VALIDITY OF SMAI-DEFINED GENOTYPES OF CAMPYLOBACTER-JEJUNI EXAMINED BY SALI, KPNI, AND BAMHI POLYMORPHISMS - EVIDENCE OF IDENTICAL CLONES INFECTING HUMANS, POULTRY, AND CATTLE

We describe here an examination of the validity of molecular types of Campylobacter jejuni as defined by separation of SmaI-digested DNA usi ng pulsed-held gel electrophoresis (PFGE), recently suggested as part of a molecular subtyping scheme. Thirty-four Danish strains from human s, water, poultry and cattle were assigned to one of six SmaI 'profile groups' (PGs), with two additional strains included as genotypically distinct controls. The interstrain relationships were reexamined by PF GE of SalI, KpnI and BamHI-digested DNA, and also by serotyping with h eat-stable antigens. All outbreak-related strains were indistinguishab le by all criteria, as were two sets of two randomly-isolated human st rains. Two groups of indistinguishable isolates contained randomly iso lated strains from more than one source (poultry, humans and/or cattle ), a finding with significant epidemiological connotations. All 'genet ically identical' strains belonged to the same serotype, whereas genet ic differences were detected between strains assigned to the same SmaI PG but differing in serotype. We conclude that PFGE-based genetic fin gerprinting can yield invaluable data for epidemiological studies of s poradic C. jejuni infection, but that results based on one restriction site polymorphism must be checked with another enzyme.