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E. coli biofilm research

E. coli in food producing environments

Shiga toxin-producing Escherichia coli (STEC), also called Verotoxin-producing E. coli (VTEC), are important food borne pathogens worldwide (19). Ruminants are regarded as the main reservoir from which STEC enter the food production chain and contaminate the environment and products. If these bacteria are able to persist and disseminate in the food production facilities and retail shops there is a considerable risk of contaminating the food products. Biofilm formation on food and food contact surfaces may also enhance the risk of transfer of virulence factor genes between the biofilm forming strains, and thereby increase the risk of spreading virulent strains to the consumer.

The National Veterinar Institue is studying biofilm formation by potentially pathogenic E. coli in cooperation with the research scientists Møretrø, Langsud and Heir at Nofima Mat, and professors Aamdal Scheie and Benneche at the University of Oslo.

Studies on on a number of strains of the serotypes O157:H7, O103:H2, O103:H25 and O26:H11 isolated from Norwegian sheep in a national surveillance program displayed large differences between serotypes regarding biofilm producing abilities. In genereal, biofilm production was highest at 20 ºC as compared to 37 ºC and 12 ºC. Two different brominated furanones significantly reduced biofilm formation.

Studies have shown that transduction within biofilms may occur. However, focus has mainly been on phage therapy as a viable alternative for controlling and removing biofilms, and not on the potential for emergence of pathogenic bacteria due to transduction of pathogenicity factor-encoding bacteriophages within the biofilm environment. The aim of this study was to study horizontal gene transfer of a Shiga toxin 2 encoding bacteriophage (Stx2 phage) within biofilms produced by E. coli O103.

Contact person National Veterinary Institute:
Live Nesse, Senior scientist, Section of Bacteriology
E-mail: live.nesse@vetinst.no
Tlf.: + 47 23 21 63 15/924 41 267

Heidi Solheim, Reseach Fellow, Section of Bacteriology
E-mail: heidi.solheim@vetinst.no
Tlf.: + 47 23 21 63 13