Subject(s)
Flavobacteriaceae Infections/classification , Flavobacteriaceae/isolation & purification , Microbiological Techniques/methods , Aged , Chryseobacterium/classification , Chryseobacterium/isolation & purification , Flavobacteriaceae/classification , Flavobacteriaceae Infections/diagnosis , Humans , Italy , MaleABSTRACT
Rainbow trout fry syndrome (RTFS) is an important infectious disease caused by Flavobacterium psychrophilum affecting farmed salmonids worldwide. Other Flavobacterium psychrophilum-like species (F. plurextorum, F. oncorhynchi, F. tructae, F. collinsii and F. piscis) have been isolated from diseased rainbow trout fry suspected of RTFS although the epidemiological and clinical relevance of these pathogens are unknown. The objective of this study was to evaluate the potential use of MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization-Time of Flight) Mass Spectrometry as method for specific identification of F. psychrophilum and its differentiation from other F. psychrophilum-like species isolated from diseased fish. Fifty-three isolates were analyzed after the creation of the Main Spectrum Profile (MSP) of reference strains of each of abovementioned species. F. psychrophilum exhibited a mass spectra very different from those of F. psychrophilum-like species, with five peaks (m/z 3654, 4585, 5388, 6730 and 7310) present only in F. psychrophilum isolates, and three peaks (m/z 6170, 7098 and 9241) absent in F. psychrophilum but present in all F. psychrophilum-like species. All F. psychrophilum isolates were correctly identified and differentiated from the F. psychrophilum-like species by MALDI-TOF. Although this approach showed a limited ability to differentiate among F. psychrophilum-like species, its complementation with a few simple biochemical tests may represent an alternative approach for the routine identification of the Flavobacterium psychrophilum-like species.
Subject(s)
Aquaculture/methods , Fish Diseases/diagnosis , Flavobacteriaceae Infections/veterinary , Flavobacterium/isolation & purification , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/veterinary , Animals , Fish Diseases/classification , Flavobacteriaceae Infections/classification , Flavobacteriaceae Infections/diagnosis , Flavobacterium/classification , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methodsSubject(s)
Bacterial Typing Techniques/methods , Fish Diseases/microbiology , Flavobacteriaceae Infections/veterinary , Flavobacterium/classification , Genome, Bacterial , Polymorphism, Restriction Fragment Length , RNA, Bacterial/analysis , RNA, Ribosomal, 16S/analysis , Animals , Electrophoresis, Agar Gel/methods , Fish Diseases/classification , Flavobacteriaceae Infections/classification , Flavobacteriaceae Infections/microbiology , Flavobacterium/isolation & purification , Polymerase Chain Reaction/methodsABSTRACT
Abstract Yellow pigmented, filamentous, Gram-negative bacteria belonging to genus Flavobacterium are commonly associated with infections in stressed fish. In this study, inter-species diversity of Flavobacterium was studied in apparently healthy freshwater farmed fishes. For this, ninety one yellow pigmented bacteria were isolated from skin and gill samples (n = 38) of three farmed fish species i.e. Labeo rohita, Catla catla and Cyprinus carpio. Among them, only twelve bacterial isolates (13.18%) were identified as Flavobacterium spp. on the basis of morphological, biochemical tests, partial 16S rDNA gene sequencing and phylogenetic analysis. On the basis of 16S rDNA gene sequencing, all the 12 isolates were 97.6-100% similar to six different formally described species of genus Flavobacterium. The 16S rDNA based phylogenetic analysis grouped these strains into six different clades. Of the 12 isolates, six strains (Fl9S1-6) grouped with F. suncheonense, two strains (Fl6I2, Fl6I3) with F. indicum and the rest four strains (Fl1A1, Fl2G1, Fl3H1 and Fl10T1) clustered with F. aquaticum, F. granuli, F. hercynium and F. terrae, respectively. None of these species except, F. hercynium were previously reported from fish. All the isolated Flavobacterium species possessed the ability of adhesion and biofilm formation to colonize the external surface of healthy fish. The present study is the first record of tropical freshwater farmed fishes as hosts to five environmentally associated species of the Flavobacterium.