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TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE IN SEWAGE ISOLATES OF ESCHERICHIA COLI
Citation:
Rice E. W, E., L A. Boczek*, AND C H. Johnson*. TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE IN SEWAGE ISOLATES OF ESCHERICHIA COLI. Presented at 43rd Interscience Conference on Antimicrobial Agents & Chemotherapy, Chicago, IL, 9/14-17, 2003.
Description:
The increase in resistance rates to trimehtoprim-sulfamethoxazole (TMP/SMX) in isolates of Escherichia coli has become a matter of increasing concern. This has been particularly true in reference to community acquired urinary tract infections (UTI). This study utilized sewage isolates collected from various geographical areas as representative of isolates which may be found in the general population.
Sewage samples were collected from eight locations in the United States and analyzed for E. coli. Random isolates were identified biochemically and screened for sensitivity to TMP/SMX, TMP, ampicillin (AM), tetracycline (TE), streptomycin (ST) and chloramphenicol (CH) using the disk diffusion method. The E-Test? was used to determine MIC levels for the TMP/SMX isolates. Phylogenetic grouping of select isolates was performed using a triplex PCR procedure.
A total of 1,712 isolates were screened from the eight sites. One-hundred and three (6%) of the isolates exhibited resistance to TMP/SMX. The prevalence of resistance varied among the locations: California (13%), Florida (2%), Maine (1%), New York (10%), Ohio(5%),Washington (6%), Wisconsin (7%), and Virginia (2%). The MIC values indicated that most isolates exhibited high level resistance to TMP/SMX. Multiple antibiotic resistance was seen in the TMP/SMX resistant isolates with 26% being resistant to three additional antibiotics and 35% being resistant to four additional antibiotics. Twelve (1%) of the isolates were resistant to all of the antibiotics tested, with nine of these isolates belonging to phylogenetic group D.
TMP/SMX resistant strains of E. coli are present in the environment and prevalence rates varied in different geographic locales. A small precentage (1%) of these strains belonged to a multi-drug resistant phenotype in phylogenetic group D which has been associated with a unique clonal group of UTI isolates of E. coli. This information may be helpful in studying the source and transmission of these isolates.