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Attachment of Escherichia coli O157:H7 to the surfaces and internal structures of apples as detected by confocal scanning laser microscopy.

Author(s) : BURNETT S. L., CHEN J., BEUCHAT L. R.

Type of article: Article

Summary

Confocal scanning laser microscopy was used to demonstrate the attachment of Escherichia coli O157:H7 transformed with a plasmid encoding for green fluorescent protein (GFP) to the surface and within the internal structures of nonwaxed red delicious cv. apples. Apples at 2 or 25 °C were inoculated with E. coli O157:H7 cell suspension at 2 or 25 °C. The effect of a negative temperature differential (cold inoculum, warm apple), a positive differential (warm inoculum, cold apple), and no differential (warm inoculum, warm apple), in combination with a pressure differential, on the attachment and infiltration of cells was determined. The pathogen was observed at depths up to 70 µm below the skin surface. Attachment to lenticels was sporadic but occasionally observed at depths of up to 40 µm. Infiltration through the floral tube and attachments to seeds, cartilaginous pericarp, and internal trichomes were observed in all apples examined, regardless of temperature differential during inoculation. The pressure differential had no effect on infiltration or attachment of E. coli O157:H7. Puncture wounds harbored greater numbers of the pathogen at greater depths than did other sites examined. Attachment or infiltration of cells was greater on intact skin and in lenticels, russet areas, and the floral tube of apples inoculated under a negative temperature differential compared to those inoculated under no temperature differential. Results suggest that E. coli O157:H7 attached to internal core structures or within tissues of apples may evade decontamination treatments. Disinfectant treatments need to be developed.

Details

  • Original title: Attachment of Escherichia coli O157:H7 to the surfaces and internal structures of apples as detected by confocal scanning laser microscopy.
  • Record ID : 2002-0234
  • Languages: English
  • Source: Appl. environ. Microbiol. - vol. 66 - n. 11
  • Publication date: 2000/11

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