Multicenter validation of PCR-based method for detection of Salmonella in chicken and pig samples.
As part of a standardization project, an interlaboratory trial including 15 laboratories from 13 European countries was conducted to evaluate the performance of a noproprietary polymerase chain reaction (PCR)-based method for the detection of Salmonella on artificially contaminated chicken rinse and pig swab samples. The 3 levels were 1-10, 10-100, and 100-1000 colony-forming units (CFU)/100 mL. Sample preparations, including inoculation and pre-enrichment in buffered peptone water (BPW), were performed centrally in a German laboratory; the pre-PCR sample preparation (by a resin-based method) and PCR assay (gel electrophoresis detection) were performed by the receiving laboratories. Aliquots of BPW enrichment cultures were sent to the participants, who analyzed them using a thermal lysis procedure followed by a validated Salmonella-specific PCR assay. The results were reported as negative or positive. Outlier results caused, for example, by gross departures from the experimental protocol, were omitted from the analysis. For both the chicken rinse and the pig swab samples, the diagnostic sensitivity was 100%, with 100% accordance (repeatability) and concordance (reproducibility). The diagnostic specificity was 80.1% (with 85.7% accordance and 67.5% concordance) for chicken rinse, and 91.7% (with 100% accordance and 83.3% concordance) for pig swab. Thus, the interlaboratory variation due to personnel, reagents, thermal cyclers, etc., did not affect the performance of the method, which will be proposed as part of a developing international PCR standard.
Federal Institute for Risk Assessment, National Salmonella Reference Laboratory, Diedersdorfer Weg, Berlin, Germany.
Burkhard
B
Malorny
Nigel
N
Cook
Martin
M
D'Agostino
Dario
D
De Medici
Luciana
L
Croci
Amir
A
Abdulmawjood
Patrick
P
Fach
Renata
R
Karpiskova
Teresa
T
Aymerich
Krysztof
K
Kwaitek
Jeffrey
J
Hoorfar
Burkhard
B
Malorny
D000818:Animals; D002645:Chickens / Q000382:microbiology*; D015169:Colony Count, Microbial; D005516:Food Microbiology / Q000592:standards*; D007753:Laboratories; D008460:Meat / Q000382:microbiology*; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000592:standards*; D012475:Salmonella / Q000737:chemistry*; D013552:Swine / Q000382:microbiology*