title: Antimicrobial resistance trends among Salmonella isolates obtained from dairy cattle in the northeastern United States, 2004-2011.
abstract: Monitoring antimicrobial resistance trends among bacteria isolated from food animals and people is necessary to inform public policy regarding appropriate antimicrobial use. Our objectives were to describe the antimicrobial resistance status of Salmonella isolates from dairy cattle in the northeastern United States and to identify trends in resistance to various antimicrobial agents over time. Data were collected retrospectively for all bovine Salmonella isolates that were obtained from samples submitted to Cornell University's Animal Health Diagnostic Center between January 1, 2004 and December 31, 2011. Temporal trends in the prevalence of resistant Salmonella were investigated for each antimicrobial agent using the Cochran-Armitage trend test. Antimicrobial susceptibility testing was performed on 2745 bovine Salmonella isolates from clinical samples submitted during the study period. Overall resistance to each antimicrobial agent ranged from 0% (amikacin, ciprofloxacin, and nalidixic acid) to 72.0% (sulfadimethoxine). There was evidence of a significantly decreasing trend in prevalence of resistance to most agents: amoxicillin/clavulanic acid (AUG), ampicillin (AMP), cefoxitin (FOX), ceftiofur (TIO), ceftriaxone (AXO), chloramphenicol (CHL), chlortetracycline (CTET), florfenicol (FFN), kanamycin (KAN), neomycin (NEO), oxytetracycline (OXY), spectinomycin (SPE), streptomycin (STR), sulfadimethoxine (SDM), sulfisoxazole (FIS), and tetracycline (TET). Among the 265 isolates that were tested using the National Antimicrobial Resistance Monitoring System (NARMS) panel, the most common resistance patterns were pansusceptible (54.0%), AUG-AMP-FOX-TIO-AXO-CHL-KAN-STR-FIS-TET (18.1%), and AUG-AMP-FOX-TIO-AXO-CHL-STR-FIS-TET (12.1%). Increasing prevalence of S. enterica serovar Cerro over the course of the study period presumably had an impact on the observed resistance trends. Nevertheless, these results do not support the notion that the current level of antimicrobial use in dairy cattle is driving an increase in the emergence and dissemination of drug-resistant Salmonella in the region served by the laboratory.
authors: Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA. kcummings@cvm.tamu.edu
authors: Kevin J
authors: KJ
authors: Cummings
authors: Gillian A
authors: GA
authors: Perkins
authors: Sarah M
authors: SM
authors: Khatibzadeh
authors: Lorin D
authors: LD
authors: Warnick
authors: Craig
authors: C
authors: Altier
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial; D005243:Feces / Q000382:microbiology; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D009511:New England; D012475:Salmonella / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D019779:Salmonella enterica / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D012703:Serotyping
chemical_list: D000900:Anti-Bacterial Agents