Phenotypic and molecular characterisation of Brucella isolates from marine mammals.
BACKGROUND
Bacteria of the genus Brucella are the causative organisms of brucellosis in animals and man. Previous characterisation of Brucella strains originating from marine mammals showed them to be distinct from the terrestrial species and likely to comprise one or more new taxa. Recently two new species comprising Brucella isolates from marine mammals, B. pinnipedialis and B. ceti, were validly published. Here we report on an extensive study of the molecular and phenotypic characteristics of marine mammal Brucella isolates and on how these characteristics relate to the newly described species.


RESULTS
In this study, 102 isolates of Brucella originating from eleven species of marine mammals were characterised. Results obtained by analysis using the Infrequent Restriction Site (IRS)-Derivative PCR, PCR-RFLP of outer membrane protein genes (omp) and IS711 fingerprint profiles showed good consistency with isolates originating from cetaceans, corresponding to B. ceti, falling into two clusters. These correspond to isolates with either dolphins or porpoises as their preferred host. Isolates originating predominantly from seals, and corresponding to B. pinnipedialis, cluster separately on the basis of IS711 fingerprinting and other molecular approaches and can be further subdivided, with isolates from hooded seals comprising a distinct group. There was little correlation between phenotypic characteristics used in classical Brucella biotyping and these groups.


CONCLUSIONS
Molecular approaches are clearly valuable in the division of marine mammal Brucella into subtypes that correlate with apparent ecological divisions, whereas conventional bioyping is of less value. The data presented here confirm that there are significant subtypes within the newly described marine mammal Brucella species and add to a body of evidence that could lead to the recognition of additional species or sub-species within this group.
Dawson
Claire E
CE
Department of Statutory and Exotic Bacterial Diseases, Veterinary Laboratories Agency, New Haw, Addlestone, Surrey, KT15 3NB, UK. c.e.dawson@vla.defra.gsi.gov.uk
Stubberfield
Emma J
EJ
Perrett
Lorraine L
LL
King
Amanda C
AC
Whatmore
Adrian M
AM
Bashiruddin
John B
JB
Stack
Judy A
JA
Macmillan
Alastair P
AP
D000818:Animals; D015373:Bacterial Typing Techniques; D002002:Brucella / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D010872:Caniformia / Q000382:microbiology*; D002591:Cetacea / Q000382:microbiology*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D013045:Species Specificity
D004269:DNA, Bacterial