Association of Screening and Treatment for Preoperative Asymptomatic Bacteriuria With Postoperative Outcomes Among US Veterans

Abstract

Importance: Limited data suggest that screening for asymptomatic bacteriuria (ASB) prior to nonurologic procedures is not useful. However, high-quality evidence to support consensus recommendations and influence clinical practice is lacking.

Objective: To characterize the association between detection and treatment of preoperative ASB and postoperative outcomes.

Design, setting, and participants: This retrospective cohort study involved patients, predominantly male veterans, who underwent surgical procedures in 109 US facilities within the US Department of Veterans Affairs health care system from October 1, 2008, to September 30, 2013. Participants included patients (n = 68 265) who had cardiac, orthopedic, or vascular surgical procedures. Each received a planned clinician review of complete medical records for antimicrobial prophylaxis as well as 30-day surgical-site infection (SSI) and urinary tract infection (UTI) outcomes, and each had a preoperative urine culture result available within the 30 days prior to the procedure. Data analysis was performed from December 2016 to August 2018.

Main outcome and measures: The primary outcome was the association between preoperative ASB and postoperative SSI. The secondary outcomes included postoperative UTI and the association between antimicrobial therapy for ASB and postoperative infectious outcomes.

Results: In total, 68 265 patients (65 664 [96.2%] were men and 2601 [3.8%] were women, with a mean [SD] age of 64.6 [9.2] years) were identified, and 17 611 (25.8%) were eligible for inclusion in the primary analysis. Preoperative urine cultures were performed in 17 749 (26.0%) patients, and the results were positive in 755 (4.3%), of which 617 (81.7%) were classified as ASB. With adjustments for age, American Society of Anesthesiologists class, smoking status, race/ethnicity, sex, and diabetes status, patients with or without ASB had similar odds of SSI (2.4% vs 1.6%; adjusted odds ratio [aOR], 1.58; 95% CI, 0.93-2.70; P = .08). Receipt of antimicrobial therapy with activity against the ASB organism was not associated with a reduced SSI risk (aOR, 1.01; 95% CI, 0.28-3.65; P = .99). Urinary tract infection occurred in 14 (3.3%) of 423 patients with ASB and 196 (1.5%) of 12 913 patients without ASB (aOR, 1.42; 95% CI, 0.80-2.49; P = .22). Treatment or prophylaxis for the ASB organism similarly was not associated with reduced odds of postoperative UTI (aOR 0.68; 95% CI, 0.20-2.30; P = .54). The ASB organisms matched a postoperative wound culture in 2 cases, both Staphylococcus aureus.

Conclusions and relevance: The findings of this study suggest that receipt of antimicrobial therapy with activity against ASB organisms identified in preoperative urine cultures was not associated with reductions in the risk for postoperative infections, including UTI and SSI; such findings suggest there is evidence for discontinuing the practice of screening and treatment for preoperative ASB.

Figure 1.. Diagram of Eligible and Included Patients

Figure 2.. Forest Plots of the Adjusted Risk for Each Selected Outcome in Patients With Preoperative Asymptomatic Bacteriuria (ASB)

Patients who received active antimicrobial therapy (ie, agent with in vitro activity against all pathogens in the ASB urine culture, and not necessarily an intent to treat the ASB pathogen) before surgery or as a surgical prophylaxis (n = 485; A), active antimicrobial therapy before surgery but not as a prophylaxis (n = 92; B), and active antimicrobial therapy as a surgical prophylaxis but not before surgery (n = 197; C). Each group was compared with those who did not receive active antimicrobial therapy against the ASB organisms before surgery or as a surgical prophylaxis (n = 132). OR indicates odds ratio; SSI, surgical site infection; UTI, urinary tract infection.