Whole genome sequencing reveals extensive community-level transmission of group A Streptococcus in remote communities.

Impetigo is common in remote Indigenous children of northern Australia, with the primary driver in this context being Streptococcus pyogenes [or group A Streptococcus (GAS)]. To reduce the high burden of impetigo, the transmission dynamics of GAS must be more clearly elucidated. We performed whole genome sequencing on 31 GAS isolates collected in a single community from children in 11 households with ⩾2 GAS-infected children. We aimed to determine whether transmission was occurring principally within households or across the community. The 31 isolates were represented by nine multilocus sequence types and isolates within each sequence type differed from one another by only 0-3 single nucleotide polymorphisms. There was evidence of extensive transmission both within households and across the community. Our findings suggest that strategies to reduce the burden of impetigo in this setting will need to extend beyond individual households, and incorporate multi-faceted, community-wide approaches.

High burden of invasive group A streptococcal disease in the Northern Territory of Australia.

Although the incidence of invasive group A streptococcal disease in northern Australia is very high, little is known of the regional epidemiology and molecular characteristics. We conducted a case series of Northern Territory residents reported between 2011 and 2013 with Streptococcus pyogenes isolates from a normally sterile site. Of the 128 reported episodes, the incidence was disproportionately high in the Indigenous population at 69·7/100 000 compared to 8·8/100 000 in the non-Indigenous population. Novel to the Northern Territory is the extremely high incidence in haemodialysis patients of 2205·9/100 000 population; and for whom targeted infection control measures could prevent transmission. The incidences in the tropical north and semi-arid Central Australian regions were similar. Case fatality was 8% (10/128) and streptococcal toxic shock syndrome occurred in 14 (11%) episodes. Molecular typing of 82 isolates identified 28 emm types, of which 63 (77%) were represented by four emm clusters. Typing confirmed transmission between infant twins. While the diverse range of emm types presents a challenge for effective coverage by vaccine formulations, the limited number of emm clusters raises optimism should cluster-specific cross-protection prove efficacious. Further studies are required to determine effectiveness of chemoprophylaxis for contacts and to inform public health response.

Reduced In Vitro Activity of Ceftaroline by Etest among Clonal Complex 239 Methicillin-Resistant Staphylococcus aureus Clinical Strains from Australia.

A total of 421 methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates were tested for ceftaroline susceptibility by Etest (bioMérieux). A multidrug resistant phenotype was found in 40.9%, and clonal complex 239 (CC239) was found in 33.5%. Ceftaroline nonsusceptibility (MIC, >1.0 µg/ml) was 16.9% overall. Nonsusceptibility was significantly higher in CC239 (41.1%, 58/141) and in isolates with a multidrug resistant phenotype (35.5%, 61/172) compared with comparators (P < 0.0001). Nonsusceptibility of common multidrug resistant MRSA clones limits the empirical use of ceftaroline for these infections.

Arthrofibrosis of the knee following a fracture of the tibial plateau.

The aim of this study was to report the incidence of arthrofibrosis of the knee and identify risk factors for its development following a fracture of the tibial plateau. We carried out a retrospective review of 186 patients (114 male, 72 female) with a fracture of the tibial plateau who underwent open reduction and internal fixation. Their mean age was 46.4 years (19 to 83) and the mean follow-up was16.0 months (6 to 80). A total of 27 patients (14.5%) developed arthrofibrosis requiring a further intervention. Using multivariate regression analysis, the use of a provisional external fixator (odds ratio (OR) 4.63, 95% confidence interval (CI) 1.26 to 17.7, p = 0.021) was significantly associated with the development of arthrofibrosis. Similarly, the use of a continuous passive movement (CPM) machine was associated with significantly less development of arthrofibrosis (OR = 0.32, 95% CI 0.11 to 0.83, p = 0.024). The effect of time in an external fixator was found to be significant, with each extra day of external fixation increasing the odds of requiring manipulation under anaesthesia (MUA) or quadricepsplasty by 10% (OR = 1.10, p = 0.030). High-energy fracture, surgical approach, infection and use of tobacco were not associated with the development of arthrofibrosis. Patients with a successful MUA had significantly less time to MUA (mean 2.9 months; sd 1.25) than those with an unsuccessful MUA (mean 4.86 months; sd 2.61, p = 0.014). For those with limited movement, therefore, performing an MUA within three months of the injury may result in a better range of movement. Based our results, CPM following operative fixation for a fracture of the tibial plateau may reduce the risk of the development of arthrofibrosis, particularly in patients who also undergo prolonged provisional external fixation.

Crusted scabies is associated with increased IL-17 secretion by skin T cells.

Scabies is an ectoparasitic infestation by the mite Sarcoptes scabiei. Although commonly self-limiting, a fraction of patients develop severely debilitating crusted scabies. The immune mechanisms underlying the development of crusted scabies are unclear, and undertaking longitudinal infection studies in humans is difficult. We utilized a porcine model to compare cellular immune responses in peripheral blood and skin of pigs with different clinical manifestations of scabies (n = 12), and in uninfected controls (n = 6). Although clinical symptoms were not evident until at least 4 weeks post-infestation, the numbers of peripheral IFNγ-secreting CD4(+) T cells and γδ T cells increased in infected pigs from week 1 post-infestation. γδ T cells remained increased in the blood at week 15 post-infestation. At week 15, skin cell infiltrates from pigs with crusted scabies had significantly higher CD8(+) T cell, γδ T cell and IL-17(+) cell numbers than those with ordinary scabies. Peripheral IL-17 levels were not increased, suggesting that localized skin IL-17-secreting T cells may play a critical role in the pathogenesis of crusted scabies development. Given the potential of anti-IL-17 immunotherapy demonstrated for other inflammatory skin diseases, this study may provide a novel therapeutic avenue for patients with recurrent crusted scabies.

Therapeutic whole lung lavage for inhaled plutonium oxide revisited.

Two reviews in the last 12 years have differed widely in their indications for the use of whole lung lavage (WLL) to remove plutonium from the lung, one recommending its use at relatively low radiation doses to prevent stochastic effects and the other recommending restricting its use to high doses to prevent deterministic effects only. Since the publication of these reviews significant data have accumulated demonstrating the increased safety of WLL, and there are additional data on stochastic and deterministic effects. We discuss deterministic and stochastic risks and the practical aspects of undertaking WLL. We recommend that each case be assessed individually.

High-resolution melting analysis of the spa locus reveals significant diversity within sequence type 93 methicillin-resistant Staphylococcus aureus from northern Australia.

High-resolution melting analysis is an inherently robust, easy and inexpensive approach to the examination of genomic regions containing single-nucleotide polymorphisms and hypervariable loci. Staphylococcus aureus sequence type (ST) 93 is a singleton, Panton-Valentine leukocidin-positive clone unique to Australia. A high-resolution melting-based method for the identification of ST93 was developed, and a similar approach was used to reveal diversity within the spa locus of this lineage. Statistical and graphical methods that account for instrumental and operator-dependent variation in high-resolution melting curves were developed, to allow greater confidence and reproducibility in deciding whether another curve is truly different from the baseline curve of an amplicon with known sequence. The data support a very early acquisition, or multiple independent acquisitions, of SCCmec by ST93 methicillin-susceptible S. aureus (MSSA), and the coexistence of MSSA and methicillin-resistant S. aureus versions of the same lineage within northern Australia.

TIARA: treatment initiatives after radiological accidents.

This paper describes the objectives, and reviews the progress, of the European project 'Treatment Initiatives After Radiological Accidents' (TIARA). TIARA forms part of the 'Preparatory Action for Security Research' (PASR) launched by the European Commission in 2004. The Preparatory Action is intended to reach preliminary conclusions on the needs for the security of EU citizens. It prepared a comprehensive Security Research Programme as part of the Commission's Seventh Framework Programme proposal, which was adopted in 2006 and launched in 2007. The principal purpose of TIARA is to constitute a European network that will participate in facilitating the management of a crisis in the event of the malevolent dispersal of radionuclides into the public environment.

The chitinase allergens Der p 15 and Der p 18 from Dermatophagoides pteronyssinus.

BACKGROUND: House dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae cause allergic disease in humans as well as in dogs. In geographical regions where the two mite species coexist, they both elicit specific immunoglobulin (Ig E) responses in humans whereas dogs preferentially react to D. farinae extracts. In dogs the main IgE binding is directed to the D. farinae chitinase allergens Der f 15 and Der f 18 and not to the groups 1 and 2 allergens as found for humans. Although the IgE response of humans to Der f 18 has been investigated there is no report on Der f 15-specific IgE in humans. OBJECTIVE: This study aimed to characterize the chitinase allergens Der p 15 and Der p 18 of D. pteronyssinus and to find out whether they are important allergens for humans. METHODS: cDNA was cloned by a polymerase chain reaction strategy from D. pteronyssinus libraries using primers based on conserved chitinase sequences. IgE binding to the recombinant polypeptides was measured by immunosorbent assay. Mice were immunized with the polypeptides and cross-reactivity examined. RESULTS: Two variants of Der p 15 were isolated, encoding mature proteins of 58.8 and 61.4 kDa. The amino acid sequences had 90% identity to Der f 15. The cDNA for Der p 18 encoded a mature protein of 49.2 kDa with 88% sequence identity to Der f 18. Der p 15-specific IgE was detected in 70% and Der p 18-specific IgE in 63% of a panel of 27 human allergic sera. CONCLUSIONS: The D. pteronyssinus chitinases Der p 15 and Der p 18 show a high frequency of binding to IgE in allergic human sera. They are therefore potentially important allergens for humans as well as dogs.

Identification of ABC transporters in Sarcoptes scabiei.

We have identified and partially sequenced 8 ABC transporters from an EST dataset of Sarcoptes scabiei var. hominis, the causative agent of scabies. Analysis confirmed that most of the known ABC subfamilies are represented in the EST dataset including several members of the multidrug resistance protein subfamily (ABC-C). Although P-glycoprotein (ABC-B) sequences were not found in the EST dataset, a partial P-glycoprotein sequence was subsequently obtained using a degenerate PCR strategy and library screening. Thus a total of 9 potential S. scabiei ABC transporters representing the subfamilies A, B, C, E, F and H have been identified. Ivermectin is currently used in the treatment of hyper-infested (crusted) scabies, and has also been identified as a potentially effective acaricide for mass treatment programmes in scabies-endemic communities. The observation of clinical and in vitro ivermectin resistance in 2 crusted scabies patients who received multiple treatments has raised serious concerns regarding the sustainability of such programmes. One possible mechanism for ivermectin resistance is through ABC transporters such as P-glycoprotein. This work forms an important foundation for further studies to elucidate the potential role of ABC transporters in ivermectin resistance of S. scabiei.

Analysis of Sarcoptes scabiei finds no evidence of infection with Wolbachia.

The endosymbiont Wolbachia has been detected in a range of filarial nematodes and parasitic mites and is known to affect host reproductive compatibility and potentially evolutionary processes. PCR of Wolbachia surface protein (wsp), ftsZ and 16SrRNA genes from individual Sarcoptes scabiei mites obtained from a series of individual hosts, and database searches of an S. scabiei var. hominis EST library failed to detect Wolbachia genes. Therefore, Wolbachia appears not to be involved in the genetic subdivision observed between varieties of host-associated S. scabiei or, involved in the inflammatory disease pathogenesis of scabies unlike its activity in filarial infection.

Mesotrione: a new selective herbicide for use in maize.

Mesotrione is a new herbicide being developed for the selective pre- and post-emergence control of a wide range of broad-leaved and grass weeds in maize (Zea mays). It is a member of the benzoylcyclohexane-1,3-dione family of herbicides, which are chemically derived from a natural phytotoxin obtained from the Californian bottlebrush plant, Callistemon citrinus. The compound acts by competitive inhibition of the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD), a component of the biochemical pathway that converts tyrosine to plastoquinone and alpha-tocopherol. Mesotrione is an extremely potent inhibitor of HPPD from Arabidopsis thaliana, with a Ki value of c 6-18 pM. It is rapidly taken up by weed species following foliar application, and is distributed within the plants by both acropetal and basipetal movement. Maize is tolerant to mesotrione as a consequence of selective metabolism by the crop plant. Slower uptake of mesotrione, relative to susceptible weed species, may also contribute to its utility as a selective herbicide for use in maize.

Inhibition of Plasmodium falciparum clag9 gene function by antisense RNA.

We have previously shown by targeted gene disruption that the clag9 gene of Plasmodium falciparum is essential for cytoadherence to CD36. Here we report inhibition of the function of clag9 by the use of an antisense RNA vector as an alternative to targeted gene disruption. We transfected an antisense construct of clag9 into the P. falciparum clone 3D7 and when the resulting line was cultured in the presence of pyrimethamine it showed 15-fold lower cytoadherence to C32 melanoma cells than the control. Reversion to wildtype upon removal of the introduced plasmid provides direct evidence that the event responsible for the phenotypic change is not at an unrelated site and this approach provides a valuable new tool in malaria transfection technology.

Genomewide search for type 2 diabetes susceptibility genes in four American populations.

Type 2 diabetes is a serious, genetically influenced disease for which no fully effective treatments are available. Identification of biochemical or regulatory pathways involved in the disease syndrome could lead to innovative therapeutic interventions. One way to identify such pathways is the genetic analysis of families with multiple affected members where disease predisposing genes are likely to be segregating. We undertook a genomewide screen (389-395 microsatellite markers) in samples of 835 white, 591 Mexican American, 229 black, and 128 Japanese American individuals collected as part of the American Diabetes Association's GENNID study. Multipoint nonparametric linkage analyses were performed with diabetes, and diabetes or impaired glucose homeostasis (IH). Linkage to diabetes or IH was detected near markers D5S1404 (map position 77 cM, LOD = 2.80), D12S853 (map position 82 cM, LOD = 2.81) and GATA172D05 (X-chromosome map position 130 cM, LOD = 2.99) in whites, near marker D3S2432 (map position 51 cM, LOD = 3.91) in Mexican Americans, and near marker D10S1412 (map position 14 cM, LOD = 2.39) in African Americans mainly collected in phase 1 of the study. Further analyses showed evidence for interactions between the chromosome 5 locus and region on chromosome 12 containing the MODY 3 gene (map position 132 cM) and between the X-chromosome locus and region near D12S853 (map position 82 cM) in whites. Although these results were not replicated in samples collected in phase 2 of the GENNID study, the region on chromosome 12 was replicated in samples from whites described by Bektas et al. (1999).

clag9: A cytoadherence gene in Plasmodium falciparum essential for binding of parasitized erythrocytes to CD36.

The propensity of isolates of the malaria parasite Plasmodium falciparum to delete a segment of chromosome 9 has provided positional information that has allowed us to identify a gene necessary for cytoadherence. It has been termed the cytoadherence-linked asexual gene (clag9). clag9 encodes at least nine exons and is expressed in blood stages. The hydrophobicity profile of the predicted CLAG9 protein identifies up to four transmembrane domains. We show here that targeted gene disruption of clag9 ablated cytoadherence to C32 melanoma cells and purified CD36. DNA-induced antibodies to the clag9 gene product reacted with a polypeptide of 220 kDa in the parental malaria clone but not in clones with a disrupted clag9 gene.

The cytoadherence linked asexual gene family of Plasmodium falciparum: are there roles other than cytoadherence?

The binding of erythrocytes infected with Plasmodium falciparum to the endothelium lining the small blood vessels of the brain and other organs can mediate severe pathology. A region at the right end of chromosome 9 has been implicated in the binding of parasitised erythrocytes to the endothelial receptor CD36. A gene expressed in asexual erythrocytic stage parasites has been identified in this region and termed the cytoadherence linked asexual gene (clag). Antisense RNA production and targeted gene disruption of clag resulted in greatly reduced binding to CD36. Hybridisation to 3D7 chromosomes showed clag to be a part of a gene family of at least nine members. All members analysed so far have a conserved gene structure of at least nine exons, as well as putative transmembrane domains. The possible functions of the gene family are discussed.