MOLECULAR FINGERPRINTING OF LEGIONELLA SPECIES BY REPETITIVE ELEMENT PCR

Repetitive element PCR (rep-PCR) uses outward-facing primers to amplif y multiple segments of DNA located between conserved repeated sequence s interspersed along the bacterial chromosome. Polymorphisms of rep PC R amplification products can serve as strain-specific molecular finger prints. Primers directed at the repetitive extragenic palindromic elem ent were used to characterize isolates of Legionella pneumophila and o ther Legionella species. Substantial variation was seen among the rep- PCR fingerprints of different Legionella species and serogroups. More limited, but distinct, polymorphisms of the rep-PCR fingerprint were e vident among epidemiologically unrelated isolates of L. pneumophila se rogroup 1. Previously characterized Legionella isolates from nosocomia l outbreaks were correctly clustered by this method. These results sug gest the presence of repetitive extragenic palindromic-like elements w ithin the genomes of members of the family Legionellaceae that can be used to discriminate between strains within a serogroup of L. pneumoph ila and between different Legionella species. rep-PCR appears to be a useful technique for the molecular fingerprinting of Legionella specie s.