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Salmonella enterica serovar Heidelberg frequently causes food-borne illness in humans. There are few data on the prevalence, antimicrobial susceptibility, and genetic diversity of Salmonella serovar Heidelberg isolates in retail meats. We compared the prevalences of Salmonella serovar Heidelberg in a sampling of 20,295 meats, including chicken breast (n ‫؍‬ 5,075), ground turkey (n ‫؍‬ 5,044), ground beef (n ‫؍‬ 5,100), and pork chops (n ‫؍‬ 5,076), collected during 2002 to 2006. Isolates were analyzed for antimicrobial susceptibility and compared genetically using pulsed-field gel electrophoresis (PFGE) and PCR for the bla CMY gene. A total of 298 Salmonella serovar Heidelberg isolates were recovered, representing 21.6% of all Salmonella serovars from retail meats. One hundred seventy-eight (59.7%) were from ground turkey, 110 (36.9%) were from chicken breast, and 10 (3.4%) were from pork chops; none was found in ground beef. One hundred ninety-eight isolates (66.4%) were resistant to at least one compound, and 49 (16.4%) were resistant to at least five compounds. Six isolates (2.0%), all from ground turkey, were resistant to at least nine antimicrobials. The highest resistance in poultry isolates was to tetracycline (39.9%), followed by streptomycin (37.8%), sulfamethoxazole (27.7%), gentamicin (25.7%), kanamycin (21.5%), ampicillin (19.8%), amoxicillin-clavulanic acid (10.4%), and ceftiofur (9.0%). All isolates were susceptible to ceftriaxone and ciprofloxacin. All ceftiofur-resistant strains carried bla CMY . PFGE using XbaI and BlnI showed that certain clones were widely dispersed in different types of meats and meat brands from different store chains in all five sampling years. These data indicate that Salmonella serovar Heidelberg is a common serovar in retail poultry meats and includes widespread clones of multidrug-resistant strains.

Escherichia coli isolates were recovered from the National Antimicrobial Resistance Monitoring System retail meat program and examined for antimicrobial susceptibility. Retail meat samples (n ‫؍‬ 11,921) from four U.S. states collected during 2002 to 2008, consisting of 2,988 chicken breast, 2,942 ground turkey, 2,991 ground beef, and 3,000 pork chop samples, were analyzed. A total of 8,286 E. coli isolates were recovered. The greatest numbers of samples contaminated with the organism were chicken (83.5%) and turkey (82.0%), followed by beef (68.9%) and pork (44.0%). Resistance was most common to tetracycline (50.3%), followed by streptomycin (34.6%), sulfamethoxazole-sulfisoxazole (31.6%), ampicillin (22.5%), gentamicin (18.6%), kanamycin (8.4%), amoxicillin-clavulanic acid (6.4%), and cefoxitin (5.2%). Less than 5% of the isolates had resistance to trimethoprim, ceftriaxone, ceftiofur, nalidixic acid, chloramphenicol, and ciprofloxacin. All isolates were susceptible to amikacin. Compared to beef and pork isolates, the poultry meat isolates had a greater percentage of resistance to all tested drugs, with the exception of chloramphenicol, to which pork isolates had the most resistance. More than half of the turkey isolates (56%) were resistant to multidrugs (>3 classes) compared to 38.9% of chicken, 17.3% of pork, and 9.3% of beef isolates. The bla CMY gene was present in all ceftriaxone-and ceftiofur-resistant isolates. The cmlA, flo, and catI genes were present in 45%, 43%, and 40% of chloramphenicol-resistant isolates, respectively. Most nalidixic acid-resistant isolates (98.5%) had a gyrA mutation in S83 or D87 or both, whereas only 6.7% had a parC mutation in either S80 or E84. The results showed that E. coli was commonly present in the retail meats, and antimicrobial resistance profiles differed according to the animal origin of the isolates. E scherichia coli is a commensal bacterium in humans and animals and has a wide range of hosts. It is commonly present in the environment and is considered an indicator of fecal contamination in food and water. E. coli can acquire, maintain, and transmit resistance genes from other organisms in the environment. Due to its ubiquity in humans and animals and its role as a pathogenic and commensal organism, E. coli has become one of the microorganisms that are commonly resistant to antimicrobials.The level of antimicrobial resistance in E. coli represents a useful indicator of resistance dissemination in bacterial populations and of selective pressure imposed by the antimicrobials used in treatment of food animals and humans (2,25,28,30). Sáenz et al. (25) showed that the frequency of resistance to different antimicrobials in E. coli differed according to the source of the isolates. E. coli isolates from broilers were resistant to ciprofloxacin (CIP) (38%) and gentamicin (GEN) (40%) compared to 0% resistance to both drugs among E. coli isolates from healthy human volunteers versus 16% and 8% resistance among E. coli isolates from human clinical specimens. Kikuvi et al....