NEW YORK (Reuters Health) Preoperative screening for and treatment of asymptomatic bacteriuria (ASB) is not associated with a decrease in surgical site or urinary tract infections, researchers say.

Antibiotic use

This large study demonstrates that routine screening of urine for bacteria before major surgical procedures does not help patients who do not have symptoms of a urinary tract infection," said Dr. Kalpana Gupta of the VA Boston Healthcare System and Boston University School of Medicine. "This result supports ending this common practice and will reduce unnecessary testing and unnecessary antibiotic use," she told Reuters Health by email. "Because the antibiotics do not help and might hurt  there is no reason to give them." 

Dr. Gupta and colleagues studied 68,265 patients (96% men; mean age, 64.6) in 109 U.S. Department of Veterans Affairs healthcare facilities. About 26% had a urine culture result available within 30 days before cardiac, orthopedic, or vascular surgical procedures. Urine cultures were positive in 4.3% of tested patients, and 81.7% of these were classified as ASB, according to the JAMA Surgery report, online December 12.

After adjustment for age, American Society of Anesthesiologists class, smoking status, race/ethnicity, sex, and diabetes status, patients with or without ASB had similar odds of a surgical site infection (2.4% vs. 1.6%; adjusted odds ratio, 1.58). Antimicrobial therapy with activity against the ASB organism was not associated with reduced risk (aOR, 1.01).

Similarly, 3.3% of patients with ASB and 1.5% of those without had a urinary tract infection (aOR, 1.42), and treatment or prophylaxis for the ASB organism was not associated with reduced odds of postoperative infection (aOR 0.68). In two cases, the ASB organisms matched a postoperative wound culture, both Staphylococcus aureus.

Summing up, the authors state, "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."

"The major limitation of the study design is the small number of women included, due to the nature of demographics in the Veterans Health Administration," Dr. Gupta said. She also noted that the study "did not evaluate and does not impact existing recommendations" to screen and treat ASB in pregnant women and patients undergoing invasive urological procedures.

Dr. David Evans, Medical Director, Level 1 Trauma Center and Nutrition Support Service at The Ohio State University Wexner Medical Center in Columbus, said by email, "Postoperative infection is one of the most feared complications of surgery particularly surgical site infections that delay healing, cause pain, increase costs of care, and may infect an implant and require its removal."

"For this reason," he told Reuters Health, "surgeons try to avoid operating when there are any signs of current infection. Some practices, like swabbing the nose for evidence of MRSA colonization, have become commonplace. But checking the urine for preoperative infection has been more controversial."