Isolation Of Salmonella Grown Poorly At 42 Degrees C From Radish Sprouts

Incubation conditions using tetrathionate broth (TT) and Rappaport-Vassiliadis broth (RV), which are typically employed as enrichment broths, were investigated for the isolation of Salmonella Brandenburg grown poorly at 42 degrees C from radish sprouts. A small number (10(2) CFU/ml of broth) of Salmonella with Pseudomonas aeruginosa were injected into TT and RV; however, Salmonella colonies were absent when these broths were incubated at 42 degrees C. No differences were observed in the detection rates of colonies on either TT or RV incubated anaerobically at 35 degrees C and aerobically at 35 degrees C, with the exception of a small number of Salmonella with P. aeruginosa on RV. In case of mixed culture of Salmonella Brandenburg and Escherichia coli in TT and RV at 42 degrees C, there were samples that Salmonella colonies were not detected. In the mixed culture of Salmonella Brandenburg and radish sprouts in TT and RV, the detection rate of Salmonella was better on incubation at 35 degrees C than that at 42 degrees C when a large number of Salmonella Brandenburg was injected (10(5) or 10(6) CFU/ml of broth). Moreover, the detection rate at colonies was better at 35 degrees C than at 42 degrees C in the case of the injection (10(2) CFU/ml of broth) into RV. On the other hand, no remarkable differences were observed in the detection rates of colonies on either TT or RV incubated anaerobically at 35 degrees C and aerobically at 35 degrees C. These results demonstrated that the isolation of Salmonella grown poorly at 42 degrees C from radish sprouts using a high temperature incubation was not favorable.