Coverage of diarrhoea‐associated E scherichia coli isolates from different origins with two types of phage cocktails

Summary Eighty‐nine T 4‐like phages from our phage collection were tested against four collections of childhood diarrhoea‐associated E scherichia coli isolates representing different geographical origins ( M exico versus   B angladesh), serotypes (69 O , 27 H serotypes), pathotypes ( ETEC , EPEC , EIEC , EAEC , VTEC , S higella ), epidemiological settings (community and hospitalized diarrhoea) and years of isolation. With a cocktail consisting of 3 to 14 T 4‐like phages, we achieved 54% to 69% coverage against predominantly EPEC isolates from M exico, 30% to 53% against mostly ETEC isolates from a prospective survey in B angladesh, 24% to 61% against a mixture of pathotypes isolated from hospitalized children in B angladesh, and 60% coverage against S higella isolates. In comparison a commercial R ussian phage cocktail containing a complex mixture of many different genera of coliphages showed 19%, 33%, 50% and 90% coverage, respectively, against the four above‐mentioned collections. Few O serotype‐specific phages and no broad‐host range phages were detected in our T 4‐like phage collection. Interference phenomena between the phage isolates were observed when constituting larger phage cocktails. Since the coverage of a given T 4‐like phage cocktail differed with geographical area and epidemiological setting, a phage composition adapted to a local situation is needed for phage therapy approaches against E . coli pathogens.