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 is a leading cause of foodborne diarrheal illness worldwide, and the emergence of antimicrobial-resistant strains is a major global public health concern. The goal of this study was to compare the activity of different fluoroquinolone antibiotics against ciprofloxacin-resistant Campylobacter jejuni and Campylobacter coli . Isolates from retail meats collected between 2002 and 2009 were selected based on their in vitro susceptibility testing results against ciprofloxacin. In total, 289 C. jejuni and 165 C. coli were collected and analyzed. All ciprofloxacin-resistant isolates had a single mutation (Thr86Ile) in their gyrase A ( gyrA ) gene and exhibited decreased susceptibility to all eight fluoroquinolones tested. Gatifloxacin, enrofloxacin, and levofloxacin showed greater activity than the other fluoroquinolone drugs in both ciprofloxacin-sensitive and -resistant strains.