[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.
Nisshin Seifun Group Inc., Research Center for Basic Science, 5-3-1, Tsurugaoka, Oi-machi, Iruma-gun, Saitama 356-8511, Japan.
Keiko
K
Tanaka
Hirofumi
H
Motoi
Yukiko
Y
Hara-Kudo
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