Effect of sample preparation and bacterial concentration on Salmonella enterica detection in poultry meat using culture methods and PCR assaying of preenrichment broths.
We evaluated the sensitivity of a PCR assay in the detection of Salmonella enterica at the broth preenrichment step of poultry meat. A total of 162 retail poultry meat samples, which were prepared by manual massaging, stomacher or no homogenization were compared for Salmonella recovery. Using these homogenization methods, the PCR assay at the broth preenrichment step detected Salmonella in, respectively, 48.9%, 62.2% and 50.0% of meat and giblet samples detected as Salmonella-positive using the culture method. In ground chicken, however, Salmonella was detected in 21.7% of samples treated by stomacher homogenization, compared to 40.7% and 48% of untreated and hand-massaged samples, respectively. These results suggest that stomaching of ground chicken causes excessive effusion of food constituents, which affects PCR results. Using the most probable number (MPN) technique, Salmonella was detected at under 1.0 CFU/g in 12 ground chicken samples and under 10(3)CFU/ml of broth in seven of the 12 broth-enriched samples, which considered the minimum concentration detectable by PCR assay. These results show that Salmonella detection using routine PCR assays is difficult in poultry meat, and in particular ground chicken, due to low amounts of Salmonella and the presence of inhibitors.
Kanki
Masashi
M
Division of Bacteriology, Osaka Prefectural Institute of Public Health, 1-3-69 Nakamichi, Higashinari-ku, Osaka 537-0025, Japan. kanki@iph.pref.osaka.jp
Sakata
Junko
J
Taguchi
Masumi
M
Kumeda
Yuko
Y
Ishibashi
Masanori
M
Kawai
Takao
T
Kawatsu
Kentaro
K
Yamasaki
Wataru
W
Inoue
Kiyoshi
K
Miyahara
Michiko
M
D000818:Animals; D002645:Chickens; D015169:Colony Count, Microbial / Q000379:methods* / Q000592:standards; D003470:Culture Media / Q000737:chemistry; D004269:DNA, Bacterial / Q000032:analysis; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D008460:Meat / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods* / Q000592:standards; D011202:Poultry Products / Q000382:microbiology*; D019779:Salmonella enterica / Q000302:isolation & purification*; D012680:Sensitivity and Specificity
D003470:Culture Media; D004269:DNA, Bacterial