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Am J Med. 2003 Oct 1;115(5):358-64.

Conventional and molecular epidemiology of trimethoprim-sulfamethoxazole resistance among urinary Escherichia coli isolates.

Author information

1
Department of Public Health, Denver Health and Hospital Authority, Colorado 80204, USA. bburman@dhha.org

Abstract

BACKGROUND:

Antibiotic resistance is increasing in Escherichia coli, the most common cause of urinary tract infections, but its epidemiology has not been well described. We evaluated the epidemiology of trimethoprim-sulfamethoxazole-resistant E. coli in a large, public health care system in Denver, Colorado.

METHODS:

Outpatients with E. coli urinary tract infections during the first 6 months of 1998 were evaluated retrospectively. A prospective study was then performed to confirm the rate of trimethoprim-sulfamethoxazole resistance. We used several strain-typing methods (pulsed-field gel electrophoresis, ribotyping, serotyping) to evaluate the molecular epidemiology of the resistance.

RESULTS:

The rate of trimethoprim-sulfamethoxazole resistance was similar in the retrospective (24% [161/681]) and prospective (23% [30/130]) phases of the study (P = 0.89). Almost all trimethoprim-sulfamethoxazole-resistant strains (98%) were resistant to at least one other antibiotic. Risk factors for infection with a resistant strain included age < or =3 years, Hispanic ethnicity, recent travel outside the United States, and a prior urinary tract infection. However, rates of resistance were >15% among nearly all of the subgroups. Most strains had high-level resistance (>1000 microg/mL) to trimethoprim-sulfamethoxazole. Of the 23 resistant isolates evaluated, 10 (43%) belonged to the clone A group. There was no correlation between conventional epidemiologic characteristics and the molecular mechanism of resistance or strain type.

CONCLUSION:

Resistance to trimethoprim-sulfamethoxazole among E. coli isolates among patients in a Denver public health care system is common, with high rates of resistance even among patients without risk factors.

PMID:
14553870
DOI:
10.1016/s0002-9343(03)00372-3
[Indexed for MEDLINE]

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