Association of systemic antimicrobials with the expression of beta-lactamases in bacteria cultured from urological patients.

BACKGROUND: Patients with abnormalities of the genitourinary tract are at high risk for infections with antimicrobial-resistant pathogens. METHODS: All urine cultures ordered by members of the Division of Urology from four quarterly one-week periods were included. All gram-negative bacilli isolated were analyzed using the Check-Points Check-MDR CT103XL assay to identify the presence of genes associated with resistance to beta-lactam antibiotics. Association between the days of antibiotics and the presence of an ESBL-producing organism was determined. RESULTS: One hundred eleven positive cultures were included in this analysis, of which 5 (4.5%) contained ESBL-producing species. Days of systemic antibiotics within 30 days of urine culture was associated with an increased risk of isolating an ESBL-producing pathogen. CONCLUSION: The overall prevalence of ESBL-producing organisms is low in this cohort. The number of days of systemic antibiotics within 30 days of a urine culture was significantly associated with increased risk of isolating an ESBL-producing organism.