1437. Safety and Effectiveness of a Laboratory Intervention to Reduce Antibiotic Consumption in Patients with Asymptomatic Bacteriuria

Background Antibiotic (AB) therapy for asymptomatic bacteriuria (ASB) persists despite evidence of lack of benefit. In 2012, our hospital piloted an intervention to stop routinely reporting positive midstream urine (MSU) from inpatients since the majority of patients were asymptomatic. Following the pilot, we moved to rejecting all MSU unless a telephone request was received. We undertook the present study to establish the safety and assess the long-term impact of this change. Methods From November 2013 to April 2019, when MSU were received from surgical wards (two surgical wards added in May 2015) and medical wards (from August 2017) in our hospital, a message was posted noting that ASB should not be treated and a call to the lab was required to initiate specimen processing. Patients were interviewed, and charts were reviewed within 24h of specimen receipt and 4d later to identify urinary tract symptoms/infection (UTS/UTI) and systemic infection. Primary outcome was serious adverse events (AEs). Secondary outcomes were: rate of MSU submitted, impact on lab workload, AB use. Results 1,678 episodes with submitted MSU were included; 995/1,678 (60%) MSU cultures were not processed. Of 683 processed, 482 (71%) were negative. 1,111/1,678 (66%) patients were asymptomatic when MSU was ordered. 1,393/1,678 (83%) had negative culture (N = 482) or completed d4 follow-up (N = 911). No symptomatic UTI/sepsis/systemic infection occurred; the only AE identified were 4 patients with prolonged UTS which might have been prevented by MSU processing (4/911; 0.4% patients with AE). Rates of MSU submitted remained stable at 12 per 1,000 patient-days, P = 0.59 (Figure 1). Proportion of processed MSU decreased from 16/22, 73% in 2013 to 67/137, 49% in 2019 (Figure 2; P = 0.002). Overall, microbiology workload decreased by 5 person-days/year (fewer MSU processed, but staff needed to respond to telephone calls). 275/1,678 (16%) patients received AB for presumed UTI; 221 (80%) treated empirically, 54 (20%) in response to positive MSU. Of 69 patients with ASB whose MSU was processed and positive, 32 (46%) were prescribed antibiotics. Assuming that 21% of rejected MSU from asymptomatic patients would have been positive, AB therapy for ASB was avoided in 66 patients. Conclusion Rejecting MSU specimens does not result in harm, and reduces lab workload and AB therapy for ASB. Disclosures All authors: No reported disclosures.