions may be optimal for proliferation of bacteria. This might also influence the rate of SSI. The purpose of the study was to examine seasonal variation in SSI after PLIF/TLIF surgery, including relationships with experience of surgeons and causal organisms. Cases with SSI after PLIF/TLIF surgery at 10 facilities between January 1, 2012, and December 31, 2014 were retrieved from a database. Infection was defined based on CDC guidelines for SSIs. Patients were followed for at least two years after surgery. Surgeries were examined in spring (April–June), summer (July–September), autumn (October–December), and winter (January–March). Seasonal variation and other factors with a potential association with SSIs were evaluated. A total of 1174 patients (607 males, 567 females) who underwent PLIF/TLIF surgery were identified. The operations were PLIF (n = 667), TLIF (n = 443), MIS-PLIF (n = 27), and MIS-TLIF (n = 37). The total SSI rate for the 2-year period was 2.5% (29/1174), and the 2-year average SSI rates for surgeries in each season were spring, 2.6% (7/266); summer, 3.9% (13/335); fall, 1.3% (4/302); winter, 1.8% (5/271). The SSI rate was significantly higher in summer than non-summer (3.9% vs. 1.9%, p