[Detection method of injured Escherichia coli O157 in noodles and vegetables].
An enrichment procedure and a polymerase chain reaction (PCR) method for the detection of injured Escherichia coli O157 in foods were examined. Freeze-injured E. coli O157 inoculated in boiled spaghetti could be detected in 6-h culture within 12 h by the PCR method. Cells injured by heating in boiled spaghetti and cells injured by chlorine treatment in raw lettuce and carrot did not grow sufficiently to be detected in 6-h culture but were detected in 18-h culture using selective agar media. The injured cells could be also detected in 18-h culture within 24 h by the PCR method. Enrichment at 42 degrees C in trypticase soy broth (TSB) was more effective than that at 42 degrees C in modified EC broth with novobiocin. These results indicated that the usage of enrichment in TSB for 18 h at 42 degrees C in combination with the PCR method is suitable for screening for E. coli O157 in boiled or chlorinated foods, even if the O157 cells are injured.
Tanaka
Keiko
K
Nisshin Seifun Group Inc., Research Center for Basic Science, 5-3-1, Tsurugaoka, Oi-machi, Iruma-gun, Saitama 356-8511, Japan.
Motoi
Hirofumi
H
Hara-Kudo
Yukiko
Y
D002364:Caseins; D002713:Chlorine; D003470:Culture Media; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005433:Flour / Q000382:microbiology*; D005516:Food Microbiology; D005615:Freezing; D006358:Hot Temperature; D016133:Polymerase Chain Reaction / Q000379:methods*; D011492:Protein Hydrolysates; D013696:Temperature; D014675:Vegetables / Q000382:microbiology*
D002364:Caseins; D003470:Culture Media; D011492:Protein Hydrolysates; C026375:trypticase-soy broth; D002713:Chlorine