Purpose: To determine and characterize current Salmonella serovars present in ground meat and pork.
Methods: A total of 480 samples were collected (231 pork and 249 beef) from March 2009 to March 2010 from grocery stores located in the metropolitan area of Washington DC. Confirmed Salmonella isolates were characterized using serotyping, antimicrobial susceptibility testing and pulse field gel electrophoresis (PFGE).
Results: Salmonella was isolated from 3.6% (9) and 5.6% (13) of ground beef and ground pork samples, respectively. While the majority of strains were serotyped as Salmonella Typhimurium (10/29), eight other serotypes were also identified: S. Derbi, S. Infantis, S. Anatum, S. Dublin, S. Thompson, S. Johannesburg, S. Uganda, and S. Cerro. More than half of the strains were resistant to at least one antimicrobial and half of them to at least three antimicrobials. Resistance was more frequently observed to streptomycin, tetracycline, and sulfisoxazole. Interestingly, most S. Typhimurim and all S. Dublin and S. Uganda strains were resistant to four or more antimicrobials, while most S. Infantis were resistant to only one antimicrobial. A total of 22 PFGE profiles were produced from 29 different isolates; multiple PFGE profiles were found in isolates originated from a same pork sample in three occasions. In contrast, only single PFGE profiles were identified among isolates recovered from each positive beef sample.
Significance: Our findings indicate that Salmonella was present in retail beef and pork products and represented multiple serotypes exhibiting various antimicrobial resistances.