Detection of freeze-injured Escherichia coli O157:H7 cells from foods by resuscitation prior to selective enrichment.
We tried to detect Escherichia coli O157:H7 in food samples artificially contaminated with freeze-injured E. coli O157:H7 using an enrichment method with modified EC broth supplemented with novobiocin (mEC + n). When the samples were cultured for enrichment immediately after inoculation of freeze-injured cells, E. coli O157:H7 was not detected in 13 out of 18 samples. However, allowing the food samples to stand for 3 h at room temperature prior to enrichment in mEC + n remarkably improved recovery of E. coli O157:H7 except for some acidic foods. E. coli O157:H7 was detected in the acidic foods by introducing a resuscitation step of 3-h of incubation in a non-selective broth at room temperature prior to enrichment with mEC + n.
Nakagawa
H
H
Tokyo Kenbikvoin Foundation, Higashikurunie, Japan.
Hara-Kudo
Y
Y
Kojima
T
T
Ikedo
M
M
Kodaka
H
H
Konuma
H
H
Kumagai
S
S
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003080:Cold Temperature; D015169:Colony Count, Microbial; D017077:Culture Media, Conditioned; D019453:Escherichia coli O157 / Q000254:growth & development / Q000302:isolation & purification*; D005516:Food Microbiology; D005615:Freezing; D006863:Hydrogen-Ion Concentration; D009675:Novobiocin / Q000494:pharmacology; D013997:Time Factors
D000900:Anti-Bacterial Agents; D017077:Culture Media, Conditioned; D009675:Novobiocin