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Genetic diversity and antimicrobial resistance of Flavobacterium psychrophilum isolated from cultured rainbow trout, Onchorynchus mykiss (Walbaum), in Spain
Author(s) -
Del Cerro A,
Márquez I,
Prieto J M
Publication year - 2010
Publication title -
journal of fish diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 85
eISSN - 1365-2761
pISSN - 0140-7775
DOI - 10.1111/j.1365-2761.2009.01120.x
Subject(s) - biology , pulsed field gel electrophoresis , microbiology and biotechnology , rainbow trout , typing , flavobacterium , plasmid , genotype , florfenicol , antimicrobial , antibiotic resistance , antibiotics , bacteria , genetics , fishery , dna , gene , pseudomonas , fish <actinopterygii>
Flavobacterium psychrophilum is the causative agent of bacterial cold‐water disease (CWD) and rainbow trout fry syndrome (RTFS) in salmonids. These diseases are a major problem in the aquaculture industry in Spain, and a better understanding of the epidemiology of F. psychrophilum isolates is necessary to improve management strategies. In this study, to investigate genetic variability of this bacterium, pulsed‐field gel electrophoresis after DNA digestion with endonuclease Stu I, plasmid profiling analysis and antimicrobial susceptibility testing were undertaken with 25 isolates of F. psychrophilum from Spain. These isolates were classified into 17 patterns by PFGE analysis, which were grouped into four clusters and seven independent branches. Twenty isolates (80%) possessed plasmids of 3.5 kb ( n = 13) or 5.5 kb ( n = 7). No plasmids were associated with antibiotic resistance to oxytetracycline (OTC) or florfenicol (FLO). Twenty isolates (80%) had minimum inhibitory concentrations (MICs) to OTC of between 2.4 and 9.7 μg mL −1 , and all isolates were susceptible to FLO. A relationship between the origin of the isolates and PFGE genotypes was found. Plasmid profile typing correlated with PFGE profile typing, whereas no correlation was found between antimicrobial susceptibility testing and PFGE profiles. These results suggest that the population of F. psychrophilum with pathogenic potential in northern Spain is quite heterogeneous.