Postoperative urinary tract infection and surgical site infection in instrumented spinal surgery: is there a link?

A potential relationship between postoperative urinary tract infection (UTI) and surgical site infection (SSI) following posterior spinal fusion and instrumentation (PSFI) was investigated. A retrospective review was performed of prospectively collected demographic, clinical and microbiological data of 466 consecutive patients (median age, 53.7 years (interquartile range (IQR) 33.8-65.6); 58.6% women) undergoing PSFI to identify those with UTI in the first 4 weeks and SSI in the first 12 weeks after PSFI. Overall, 40.8% had an American Society of Anesthesiologists score of >2, and 49.8% had undergone fusion of more than three segments. Eighty-nine patients had UTI, 54 had SSI, and 22 had both conditions. In nine of the 22 (38%) cases, the two infections were caused by the same microorganism. The urinary tract was the probable source of SSI by Gram-negative bacteria in 38% (8/21) of cases. On multivariate analysis, UTI (OR 3.1, 95% CI 1.6-6.1; P 0.001) and instrumentation of more than three segments (OR 2.7, 95% CI 1.1-6.3; P 0.024) were statistically associated with SSI. Patients receiving ciprofloxacin for UTI had higher microbial resistance rates to fluoroquinolones at SSIs (46.13%) than those without ciprofloxacin (21.9%), although the difference did not reach statistical significance (p 0.1). In our series, UTI was significantly associated with SSI after PSFI. On the basis of our results, we conclude that further efforts to reduce the incidence of postoperative UTI and provide adequate empirical antibiotic therapy that avoids quinolones whenever possible may help to reduce SSI rates and potential microbial resistance.