PREVALENCE OF SALMONELLA IN RAW MEAT USED IN DIETS OF RACING GREYHOUNDS

One hundred twelve samples of commercial raw meat used in greyhound di ets were collected and cultured for Salmonella using standard procedur es. Fifty (44.64%) of these samples were positive for Salmonella. Salm onella typhimurium was the most frequently isolated serovar (48%), fol lowed by S. newport (12.76%), S. agona (8.5 1%), and S. muenster (6.38 %). The remaining 10 serovars recovered in this study represented 27.5 9% of the total Salmonella isolates. In addition, the meat samples wer e screened for Salmonella using a commercial DNA probe. Of the 106 sam ples tested, 70 (66.03%) were positive for Salmonella, which indicated that the DNA probe assay was more sensitive than the culture method f or screening of Salmonella in raw meat. Antimicrobial susceptibility t esting revealed that most of the Salmonella isolates were sensitive to a variety of antimicrobials, particularly amikacin and apramycin, and resistant to some others, such as clindamycin, erythromycin, penicill in, and sulfadimethoxine. The cumulative percentages of susceptibility (MIC50 and MIC90) of the Salmonella isolates were also determined. Mo st isolates were susceptible (MIC90) to low concentrations of gentamic in (2.0 mug/ml), imipenem (less-than-or-equal-to 0.25 mug/ml), and cip rofloxacin (less-than-or-equal-to 5 mug/ml). Marked resistance was fou nd with the other antimicrobial agents. However, the high MIC values f ound for these isolates would not be achievable in vivo with the norma l recommended doses of antimicrobial agents, so their use would not be beneficial. Numerous plasmid patterns were found in 17 randomly selec ted Salmonella isolates. Eight of the 17 isolates had 2-7 plasmids ran ging from 2.4 to 15 kilobases in size. Eight isolates also exhibited l arge plasmids in the range of 50-60 and 95-105 kilobases. Large plasmi ds migrated above the chromosal DNA. Six isolates did not demonstrate any visible plasmids.