title: High levels of contamination and antimicrobial-resistant non-typhoidal Salmonella serovars on pig and poultry farms in the Mekong Delta of Vietnam.
abstract: We investigated the prevalence, diversity, and antimicrobial resistance (AMR) profiles of non-typhoidal Salmonella (NTS) and associated risk factors on 341 pig, chicken, and duck farms in Dong Thap province (Mekong Delta, Vietnam). Sampling was stratified by species, district (four categories), and farm size (three categories). Pooled faeces, collected using boot swabs, were tested using ISO 6575: 2002 (Annex D). Isolates were serogrouped; group B isolates were tested by polymerase chain reaction to detect S. Typhimurium and (monophasic) serovar 4,[5],12:i:- variants. The farm-level adjusted NTS prevalence was 64·7%, 94·3% and 91·3% for chicken, duck and pig farms, respectively. Factors independently associated with NTS were duck farms [odds ratio (OR) 21·2], farm with >50 pigs (OR 11·9), pig farm with 5-50 pigs (OR 4·88) (vs. chickens), and frequent rodent sightings (OR 2·3). Both S. Typhimurium and monophasic S. Typhimurium were more common in duck farms. Isolates had a high prevalence of resistance (77·6%) against tetracycline, moderate resistance (20-30%) against chloramphenicol, sulfamethoxazole-trimethoprim, ampicillin and nalidixic acid, and low resistance (<5%) against ciprofloxacin and third-generation cephalosporins. Multidrug resistance (resistance against ⩾3 classes of antimicrobial) was independently associated with monophasic S. Typhimurium and other group B isolates (excluding S. Typhimurium) and pig farms. The unusually high prevalence of NTS on Mekong Delta farms poses formidable challenges for control.
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: L T P
authors.initials: LT
authors.lastname: Tu
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: N V M
authors.initials: NV
authors.lastname: Hoang
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: N V
authors.initials: NV
authors.lastname: Cuong
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: J
authors.initials: J
authors.lastname: Campbell
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: J E
authors.initials: JE
authors.lastname: Bryant
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: N T
authors.initials: NT
authors.lastname: Hoa
authors.affiliation: Sub-Department of Animal Health Dong Thap,Cao Lanh,Vietnam.
authors.forename: B T
authors.initials: BT
authors.lastname: Kiet
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: C
authors.initials: C
authors.lastname: Thompson
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: D T
authors.initials: DT
authors.lastname: Duy
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: V V
authors.initials: VV
authors.lastname: Phat
authors.affiliation: Sub-Department of Animal Health Dong Thap,Cao Lanh,Vietnam.
authors.forename: V B
authors.initials: VB
authors.lastname: Hien
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: G
authors.initials: G
authors.lastname: Thwaites
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: S
authors.initials: S
authors.lastname: Baker
authors.affiliation: Hospital for Tropical Diseases,Wellcome Trust Major Overseas Programme,Oxford University Clinical Research Unit,Ho Chi Minh City,Vietnam.
authors.forename: J J
authors.initials: JJ
authors.lastname: Carrique-Mas
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D024881:Drug Resistance, Bacterial; D004787:Environmental Pollution; D005243:Feces / Q000382:microbiology; D011200:Poultry; D015995:Prevalence; D012475:Salmonella / Q000187:drug effects / Q000302:isolation & purification*; D012481:Salmonella Infections, Animal / Q000453:epidemiology* / Q000382:microbiology; D012703:Serotyping; D013552:Swine; D014744:Vietnam
keywords: Epidemiology; Salmonella; zoonoses