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ABSTRACT: Members of most Chryseobacterium species occur in aquatic environments or food products, while strains of some other species are pathogenic to humans and animals. A collection of 52 Chryseobacterium sp. strains isolated from diseased fish, one frog isolate and 22 reference strains were included in a polyphasic taxonomy study. Fourteen clusters of strains were delineated following the comparison of whole-cell protein profiles. Most of these clusters were confirmed when the phenotypic and RAPD profiles and the 16S rRNA gene sequences were compared. Fatty acid composition helped differentiate the Chryseobacterium strains from members of related genera. None of the fish isolates could be allocated to the two species previously reported from fish but two isolates belonged to C. joostei, while the frog isolate was identified as Elizabethkingia meningoseptica, a human pathogen previously included in the genus Chryseobacterium. Three clusters grouping from 3 to 13 isolates will probably constitute the core of new Chryseobacterium species but all other isolates occupied separate or uncertain positions in the genus. This study further demonstrated the overall high similarity displayed by most Chryseobacterium strains whatever the technique used and the resulting difficulty in delineating new species in the genus. Members of this bacterial group should be considered potential emergent pathogens in various fish and frog species, farming conditions and geographical areas.
Systematic and Applied Microbiology 10/2005; 28(7):640-60. · 3.37 Impact Factor
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ABSTRACT: To assess the susceptibility of Chryseobacterium isolates of fish and aquatic habitats to antimicrobial compounds. Special attention was paid to the resistance to chloramphenicol and florfenicol, a phenicol derivative recently licensed for use in veterinary medicine and fish farming.
Sixty-seven Chryseobacterium spp. isolates and reference strains, originating mainly from different aquatic habitats, were tested using the disk-diffusion method. In addition, agar dilution was used for assessing minimum inhibitory concentration of chloramphenicol and florfenicol. In spite of (i) conditions that hampered properly standardized experiments and (ii) the heterogeneity of the isolates resulting in some aberrant values in diffusion, correlation between the two methods was confirmed. Most of the isolates exhibited considerable multiresistance to most antimicrobial drug families, and many were clearly resistant to phenicols. Molecular investigations conducted on 10 strains selected for high resistance to florfenicol did not establish the existence of floR or cmlA genes currently reported in the literature as responsible for florfenicol resistance. Nevertheless, when an efflux pump inhibitor, phenyl-arginin-beta-naphthylamide, was combined with diffusion tests, drug susceptibility to florfenicol was restored, suggesting that Chryseobacterium's resistance to this molecule is under the control of efflux mechanisms.
Constitutive multiresistance to antibiotics is common in chryseobacteria isolated from the aquatic environment. Although no gene related to the floR family could be detected, efflux mechanisms could partly support the resistance to phenicols.
These results explain the difficulty of treatment and clearly reflect the properties previously reported in Chryseobacterium isolates of human origin. Because several species have been involved in opportunistic infections in humans, the possible role of aquatic organisms as a source of infection should be considered.
Journal of Applied Microbiology 02/2005; 99(2):323-32. · 2.34 Impact Factor
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ABSTRACT: To investigate the distribution of antimicrobial resistance to phenicols in the fish pathogenic bacteria Aeromonas salmonicida, motile Aeromonas, Yersinia ruckeri, lactic bacteria and the nutritionally fastidious Flavobacterium psychrophilum. The last species was screened on two media (diluted Mueller-Hinton and peptone-enriched Anacker and Ordal), both supplemented with horse serum.
Minimal inhibitory concentration (MIC) assessment, using the agar dilution method according to proposed standards, confirmed that chloramphenicol resistance was more frequent and expressed at higher levels than florfenicol resistance. A significant resistant population, highlighted by the bimodal distribution of MICs, was detected only for chloramphenicol in A. salmonicida. No link could be found with the geographical origin of the isolates or fish species. Other cases of resistance appeared randomly distributed or related to the natural properties of the bacterial species. Although the two media used for testing F. psychrophilum resulted in comparable performances in dilution methods, Anacker and Ordal was more adapted to disc diffusion tests.
Despite wide use, resistance to florfenicol does not seem to occur frequently in French fish farms.
It is important to maintain a surveillance, as development of florfenicol resistance has occasionally been documented. For this purpose, and for the species studied in this work, the recently proposed standards appear generally well-adapted.
Journal of Applied Microbiology 02/2003; 95(5):1008-15. · 2.34 Impact Factor
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ABSTRACT: Five strains of gliding bacteria were isolated in France from farmed diseased rainbow trouts reared at low water temperature. The resemblance of these bacteria to the known fish pathogen "Cytophaga psychrophila" led to their comparative study with reference strain NCMB 1947 and with an American isolate. Morphological, physiological, and biochemical characteristics of the seven strains proved to be similar. Comparison of their DNA by the S1 nuclease DNA-DNA hybridization method showed that the seven strains formed a tight genomic species with DNA relatedness above 90%. This is the first identification of this fish pathogen in a European country. The main phenotypic characteristics differentiating this bacterium from other nonpathogenic gliding bacteria of fish origin include a poor gliding movement, yellow compact or weakly rhizoid colonies on solid media, and the presence of flexirubin-type pigments. The inability to metabolize any carbohydrates, the strong proteolytic activity, the absence of growth in more than 0.5% NaCl, and the tolerance to a maximum temperature of 25 degrees C are also useful characteristics of this group of bacteria.
Applied and Environmental Microbiology 08/1989; 55(7):1796-800. · 3.83 Impact Factor
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ABSTRACT: Cinq ammoniums quaternaires disponibles sur le marché français ont été testés pour déterminer leur activité sur deux virus et cinq espèces bactériennes. Une concentration de 125 mg/l est suffisante pour détruire en 5 minutes le virus de la Septicémie Hémorragique Virale , mais 12500 mg/l est une concentration insuffisante pour obtenir le même résultat avec le virus de la Nécrose Pancréatique Infectieuse. Une concentration de 100 mg/l inactive totalement les espèces bactériennes util sées en 2 minutes, ce résultat n'étant pas toujours obtenu avec 10 mg/l . Les Myxobactéries se révèlent les plus sensibles , une certaine inactivation étant encore notée à 1 mg/l pendant 1 0 min. en eau distillée. Les limites de l'utilisation de ces composés en salmoniculture sont discutées. Five quaternary ammonium compounds available in France have been tested for determining their activity against two viruses and five bacteria. A concentration of 125 mg/l is sufficient to inactivate Viral Haemorrhagic Septicaemia Virus wit hin 5 minutes, but 12500 mg/l is not sufficient for obtaining the same result with Infectious Pancreatic Necrosis Virus . The bacteria are totally inactivated with in 2 minutes by a concentration of 100 mg/l , but this result is not always achieved at 10 mg/l . The Myxobacteria prove the most susceptible, some inactivation being observed with 1 mg/l during 10 min in distilled water. The limits of quaternary ammonium compounds in trout farming are discussed.
http://dx.doi.org/10.1051/kmae:1987008.
