Evaluation of colicins for inhibitory activity against diarrheagenic Escherichia coli strains, including serotype O157:H7.
Twenty-four Escherichia coli strains producing standard colicins were evaluated for inhibitory activity against 27 diarrheagenic E. coli strains of serotypes O15:H-, O26:(H11, H-), and O111:(H8, H11, H-), including O157:H7, representing diarrheagenic E. coli clones, 3, 4, 8, 9, and 10. Overlay techniques were used to assess inhibition on Luria agar and Luria agar supplemented with 0.25 micrograms of mitomycin C per ml to induce colicin production. As a group, the A colicins (Col) E1 to E8, K, and N inhibited 23 to 25 (85.2 to 92.6%) of the 27 diarrheagenic strains on mitomycin C-containing agar, whereas the most active group B colicins, Col D and Ia, inhibited 9 and 12 (33.3 and 44.4%), of the diarrheagenic strains, respectively. Col G and H and Mcc B17 inhibited 22 to 27 (81.5 to 100%) of the diarrheagenic strains on Luria agar but were suppressed on mitomycin C-containing agar medium. All O157:H7 strains evaluated were sensitive to Col E1 to E8, K, and N on mitomycin C-containing agar and to Col G and H and Mcc B17 on Luria agar. Sensitivity to colicins of the selected set of diarrheagenic strains was in the order diarrheagenic E. coli clone 9 > 4 > 3 > 10 > 8 and was not restricted to strains of a single clone or serotype. Strain 8C from clone 8 was resistant to most test colicins. There is potential for using colicins in foods and agriculture to inhibit sensitive diarrheagenic E. coli strains, including serotype O157:H7.
Murinda
S E
SE
Department of Food Science, Pennsylvania State University, University Park 16802, USA.
Roberts
R F
RF
Wilson
R A
RA
D000818:Animals; D003087:Colicins / Q000096:biosynthesis / Q000494:pharmacology*; D003470:Culture Media; D003967:Diarrhea / Q000209:etiology*; D010450:Endopeptidases / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects* / Q000472:pathogenicity; D006801:Humans; D012703:Serotyping
D003087:Colicins; D003470:Culture Media; D010450:Endopeptidases