title: Characterization and transferability of class 1 integrons in commensal bacteria isolated from farm and nonfarm environments.
abstract: This study assessed the distribution of class 1 integrons in commensal bacteria isolated from agricultural and nonfarm environments, and the transferability of class 1 integrons to pathogenic bacteria. A total of 26 class 1 integron-positive isolates were detected in fecal samples from cattle operations and a city park, water samples from a beef ranch and city lakes, and soil, feed (unused), manure, and compost samples from a dairy farm. Antimicrobial susceptibility testing of class 1 integron-positive Enterobacteriaceae isolates from city locations displayed multi-resistance to 12-13 out of the 22 antibiotics tested, whereas class 1 integron-positive Enterobacteriaceae isolates from cattle operations only displayed tetracycline resistance. Most class 1 integrons had one gene cassette belonging to the aadA family that confers resistance to streptomycin and spectinomycin. One isolate from a dog fecal sample collected from a city dog park transferred its class 1 integron to a strain of Escherichia coli O157:H7 at a frequency of 10(-7) transconjugants/donor by in vitro filter mating experiments under the stated laboratory conditions. Due to the numerous factors that may affect the transferability testing, further investigation using different methodologies may be helpful to reveal the transferability of the integrons from other isolates. The presence of class 1 integrons among diverse commensal bacteria from agricultural and nonfarm environments strengthens the possible role of environmental commensals in serving as reservoirs of antibiotic resistance genes.
authors: Food Safety Cluster, Department of Animal Sciences, Center for Meat Safety & Quality, Colorado State University, Fort Collins, Colorado 80523-1171, USA.
authors: Hua
authors: H
authors: Yang
authors: Oleksandr A
authors: OA
authors: Byelashov
authors: Ifigenia
authors: I
authors: Geornaras
authors: Lawrence D
authors: LD
authors: Goodridge
authors: Kendra K
authors: KK
authors: Nightingale
authors: Keith E
authors: KE
authors: Belk
authors: Gary C
authors: GC
authors: Smith
authors: John N
authors: JN
authors: Sofos
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D002417:Cattle; D002511:Cephalosporins / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics; D004285:Dogs; D024901:Drug Resistance, Multiple, Bacterial; D004783:Environmental Microbiology; D019453:Escherichia coli O157 / Q000187:drug effects / Q000235:genetics; D005243:Feces / Q000382:microbiology*; D032023:Integrons; D008826:Microbial Sensitivity Tests; D012988:Soil Microbiology; D013752:Tetracycline / Q000494:pharmacology; D013753:Tetracycline Resistance
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004269:DNA, Bacterial; C053503:ceftiofur; D013752:Tetracycline