We developed a novel quantitative method for detecting S. aureus using the DOXTM system. A total of 19 strains of S. aureus, and 36 strains of non-S. aureus containing 27 species were examined. The mean positive rate of the high- (103 CFU/ml), medium- (102 CFU/ml), and low-concentration (10 CFU/ml) S. aureus samples was all 100%. The relationship between detection time and bacterial count of the 19 S. aureus had a good linear calibration curve. For the 36 non-S. aureus samples, the mean negative rates for the high-concentration (106 CFU/ml) samples and the medium-concentration (103 CFU/ml) samples were both 94.4% (34/36). The 2 positive non-S. aureus samples were S. xylosus ATCC 29971 and Enterococcus faecalis ATCC 29212. Furthermore, a recovery examination was carried out by inoculating 20 food samples with S. aureus isolated from rice ball and each sample was examined 2 times. S. aureus was detected in all samples inoculated with a low concentration of the organism (1.30-1.37 log CFU/ml), and the detection time of the positive samples was 477-807 min (9.7 hrs on average). The DOX system provided rapid results (usually within 10 hrs) and required no special techniques for measurement. Therefore, the DOX system may be a useful tool for determining the absence of S. aureus in food and environmental samples at food processing companies. However, more validation studies and field studies are needed.
Faculty of Veterinary Science, Chulalongkorn University
Tanno, Shouichi; Fukui, Naoki; Utaka, Yukihiro; Itabashi, Yumiko; Morita, Yukio; and Boonmar, Sumalee
"Quantitative method for detecting Staphylococcus aureus using Bio-Theta DOXTM system,"
The Thai Journal of Veterinary Medicine: Vol. 46:
3, Article 14.
Available at: https://digital.car.chula.ac.th/tjvm/vol46/iss3/14