8 results on '"Phillip M. Giffard"'
Search Results
2. Global Scale Dissemination of ST93: A Divergent Staphylococcus aureus Epidemic Lineage That Has Recently Emerged From Remote Northern Australia
- Author
-
Sebastiaan J. van Hal, Eike J. Steinig, Patiyan Andersson, Matthew T. G. Holden, Simon R. Harris, Graeme R. Nimmo, Deborah A. Williamson, Helen Heffernan, S. R. Ritchie, Angela M. Kearns, Matthew J. Ellington, Elizabeth Dickson, Herminia de Lencastre, Geoffrey W. Coombs, Stephen D. Bentley, Julian Parkhill, Deborah C. Holt, Phillip M. Giffard, and Steven Y. C. Tong
- Subjects
Staphylococcus aureus ,MRSA ,community-associated ,ST93 ,evolution ,Aboriginal ,Microbiology ,QR1-502 - Abstract
Background: In Australia, community-associated methicillin-resistant Staphylococcus aureus (MRSA) lineage sequence type (ST) 93 has rapidly risen to dominance since being described in the early 1990s. We examined 459 ST93 genome sequences from Australia, New Zealand, Samoa, and Europe to investigate the evolutionary history of ST93, its emergence in Australia and subsequent spread overseas.Results: Comparisons with other S. aureus genomes indicate that ST93 is an early diverging and recombinant lineage, comprising of segments from the ST59/ST121 lineage and from a divergent but currently unsampled Staphylococcal population. However, within extant ST93 strains limited genetic diversity was apparent with the most recent common ancestor dated to 1977 (95% highest posterior density 1973–1981). An epidemic ST93 population arose from a methicillin-susceptible progenitor in remote Northern Australia, which has a proportionally large Indigenous population, with documented overcrowded housing and a high burden of skin infection. Methicillin-resistance was acquired three times in these regions, with a clade harboring a staphylococcal cassette chromosome mec (SCCmec) IVa expanding and spreading to Australia’s east coast by 2000. We observed sporadic and non-sustained introductions of ST93-MRSA-IVa to the United Kingdom. In contrast, in New Zealand, ST93-MRSA-IVa was sustainably transmitted with clonal expansion within the Pacific Islander population, who experience similar disadvantages as Australian Indigenous populations.Conclusion: ST93 has a highly recombinant genome including portions derived from an early diverging S. aureus population. Our findings highlight the need to understand host population factors in the emergence and spread of antimicrobial resistant community pathogens.
- Published
- 2018
- Full Text
- View/download PDF
3. Longitudinal whole-genome based comparison of carriage and infection associated Staphylococcus aureus in northern Australian dialysis clinics
- Author
-
Steven Y. C. Tong, Heather Hall, Phillip M. Giffard, Rachael A. Lilliebridge, Judith Wilson, Deborah C. Holt, Sian Graham, Jaquelyne T. Hughes, Tegan M. Harris, and David Croker
- Subjects
Staphylococcus ,Single Nucleotide Polymorphisms ,Skin infection ,medicine.disease_cause ,Medical Conditions ,Leukocidins ,Epidemiology ,Infection control ,Longitudinal Studies ,Prospective Studies ,Skin Diseases, Infectious ,Pathology and laboratory medicine ,education.field_of_study ,Multidisciplinary ,Transmission (medicine) ,Genomics ,Medical microbiology ,Staphylococcal Infections ,Infectious Diseases ,Nephrology ,Staphylococcus aureus ,Carrier State ,Medicine ,Methicillin-resistant Staphylococcus aureus ,Pathogens ,Anatomy ,Research Article ,Skin Infections ,Adult ,medicine.medical_specialty ,Science ,Bacterial Toxins ,Population ,Exotoxins ,Dermatology ,Nose ,Microbiology ,Skin Diseases ,Polymorphism, Single Nucleotide ,Signs and Symptoms ,Bacterial Proteins ,Renal Dialysis ,Internal medicine ,Medical Dialysis ,Genetics ,medicine ,Humans ,Penicillin-Binding Proteins ,education ,Medicine and health sciences ,Biology and life sciences ,Bacteria ,Whole Genome Sequencing ,business.industry ,Organisms ,Australia ,biochemical phenomena, metabolism, and nutrition ,bacterial infections and mycoses ,medicine.disease ,Microbial pathogens ,Carriage ,Genes, Bacterial ,Face ,Lesions ,Bacterial pathogens ,Clinical Medicine ,business ,Head ,Multilocus Sequence Typing - Abstract
Background The study objective was to reveal reservoirs potentially leading to Staphylococcus aureus infections in haemodialysis clinic clients in the tropical north of the Australian Northern Territory (NT). This client population are primarily Aboriginal Australians who have a greater burden of ill health than other Australians. Reservoir identification will enhance infection control in this client group, including informing potential S. aureus decolonisation strategies. Methods and findings The study participants were 83 clients of four haemodialysis clinics in the Darwin region of the NT, and 46 clinical staff and researchers who had contact with the clinic clients. The study design was longitudinal, encompassing swabbing of anatomical sites at two month intervals to yield carriage isolates, and also progressive collection of infection isolates. Swab sampling was performed for all participants, and infection isolates collected for dialysis clients only. Analysis was based on the comparison of 139 carriage isolates and 27 infection isolates using whole genome sequencing. Genome comparisons were based on of 20,651 genome-wide orthologous SNPs, presence/absence of the mecA and pvl genes, and inferred multilocus sequence type and clonal complex. Pairs of genomes meeting the definition of “not discriminated” were classed as defining potential transmission events. The primary outcome was instances of potential transmission between a carriage site other than a skin lesion and an infection site, in the same individual. Three such instances were identified. Two involved ST762 (CC1) PVL- MRSA, and one instance ST121 PVL+ MSSA. Three additional instances were identified where the carriage strains were derived from skin lesions. Also identified were six instances of potential transmission of a carriage strains between participants, including transmission of strains between dialysis clients and staff/researchers, and one potential transmission of a clinical strain between participants. There were frequent occurrences of longitudinal persistence of carriage strains in individual participants, and two examples of the same strain causing infection in the same participants at different times. Strains associated with infections and skin lesions were enriched for PVL and mecA in comparison to strains associated with long term carriage. Conclusions This study indicated that strains differ with respect to propensity to stably colonise sites such as the nose, and cause skin infections. PVL+ strains were associated with infection and skin lesions and were almost absent from the carriage sites. PVL- MRSA (mainly CC1) strains were associated with infection and also with potential transmission events involving carriage sites, while PVL- MSSA were frequently observed to stably colonise individuals without causing infection, and to be rarely transmitted. Current clinical guidelines for dialysis patients suggest MRSA decolonisation. Implementation in this client group may impact infections by PVL- MRSA, but may have little effect on infection by PVL+ strains. In this study, the PVL+ strains were predominant causes of infection but rarely colonised typical carriage sites such as the nose, and in the case of ST121, were MSSA. The important reservoirs for infection by PVL+ strains appeared to be prior infections.
- Published
- 2021
4. Diversity of emm sequence types in group A beta-haemolytic streptococci in two remote Northern Territory Indigenous communities: Implications for vaccine development
- Author
-
Allen C. Cheng, Malcolm I. McDonald, Jonathan R. Carapetis, Bart J. Currie, Rebecca J. Towers, Leisha J. Richardson, and Phillip M. Giffard
- Subjects
DNA, Bacterial ,Rural Population ,Veterinary medicine ,Native Hawaiian or Other Pacific Islander ,Streptococcus pyogenes ,Biology ,Indigenous ,Microbiology ,stomatognathic system ,Streptococcal Infections ,Genetic variation ,Genotype ,Northern Territory ,otorhinolaryngologic diseases ,Humans ,Genetic variability ,Typing ,Antigens, Bacterial ,Streptococcus vaccine ,General Veterinary ,General Immunology and Microbiology ,Public Health, Environmental and Occupational Health ,Genetic Variation ,Sequence Analysis, DNA ,Bacterial Typing Techniques ,Vaccination ,Infectious Diseases ,Molecular Medicine ,Bacterial antigen ,Carrier Proteins ,Bacterial Outer Membrane Proteins - Abstract
There is a high burden of disease due to group A streptococcus (GAS) in remote Northern Territory (NT) Indigenous communities. A proposed 26-valent GAS M-type vaccine covers 80-90% of pharyngeal and invasive isolates in the US. We examined the diversity and distribution of emm types in two remote Indigenous communities in the NT Top End over a 17-year period and compared them to the proposed vaccine types. Eighty emm types were identified between 1991 and 2007. Diversity in both communities was high (overall Simpson's index 0.976), but varied between communities. Prior to 2004, 71 emm types were identified and an additional 9 emm types were identified during a period of active surveillance in 2004-2005. The proposed 26-valent vaccine would be expected to cover only 20% of emm types recovered in this study. Of the 80 emm types, 16 (20%) were new sequence types identified since the last assignment of M types in 2002. The diversity of streptococcal isolates was higher than that reported from most industrialized countries, and similar to that described in several developing countries. A vaccine based on such a variable antigen is unlikely to provide effective protection in the highest risk populations.
- Published
- 2010
5. Roles of the trkB and trkC gene products of Escherichia coli in K+ transport
- Author
-
Wolfgang Epstein, Phillip M. Giffard, Geoffrey C. Rowland, and Ian R. Booth
- Subjects
Genetics ,Biological Transport ,General Medicine ,Tropomyosin receptor kinase B ,Biology ,medicine.disease_cause ,Biochemistry ,Tropomyosin receptor kinase C ,Kinetics ,Suppression, Genetic ,Lac Operon ,Genes, Bacterial ,Mutation ,medicine ,Escherichia coli ,Potassium ,Gene ,Alleles ,Plasmids - Abstract
Resume Les mutations d'Escherichia coli aux loci trkB et trkC produisent un degagement anormal de K+. Ces mutations sont partiellement dominantes chez les diploides et reviennent frequemment a l'etat nul par ce qui semble etre une suppression intragenique. Ces mutations peuvent etre renversees par insertion Tn10 dans le gene mute, et les revertants spontanes sont completement recessifs a l'allele mutant chez les diploides. Le degagement de K+ produit par NEM* et par DNP* persiste chez des souches ou les mutations sont presumees nulles a l'un et l'autre locus, indiquant qu'aucun des produits de ces deux genes n'est la cible primaire de l'effet de ces inhibiteurs sur le degagement de K+. Les resultats concordent avec l'opinion selon laquelle trkB et trKC codent pour des systemes independants pour le degagement de K+. Les mutations a ce loci alterent la regulation du processus de telle facon que le degagement de K+ a lieu de maniere inappropriee. Une seconde mutation vers l'etat nul abolit ce degagement anormal de K+. Il est possible que ces genes codent pour des antiporteurs K+/H+, une activite qui, selon ce qui a ete postule, entraine le degagement de K+ et qui, selon ce qui a ete demontre, existe chez E. coli et d'autres bacteries.
- Published
- 1985
6. Corrigenda
- Author
-
Sanmarie Schlebusch, Flavia Huygens, Gail M. Williams, Wendy J. Munckhof, Graeme R. Nimmo, J. M. Schooneveldt, Alex J. Stephens, and Phillip M. Giffard
- Subjects
Microbiology (medical) ,Infectious Diseases ,Staphylococcus aureus ,business.industry ,medicine ,Clinical Microbiology and Infection ,Nasal carriage ,General Medicine ,medicine.disease_cause ,business ,Community associated ,Microbiology - Full Text
- View/download PDF
7. Longitudinal whole-genome based comparison of carriage and infection associated Staphylococcus aureus in northern Australian dialysis clinics.
- Author
-
Deborah C Holt, Tegan M Harris, Jaquelyne T Hughes, Rachael Lilliebridge, David Croker, Sian Graham, Heather Hall, Judith Wilson, Steven Y C Tong, and Phillip M Giffard
- Subjects
Medicine ,Science - Abstract
BackgroundThe study objective was to reveal reservoirs potentially leading to Staphylococcus aureus infections in haemodialysis clinic clients in the tropical north of the Australian Northern Territory (NT). This client population are primarily Aboriginal Australians who have a greater burden of ill health than other Australians. Reservoir identification will enhance infection control in this client group, including informing potential S. aureus decolonisation strategies.Methods and findingsThe study participants were 83 clients of four haemodialysis clinics in the Darwin region of the NT, and 46 clinical staff and researchers who had contact with the clinic clients. The study design was longitudinal, encompassing swabbing of anatomical sites at two month intervals to yield carriage isolates, and also progressive collection of infection isolates. Swab sampling was performed for all participants, and infection isolates collected for dialysis clients only. Analysis was based on the comparison of 139 carriage isolates and 27 infection isolates using whole genome sequencing. Genome comparisons were based on of 20,651 genome-wide orthologous SNPs, presence/absence of the mecA and pvl genes, and inferred multilocus sequence type and clonal complex. Pairs of genomes meeting the definition of "not discriminated" were classed as defining potential transmission events. The primary outcome was instances of potential transmission between a carriage site other than a skin lesion and an infection site, in the same individual. Three such instances were identified. Two involved ST762 (CC1) PVL- MRSA, and one instance ST121 PVL+ MSSA. Three additional instances were identified where the carriage strains were derived from skin lesions. Also identified were six instances of potential transmission of a carriage strains between participants, including transmission of strains between dialysis clients and staff/researchers, and one potential transmission of a clinical strain between participants. There were frequent occurrences of longitudinal persistence of carriage strains in individual participants, and two examples of the same strain causing infection in the same participants at different times. Strains associated with infections and skin lesions were enriched for PVL and mecA in comparison to strains associated with long term carriage.ConclusionsThis study indicated that strains differ with respect to propensity to stably colonise sites such as the nose, and cause skin infections. PVL+ strains were associated with infection and skin lesions and were almost absent from the carriage sites. PVL- MRSA (mainly CC1) strains were associated with infection and also with potential transmission events involving carriage sites, while PVL- MSSA were frequently observed to stably colonise individuals without causing infection, and to be rarely transmitted. Current clinical guidelines for dialysis patients suggest MRSA decolonisation. Implementation in this client group may impact infections by PVL- MRSA, but may have little effect on infection by PVL+ strains. In this study, the PVL+ strains were predominant causes of infection but rarely colonised typical carriage sites such as the nose, and in the case of ST121, were MSSA. The important reservoirs for infection by PVL+ strains appeared to be prior infections.
- Published
- 2021
- Full Text
- View/download PDF
8. Global Scale Dissemination of ST93: A Divergent Staphylococcus aureus Epidemic Lineage That Has Recently Emerged From Remote Northern Australia
- Author
-
Sebastiaan J. van Hal, Eike J. Steinig, Patiyan Andersson, Matthew T. G. Holden, Simon R. Harris, Graeme R. Nimmo, Deborah A. Williamson, Helen Heffernan, S. R. Ritchie, Angela M. Kearns, Matthew J. Ellington, Elizabeth Dickson, Herminia de Lencastre, Geoffrey W. Coombs, Stephen D. Bentley, Julian Parkhill, Deborah C. Holt, Phillip M. Giffard, and Steven Y. C. Tong
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.