Lactococcus garvieae strains isolated from rainbow trout and yellowtail in Australia, South Africa and Japan differentiated by repetitive sequence markers

Lactococcus garvieae is an emerging important epizootiological pathogen. A total of 25 Lactococcus garvieae isolates from diseased rainbow trout (Oncorhynchus mykiss) and yellowtail (Seriola quinqueradiata) from Japan, South Africa and Australia (Tasmania and Victoria) and type strains were analysed by repetitive sequence based PCR targeting repetitive extragenic palindromes (REP) and BOX interspersed DNA sequences. Both primer sets generated five different banding profiles with isolates from South Africa, Tasmania and Victoria sharing common profiles. Japanese isolates could easily be distinguished from all other isolates on the basis of banding profile and BOX primers enabled differentiation of capsular types for these strains. The type strain L. garvieae NCFB 2157 produced a unique profile significantly different from other strains with both oligonucleotide primer sets. REP-PCR and BOX-PCR offer a rapid, cost effective and straightforward means for strain differentiation of this important fish and emerging zoonotic pathogen.