The role of drinking water as a source of transmission of antimicrobial resistant Escherichia coli Brenda L. Coleman, Allison McGeer, Marina Salvadori, Ian Johnson, Iris Gutmanis, Sue Bondy, Norm Neuman, Marie Louis, Scott McEwen, Fran Jamieson, & Rebecca Irwin

Antimicrobial Resistance What is it? Why do we care? How does it occur? –Selective pressure –Transmission

Escherichia coli Human colonization Human infection Water as a vehicle for transmission E. coli indicator of contamination

Private drinking water 10-50% of Canadian households 30-50% test water 2-20% contaminated with E. coli

Objectives 1.Measure the proportion of E. coli positive water samples that are antimicrobial resistant (AR) 2.Measure the prevalence of human carriage of AR E. coli 3.Determine whether the use of water contaminated with AR E. coli is associated with human carriage

Sampling Public health labs (Water samples) Standard testing for bacterial contamination at participating laboratories E. coli - positive No bacterial contamination  Surveillance (Water samples) E. coli susceptibility tested sample ResistantSusceptible  Case-control (Households) Eligible & non-replicate households Household questionnaire CaseControl AControl B  Cross-sectional (Individuals) Eligible individuals Personal questionnaire & rectal swab Resistant Susceptible

Water samples 340,009 tested  15,238 E. coli (4.5%)  6,492 susceptibility tested  645 resistant (9.9%)

Human samples 1,710 households eligible ↓ 831 household questionnaires ↓ 655 households → 985 personal questionnaires ↓ 488 households ←699 rectal swabs

Households & Subjects 488 households 108 with AR E. coli water source –69 with untreated AR E. coli 699 subjects 12 to 87 years old Males = females 433 (62%) used tap water only 376 (54%) travelled outside Canada 185 (27%) had direct livestock contact 85 (12%) used antibiotic

Proportion of rectal swabs with AR E. coli Ontario,

Theorized relationship between human carriage & consumption of antimicrobial resistant E. coli Potential effect modifier: Bottled water Primary predictor: Outcome: Water used Carriage of antimicrobial resistant E. coli Potential confounders: AgeAntibiotic use SexHospitalization Household educationChild in day care Household incomeHousehold size Laboratory regionContact with livestock Mode of data collectionFarming property Days between water sampleContact with dog/cat & interviewContact with raw meat Travel

Final multivariable model PredictorRR95% Conf. interval Water used (contaminated & not treated) , 1.7 Travel outside Canada1.31.1, 1.6 Contact with cattle1.31.0, 1.5 Sex (male)1.21.0, 1.5

Limitations Convenience sample Age of subjects Lack of exposure dose/treatment of water Causation

Conclusions Private drinking water sources are contaminated with AR E. coli Relatively high prevalence of AR E. coli carriage in non-institutionalized residents Carriage of AR E. coli is associated with the use of contaminated water