Significant healthcare resource utilisation in the management of skin and soft tissue infections in the Torres Strait, Australia.

INTRODUCTION: Aboriginal and Torres Strait Islander Peoples (First Nations Australians) living in remote communities are hospitalised with skin and soft tissue infections (SSTIs) at three times the rate of non-First Nations Australians. The Torres Strait in tropical northern Australia has a highly dispersed population mainly comprising First Nations Australians. This study aimed to define the health service utilisation and health system costs associated with SSTIs in the Torres Strait and to improve the quality of regional healthcare delivery. METHODS: The research team conducted a retrospective, de-identified audit of health records for a 2-year period, 2018-2019. The aim was to define health service utilisation, episodes of outpatient care, emergency department care, inpatient care and aeromedical retrieval services for SSTIs. RESULTS: Across 2018 - 2019, there were 3509 outpatient episodes of care for SSTIs as well as 507 emergency department visits and 100 hospitalisations. For individuals with an SSTI, the mean outpatient clinic episode cost $240; the mean emergency department episode cost $400.85, the mean inpatient episode cost $8403.05 while an aeromedical retrieval service cost $18,670. The total costs to the health system for all services accessed for SSTI management was $6,169,881 per year, 3% of the total annual health service budget. CONCLUSION: Healthcare costs associated with SSTIs in the Torres Strait are substantial. The implementation of effective preventative and primary care interventions may enable resources to be reallocated to address other health priorities in the Torres Strait.

Overlapping Streptococcus pyogenes and Streptococcus dysgalactiae subspecies equisimilis household transmission and mobile genetic element exchange.

Streptococcus dysgalactiae subspecies equisimilis (SDSE) and Streptococcus pyogenes share skin and throat niches with extensive genomic homology and horizontal gene transfer (HGT) possibly underlying shared disease phenotypes. It is unknown if cross-species transmission interaction occurs. Here, we conduct a genomic analysis of a longitudinal household survey in remote Australian First Nations communities for patterns of cross-species transmission interaction and HGT. Collected from 4547 person-consultations, we analyse 294 SDSE and 315 S. pyogenes genomes. We find SDSE and S. pyogenes transmission intersects extensively among households and show that patterns of co-occurrence and transmission links are consistent with independent transmission without inter-species interference. We identify at least one of three near-identical cross-species mobile genetic elements (MGEs) carrying antimicrobial resistance or streptodornase virulence genes in 55 (19%) SDSE and 23 (7%) S. pyogenes isolates. These findings demonstrate co-circulation of both pathogens and HGT in communities with a high burden of streptococcal disease, supporting a need to integrate SDSE and S. pyogenes surveillance and control efforts.

Evaluating the role of asymptomatic throat carriage of Streptococcus pyogenes in impetigo transmission in remote Aboriginal communities in Northern Territory, Australia: a retrospective genomic analysis.

BACKGROUND: Streptococcus pyogenes, or group A Streptococcus (GAS), infections contribute to a high burden of disease in Aboriginal Australians, causing skin infections and immune sequelae such as rheumatic heart disease. Controlling skin infections in these populations has proven difficult, with transmission dynamics being poorly understood. We aimed to identify the relative contributions of impetigo and asymptomatic throat carriage to GAS transmission. METHODS: In this genomic analysis, we retrospectively applied whole genome sequencing to GAS isolates that were collected as part of an impetigo surveillance longitudinal household survey conducted in three remote Aboriginal communities in the Northern Territory of Australia between Aug 6, 2003, and June 22, 2005. We included GAS isolates from all throats and impetigo lesions of people living in two of the previously studied communities. We classified isolates into genomic lineages based on pairwise shared core genomes of more than 99% with five or fewer single nucleotide polymorphisms. We used a household network analysis of epidemiologically and genomically linked lineages to quantify the transmission of GAS within and between households. FINDINGS: We included 320 GAS isolates in our analysis: 203 (63%) from asymptomatic throat swabs and 117 (37%) from impetigo lesions. Among 64 genomic lineages (encompassing 39 emm types) we identified 264 transmission links (involving 93% of isolates), for which the probable source was asymptomatic throat carriage in 166 (63%) and impetigo lesions in 98 (37%). Links originating from impetigo cases were more frequent between households than within households. Households were infected with GAS for a mean of 57 days (SD 39 days), and once cleared, reinfected 62 days (SD 40 days) later. Increased household size and community presence of GAS and scabies were associated with slower clearance of GAS. INTERPRETATION: In communities with high prevalence of endemic GAS-associated skin infection, asymptomatic throat carriage is a GAS reservoir. Public health interventions such as vaccination or community infection control programmes aimed at interrupting transmission of GAS might need to include consideration of asymptomatic throat carriage. FUNDING: Australian National Health and Medical Research Council.

Estimation of the force of infection and infectious period of skin sores in remote Australian communities using interval-censored data.

Prevalence of impetigo (skin sores) remains high in remote Australian Aboriginal communities, Fiji, and other areas of socio-economic disadvantage. Skin sore infections, driven primarily in these settings by Group A Streptococcus (GAS) contribute substantially to the disease burden in these areas. Despite this, estimates for the force of infection, infectious period and basic reproductive ratio-all necessary for the construction of dynamic transmission models-have not been obtained. By utilising three datasets each containing longitudinal infection information on individuals, we estimate each of these epidemiologically important parameters. With an eye to future study design, we also quantify the optimal sampling intervals for obtaining information about these parameters. We verify the estimation method through a simulation estimation study, and test each dataset to ensure suitability to the estimation method. We find that the force of infection differs by population prevalence, and the infectious period is estimated to be between 12 and 20 days. We also find that optimal sampling interval depends on setting, with an optimal sampling interval between 9 and 11 days in a high prevalence setting, and 21 and 27 days for a lower prevalence setting. These estimates unlock future model-based investigations on the transmission dynamics of skin sores.

Epidemiological consequences of enduring strain-specific immunity requiring repeated episodes of infection.

Group A Streptococcus (GAS) skin infections are caused by a diverse array of strain types and are highly prevalent in disadvantaged populations. The role of strain-specific immunity in preventing GAS infections is poorly understood, representing a critical knowledge gap in vaccine development. A recent GAS murine challenge study showed evidence that sterilising strain-specific and enduring immunity required two skin infections by the same GAS strain within three weeks. This mechanism of developing enduring immunity may be a significant impediment to the accumulation of immunity in populations. We used an agent-based mathematical model of GAS transmission to investigate the epidemiological consequences of enduring strain-specific immunity developing only after two infections with the same strain within a specified interval. Accounting for uncertainty when correlating murine timeframes to humans, we varied this maximum inter-infection interval from 3 to 420 weeks to assess its impact on prevalence and strain diversity, and considered additional scenarios where no maximum inter-infection interval was specified. Model outputs were compared with longitudinal GAS surveillance observations from northern Australia, a region with endemic infection. We also assessed the likely impact of a targeted strain-specific multivalent vaccine in this context. Our model produced patterns of transmission consistent with observations when the maximum inter-infection interval for developing enduring immunity was 19 weeks. Our vaccine analysis suggests that the leading multivalent GAS vaccine may have limited impact on the prevalence of GAS in populations in northern Australia if strain-specific immunity requires repeated episodes of infection. Our results suggest that observed GAS epidemiology from disease endemic settings is consistent with enduring strain-specific immunity being dependent on repeated infections with the same strain, and provide additional motivation for relevant human studies to confirm the human immune response to GAS skin infection.

Doing it hard in the bush: Aligning what gets measured with what matters.

What gets measured gets managed. Funding of health services is substantially determined by operational activity and specific outcome indicators. In day-to-day clinical decision-making, surrogate markers, such as glycosylated haemoglobin and blood pressure, are commonly used to modify risks of 'hard' outcomes that include kidney failure, ischaemic cardiac events, stroke and all-cause mortality. In many settings, surrogates are all we have to go on. As a consequence, current health funding models heavily rely on surrogate-based key performance indicators [KPIs]. While surrogates are convenient and provide immediate information, there is an obligation to ensure that they are appropriate, reliable and validated in context. In contrast, hard outcomes, the real consequences of illness, are usually realised over an extended timeframe. Additionally, and for a host of reasons, hard endpoints have the greatest social, emotional and economic impact for people at the far end of the health system; those in rural and remote settings - 'in the bush' - especially Indigenous Australians. We propose a health service assessment approach that aligns short-term decision-making with patient-centred and longer term hard outcomes, one that takes into account community, cultural and environmental factors, especially remoteness. Communities should have a major say in determining what health indicators are measured and managed.

Do worms protect against the metabolic syndrome? A systematic review and meta-analysis.

AIMS: There is increasing evidence on the role of helminth infections in modifying autoimmune and allergic diseases. These infections may have similar effect in other inflammatory processes, such as insulin resistance. This review aims to examine the literature on the effect of helminthic infections on metabolic outcomes in humans. METHODS: Using the PRISMA protocol, we searched the literature using PubMed, MEDLINE, and a manual review of reference lists. Human studies published in English after 1995 were included. Four papers were included in this review. Data was extracted and a meta-analysis was conducted using a random-effects model. Heterogeneity was assessed using Tau(2) and I(2) tests. RESULTS: The included studies found that infection was associated with lower glucose levels, less insulin resistance, and/or a lower prevalence of metabolic syndrome (MetS) or type 2 diabetes mellitus (T2DM). Meta-analysis showed that participants with a previous or current helminth infection were 50% less likely to have an endpoint of metabolic dysfunction in comparison to uninfected participants (OR 0.50; 95% CI 0.38-0.66). CONCLUSION: This review has shown that helminth infections can be associated with improved metabolic outcomes. Understanding of the mechanisms underlying this relationship could facilitate the development of novel strategies to prevent or delay T2DM.

Short-course oral co-trimoxazole versus intramuscular benzathine benzylpenicillin for impetigo in a highly endemic region: an open-label, randomised, controlled, non-inferiority trial.

BACKGROUND: Impetigo affects more than 110 million children worldwide at any one time. The major burden of disease is in developing and tropical settings where topical antibiotics are impractical and lead to rapid emergence of antimicrobial resistance. Few trials of systemic antibiotics are available to guide management of extensive impetigo. As such, we aimed to compare short-course oral co-trimoxazole with standard treatment with intramuscular benzathine benzylpenicillin in children with impetigo in a highly endemic setting. METHODS: In this randomised, controlled, non-inferiority trial, Indigenous Australian children aged 3 months to 13 years with purulent or crusted non-bullous impetigo were randomly assigned (1:1:1) to receive benzathine benzylpenicillin (weight-banded injection), twice-daily co-trimoxazole for 3 days (4 mg/kg plus 20 mg/kg per dose), or once-daily co-trimoxazole for 5 days (8 mg/kg plus 40 mg/kg per dose). At every visit, participants were randomised in blocks of six and 12, stratified by disease severity. Randomisation was done by research nurses and codes were in sealed, sequentially numbered, opaque envelopes. Independent reviewers masked to treatment allocation compared digital images of sores from days 0 and 7. The primary outcome was treatment success at day 7 in a modified intention-to-treat analysis. This trial is registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12609000858291. FINDINGS: Between Nov 26, 2009, and Nov 20, 2012, 508 patients were randomly assigned to receive benzathine benzylpenicillin (n=165 [156 analysed]), twice-daily co-trimoxazole for 3 days (n=175 [173 analysed]), or once-daily co-trimoxazole for 5 days (n=168 [161 analysed]). Treatment was successful in 133 (85%) children who received benzathine benzylpenicillin and 283 (85%) who received pooled co-trimoxazole (absolute difference 0·5%; 95% CI -6·2 to 7·3), showing non-inferiority of co-trimoxazole (10% margin). Results for twice-daily co-trimoxazole for 3 days and once-daily co-trimoxazole for 5 days were similar. Adverse events occurred in 54 participants, 49 (90%) of whom received benzathine benzylpenicillin. INTERPRETATION: Short-course co-trimoxazole is a non-inferior, alternative treatment to benzathine benzylpenicillin for impetigo; it is palatable, pain-free, practical, and easily administered. FUNDING: Australian National Health and Medical Research Council.

Improvement in rheumatic fever and rheumatic heart disease management and prevention using a health centre-based continuous quality improvement approach.

BACKGROUND: Rheumatic heart disease (RHD) remains a major health concern for Aboriginal Australians. A key component of RHD control is prevention of recurrent acute rheumatic fever (ARF) using long-term secondary prophylaxis with intramuscular benzathine penicillin (BPG). This is the most important and cost-effective step in RHD control. However, there are significant challenges to effective implementation of secondary prophylaxis programs. This project aimed to increase understanding and improve quality of RHD care through development and implementation of a continuous quality improvement (CQI) strategy. METHODS: We used a CQI strategy to promote implementation of national best-practice ARF/RHD management guidelines at primary health care level in Indigenous communities of the Northern Territory (NT), Australia, 2008-2010. Participatory action research methods were employed to identify system barriers to delivery of high quality care. This entailed facilitated discussion with primary care staff aided by a system assessment tool (SAT). Participants were encouraged to develop and implement strategies to overcome identified barriers, including better record-keeping, triage systems and strategies for patient follow-up. To assess performance, clinical records were audited at baseline, then annually for two years. Key performance indicators included proportion of people receiving adequate secondary prophylaxis (≥80% of scheduled 4-weekly penicillin injections) and quality of documentation. RESULTS: Six health centres participated, servicing approximately 154 people with ARF/RHD. Improvements occurred in indicators of service delivery including proportion of people receiving ≥40% of their scheduled BPG (increasing from 81/116 [70%] at baseline to 84/103 [82%] in year three, p = 0.04), proportion of people reviewed by a doctor within the past two years (112/154 [73%] and 134/156 [86%], p = 0.003), and proportion of people who received influenza vaccination (57/154 [37%] to 86/156 [55%], p = 0.001). However, the proportion receiving ≥80% of scheduled BPG did not change. Documentation in medical files improved: ARF episode documentation increased from 31/55 (56%) to 50/62 (81%) (p = 0.004), and RHD risk category documentation from 87/154 (56%) to 103/145 (76%) (p < 0.001). Large differences in performance were noted between health centres, reflected to some extent in SAT scores. CONCLUSIONS: A CQI process using a systems approach and participatory action research methodology can significantly improve delivery of ARF/RHD care.

Longitudinal nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in indigenous Australian and Alaska native children with bronchiectasis.

BACKGROUND: Indigenous children in Australia and Alaska have very high rates of chronic suppurative lung disease (CSLD)/bronchiectasis. Antibiotics, including frequent or long-term azithromycin in Australia and short-term beta-lactam therapy in both countries, are often prescribed to treat these patients. In the Bronchiectasis Observational Study we examined over several years the nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in these two PCV7-vaccinated populations. METHODS: Indigenous children aged 0.5-8.9 years with CSLD/bronchiectasis from remote Australia (n = 79) and Alaska (n = 41) were enrolled in a prospective cohort study during 2004-8. At scheduled study visits until 2010 antibiotic use in the preceding 2-weeks was recorded and nasopharyngeal swabs collected for culture and antimicrobial susceptibility testing. Analysis of respiratory bacterial carriage and antibiotic resistance was by baseline and final swabs, and total swabs by year. RESULTS: Streptococcus pneumoniae carriage changed little over time. In contrast, carriage of Haemophilus influenzae declined and Staphylococcus aureus increased (from 0% in 2005-6 to 23% in 2010 in Alaskan children); these changes were associated with increasing age. Moraxella catarrhalis carriage declined significantly in Australian, but not Alaskan, children (from 64% in 2004-6 to 11% in 2010). While beta-lactam antibiotic use was similar in the two cohorts, Australian children received more azithromycin. Macrolide resistance was significantly higher in Australian compared to Alaskan children, while H. influenzae beta-lactam resistance was higher in Alaskan children. Azithromycin use coincided significantly with reduced carriage of S. pneumoniae, H. influenzae and M. catarrhalis, but increased carriage of S. aureus and macrolide-resistant strains of S. pneumoniae and S. aureus (proportion of carriers and all swabs), in a 'cumulative dose-response' relationship. CONCLUSIONS: Over time, similar (possibly age-related) changes in nasopharyngeal bacterial carriage were observed in Australian and Alaskan children with CSLD/bronchiectasis. However, there were also significant frequency-dependent differences in carriage and antibiotic resistance that coincided with azithromycin use.

Is Streptococcus pyogenes resistant or susceptible to trimethoprim-sulfamethoxazole?

Streptococcus pyogenes is commonly believed to be resistant to trimethoprim-sulfamethoxazole (SXT), resulting in reservations about using SXT for skin and soft tissue infections (SSTI) where S. pyogenes is involved. S. pyogenes' in vitro susceptibility to SXT depends on the medium's thymidine content. Thymidine allows S. pyogenes to bypass the sulfur-mediated inhibition of folate metabolism and, historically, has resulted in apparently reduced susceptibility of S. pyogenes to sulfur antibacterials. The low thymidine concentration in Mueller-Hinton agar (MHA) is now regulated. We explored S. pyogenes susceptibility to SXT on various media. Using two sets of 100 clinical S. pyogenes isolates, we tested for susceptibility using SXT Etests on MHA containing defibrinated horse blood and 20 mg/liter ß-NAD (MHF), MHA with sheep blood (MHS), MHA alone, MHA with horse blood (MHBA), and MHA with lysed horse blood (MHLHBA). European Committee on Antibacterial Susceptibility Testing (EUCAST) breakpoints defined susceptibility (MIC, ≤ 1 mg/liter) and resistance (MIC, >2 mg/liter). In study 1, 99% of S. pyogenes isolates were susceptible to SXT on MHA, MHBA, and MHLHBA, with geometric mean MICs of 0.04, 0.04, and 0.05 mg/liter, respectively. In study 2, all 100 S. pyogenes isolates were susceptible to SXT on MHF, MHS, MHA, and MHLHBA with geometric mean MICs of 0.07, 0.16, 0.07, and 0.09 mg/liter, respectively. This study confirms the in vitro susceptibility of S. pyogenes to SXT, providing support for the use of SXT for SSTIs. A clinical trial using SXT for impetigo is ongoing.

Chronic suppurative lung disease and bronchiectasis in children and adults in Australia and New Zealand.

Consensus recommendations for managing chronic suppurative lung disease (CSLD) and bronchiectasis, based on systematic reviews, were developed for Australian and New Zealand children and adults during a multidisciplinary workshop. The diagnosis of bronchiectasis requires a high-resolution computed tomography scan of the chest. People with symptoms of bronchiectasis, but non-diagnostic scans, have CSLD, which may progress to radiological bronchiectasis. CSLD/bronchiectasis is suspected when chronic wet cough persists beyond 8 weeks. Initial assessment requires specialist expertise. Specialist referral is also required for children who have either two or more episodes of chronic (> 4 weeks) wet cough per year that respond to antibiotics, or chest radiographic abnormalities persisting for at least 6 weeks after appropriate therapy. Intensive treatment seeks to improve symptom control, reduce frequency of acute pulmonary exacerbations, preserve lung function, and maintain a good quality of life. Antibiotic selection for acute infective episodes is based on results of lower airway culture, local antibiotic susceptibility patterns, clinical severity and patient tolerance. Patients whose condition does not respond promptly or adequately to oral antibiotics are hospitalised for more intensive treatments, including intravenous antibiotics. Ongoing treatment requires regular and coordinated primary health care and specialist review, including monitoring for complications and comorbidities. Chest physiotherapy and regular exercise should be encouraged, nutrition optimised, environmental pollutants (including tobacco smoke) avoided, and vaccines administered according to national immunisation schedules. Individualised long-term use of oral or nebulised antibiotics, corticosteroids, bronchodilators and mucoactive agents may provide a benefit, but are not recommended routinely.

Clinical correlates of Panton-Valentine leukocidin (PVL), PVL isoforms, and clonal complex in the Staphylococcus aureus population of Northern Australia.

BACKGROUND: Regional differences in the prevalence of Panton-Valentine leukocidin (PVL) and PVL isoform-harboring strains as well as in the local population structure of Staphylococcus aureus may influence the clinical spectrum of S. aureus infections. METHODS: Using a prospective collection of S. aureus isolates from northern Australia, we determined differences between infections caused by (1) PVL(+) and PVL(-) isolates, (2) PVL histidine (H) isoform- and PVL arginine (R) isoform-harboring isolates, and (3) different lineages, including the genetically divergent clonal complex (CC) 75 and the PVL(+) CC93. RESULTS: PVL(+) isolates comprised 54% (128/239) of community-associated methicillin-resistant isolates and 40% (95/239) of methicillin-susceptible S. aureus (MSSA) isolates. There were 113 H isoform- and 110 R isoform-harboring isolates. PVL was associated with truly community-acquired disease, younger age, and presentation with sepsis. We found no differences in infections due to H isoform-harboring isolates, compared with R isoform-harboring isolates. CC93 was the most prevalent lineage. The genetically divergent CC75 caused clinical disease similar to that of other S. aureus clones. CONCLUSIONS: PVL(+) and PVL(-) infections are clearly distinct. MSSA contributes a large but underrecognized burden of PVL(+) disease. Compared with elsewhere in the world, there is a relative abundance of the clade that contains CC93 and CC121 in both northern Australia and Asia.

Diversity of emm sequence types in group A beta-haemolytic streptococci in two remote Northern Territory Indigenous communities: implications for vaccine development.

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.

Trimethopim-sulfamethoxazole compared with benzathine penicillin for treatment of impetigo in Aboriginal children: a pilot randomised controlled trial.

We conducted a pilot randomized controlled trial comparing trimethoprim-sulfamethoxazole to benzathine penicillin for treatment of impetigo in Aboriginal children. Treatment was successful in 7 of 7 children treated with trimethoprim-sulfamethoxazole and 5 of 6 treated with benzathine penicillin. Trimethoprim-sulfamethoxazole achieved microbiological clearance and healing of sores from which beta-hemolytic streptococci and community-associated methicillin-resistant Staphylococcus aureus were initially cultured.

Incomplete protection against hepatitis B among remote Aboriginal adolescents despite full vaccination in infancy.

The objective of this study was to determine long-term immunity to hepatitis B virus (HBV) in a cohort of adolescents who received plasma-derived HBV vaccine in 1989 and 1990 in a remote Australian Aboriginal community. This was done using a serological survey; primary outcome measures were cut-off titres of HBsAb, and the presence of HBcAb and/or HBsAg. Of 37 adolescents in the cohort, 4 (11%) had evidence of active infection, one with abnormal liver enzymes, 7 (19%) had evidence of past infection, 15 (41%) were HBsAb positive in low titre and 11 (30%) were classed as immune. It was concluded that there was relatively poor long-term serological immunity to HBV vaccination in this group; a finding which is in keeping with similar studies in Indigenous and remote populations elsewhere. This finding raises the concern that a significant proportion of Aboriginal adolescents in other remote communities (vaccinated in 1989 and 1990) were not adequately protected by the vaccine. If so, there will be an unexpected burden of chronic HBV infection in these settings and a substantial group who are non-immune, despite having received complete HBV vaccination courses as infants. The authors recommend followup serosurveys in remote Aboriginal communities to identify people with low HBsAb titres, especially those without an adequate anamnestic response to another dose of HBV vaccine. In addition, community-based active surveillance programs will be required to detect people with chronic HBV infection and provide access to monitoring and appropriate treatment.

Community-associated strains of methicillin-resistant Staphylococcus aureus and methicillin-susceptible S. aureus in indigenous Northern Australia: epidemiology and outcomes.

BACKGROUND: Some strains of non-multidrug-resistant, methicillin-resistant Staphylococcus aureus (nmMRSA) in Australia are likely to have emerged from strains of methicillin-susceptible S. aureus (MSSA) in remote Aboriginal communities. OBJECTIVE: To describe the clinical epidemiology of infection due to community-associated MRSA strains in an Australian tropical hospital setting with a significant Aboriginal population and to compare infections caused by community-associated strains of MRSA, health-care-associated strains of MRSA, and MSSA strains with respect to demographic risk factors and clinical outcomes. Methods. We queried the microbiology database for the Top End of the Northern Territory, Australia, to determine population incidences for S. aureus infection and conducted a prospective matched case-control study to compare infection due to nmMRSA, MSSA, or multidrug-resistant MRSA at the Royal Darwin Hospital. RESULTS: The annual incidence of S. aureus bacteremia was 65 cases per 100,000 population, but in the Aboriginal population the incidence was 172 cases per 100,000 population (odds ratio [OR] compared with non-Aboriginal population, 5.8 [95% confidence interval {CI}, 3.8-8.9). Female sex (adjusted OR [aOR], 1.5 [95% CI, 1.1-2.0) and remote residence (aOR, 1.8 [95% CI, 1.2-2.5]) were associated with the isolation of nmMRSA rather than MSSA, but disease spectrum and outcomes were similar. Among those from whom nmMRSA was isolated, Aboriginal patients were younger (aOR for each additional year, 0.94 [95% CI, 0.92-0.96]), more likely to be female (aOR, 3.8 [95% CI, 1.7-8.5]), and more likely to reside in a remote community (aOR, 29 [95% CI, 8.9-94]) than non-Aboriginal patients. The presence of Panton-Valentine leukocidin in nmMRSA was associated with double the odds of sepsis (aOR, 2.2 [95% CI, 1.1-4.6]). CONCLUSIONS: The association of nmMRSA infection with female sex and remote residence supports the hypothesis that nmMRSA arose from MSSA strains in remote Aboriginal communities where staphylococcal disease is highly prevalent. The similar clinical spectrum and outcomes for nmMRSA infection and MSSA infection suggest that virulence is not correlated with resistance phenotype.

Global implications of the emergence of community-associated methicillin-resistant Staphylococcus aureus in Indigenous populations.

The emergence of community-associated methicillin-resistant Staphylococcus aureus (MRSA) in Australia may have been facilitated by conditions in socially disadvantaged populations--particularly, remote Australian Aboriginal communities. The appearance of community-associated MRSA was first noticed in Australia during the early 1980s; subsequently, several genetically diverse strains have independently emerged from geographically distinct regions. Molecular and epidemiological studies support the role of genetic transfer of resistance determinants (SCCmecIV) in this process. Conditions in Aboriginal communities--namely, domestic crowding, poor hygiene, and high rates of scabies, pyoderma, and antibiotic use--have facilitated both the clonal expansion and de novo emergence of strains of community-associated MRSA. Combating the worldwide emergence and spread of community-associated MRSA may require novel community-level control strategies targeted at specific groups, such as remote Indigenous populations.

Rheumatic fever and social justice.

High rates of this disease are the face of Indigenous disadvantage.

Low rates of streptococcal pharyngitis and high rates of pyoderma in Australian aboriginal communities where acute rheumatic fever is hyperendemic.

BACKGROUND: Acute rheumatic fever is a major cause of heart disease in Aboriginal Australians. The epidemiology differs from that observed in regions with temperate climates; streptococcal pharyngitis is reportedly rare, and pyoderma is highly prevalent. A link between pyoderma and acute rheumatic fever has been proposed but is yet to be proven. Group C beta-hemolytic streptococci and group G beta-hemolytic streptococci have also been also implicated in the pathogenesis. METHODS: Monthly, prospective surveillance of selected households was conducted in 3 remote Aboriginal communities. People were questioned about sore throat and pyoderma; swab specimens were obtained from all throats and any pyoderma lesions. Household population density was determined. RESULTS: From data collected during 531 household visits, the childhood incidence of sore throat was calculated to be 8 cases per 100 person-years, with no cases of symptomatic group A beta-hemolytic streptococci pharyngitis. The median point prevalence for throat carriage was 3.7% for group A beta-hemolytic streptococci, 0.7% for group C beta-hemolytic streptococci, and 5.1% for group G beta-hemolytic streptococci. Group A beta-hemolytic streptococci were recovered from the throats of 19.5% of children at some time during the study. There was no seasonal trend or correlation with overcrowding. Almost 40% of children had pyoderma at least once, and the prevalence was greatest during the dry season. In community 1, the prevalence of pyoderma correlated with household crowding. Group C and G beta-hemolytic streptococci were rarely recovered from pyoderma lesions. CONCLUSIONS: These data are consistent with the hypothesis that recurrent skin infections immunize against throat colonization and infection. High rates of acute rheumatic fever were not driven by symptomatic group A beta-hemolytic streptococci throat infection. Group G and C beta-hemolytic streptococci were found in the throat but rarely in pyoderma lesions.