Detection of freeze-injured Escherichia coli O157:H7 cells from foods by resuscitation prior to selective enrichment

Int J Food Microbiol. 2000 Sep 15;60(1):107-10. doi: 10.1016/s0168-1605(00)00325-1.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Cold Temperature
  • Colony Count, Microbial
  • Culture Media, Conditioned
  • Escherichia coli O157 / growth & development
  • Escherichia coli O157 / isolation & purification*
  • Food Microbiology*
  • Freezing*
  • Hydrogen-Ion Concentration
  • Novobiocin / pharmacology
  • Time Factors

Substances

  • Anti-Bacterial Agents
  • Culture Media, Conditioned
  • Novobiocin