Phage typing of Campylobacter jejuni and Campylobacter coli and its use asan adjunct to serotyping

Campylobacter is the most commonly reported cause of gastro-intestinal infe ction in England and Wales, with over 50000 reported cases in 1997. The maj ority of human campylobacter isolates in England and Wales are C. jejuni (c . 90 %) with most of the remainder being C. coli. We describe the use of ph age typing as an extension to serotyping for more detailed characterization within these two species. The scheme was piloted during a study of 2407 C. jejuni and 182 C. coli strains isolated in Wales between April 1996 and Ma rch 1997. Fifty-seven C. jejuni phage types were identified, with the ten m ost prevalent phage types accounting for 60 % of isolates tested; 16 % of i solates were untypable. The most common phage type was PT 1 which represent ed c. 20 % of isolates. A further 7 % of isolates reacted with the phages b ut did not conform to a designated type (RDNC). Only 12 phage types were id entified among C, coli, with the two most common types, PT 2 and PT 7 accou nting for 75.2% of isolates. When used in conjunction with serotyping, the ability of phage typing to identify between 6 and 29 subtypes within each o f the predominant HS types has enabled a further level of discrimination to be achieved that enhances the epidemiological typing of C. jejuni and C. c oli.