Application of bacteriophages to control intestinal Escherichia coli O157:H7 levels in ruminants

Appl Environ Microbiol. 2006 Aug;72(8):5359-66. doi: 10.1128/AEM.00099-06.

Abstract

A previously characterized O157-specific lytic bacteriophage KH1 and a newly isolated phage designated SH1 were tested, alone or in combination, for reducing intestinal Escherichia coli O157:H7 in animals. Oral treatment with phage KH1 did not reduce the intestinal E. coli O157:H7 in sheep. Phage SH1 formed clear and relatively larger plaques on lawns of all 12 E. coli O157:H7 isolates tested and had a broader host range than phage KH1, lysing O55:H6 and 18 of 120 non-O157 E. coli isolates tested. In vitro, mucin or bovine mucus did not inhibit bacterial lysis by phage SH1 or KH1. A phage treatment protocol was optimized using a mouse model of E. coli O157:H7 intestinal carriage. Oral treatment with SH1 or a mixture of SH1 and KH1 at phage/bacterium ratios > or = 10(2) terminated the presence of fecal E. coli O157:H7 within 2 to 6 days after phage treatment. Untreated control mice remained culture positive for >10 days. To optimize bacterial carriage and phage delivery in cattle, E. coli O157:H7 was applied rectally to Holstein steers 7 days before the administration of 10(10) PFU SH1 and KH1. Phages were applied directly to the rectoanal junction mucosa at phage/bacterium ratios calculated to be > or = 10(2). In addition, phages were maintained at 10(6) PFU/ml in the drinking water of the phage treatment group. This phage therapy reduced the average number of E. coli O157:H7 CFU among phage-treated steers compared to control steers (P < 0.05); however, it did not eliminate the bacteria from the majority of steers.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Bacteriolysis
  • Cattle
  • Cattle Diseases / microbiology
  • Cattle Diseases / therapy
  • Coliphages / physiology*
  • Drinking
  • Escherichia coli Infections / microbiology
  • Escherichia coli Infections / therapy
  • Escherichia coli O157 / pathogenicity
  • Escherichia coli O157 / physiology*
  • Escherichia coli O157 / virology*
  • Fresh Water / virology
  • Intestines* / microbiology
  • Intestines* / virology
  • Lysogeny
  • Mice
  • Ruminants* / microbiology
  • Ruminants* / virology
  • Sheep
  • Sheep Diseases / microbiology
  • Sheep Diseases / therapy
  • Viral Plaque Assay