Extended phage-typing scheme for Campylobacter jejuni and Campylobacter coli.

The extended phage-typing scheme described for Campylobacter jejuni and Campylobacter coli has established 46 different phage types using 19 typing phages. Altogether 754 campylobacter isolates, 672 C. jejuni and 82 C. coli, isolated from human and non-human sources received from 17 different countries were phage-typed. Overall, 80.6% of the total isolates were typable. Among typable strains, 9 phage types (3, 5, 10, 11, 18, 19, 23, 26 and 44) represented 57.0% of the strains, 21.3% of the strains belonged to another 37 phage types and the remaining 2.3% of isolates were designated atypical. The most common phage type 11 (140/754) was frequently observed among C. jejuni isolates from human (113/561) and non-human sources (18/111), whereas type 44 was frequent among C. coli isolates from human (22/59) and from non-human sources (8/23). A study of the animal host-associations of common phage types showed that contaminated cattle and poultry appear to be the most common sources of human infection. The greatest variety of phage types was observed in Canada (24 phage types), followed by Portugal (17 types) and the UK (14 types), reflecting the larger sample sizes from these countries. Phage type 11 was encountered in 12 different countries and prevalence of other phage types varied from one country to another. The number of isolates typable with the scheme varied from 93.2% (261/280) in Canada to 61% (47/77) in Thailand. However, the number and diversity of phage types makes phage typing the method of choice in epidemiological studies of campylobacter infections.