Group A streptococcal (GAS) infections are associated with a number of human diseases, including ... more Group A streptococcal (GAS) infections are associated with a number of human diseases, including pharyngitis, impetigo, necrotizing fasciitis, streptococcal toxic shock syndrome and rheumatic heart disease. An increase in the incidence of severe GAS infections in Western countries, and the awareness of the burden of GAS-associated diseases in developing nations, which remains high in spite of the availability of antibiotics, has provided the impetus for development of a safe and efficacious GAS vaccine. This has focused on the M protein, a major GAS virulence factor, however, with the publication of several GAS genomes, a number of non-M vaccine candidates are now under investigation.
International journal of medical microbiology : IJMM, 2007
Group A streptococcus (GAS) is responsible for a range of human diseases that vary in their clini... more Group A streptococcus (GAS) is responsible for a range of human diseases that vary in their clinical manifestations and severity. While numerous virulence factors have been described, the way these factors interact to promote different streptococcal diseases is less clear. In order to identify multifactorial relationships between GAS and the human host, novel high-throughput techniques such as microarrays are necessary. We have performed comparative studies using custom-designed virulence arrays to enhance our understanding of the high degree of genotypic variation that occurs in streptococci. This study has pointed to mobile genetic elements as the major agents that promote variation. Our results show that multiple combinations of genes might bring about similar clinical pictures. This adds further complexity to the intricate relationship between pathogen and host.
Background: Integrative conjugative elements (ICEs) are mobile genetic elements (MGEs) that posse... more Background: Integrative conjugative elements (ICEs) are mobile genetic elements (MGEs) that possess all genes necessary for excision, transfer and integration into recipient genome. They also carry accessory genes that impart new phenotypic features to recipient strains. ICEs therefore play an important role in genomic plasticity and population structure. We previously characterised ICESde3396, the first ICE identified in the β-hemolytic Streptococcus dysgalactiae subsp equisimilis (SDSE) and demonstrated its transfer to single isolates of Streptococcus pyogenes (group A streptococcus, GAS) and Streptococcus agalactiae (group B streptococcus, GBS). While molecular studies found the ICE in multiple SDSE and GBS isolates, it was absent in all GAS isolates examined.
We have constructed a targeted GAS virulence array containing 228 group A streptococcal genes. Us... more We have constructed a targeted GAS virulence array containing 228 group A streptococcal genes. Using this array we profiled the virulence gene repertoire of 45 GAS isolates from The Netherlands. Cluster analysis of the array data for these strains successfully grouped strains by emm-type. Statistical analysis of the distribution of genes between emm-types showed that bacteriophage related genes were a significant contributor to the inter-emm-type genetic variation. However we also identified a number of non-phage genes whose distribution varied between emmtypes. We hypothesise that these genes may be remnant or uncharacterised phage-related genes. D 2005 Published by Elsevier B.V.
A total of 258 bovine-associated Staphylococcus aureus isolates from the United States, Chile, an... more A total of 258 bovine-associated Staphylococcus aureus isolates from the United States, Chile, and the United Kingdom, plus the reference isolate S. aureus Newbould 305 (NCIMB 702892), were analyzed by multilocus sequence typing (MLST). A collection of previously characterized United Kingdom isolates were also included in the analysis. The results demonstrated that MLST is suitable for the differentiation of bovine S. aureus isolates from various sites (milk, teat skin, milking machine unit liners, hands, and bedding) and countries. The theory of the host specificity of S. aureus is supported by the detection of a previously undescribed clonal complex that comprised 87.4% of the isolates studied, with representatives from all geographic locations investigated. This suggests that a single clonal group has achieved a widespread distribution and is responsible for the majority of infections. Some sequence types (STs; ST25, ST115, ST124, and ST126) demonstrated site specificity, as they were significantly (P < 0.05) associated with milk or teat skin.
Group A streptococcal (GAS) infections are associated with a number of human diseases, including ... more Group A streptococcal (GAS) infections are associated with a number of human diseases, including pharyngitis, impetigo, necrotizing fasciitis, streptococcal toxic shock syndrome and rheumatic heart disease. An increase in the incidence of severe GAS infections in Western countries, and the awareness of the burden of GAS-associated diseases in developing nations, which remains high in spite of the availability of antibiotics, has provided the impetus for development of a safe and efficacious GAS vaccine. This has focused on the M protein, a major GAS virulence factor, however, with the publication of several GAS genomes, a number of non-M vaccine candidates are now under investigation.
International journal of medical microbiology : IJMM, 2007
Group A streptococcus (GAS) is responsible for a range of human diseases that vary in their clini... more Group A streptococcus (GAS) is responsible for a range of human diseases that vary in their clinical manifestations and severity. While numerous virulence factors have been described, the way these factors interact to promote different streptococcal diseases is less clear. In order to identify multifactorial relationships between GAS and the human host, novel high-throughput techniques such as microarrays are necessary. We have performed comparative studies using custom-designed virulence arrays to enhance our understanding of the high degree of genotypic variation that occurs in streptococci. This study has pointed to mobile genetic elements as the major agents that promote variation. Our results show that multiple combinations of genes might bring about similar clinical pictures. This adds further complexity to the intricate relationship between pathogen and host.
Background: Integrative conjugative elements (ICEs) are mobile genetic elements (MGEs) that posse... more Background: Integrative conjugative elements (ICEs) are mobile genetic elements (MGEs) that possess all genes necessary for excision, transfer and integration into recipient genome. They also carry accessory genes that impart new phenotypic features to recipient strains. ICEs therefore play an important role in genomic plasticity and population structure. We previously characterised ICESde3396, the first ICE identified in the β-hemolytic Streptococcus dysgalactiae subsp equisimilis (SDSE) and demonstrated its transfer to single isolates of Streptococcus pyogenes (group A streptococcus, GAS) and Streptococcus agalactiae (group B streptococcus, GBS). While molecular studies found the ICE in multiple SDSE and GBS isolates, it was absent in all GAS isolates examined.
We have constructed a targeted GAS virulence array containing 228 group A streptococcal genes. Us... more We have constructed a targeted GAS virulence array containing 228 group A streptococcal genes. Using this array we profiled the virulence gene repertoire of 45 GAS isolates from The Netherlands. Cluster analysis of the array data for these strains successfully grouped strains by emm-type. Statistical analysis of the distribution of genes between emm-types showed that bacteriophage related genes were a significant contributor to the inter-emm-type genetic variation. However we also identified a number of non-phage genes whose distribution varied between emmtypes. We hypothesise that these genes may be remnant or uncharacterised phage-related genes. D 2005 Published by Elsevier B.V.
A total of 258 bovine-associated Staphylococcus aureus isolates from the United States, Chile, an... more A total of 258 bovine-associated Staphylococcus aureus isolates from the United States, Chile, and the United Kingdom, plus the reference isolate S. aureus Newbould 305 (NCIMB 702892), were analyzed by multilocus sequence typing (MLST). A collection of previously characterized United Kingdom isolates were also included in the analysis. The results demonstrated that MLST is suitable for the differentiation of bovine S. aureus isolates from various sites (milk, teat skin, milking machine unit liners, hands, and bedding) and countries. The theory of the host specificity of S. aureus is supported by the detection of a previously undescribed clonal complex that comprised 87.4% of the isolates studied, with representatives from all geographic locations investigated. This suggests that a single clonal group has achieved a widespread distribution and is responsible for the majority of infections. Some sequence types (STs; ST25, ST115, ST124, and ST126) demonstrated site specificity, as they were significantly (P < 0.05) associated with milk or teat skin.
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Papers by David McMillan