Fatal marine
Brucella
infections with histologic lesions specific to the central nervous system (CNS), known as neurobrucellosis, have been described in 5 species of odontocete cetaceans in the UK: ...striped dolphins
Stenella coeruleoalba
, Atlantic white-sided dolphins
Lagenorhynchus acutus
, short-beaked common dolphins
Delphinus delphis
, long-finned pilot whale
Globicephala melas
and Sowerby’s beaked whale
Mesoplodon bidens
. To date, these CNS lesions have only been associated with
Brucella ceti
ST26 and not with
B. pinnipedialis
, which is rarely isolated from cetaceans and, although commonly found in various seal species, has never been associated with any pathology. This paper describes the first report of neurobrucellosis in a common minke whale
Balaenoptera acutorostrata
which was associated with the isolation of
Brucella pinnipedialis
ST24 and co-infection with
Balaenoptera acutorostrata
gamma-herpesvirus 2. This is the first report of neurobrucellosis in any species of mysticete and the first report of
Brucella pinnipedialis
in association with any pathology in any species of marine mammal, which may be due to co-infection with a herpesvirus, as these are known to be associated with immunosuppression.
Brucella ceti
has been recovered from a number species of cetaceans worldwide over the last 25 yr. Here we report, for the first time, the recovery of
B. ceti
from a Risso’s dolphin
Grampus griseus
...and a killer whale
Orcinus orca
. Recovery from an abdominal mass in the dolphin provides further evidence of the systemic pathogenic potential for
B. ceti
infection in cetaceans. The isolation of
B. ceti
ST23 (porpoise cluster) from a killer whale from a group known to eat other marine mammals raises the possibility of infection via ingestion. This report takes the number of cetacean species in UK coastal waters from which
B. ceti
has been isolated to 11 and highlights the value of routine, comprehensive and specific screening for significant pathogens such as
Brucella
sp. by strandings networks.
Brucella species infecting marine mammals was first reported in 1994 and in the years since has been documented in various species of pinnipeds and cetaceans. While these reports have included ...species that inhabit Arctic waters, the few available studies on bearded seals Erignathus barbatus have failed to detect Brucella infection to date. We report the first isolation of Brucella pinnipedialis from a bearded seal. The isolate was recovered from the mesenteric lymph node of a bearded seal that stranded in Scotland and typed as ST24, a sequence type associated typically with pinnipeds. Furthermore, serological studies of free-ranging bearded seals in their native waters detected antibodies to Brucella in seals from the Chukchi Sea (1990-2011; 19%) and Svalbard (1995-2007; 8%), whereas no antibodies were detected in bearded seals from the Bering Sea or Bering Strait or from captive bearded seals.
Streptococcus pyogenes is the causative agent in a wide range of diseases of humans of varying severity. During a study scanning the genome sequence of a serotype M1 invasive isolate SF370 for novel ...surface proteins, an ORF, designated sclB, was identified. The putative protein encoded by sclB contains both a signal peptide and classic Gram-positive wall-associated sequences. Comparison of the sequences of this ORF with those from a number of unrelated isolates demonstrated that sclB encodes a putative surface protein with a variable N-terminal sequence followed by a variable length tract of collagen-like GXY(n) repeats. A further feature of sclB is the presence of CAAAA repeat tracts immediately downstream of the putative start codon. The number of these pentameric repeats varies from 4 to 15 between strains and variation in repeat number results in the predicted SclB protein being either in or out of frame relative to the start codon. These observations suggest that expression of this protein may be regulated at the translational level as a result of gain or loss of CAAAA repeats. While the function of SclB remains to be elucidated, an sclB-specific transcript was detected by RT-PCR during in vitro culture. Finally, it is shown that a second gene, sclA, potentially encoding a protein with a similar extensive collagen-like structure and variable N-terminal sequence, is present in all isolates of S. pyogenes tested to date. Thus S. pyogenes harbours a novel family of structurally related and surface-exposed proteins of potential importance in the pathogenic process.
The oral streptococcal group (mitis phylogenetic group) currently consists of nine recognized species, although the group has been traditionally difficult to classify, with frequent changes in ...nomenclature over the years. The pneumococcus (Streptococcus pneumoniae), an important human pathogen, is traditionally distinguished from the most closely related oral streptococcal species Streptococcus mitis and Streptococcus oralis on the basis of three differentiating characteristics: optochin susceptibility, bile solubility, and agglutination with antipneumococcal polysaccharide capsule antibodies. However, there are many reports in the literature of pneumococci lacking one or more of these defining characteristics. Sometimes called "atypical" pneumococci, these isolates can be the source of considerable confusion in the clinical laboratory. Little is known to date about the genetic relationships of such organisms with classical S. pneumoniae isolates. Here we describe these relationships based on sequence analysis of housekeeping genes in comparison with previously characterized isolates of S. pneumoniae, S. mitis, and S. oralis. While most pneumococci were found to represent a closely related group these studies identified a subgroup of atypical pneumococcal isolates (bile insoluble and/or "acapsular") distinct from, though most closely related to, the "typical" pneumococcal isolates. However, a large proportion of isolates, found to be atypical on the basis of capsule reaction alone, did group with typical pneumococci, suggesting that they have either lost capsule production or represent as-yet-unrecognized capsular types. In contrast to typical S. pneumoniae, isolates phenotypically identified as S. mitis and S. oralis, which included isolates previously characterized in taxonomic studies, were genetically diverse. While most of the S. oralis isolates did fall into a well-separated group, S. mitis isolates did not cluster into a well-separated group. During the course of these studies we also identified a number of potentially important pathogenic isolates, which were frequently associated with respiratory disease, that phenotypically and genetically are most closely related to S. mitis but which harbor genes encoding the virulence determinants pneumolysin and autolysin classically associated with S. pneumoniae.
Amplified fragment length polymorphism (AFLP) is a whole-genome fingerprinting method that relies on the selective PCR amplification of restriction fragments. The potential of this approach for the ...discrimination of Brucella isolates at the species and intraspecies level was assessed. A number of different combinations of restriction enzymes and selective primers were examined, and one, using EcoRI and MseI with additional selective TC bases on the MseI primer, was selected for full assessment against a panel of Brucella isolates. The technique could readily differentiate Brucella spp. from all Ochrobactrum spp. representing the group of organisms most closely related to Brucella spp. Application of AFLP highlighted the genetic homogeneity of BRUCELLA: In spite of this determination of AFLP profiles of large numbers of isolates of human and animal origin, including Brucella abortus, B. melitensis, B. ovis, B. neotomae, marine mammal isolates (no species name), B. canis, and B. suis, confirmed that all but the latter two species could be separated into distinct clusters based on characteristic and conserved differences in profile. Only B. suis and B. canis isolates clustered together and could not be distinguished by this approach, adding to questions regarding the validity of species assignments in this group. Under the conditions examined in the present study only limited intraspecies genomic differences were detected, and thus this AFLP approach is likely to prove most useful for identification to the species level. However, combination of several of the useful restriction enzyme-primer combinations identified in the present study could substantially add to the discriminatory power of AFLP when applied to Brucella and enhance the value of this approach.
PDF
