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Antimicrobial resistance in uncomplicated urinary tract infections in 3 California EDs
Shannon E Moffett1, Bradley W Frazee, John C Stein
1Department of Emergency Medicine, Alameda County Medical Center-Highland Campus, Oakland, CA 94602, USA. smoffett@stanfordalumni.org
Background:
Increased trimethoprim/sulfamethoxazole (TMP/SMX) resistance has led to changes in empiric treatment of female urinary tract infections (UTI) in the emergency department (ED), particularly increased use of fluoroquinolones (Acad Emerg Med.2009;16(6):500-507). Whether prescribing changes have affected susceptibility in uropathogens is unclear. Using narrow-spectrum agents and therapy tailored to local susceptibilities remain important goals.
Objective:
The primary goal of this study is to characterize the susceptibility patterns of uropathogens among ambulatory female ED patients with UTI. Its secondary goal is to identify demographic or clinical factors predictive of resistance to narrow-spectrum agents.
Methods:
This was a cross-sectional study of women with suspected UTI referred to a trial of computer kiosk-aided treatment of UTI in 3 Northern California EDs. Demographic and clinical data were gathered from the kiosk and chart, and features associated with resistance were identified by bivariate and multivariable regression analysis.
Results:
Two hundred eighty-three participants, aged 15 to 84 years, were diagnosed with UTI and cultured. One hundred thirty-five (48%) of cultures were positive, with full susceptibilities reported (81% Escherichia coli). Only 2 isolates (1.5%) were fluoroquinolone resistant. Resistance to TMP/SMX was 18%, to nitrofurantoin 5%, and to cefazolin 4%. Seventy-four percent were sensitive to all 3 narrow-spectrum agents. Resistance to narrow-spectrum agents did not vary significantly by diagnosis, age, recent UTI, or any clinical or demographic factors; but overall, there was a trend toward lower resistance rates in our population than in our hospitals' published antibiograms.
Conclusion:
In our population of ambulatory female ED patients, resistance to TMP/SMX is just below the 20% threshold that the Infectious Disease Society of America recommends for continued empiric use (Clin Infect Dis.1999;29(4):745-758, Clin Infect Dis.2011;52(5):e103-120), whereas resistance to other narrow-spectrum agents, such as nitrofurantoin and cephalexin, may be lower than published antibiograms for our sites. Fluoroquinolone resistance remains very low.
Insights
Urinary tract infection (UTI) resistance to trimethoprim/sulfamethoxazole (TMP/SMX) is below 20% in female emergency department patients. Fluoroquinolone resistance remains very low, suggesting narrow-spectrum agents may be effective.
Area of Science:
- Infectious Diseases
- Clinical Microbiology
- Emergency Medicine
Background:
- Rising trimethoprim/sulfamethoxazole (TMP/SMX) resistance has altered empiric treatment for female urinary tract infections (UTIs) in emergency departments (EDs).
- Increased use of fluoroquinolones has been observed, but the impact on uropathogen susceptibility is not well understood.
- Maintaining susceptibility to narrow-spectrum agents and tailoring therapy to local resistance patterns are key objectives in UTI management.
Purpose of the Study:
- To characterize uropathogen susceptibility patterns in ambulatory female ED patients diagnosed with UTI.
- To identify demographic and clinical factors associated with resistance to narrow-spectrum antimicrobial agents.
Main Methods:
- A cross-sectional study was conducted involving women with suspected UTI in three Northern California EDs.
- Data on demographics and clinical factors were collected via computer kiosk and patient charts.
- Bivariate and multivariable regression analyses were used to identify predictors of antimicrobial resistance.
Main Results:
- Of 283 participants, 135 (48%) had positive cultures, predominantly Escherichia coli (81%).
- Resistance rates were 18% for TMP/SMX, 5% for nitrofurantoin, and 4% for cefazolin; only 1.5% of isolates were fluoroquinolone resistant.
- Seventy-four percent of uropathogens were susceptible to all three narrow-spectrum agents evaluated. Resistance did not significantly vary by clinical or demographic factors.
Conclusions:
- TMP/SMX resistance in this female ED patient population is below the 20% Infectious Disease Society of America threshold for continued empiric use.
- Resistance to nitrofurantoin and cephalexin may be lower than reported in local hospital antibiograms.
- Fluoroquinolone resistance remains notably low in this cohort, supporting their potential role in specific UTI treatment guidelines.
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