Genetic analysis and antimicrobial susceptibility of Francisella noatunensis subsp. orientalis (syn. F. asiatica) isolates from fish

Francisella noatunensis subsp. orientalis (syn. F. asiatica) (Fno) is an emergent fish pathogen that causes acute to chronic disease in a wide variety of freshwater, brackish and marine fish. Due to the emergent nature of this bacterium, established protocols to measure antimicrobial susceptibility are lacking. In this project we compare three different methods to examine the antimicrobial susceptibility (Etest, broth microdilution and disk diffusion) of 10 different isolates of Fno from two different fish species and four different geographic outbreaks from 2006 to 2010. PCR mediated genomic fingerprinting (rep-PCR) performed on the different isolates confirmed genetic homogeneity amongst the different isolates. The in vitro susceptibility data presented here provides important baseline data for future research monitoring the development of antibiotic resistance among Fno isolates as well as provides invaluable data for the development of potential therapeutics.