Predictors of Post-operative Urinary Tract Infection after Bariatric Surgery

Zachary M Helmen, BS, Melissa C Helm, BS, Joseph H Helm, MD, Alexander Nielsen, BS, Matthew E Bosler, BA, Tammy Kindel, MD, PhD, Jon C Gould, MD. Medical College of Wisconsin

Introduction: Urinary tract infections (UTIs) are a common post-operative complication. Patient factors and perioperative processes may contribute to an increased risk of UTI within 30 days of surgery. The purpose of this study was to assess the incidence and risk factors associated with UTIs in bariatric surgery patients.

Methods and Procedures: This study was a retrospective analysis of adult patients who underwent bariatric surgery at a single program between March 2012 and June 2016. Patients were identified using the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program database. Standard protocol was antibiotic prophylaxis with Ancef, whereas patients with a penicillin allergy typically received clindamycin. Foley catheters were placed selectively when a long operating room time was anticipated, most often in revision cases. The occurrence of 30-day (±2 weeks) post-operative UTI was the primary outcome, defined as an infection in the urinary tract in which antimicrobial therapy was instituted.

Results: Bariatric surgery was performed in 694 patients, 574 (82.7%) females and 120 (17.3%) males. UTI was observed in 31 (5.4%) females and 2 (1.7%) males. Gram-negative bacteria accounted for 96.3% of UTIs (64% E.coli). On univariate analysis age, OR time, placement of a Foley catheter, prophylaxis with clindamycin, and revisional surgery were significantly correlated with UTI. A multivariate logistic regression model revealed that clindamycin prophylaxis, revision surgeries, and age were statistically significant in predicting UTIs in female patients. The risk of getting a UTI increased 4.83-fold [95% CI: 2.27-10.31] with clindamycin use, 5.52-fold [95% CI: 1.96-15.63] with revision surgery, and 1.23-fold [95% CI: 1.04-1.45] for every 5 years gained in age. Foley catheter use and OR time were significantly correlated with revision procedures and therefore were not included in the model.

Conclusions: Older age, clindamycin as prophylaxis, and revision procedures comprised the main risk factors for predicting UTIs in women who undergo bariatric surgery in this experience. While revision procedures alone are not likely the cause of UTIs, they are associated with longer surgeries and consequently, Foley catheters. Clindamycin monotherapy may leave patients susceptible to gram-negative organisms. In patients with a penicillin allergy, the use of combination therapy (clindamycin with an aminoglycoside) may be effective in decreasing the observed rate of UTI. This combination is affordable and supported by the Surgical Care Improvement Project (SCIP) guidelines. Other modifiable risk factors such as avoidance of an indwelling catheter and limiting catheter duration should be considered.