Antimicrobial therapy for asymptomatic bacteriuria (ASB) is recommended for pregnant patients and those undergoing genitourinary procedures. In other populations, treatment has not been demonstrated to confer benefit and is associated with adverse drug reactions, selection for infection with increasingly drug-resistant bacteria, and Clostridium difficile infection. We undertook a prospective audit of urine culture ordering practices among medical and surgical inpatients at 2 acute care teaching hospitals to identify the proportion of urine cultures ordered without clinical indication that lead to antimicrobial therapy for ASB.

During August and September 2012, consecutive urine cultures from nonpregnant ward patients were identified within 24 hours of culture ordering. Each patient was interviewed by the study team to determine the presence of urinary tract infection (UTI) using standard surveillance criteria. Non-catheterized patients met clinical indications for UTI if they had fever (temperature >38°C) without another explanation or at least 1 urinary symptom (dysuria, urgency, frequency, costovertebral angle tenderness, or suprapubic pain or tenderness). Catheterized patients met clinical indications for UTI if they had fever, suprapubic pain, or costovertebral angle tenderness. Other reasons for ordering cultures were documented on the basis of care provider interviews before culture results were known. Culture results and antimicrobial prescriptions were documented 72 hours later. The study was approved by the research ethics boards of Mount Sinai Hospital (472 beds) and University Health Network (408 beds; Toronto General Hospital site).