Between 2002 and 2017, the National Antimicrobial Resistance Monitoring System (NARMS) recovered 5,803 Salmonella isolates from retail meat collected in 21 states. Isolates were from chicken parts (CP), ground turkey (GT), pork chops (PC), and ground beef (GB). NARMS tested Salmonella for susceptibility to: amoxicillin/clavulanic acid (AMC), ampicillin (AMP), azithromycin (AZI), cefoxitin (FOX), ceftiofur (TIO), ceftriaxone (AXO), chloramphenicol (CHL), gentamicin (GEN), nalidixic acid (NAL), streptomycin (STR), tetracycline (TET), trimethoprim/sulfamethoxazole ( cotrimoxazole ) (COT), sulfisoxazole (FIS), and ciprofloxacin (CIP). Using the chi-square test of association, we looked for a potential association between where retail meat was purchased and Salmonella prevalence and susceptibility (resistant or susceptible). This was to test for possible geographic differences in the distribution of antimicrobial resistant Salmonella . We adopted the United States Department of Agriculture (USDA) Office of Investigation, Enforcement and Audit map for the regional subdivision used in this study. The results show a significant association between region, Salmonella prevalence, and Salmonella resistance to the above antimicrobials tested except for cotrimoxazole, streptomycin, ciprofloxacin, and azithromycin. The analysis identified the Northeast as the most influential contributor to overall prevalence and resistance in most of the drugs tested, with Salmonella Typhimurium driving these associations. Although this work did not bring to light what accounts for the differential prevalence and resistance of Salmonella Typhimurium in the northeast, lack of certain resistance mechanisms in other regions was ruled out by the analysis on 484 of 485 sequenced isolates with resistance to ampicillin, sulfonamides, and tetracycline.
ABSTRACT Campylobacter spp. commonly cause gastrointestinal illness in humans. Poultry meats have long been considered the predominant source of these infections, but few in-depth Campylobacter source attribution studies have been completed. We analyzed more than 1,300 Campylobacter isolates recovered from a number of animal and food sources, including dairy and beef cattle, pigs, poultry, and retail poultry meat, and compared them with Campylobacter isolates recovered from human clinical samples. Each isolate was subtyped using pulsed-field gel electrophoresis (PFGE) with Sma I and queried against the Centers for Disease Control and Prevention PulseNet database to identify human isolates with indistinguishable patterns. Half (49.5%) of the PFGE patterns from poultry animal and retail meat isolates were indistinguishable from patterns of at least one human isolate. Among the isolates from beef and dairy cows, 56.6 and 65.0%, respectively, of their PFGE patterns were indistinguishable from those of human isolates. Only a small portion of the PFGE patterns of Campylobacter isolated from pigs (9.5%) were found to have PFGE patterns in common with human isolates. These data imply that cattle may be larger contributors to Campylobacter infections than previously recognized and help further our understanding of potential sources of human campylobacteriosis.