Impact of Culturing All Uncomplicated Urinary Tract Infections on the Estimated Prevalence Of Resistance in the Primary Care Setting

BACKGROUND: Urine cultures to confirm a urinary tract infection (UTI) are not consistently collected in the primary care setting; thus estimates of the prevalence of resistance in uropathogens may be biased. As part of an ongoing study, microbiologic cultures were collected for all patients presenting with uncomplicated UTI at primary care clinics over a six-month period to assess the potential misclassification in frequency of resistance. METHODS: Data from an electronic health record repository were used to identify clinic encounters for women with a diagnosis code for unspecified UTI or cystitis from six primary care clinics between October 1, 2015 and February 28, 2017 in this cross-sectional study. Prior to August 22, 2016, urine microbiology cultures were collected at the discretion of the provider (usual care period), and from August 22, 2016 to February 28, 2017 urinary microbiology cultures were collected from all patients suspected of having uncomplicated UTI (full culturing period). Urinary microbiology culture and pharmacy data occurring within three days of the encounter were collected. Antibiotic susceptibility data was summarized for isolated Enterobacteriaceae. Frequency of susceptibility to trimethoprim-sulfamethoxazole (TMP-SMX), nitrofurantoin, and fluoroquinolones were compared between usual care vs. the full culturing periods using a chi-square test. RESULTS: We identified 131 urine microbiology cultures in the usual care period and 104 in the full culturing period with 61.1% and 55.8%, respectively, being positive cultures. Enterobacteriaceae were isolated from 85.0% of positive cultures in the usual care period and 86.2% in the full culturing period. Between the usual and full culturing periods, antibiotic susceptibility in the Enterobacteriaceae did not differ statistically for TMP-SMX (85.1% vs.. 88.0%; P = 0.65), nitrofurantoin (98.5% vs. 94.0%; P = 0.19), and fluoroquinolones (89.6% vs. 90.0%; P = 0.94). CONCLUSION: Full culturing did not significantly change estimates of the prevalence of antibiotic resistance among Enterobacteriaceae isolated from urine samples. Current urine culturing practices provide adequate susceptibility information to inform empiric prescribing for women with uncomplicated UTIs. DISCLOSURES: J. C. McGregor, Merck & Co.: Grant Investigator, Research grant