High-resolution genotyping of Campylobacter strains isolated from poultry and humans with amplified fragment length polymorphism fingerprinting

For epidemiological studies of Campylobacter infections, molecular typing m ethods that can differentiate campylobacters at the strain level are needed . In this study we used a recently developed genotyping method, amplified f ragment length polymorphism (AFLP), which is based on selective amplificati on of restriction fragments of chromosomal DNA, for genetic typing of Campy lobacter jejuni and Campylobacter coil strains derived from humans and poul try. We developed an automated AFLP fingerprinting method in which restrict ion endonucleases HindIII and HhaI were used in combination with one set of selective PCR primers. This method resulted in evenly distributed band pat terns for amplified fragments ranging from 50 to 500 bp long. The discrimin ately power of AFLP was assessed with a C. jejuni strain, an isogenic flage llin mutant, and distinct C. jejuni strains having known pulsed-field gel e lectrophoresis and fla PCR-restriction fragment length polymorphism genotyp es. Unrelated C. jejuni strains produced heterogeneous patterns, whereas ge netically related strains produced similar AFLP patterns. Twenty-five Campy lobacter strains obtained from poultry farms in The Netherlands grouped in three C. jejuni clusters that were separate from a C. coli cluster. The ban d patterns of 10 C. jejuni strains isolated from humans were heterogeneous, and most of these strains grouped with poultry strains. Our results show t hat AFLP analysis can distinguish genetically unrelated strains from geneti cally related strains of Campylobacter species. However, desirable genetica lly related strains can be differentiated by using other genotyping methods . We concluded that automated AFLP analysis is an attractive tool which can be used as a primary method for subtyping large numbers of Campylobacter s trains and is extremely useful for epidemiological investigations.