title: Prevalence and risk factors for carriage of antimicrobial-resistant Escherichia coli on household and small-scale chicken farms in the Mekong Delta of Vietnam.
abstract: OBJECTIVE
  To describe the prevalence of antimicrobial resistance among commensal Escherichia coli isolates on household and small-scale chicken farms, common in southern Vietnam, and to investigate the association of antimicrobial resistance with farming practices and antimicrobial usage.
  
  
  METHODS
  We collected data on farming and antimicrobial usage from 208 chicken farms. E. coli was isolated from boot swab samples using MacConkey agar (MA) and MA with ceftazidime, nalidixic acid or gentamicin. Isolates were tested for their susceptibility to 11 antimicrobials and for ESBL production. Risk factor analyses were carried out, using logistic regression, at both the bacterial population and farm levels.
  
  
  RESULTS
  E. coli resistant to gentamicin, ciprofloxacin and third-generation cephalosporins was detected on 201 (96.6%), 191 (91.8%) and 77 (37.0%) of the farms, respectively. Of the 895 E. coli isolates, resistance to gentamicin, ciprofloxacin and third-generation cephalosporins was detected in 178 (19.9%), 291 (32.5%) and 29 (3.2%) of the isolates, respectively. Ciprofloxacin resistance was significantly associated with quinolone usage (OR = 2.26) and tetracycline usage (OR = 1.70). ESBL-producing E. coli were associated with farms containing fish ponds (OR = 4.82).
  
  
  CONCLUSIONS
  Household and small farms showed frequent antimicrobial usage associated with a high prevalence of resistance to the most commonly used antimicrobials. Given the weak biocontainment, the high prevalence of resistant E. coli could represent a risk to the environment and to humans.
authors.affiliation: Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands Department of Global Health-Amsterdam Institute for Global Health and Development, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands Oxford University Clinical Research Unit, Centre for Tropical Medicine, Ho Chi Minh City, Vietnam trungnv@oucru.org.
authors.forename: Vinh Trung
authors.initials: VT
authors.lastname: Nguyen
authors.affiliation: Oxford University Clinical Research Unit, Centre for Tropical Medicine, Ho Chi Minh City, Vietnam Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Carrique-Mas
authors.affiliation: Oxford University Clinical Research Unit, Centre for Tropical Medicine, Ho Chi Minh City, Vietnam Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Thi Hoa
authors.initials: TH
authors.lastname: Ngo
authors.affiliation: Sub-Department of Animal Health, My Tho, Tien Giang, Vietnam.
authors.forename: Huynh Mai
authors.initials: HM
authors.lastname: Ho
authors.affiliation: Oxford University Clinical Research Unit, Centre for Tropical Medicine, Ho Chi Minh City, Vietnam.
authors.forename: Thanh Tuyen
authors.initials: TT
authors.lastname: Ha
authors.affiliation: Oxford University Clinical Research Unit, Centre for Tropical Medicine, Ho Chi Minh City, Vietnam Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: James I
authors.initials: JI
authors.lastname: Campbell
authors.affiliation: Oxford University Clinical Research Unit, Centre for Tropical Medicine, Ho Chi Minh City, Vietnam.
authors.forename: Thi Nhung
authors.initials: TN
authors.lastname: Nguyen
authors.affiliation: Oxford University Clinical Research Unit, Centre for Tropical Medicine, Ho Chi Minh City, Vietnam.
authors.forename: Ngoc Nhung
authors.initials: NN
authors.lastname: Hoang
authors.affiliation: Oxford University Clinical Research Unit, Centre for Tropical Medicine, Ho Chi Minh City, Vietnam.
authors.forename: Van Minh
authors.initials: VM
authors.lastname: Pham
authors.affiliation: Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands Central Veterinary Institute of Wageningen UR, Lelystad, The Netherlands.
authors.forename: Jaap A
authors.initials: JA
authors.lastname: Wagenaar
authors.affiliation: Center for Social Science and Global Health, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Anita
authors.initials: A
authors.lastname: Hardon
authors.affiliation: Sub-Department of Animal Health, My Tho, Tien Giang, Vietnam.
authors.forename: Quoc Hieu
authors.initials: QH
authors.lastname: Thai
authors.affiliation: Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands Department of Global Health-Amsterdam Institute for Global Health and Development, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands Oxford University Clinical Research Unit, Centre for Tropical Medicine, Ho Chi Minh City, Vietnam.
authors.forename: Constance
authors.initials: C
authors.lastname: Schultsz
mesh_terms: D000818:Animals; D000829:Animals, Domestic; D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D002645:Chickens; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D012307:Risk Factors; D014744:Vietnam / Q000453:epidemiology
keywords: antimicrobial resistance; antimicrobial use; poultry; treatment incidence