Evaluation of two real-time polymerase chain reaction pathogen detection kits for Salmonella spp. in food.
OBJECTIVE
To evaluate the LightCycler Salmonella Detection Kit and the TaqMan Salmonella Gold Detection and Quantitation Kit for the real-time PCR detection of Salmonella in various food samples.


RESULTS
Ready-to-eat foods and raw food samples were artificially contaminated with Salmonella serotypes. In the specificity test, bacterial DNA extracted from sample pre-enrichment culture was analysed with the detection kits performed respectively on the LightCycler Instrument or the ABI Prism 7000 Sequence Detection System. No false-positive or false-negative results were obtained, although the LightCycler system generated invalid PCR results on two occasions. In the sensitivity test using the LightCycler system, Salmonella could be detected in pre-enrichment cultures of 25-g samples inoculated with as low as 1.5 x 10(3) CFU (depending on food type), and false-negative results were obtained for samples with low inoculum levels.


CONCLUSIONS
Two commercial kits for real-time PCR detection of Salmonella were evaluated.


CONCLUSIONS
Evaluation using more food types and matrices, and foods that contain low number of Salmonella or high number of other competing bacteria, is needed before adopting the real-time PCR technique for routine food tests.
Cheung
P-Y
PY
Department of Health, Public Health Laboratory, Public Health Laboratory Centre, Hong Kong, China. cheungpi@yahoo.com
Chan
C W
CW
Wong
W
W
Cheung
T L
TL
Kam
K M
KM
D001431:Bacteriological Techniques; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics / Q000302:isolation & purification; D005188:False Negative Reactions; D005189:False Positive Reactions; D005502:Food; D005516:Food Microbiology; D016133:Polymerase Chain Reaction / Q000379:methods*; D012475:Salmonella / Q000235:genetics / Q000302:isolation & purification*; D012680:Sensitivity and Specificity
D004269:DNA, Bacterial