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      Genetic diversity of geographically distinct Streptococcus dysgalactiae isolates from fish


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          Streptococcus dysgalactiae is an emerging pathogen of fish. Clinically, infection is characterized by the development of necrotic lesions at the caudal peduncle of infected fishes. The pathogen has been recently isolated from different fish species in many countries. Twenty S. dysgalactiae isolates collected from Japan, Taiwan, Malaysia and Indonesia were molecularly characterized by biased sinusoidal field gel electrophoresis (BSFGE) using SmaI enzyme, and tuf gene sequencing analysis. DNA sequencing of ten S. dysgalactiae revealed no genetic variation in the tuf amplicons, except for three strains. The restriction patterns of chromosomal DNA measured by BSFGE were differentiated into six distinct types and one subtype among collected strains. To our knowledge, this report gives the first snapshot of S. dysgalactiae isolates collected from different countries that are localized geographically and differed on a multinational level. This genetic unrelatedness among different isolates might suggest a high recombination rate and low genetic stability.

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          Positional effect of single bulge nucleotide on PNA(peptide nucleic acid)/DNA hybrid stability

          We report positional effect of bulge nucleotide on PNA/DNA hybrid stability. CD spectra showed that PNA/DNA hybrids required at least seven base pairings at a stem region to form a bulged structure. On the other hand, DNA/DNA could form bulged structure when there are only four base pairings adjacent to the bulge nucleotide. We discuss why PNA requests such a many base pairings to form bulged structure from a nearest neighbor standpoint.
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            Overview of molecular typing methods for outbreak detection and epidemiological surveillance.

            Typing methods for discriminating different bacterial isolates of the same species are essential epidemiological tools in infection prevention and control. Traditional typing systems based on phenotypes, such as serotype, biotype, phage-type, or antibiogram, have been used for many years. However, more recent methods that examine the relatedness of isolates at a molecular level have revolutionised our ability to differentiate among bacterial types and subtypes. Importantly, the development of molecular methods has provided new tools for enhanced surveillance and outbreak detection. This has resulted in better implementation of rational infection control programmes and efficient allocation of resources across Europe. The emergence of benchtop sequencers using next generation sequencing technology makes bacterial whole genome sequencing (WGS) feasible even in small research and clinical laboratories. WGS has already been used for the characterisation of bacterial isolates in several large outbreaks in Europe and, in the near future, is likely to replace currently used typing methodologies due to its ultimate resolution. However, WGS is still too laborious and time-consuming to obtain useful data in routine surveillance. Also, a largely unresolved question is how genome sequences must be examined for epidemiological characterisation. In the coming years, the lessons learnt from currently used molecular methods will allow us to condense the WGS data into epidemiologically useful information. On this basis, we have reviewed current and new molecular typing methods for outbreak detection and epidemiological surveillance of bacterial pathogens in clinical practice, aiming to give an overview of their specific advantages and disadvantages.
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              1. All except two of 106 strains of hemolytic streptococci isolated from man, other animals, milk, and cheese have been classified into five groups, which bear a definite relationship to the sources of the cultures. These broad groups may be subdivided into specific types by methods discussed elsewhere. The specific group classification is made possible by employing two special reagents: (a) extracts prepared by treatment of the bacteria with hot hydrochloric acid, and (b) serum of animals immunized with formalinized cultures. This differentiation is not detected by the agglutination reaction. The grouping agrees with that described by other investigators on the basis of cultural and biochemical characteristics. 2. The group-specific substance present in strains of Group A has been identified chemically as carbohydrate in nature. The chemical composition of the specific substances upon which the specificity of the other groups depends has not been determined. It seems not unlikely, however, that all of them may belong in the general class of carbohydrates, each being chemically distinct and serologically specific in the individual groups.

                Author and article information

                J Adv Res
                J Adv Res
                Journal of Advanced Research
                12 December 2013
                March 2015
                12 December 2013
                : 6
                : 2
                : 233-238
                [a ]Department of Fish Diseases and Management, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt
                [b ]Departments of Poultry and Fish Diseases, Faculty of Veterinary Medicine, Tripoli University, Tripoli, Libya
                [c ]Graduate Institute of Animal Vaccine Technology, National Pingtung University of Science and Technology, Pingtung, Taiwan
                [d ]Department of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
                Author notes
                [* ]Corresponding author. Tel.: +20 1122671243; fax: +20 2 35725240/35710305. m.abdelsalam@ 123456staff.cu.edu.eg
                © 2013 Production and hosting by Elsevier B.V. on behalf of Cairo University.

                This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

                : 14 September 2013
                : 13 November 2013
                : 5 December 2013
                Short Communication

                streptococcus dysgalactiae,epidemiology,tuf gene sequencing,bsfge


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