The preliminary results indicated that the RambaQUICK Salmonella (RQS), a new rapid selective enrichment broth, was possible to support the growth of all tested strains of four Salmonella Enteritidis and one S. Typhimurium, and inhibited the growth of all tested non-Salmonella microorganisms. Furthermore, we compared the performance of the two enrichment methods, Rappaport-Vassiliadis selective enrichment followed Buffered peptone water pre-enrichment (BPW-RV) method and RQS selective enrichment from BPW (BPW-RQS) method, using 224 of routine samples suspected Salmonella spp polution. and 58 samples of retail chicken meats. Of 282 samples tested, the detection rate of BPW-RQS method for Salmonella spp. (63.8%; 37/58) was higher than BPW-RV method (31.0%; 18/58) in retaile chicken meats, and 224 were negative by both methods in routine samples. It is summarized that BPW-RQS method make possible the identification of Salmonella within the 2 days, then the results of Salmonella could inform as the quality control data attached with viable counts, coliforms, and Staphylococcus aureus. From these results, we concluded that BPW-RQS method was useful for the quality control work flow in the laboratory of food industry.
Twenty-four Shigella spp. strains randomly selected from 58 stock strains were analyzed for hemolytic activity on enterohemolysin blood agar (E-Hly agar) incubated at 35°C and 44°C in aerobic and anaerobic conditions. Hemolytic activity was observed more clearly in the case of incubation at 44°C than 35°C. Therefore, all Shigella spp. stock strains (50 S. sonnei strains, seven S. flexneri strains, one S. boydii strain) and 36 strains of Enterobacteriaceae were analyzed for hemolytic activity on E-Hly agar incubated at 44°C for 20 hr in aerobic and anaerobic conditions. All Shigella spp. strains were positive for hemolytic activity in anaerobic incubation however some Shigella spp. strains were negative in aerobic incubation. Though, some strains of Enterobacteriaceae were hemolytic on E-Hly agar, these strains were considered to distinct from Shigella spp. strains on selective agar. We tried to recover S. sonnei from spiked Japanese littleneck clam samples. S. sonnei was recovered by screening test using marker of hemolytic activity on E-Hly agar incubated at 44°C for 20 hr in anaerobic condition.