In this work, we applied the random amplified polymorphic DNA (RAPD) technique to
evaluate the genetic diversity in Photobacterium damselae subsp. piscicida (formerly Pasteurella
piscicida), an important pathogen for different marine fish. Regardless of the oligonucleotide
primer employed, the 29 isolates of Ph. damselae subsp. piscicida tested were separated into
two groups, the RAPD-PCR analysis differentiated the European strains from the Japanese
strains. The similarity between both groups estimated on the basis of the Dice coefficient was
75–80%. These results show that European and Japanese isolates of Ph. damselae subsp.
piscicida, regardless of their host fish species, belong to two different clonal lineages. Our
findings also indicate that RAPD profiling constitutes a useful tool for epidemiological studies
of this fish pathogen.