title: Dairy farm age and resistance to antimicrobial agents in Escherichia coli isolated from dairy topsoil.
abstract: Antimicrobial agent usage is common in animal agriculture for therapeutic and prophylactic purposes. Selective pressure exerted by these antimicrobials on soil bacteria could result in the selection of strains that are resistant due to chromosomal- or plasmid-derived genetic components. Multiple antimicrobial resistances in Escherichia coli and the direct relationship between antimicrobial agent use over time has been extensively studied, yet the relationship between the age of an animal agriculture environment such as a dairy farm and antibiotic resistance remains unclear. Therefore, we tested the hypothesis that antimicrobial-resistance profiles of E. coli isolated from dairy farm topsoil correlate with dairy farm age. E. coli isolated from eleven dairy farms of varying ages within Roosevelt County, NM were used for MIC determinations to chloramphenicol, nalidixic acid, penicillin, tetracycline, ampicillin, amoxicillin/clavulanic acid, gentamicin, trimethoprim/sulfamethoxazole, cefotaxime, and ciprofloxacin. The minimum inhibitory concentration values of four antibiotics ranged 0.75 to >256 μg/ml, 1 to >256 μg/ml, 12 to >256 μg/ml, and 0.75 to >256 μg/ml for chloramphenicol, nalidixic acid, penicillin, and tetracycline, respectively. The study did not show a direct relationship between antibiotic resistance and the age of dairy farms.
authors.affiliation: Department of Biology, Eastern New Mexico University, Roosevelt Hall, Room 101, Station 33, Portales, NM 88130, USA.
authors.forename: Suzanna E
authors.initials: SE
authors.lastname: Jones
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Burgos
authors.forename: Marvin M F
authors.initials: MM
authors.lastname: Lutnesky
authors.forename: Johnny A
authors.initials: JA
authors.lastname: Sena
authors.forename: Sanath
authors.initials: S
authors.lastname: Kumar
authors.forename: Lindsay M
authors.initials: LM
authors.lastname: Jones
authors.forename: Manuel F
authors.initials: MF
authors.lastname: Varela
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003612:Dairying; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D009516:New Mexico; D012988:Soil Microbiology
chemical_list: D000900:Anti-Bacterial Agents