Assessment of resistance to colicinogenic Escherichia coli by E. coli O157:H7 strains.
OBJECTIVE
To assess a collection of 96 Escherichia coli O157:H7 strains for their resistance potential against a set of colicinogenic E. coli developed as a probiotic for use in cattle.


RESULTS
Escherichia coli O157:H7 strains were screened for colicin production, types of colicins produced, presence of colicin resistance and potential for resistance development. Thirteen of 14 previously characterized colicinogenic E. coli strains were able to inhibit 74 serotype O157:H7 strains. Thirteen E. coli O157:H7 strains were found to be colicinogenic and 11 had colicin D genes. PCR products for colicins B, E-type, Ia/Ib and M were also detected. During in vitro experiments, the ability to develop colicin resistance against single-colicin producing E. coli strains was observed, but rarely against multiple-colicinogenic strains. The ability of serotype O157:H7 strains to acquire colicin plasmids or resistance was not observed during a cattle experiment.


CONCLUSIONS
Escherichia coli O157:H7 has the potential to develop single-colicin resistance, but simultaneous resistance against multiple colicins appears to be unlikely. Colicin D is the predominant colicin produced by colicinogenic E. coli O157:H7 strains.


CONCLUSIONS
The potential for resistance development against colicin-based strategies for E. coli O157:H7 control may be very limited if more than one colicin type is used.
Schamberger
G P
GP
Department of Food Science and Nutrition, University of Minnesota, St Paul, MN, USA.
Diez-Gonzalez
F
F
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology; D003087:Colicins / Q000378:metabolism; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology; D019453:Escherichia coli O157; D005516:Food Microbiology; D008460:Meat; D008826:Microbial Sensitivity Tests; D019936:Probiotics
D003087:Colicins