Reduction of Escherichia coli O157:H7 populations in cattle by addition of colicin E7-producing E. coli to feed

• Published in: Applied and Environmental Microbiology Vol. 70; no. 10; pp. 6053 - 6060
• Main Authors: Schamberger, G.P, Phillips, R.L, Jacobs, J.L, Diez-Gonzalez, F
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.10.2004
• Subjects: Animal Feed; Animals; Bacteria; Bacteriology; Biological and medical sciences; biosynthesis; calf feeding; Cattle; Cattle - microbiology; cattle feeding; colicins; Colicins - biosynthesis; Colony Count, Microbial; Escherichia coli; Escherichia coli - physiology; Escherichia coli O157 - isolation & purification; Escherichia coli O157 - pathogenicity; Escherichia coli O157:H7; excretion; fecal shedding; Feces; Feces - microbiology; feed additives; Feeds; Food Microbiology; food pathogens; Fundamental and applied biological sciences. Psychology; human food chain; Humans; Male; Microbiology; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Probiotics; Time Factors; Bovine; Escherichia coli; Bacteriocin; Colicin; Vertebrata; Mammalia; Pathogen strain; Bacteria; Livestock; Artiodactyla; Ungulata; Enterobacteriaceae; Feed
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.70.10.6053-6060.2004

A cattle trial using artificially inoculated calves was conducted to determine the effect of the addition of colicinogenic Escherichia coli strains capable of producing colicin E7 (a 61-kDa DNase) to feed on the fecal shedding of serotype O157:H7. The experiment was divided into three periods. In period 1, which lasted 24 days, six calves were used as controls, and eight calves received 10(7) CFU of E. coli (a mixture of eight colicinogenic E. coli strains) per g of feed. Both groups were orally inoculated with nalidixic acid-resistant E. coli O157:H7 strains 7 days after the treatment started. In periods 2 and 3, the treatment and control groups were switched, and the colicinogenic E. coli dose was increased 10-fold. During period 3, which lasted as long as period 1, both groups were reinoculated with E. coli O157:H7. The numbers of E. coli O157:H7 were consistently greater in the control groups during the three periods, but comparisons within each time period determined a statistically significant (P < 0.05) difference only at day 21 of period 1. However, when the daily average counts were compared between the period 1 control group and the period 3 treatment group that included the same six animals, an overall reduction of 1.1 log10 CFU/g was observed, with a maximum decrease of 1.8 log10 CFU/g at day 21 (overall statistical significance, P = 0.001). Serotype O157:H7 was detected in 44% of the treatment group's intestinal tissue samples and in 64% of those from the control group (P < 0.04). These results indicated that the daily addition of 10(8) CFU of colicin E7-producing E. coli per gram of feed could reduce the fecal shedding of serotype O157:H7.