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Open Access Highly Accessed Research article

Clustering subspecies of Aeromonas salmonicida using IS630 typing

Nicole Studer, Joachim Frey* and Philippe Vanden Bergh

Author Affiliations

Institute of Veterinary Bacteriology, University of Bern, Länggassstrasse 122, Bern, Switzerland

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BMC Microbiology 2013, 13:36  doi:10.1186/1471-2180-13-36

Published: 13 February 2013

Abstract

Background

The insertion element IS630 found in Aeromonas salmonicida belongs to the IS630-Tc1-mariner superfamily of transposons. It is present in multiple copies and represents approximately half of the IS present in the genome of A. salmonicida subsp. salmonicida A449.

Results

By using High Copy Number IS630 Restriction Fragment Length Polymorphism (HCN-IS630-RFLP), strains of various subspecies of Aeromonas salmonicida showed conserved or clustering patterns, thus allowing their differentiation from each other. Fingerprints of A. salmonicida subsp. salmonicida showed the highest homogeneity while ‘atypical’ A. salmonicida strains were more heterogeneous. IS630 typing also differentiated A. salmonicida from other Aeromonas species. The copy number of IS630 in Aeromonas salmonicida ranges from 8 to 35 and is much lower in other Aeromonas species.

Conclusions

HCN-IS630-RFLP is a powerful tool for subtyping of A. salmonicida. The high stability of IS630 insertions in A. salmonicida subsp. salmonicida indicates that it might have played a role in pathoadaptation of A. salmonicida which has reached an optimal configuration in the highly virulent and specific fish pathogen A. salmonicida subsp. salmonicida.

Keywords:
Aeromonas salmonicida; HCN-IS630-RFLP; IS element; Subtyping; Tc1 Mariner transposon; Salmonidae; Pathoadaptation