Phenotypic antibiotic resistance of Escherichia coli and E. coli O157 isolated from water, sediment and biofilms in an agricultural watershed in British Columbia

This study examined the distribution of antibiotic resistant Escherichia coli and E. coli O157 isolated from water, sediment and biofilms in an intensive agricultural watershed (Elk Creek, British Columbia) between 2005 and 2007. It also examined physical and chemical water parameters associated wit...

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Bibliographic Details
Published in:The Science of the total environment 2013-01, Vol.443, p.315-323
Main Authors: Maal-Bared, Rasha, Bartlett, Karen H., Bowie, William R., Hall, Eric R.
Format: Article
Language:English
Subjects:
Agriculture
Ampicillin
Antibiotics
Biofilms
British
British Columbia
Drug Resistance, Microbial
E. coli O157
Escherichia coli
Escherichia coli - drug effects
Escherichia coli - isolation & purification
Geologic Sediments - microbiology
Microbial Sensitivity Tests
Minimum inhibitory concentration (MIC)
Multiple antibiotic resistance (MAR)
Sediment
Sediments
Streptomycin
Tetracyclines
Water Microbiology
Watersheds
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Summary:This study examined the distribution of antibiotic resistant Escherichia coli and E. coli O157 isolated from water, sediment and biofilms in an intensive agricultural watershed (Elk Creek, British Columbia) between 2005 and 2007. It also examined physical and chemical water parameters associated with antibiotic resistance. Broth microdilution techniques were used to determine minimum inhibitory concentrations (MIC) for E. coli (n=214) and E. coli O157 (n=27) recovered isolates for ampicillin, cefotaxime, ciprofloxacin, nalidixic acid, streptomycin and tetracycline. Both E. coli and E. coli O157 isolates showed highest frequency of resistance to tetracycline, ampicillin, streptomycin and nalidixic acid; respectively. For E. coli, the highest frequency of resistance was observed at the most agriculturally-impacted site, while the lowest frequency of resistance was found at the headwaters. Sediment and river rock biofilms were the most likely to be associated with resistant E. coli, while water was the least likely. While seasonality (wet versus dry) had no relationship with resistance frequency, length of biofilm colonization of the substratum in the aquatic environment only affected resistance frequency to nalidixic acid and tetracycline. Multivariate logistic regressions showed that water depth, nutrient concentrations, temperature, dissolved oxygen and salinity had statistically significant associations with frequency of E. coli resistance to nalidixic acid, streptomycin, ampicillin and tetracycline. The results indicate that antibiotic resistant E. coli and E. coli O157 were prevalent in an agricultural stream. Since E. coli is adept at horizontal gene transfer and prevalent in biofilms and sediment, where ample opportunities for genetic exchange with potential environmental pathogens present themselves, resistant isolates may present a risk to ecosystem, wildlife and public health. ► Antibiotic resistant E. coli and E. coli O157 were prevalent in Elk Creek. ► Resistance was highest to tetracycline, ampicillin and streptomycin. ► Biofilm and sediment isolates were more likely to be resistant than water isolates. ► Some water quality variables (nutrients, temperature, DO and salinity) impact AMR. ► Biofilms and sediment are important reservoirs of AMR E. coli that could pose a risk to public health.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2012.10.106