Objective: To assess the safety, sustainability, and effectiveness of a laboratory intervention to reduce processing of midstream urine (MSU) cultures.
Design: Prospective observational cohort.
Setting: Medical and surgical inpatients in a tertiary-care hospital.
Participants: The study included 1,678 adult inpatients with an order for MSU culture.
Methods: From 2013 to 2019, ordered MSU cultures were not processed unless the laboratory was called. Patients were interviewed on days 0 and 4; from 2017 to 2019, day-30 follow-up was added. Primary outcome was serious adverse events due to not processing MSU cultures. Secondary outcomes were nonserious adverse events due to not processing MSU cultures, rates of MSU cultures submitted, proportion of MSU cultures processed, proportion of patients prescribed urinary tract infection (UTI)-directed antibiotics, and laboratory workload.
Results: Among 912 and 459 patients followed to days 4 and 30, respectively, no serious adverse events attributable to not processing MSU cultures were identified. However, 6 patients (0.66%) had prolonged urinary symptoms potentially associated with not processing MSU cultures. We estimated that 4 patients missed having empiric antibiotics stopped in response to negative MSU cultures, and 99 antibiotic courses for asymptomatic bacteriuria (ASB) and 8 antibiotic-associated adverse events were avoided. The rate of submitted MSU samples and proportion of patients receiving empiric UTI-directed antibiotics did not change. The proportion of MSU cultures processed declined from 59% to 49% (P < .0001), and total laboratory workload was reduced by 185 hours.
Conclusions: De-adopting the processing of MSU cultures from medical and surgical inpatient units is safe and sustainable, and it reduces antibiotic prescriptions for ASB at a cost of prolonged urinary symptoms in a small proportion of patients.