We developed a quantitative method for detecting Listeria species in food using the DOXTM system. The system could detect low concentrations (10 cfu/ml) of Listeria monocytogenes, L. innocua, and L. welshimeri, and could not detect medium concentrations (103 cfu/ml) of the 29 non-Listeria organisms examined in this study. The relationship between detection time and bacterial count of the 3 Listeria species had a good linear calibration curve. We carried out a recovery examination by inoculating 15 food samples with L. monocytogenes, and each sample was examined 5 times. L. monocytogenes was detected in 68 of the 75 samples inoculated with an ultra-low concentration of bacteria (<1 log cfu/ml), and the detection time of the positive samples was 1,052–1,870 min (average, 21.9 h). The DOX system provides rapid results (usually within 1 day), and requires no special techniques for measurement. The DOX system may be a useful tool for determining the presence of Listeria spp. in food and environmental samples at food processing companies, though more validation studies and field studies are needed.
Faculty of Veterinary Science, Chulalongkorn University
Tanno, Shouichi; Fukui, Naoki; Utaka, Yukihiro; Ohkawa, Saburo; Morita, Yukio; and Boonmar, Sumalee
"Quantitative Method for Detecting Listeria Species using the Bio-Theta DOXTM System,"
The Thai Journal of Veterinary Medicine: Vol. 45:
4, Article 8.
Available at: https://digital.car.chula.ac.th/tjvm/vol45/iss4/8