Biomedical subjects

F M Colles

Publications and source records attributed to F M Colles.

4 recordsLinked to original sources

PubMed2003

Reference isolates for the clonal complexes of Campylobacter jejuni.

AIMS: To identify and make available through the National Collection of Type Cultures (NCTC) a set of reference isolates for the clonal complexes of Campylobacter jejuni. METHODS AND RESULTS: The development of a multilocus sequence typing scheme for C. jejuni enabled the genetic characterization of a large number of isolates (n = 814) from cases of human disease, animals, birds and their food products. The nucleotide sequence data were used to assign each isolate an allelic profile or sequence type (ST) and examine the C. jejuni population structure in terms of clonal complexes. The clonal complexes consisted of an abundant central or founder genotype (ST), after which the complex was named, together with very closely related, generally less abundant genotypes differing from the founder at one, two or three loci. The clonal complex is an informative unit for the study C. jejuni epidemiology. It provides data which enabled the choice of 13 C. jejuni founder isolates for submission to the NCTC as a representative cross-section of the C. jejuni population. CONCLUSIONS: These 13 isolates provide a defined resource for further research into aspects of C. jejuni biology such as genomic diversity, virulence and adaptation to particular hosts or environmental survival. SIGNIFICANCE AND IMPACT OF STUDY: This isolate collection is available through the NCTC and provides a resource for further research.

Alleles↗

PubMed2003

Genetic diversity of Campylobacter jejuni isolates from farm animals and the farm environment.

The genetic diversity of Campylobacter jejuni isolates from farm animals and their environment was investigated by multilocus sequence typing (MLST). A total of 30 genotypes, defined by allelic profiles (assigned to sequence types [STs]), were found in 112 C. jejuni isolates originating in poultry, cattle, sheep, starlings, and slurry. All but two of these genotypes belonged to one of nine C. jejuni clonal complexes previously identified in isolates from human disease and retail food samples and one clonal complex previously associated with an environmental source. There was some evidence for the association of certain clonal complexes with particular farm animals: isolates belonging to the ST-45 complex predominated among poultry isolates but were absent among sheep isolates, while isolates belonging to the ST-61 and ST-42 complexes were predominant among sheep isolates but were absent from the poultry isolates. In contrast, ST-21 complex isolates were distributed among the different isolation sources. Comparison with MLST data from 91 human disease isolates showed small but significant genetic differentiation between the farm and human isolates; however, representatives of six clonal complexes were found in both samples. These data demonstrate that MLST and the clonal complex model can be used to identify and compare the genotypes of C. jejuni isolates from farm animals and the environment with those from retail food and human disease.

Alleles↗

PubMed2001

Multilocus sequence typing system for Campylobacter jejuni.

The gram-negative bacterium Campylobacter jejuni has extensive reservoirs in livestock and the environment and is a frequent cause of gastroenteritis in humans. To date, the lack of (i) methods suitable for population genetic analysis and (ii) a universally accepted nomenclature has hindered studies of the epidemiology and population biology of this organism. Here, a multilocus sequence typing (MLST) system for this organism is described, which exploits the genetic variation present in seven housekeeping loci to determine the genetic relationships among isolates. The MLST system was established using 194 C. jejuni isolates of diverse origins, from humans, animals, and the environment. The allelic profiles, or sequence types (STs), of these isolates were deposited on the Internet (http://mlst.zoo.ox.ac.uk), forming a virtual isolate collection which could be continually expanded. These data indicated that C. jejuni is genetically diverse, with a weakly clonal population structure, and that intra- and interspecies horizontal genetic exchange was common. Of the 155 STs observed, 51 (26% of the isolate collection) were unique, with the remainder of the collection being categorized into 11 lineages or clonal complexes of related STs with between 2 and 56 members. In some cases membership in a given lineage or ST correlated with the possession of a particular Penner HS serotype. Application of this approach to further isolate collections will enable an integrated global picture of C. jejuni epidemiology to be established and will permit more detailed studies of the population genetics of this organism.

Alleles↗

PubMed2001

Sequence typing confirms that Campylobacter jejuni strains associated with Guillain-Barré and Miller-Fisher syndromes are of diverse genetic lineage, serotype, and flagella type.

Guillain-Barré syndrome (GBS) and Miller-Fisher syndrome (MFS) are correlated with prior infection by Campylobacter jejuni in up to 40% of cases. Nucleotide sequence-based typing of 25 C. jejuni isolates associated with neuropathy permitted robust comparisons with equivalent data from approximately 800 C. jejuni isolates not associated with neuropathy. A total of 13 genetic lineages and 20 flaA short variable region nucleotide sequences were present among the 25 isolates. A minority of isolates (4 of 25) had the flaA short variable region nucleotide sequences that were previously proposed as a marker for GBS-associated isolates. These 4 isolates probably represented the Penner serotype 19 lineage, which has been proposed to have an association with GBS.

Bacterial Typing Techniques↗