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Streptococcus pyogenes (Group A Streptococcus; GAS) is a Gram-positive bacterium responsible for substantial human mortality and morbidity. Conventional diagnosis of GAS pharyngitis relies on throat swab culture, a low-throughput, slow, and relatively invasive 'gold standard'. While molecular approaches are becoming increasingly utilized, the potential of saliva as a diagnostic fluid for GAS infection remains largely unexplored. Here, we present a novel, high-throughput, sensitive, and robust speB qPCR assay that reliably detects GAS in saliva using innovative 3base™ technology (Genetic Signatures Limited, Sydney, Australia). The assay has been validated on baseline, acute, and convalescent saliva samples generated from the Controlled Human Infection for Vaccination Against Streptococcus (CHIVAS-M75) trial, in which healthy adult participants were challenged with emm75 GAS. In these well-defined samples, our high-throughput assay outperforms throat culture and conventional qPCR in saliva respectively, affirming the utility of the 3base™ platform, demonstrating the feasibility of saliva as a diagnostic biofluid, and paving the way for the development of novel non-invasive approaches for the detection of GAS and other oropharyngeal pathogens.

Critical knowledge gaps regarding infection with Mycobacterium ulcerans, the cause of Buruli ulcer (BU), have impeded development of new therapeutic approaches and vaccines for prevention of this neglected tropical disease. Here, we review the current understanding of host-pathogen interactions and correlates of immune protection to explore the case for establishing a controlled human infection model of M. ulcerans infection. We also summarise the overarching safety considerations and present a rationale for selecting a suitable challenge strain.

AIM: Paediatric intensive care unit (PICU) admissions for empyema increased following the 13-valent pneumococcal conjugate vaccine (PCV13). We describe the clinical characteristics, management and outcomes for children with empyema and compare incidence before and after PCV13. METHODS: Retrospective study of patients <18 years admitted to The Royal Children's Hospital Melbourne PICU with empyema between January 2016 and July 2019. We investigated the incidence of empyema during two time periods: 2007-2010 (pre-PCV13) and 2016-2019 (post-PCV13). RESULTS: Seventy-one children (1.9% of all PICU admissions) were admitted to PICU with empyema between 2016 and 2019. Sixty-one (86%) had unilateral disease, 11 (16%) presented with shock and 44 (62%) were ventilated. Streptococcus pneumoniae and group A Streptococcus were the most commonly identified pathogens. Forty-five (63%) were managed with video-assisted thoracoscopic surgery (VATS). There was a 31% reduction in empyema hospitalisations as a proportion of all hospitalisations (IRR 0.69, 95% CI 0.59-0.8), but a 2.8-fold increase in empyema PICU admissions as a proportion of all PICU admissions (95% CI 2.2-3.5, P < 0.001). For the PICU cohort, this was accompanied by reduction in PIM2 probability of death (median 1% vs. 1.9%, P = 0.02) and duration of intubation (median 69 h vs. 126.5 h, P = 0.045). CONCLUSIONS: In children with empyema in PICU 62% required ventilation, 16% had features of shock and 63% received VATS. Empyema admissions, as a proportion of all PICU admissions, increased in the era post-PCV13 compared to pre-PCV13 despite no increase in illness severity at admission.

INTRODUCTION: Regular intramuscular benzathine penicillin G injections have been the cornerstone of rheumatic heart disease (RHD) secondary prophylaxis since the 1950s. As the pharmacological correlate of protection remains unknown, it is difficult to recommend changes to this established regimen. Determining the minimum effective penicillin exposure required to prevent Streptococcus pyogenes infection will accelerate development of new long-acting penicillins for RHD prevention as well as inform opportunities to improve existing regimens. The CHIPS trial will address this knowledge gap by directly testing protection afforded by different steady state plasma concentrations of penicillin in an established model of experimental human S. pyogenes pharyngitis. METHODS AND ANALYSIS: This is a double-blinded, placebo-controlled, randomised experimental human infection study. Sixty healthy adult volunteers aged 18-40 years will be recruited and randomised 1:1:1:1:1 to continuous intravenous penicillin infusions targeting five different steady state plasma concentrations of 0 (placebo), 3, 6, 12 and 20 ng/mL via a midline catheter. Each participant's penicillin pharmacokinetic parameters will be established prior to the challenge, to ensure accurate dosing for the continuous infusion. Following the challenge with a well-characterised strain of S. pyogenes, participants will be observed for up to 6 days for the development of pharyngitis and treated with antibiotics prior to discharge. The primary objective is to determine the minimum effective steady-state plasma penicillin concentration required to prevent experimental pharyngitis. Secondary objectives will explore systemic and mucosal immunoinflammatory responses during pharyngitis, bacterial colonisation dynamics, environmental contamination and qualitative evaluation of the participant experience. ETHICS AND DISSEMINATION: Ethical approval has been obtained (Bellberry Human Research Ethics Committee). Findings will be r

BACKGROUND: Streptococcus pyogenes causes a profound global burden of morbidity and mortality across its diverse clinical spectrum. To support a new controlled human infection ('challenge') model seeking to accelerate S. pyogenes vaccine development, we aimed to develop an accurate and reliable molecular method for quantifying bacterial load from pharyngeal swabs collected during experimental human pharyngitis. METHODS: Combined sequential RNA + DNA extraction from throat swabs was compared to traditional separate RNA-only and DNA-only extractions. An emm-type specific qPCR was developed to detect the emm75 challenge strain. Results from the qPCR were compared to culture, using throat swab samples collected in a human challenge study. RESULTS: The qPCR was 100% specific for the emm75 challenge strain when tested against a panel of S. pyogenes emm-types and other respiratory pathogens. Combined RNA + DNA extraction had similar yield to traditional separate extractions. The combined extraction method and emm75 qPCR had 98.8% sensitivity compared to culture for throat swabs collected from challenge study participants. CONCLUSIONS: We have developed a reliable molecular method for measuring S. pyogenes bacterial load from throat swabs collected in a controlled human infection model of S. pyogenes pharyngitis. TRIAL REGISTRATION: NCT03361163 on 4th December 2017.

BACKGROUND: Streptococcus pyogenes is a leading cause of infection-related morbidity and mortality. A reinvigorated vaccine development effort calls for new clinically relevant human S pyogenes experimental infection models to support proof of concept evaluation of candidate vaccines. We describe the initial Controlled Human Infection for Vaccination Against S pyogenes (CHIVAS-M75) study, in which we aimed to identify a dose of emm75 S pyogenes that causes acute pharyngitis in at least 60% of volunteers when applied to the pharynx by swab. METHODS: This observational, dose-finding study was done in a clinical trials facility in Melbourne (VIC, Australia). Groups of healthy volunteers aged 18-40 years, at low risk of complicated S pyogenes disease, and without high type-specific anti-emm75 IgG antibodies against the challenge strain were challenged and closely monitored as inpatients for up to 6 days, and then as outpatients for 6 months. Antibiotics were started upon diagnosis (clinical signs and symptoms of pharyngitis and a positive rapid molecular test) or after 5 days in those without pharyngitis. Rapid test results were confirmed by standard bacterial culture. After a sentinel participant, cohorts of five and then ten participants were challenged, with protocol-directed dose-escalation or de-escalation for subsequent cohorts. The primary outcome was the proportion of participants at each dose level with pharyngitis by day 5 after challenge. The study is registered with ClinicalTrials.gov, NCT03361163. FINDINGS: Between July 10, 2018, and Sept 23, 2019, 25 healthy adults were challenged with emm75 S pyogenes and included in analyses. Pharyngitis was diagnosed in 17 (85%; 95% CI 62-97) of 20 participants at the starting dose level (1-3 × 105 colony-forming units [CFU]/mL). This high proportion prompted dose de-escalation. At the lower dose level (1-3 × 104 CFU/mL), pharyngitis was diagnosed in one of five participants. Immunological, biochemical, and microbiologi

Paradoxical reactions in central nervous system tuberculosis (CNS-TB) are associated with significant morbidity and mortality. We describe 4 HIV-uninfected children treated for CNS-TB with severe paradoxical reactions unresponsive to corticosteroids. All made recovery after treatment with infliximab, highlighting the safety and effectiveness of infliximab for this complication, and need for prospective trials.

Social distancing measures instituted due to #SARSCoV2 have dramatically reduced paediatric thoracic empyema cases in Australia https://bit.ly/3akG98M.

Controlled Human Infection Model (CHIM) research involves the infection of otherwise healthy participants with disease often for the sake of vaccine development. The COVID-19 pandemic has emphasised the urgency of enhancing CHIM research capability and the importance of having clear ethical guidance for their conduct. The payment of CHIM participants is a controversial issue involving stakeholders across ethics, medicine and policymaking with allegations circulating suggesting exploitation, coercion and other violations of ethical principles. There are multiple approaches to payment: reimbursement, wage payment and unlimited payment. We introduce a new Payment for Risk Model, which involves paying for time, pain and inconvenience and for risk associated with participation. We give philosophical arguments based on utility, fairness and avoidance of exploitation to support this. We also examine a cross-section of the UK public and CHIM experts. We found that CHIM participants are currently paid variable amounts. A representative sample of the UK public believes CHIM participants should be paid approximately triple the UK minimum wage and should be paid for the risk they endure throughout participation. CHIM experts believe CHIM participants should be paid more than double the UK minimum wage but are divided on the payment for risk. The Payment for Risk Model allows risk and pain to be accounted for in payment and could be used to determine ethically justifiable payment for CHIM participants.Although many research guidelines warn against paying large amounts or paying for risk, our empirical findings provide empirical support to the growing number of ethical arguments challenging this status quo. We close by suggesting two ways (value of statistical life or consistency with risk in other employment) by which payment for risk could be calculated.

AIM: Acute rheumatic fever (ARF) most commonly presents in children aged 5-14 years old. Lifelong rheumatic heart disease (RHD) can result. This study investigated time trends in ARF and RHD using inpatient data from the Royal Children's Hospital, Melbourne (RCH). METHODS: A retrospective cohort study covering the period 1937-2013 was conducted using records from RCH, a quaternary paediatric hospital in Melbourne, Victoria, Australia. Patient data were identified using RCH classification of diseases coding for ARF or RHD for years <1952. For the period 1952-1987, this system was used in addition to identifying International Classification of Disease (ICD) discharge codes that corresponded to ARF or RHD. From 1988-2013, only ICD codes were used to identify patient data. Descriptive epidemiological analyses were performed, including incidence rate calculations using historical census population denominator data. Analyses focussed on children in the peak age group. RESULTS: Among children aged five to 14 years, a total of 4337 RCH admissions with ARF/RHD occurred for 3015 patients. A sharp decline in first ARF/RHD hospitalisations at RCH occurred from 1959, following a peak mean annual incidence rate during 1944-1947 of 40.1/100 000 children (95% confidence interval (CI): 36.6-43.9; P < 0.05). Over 1996-2013, the mean annual incidence rate was 1.6/100 000 (95% CI: 1.3-1.8) and reached 2.3/100 000 (95% CI: 1.3-3.7) in 2005. CONCLUSION: The burden of ARF and RHD treated at RCH declined following the 1940s, mirroring changes seen in North America and Europe. Despite this, inpatient treatment for these conditions continued to be provided right up until the end of the study period.

AIM: Community-acquired pneumonia (CAP) complicated by pleural empyema is an important paediatric problem. Antibiotic management decisions are made on the basis of little available data and without strong specific recommendations in guidelines. METHODS: This was an online survey of paediatric infectious diseases (PID) physicians disseminated by major international professional organisations, examining empiric and targeted antibiotic choice, switch to oral antibiotics and duration of treatment for two hypothetical cases of contrasting severity. RESULTS: This study included 183 responses, mostly from North America, Western Europe and Australia/New Zealand. Increased disease severity was significantly associated with broader-spectrum and combination empiric and targeted antibiotic treatment, empiric methicillin-resistant Staphylococcus aureus (MRSA) coverage and both longer intravenous (IV) and total duration of antibiotic treatment. Empirical MRSA coverage was also associated with local prevalence. Clinical progress was most important for determining the timing of the switch from IV to oral antibiotics. Few respondents chose antibiotics with activity against organisms associated with atypical pneumonia (e.g. Mycoplasma, Chlamydia), and most did not choose agents that inhibit protein synthesis (e.g. clindamycin), even in the case of a severe invasive group A streptococcal infection. Some variation in targeted treatment choices reflected areas of uncertainty, such as Streptococcus pneumoniae susceptibility breakpoints, comparative effectiveness of anti-staphylococcal penicillins and first-generation cephalosporins for serious S. aureus infections and linezolid and vancomycin for MRSA pneumonia. CONCLUSIONS: This international survey of PID physicians highlights the priority targets for clinical research to improve antibiotic treatment of CAP complicated by empyema. Interventions that might be studied include empirical antibiotic guidelines stratified by case severity, a

BACKGROUND: In high-burden settings, guidelines recommend antibiotic treatment for all suspected group A Streptococcus (GAS) infections to prevent rheumatic fever and poststreptococcal glomerulonephritis. Highly sensitive rapid GAS tests could reduce unnecessary antibiotic use in these settings. METHODS: This was a prospective study of the Xpert Xpress Strep A (Cepheid) molecular test compared with culture of throat swab samples collected at a referral hospital in northern Australia. Demographic and clinical data and results of streptococcal serology and culture were collected. RESULTS: Of 164 throat swab samples, 145 (88%) were eligible for inclusion; 49 (34%) were molecular test positive and 24 (17%) were culture positive for GAS. The sensitivity, specificity, and positive and negative predictive values for the molecular test versus culture were 100.0%, 79.3%, 48.8%, and 100.0%, respectively. Among 25 samples testing positive with the molecular test and negative with culture, group C or G streptococci were cultured in 2, and a plausible clinical explanation, such as pharyngotonsillitis, or rheumatic fever with positive results of streptococcal serology, was apparent in 19 instances. In 25 patients with rheumatic fever or poststreptococcal glomerulonephritis diagnoses, molecular testing nearly trebled the detection of GAS in throat swab samples, from 3 (12%) detected with culture to 8 (32%) detected with molecular testing. Reasons for "false-positive" molecular test results could include the presence of GAS below the threshold of culture detection or persistence of nonviable organisms after infection. CONCLUSION: Implementation of molecular testing could improve antibiotic use in this high-burden setting. The incremental yield in poststreptococcal syndromes, by which time cultures are negative, has high potential in the diagnostic workup of autoimmune poststreptococcal syndromes and warrants further investigation.

Group A Streptococcus (GAS) is a major cause of global infection-related morbidity and mortality. A modern controlled human infection model (CHIM) of GAS pharyngitis can accelerate vaccine development and pathogenesis research. A robust rationale for strain selection is central to meeting ethical, scientific, and regulatory requirements. Multifaceted characterization studies were done to compare a preferred candidate emm75 (M75) GAS strain to three other strains: an alternative candidate emm12 (M12) strain, an M1 strain used in 1970s pharyngitis CHIM studies (SS-496), and a representative (5448) of the globally disseminated M1T1 clone. A range of approaches were used to explore strain growth, adherence, invasion, delivery characteristics, short- and long-term viability, phylogeny, virulence factors, vaccine antigens, resistance to killing by human neutrophils, and lethality in a murine invasive model. The strains grew reliably in a medium without animal-derived components, were consistently transferred using a swab method simulating the CHIM protocol, remained viable at -80°C, and carried genes for most candidate vaccine antigens. Considering GAS molecular epidemiology, virulence factors, in vitro assays, and results from the murine model, the contemporary strains show a spectrum of virulence, with M75 appearing the least virulent and 5448 the most. The virulence profile of SS-496, used safely in 1970s CHIM studies, was similar to that of 5448 in the animal model and virulence gene carriage. The results of this multifaceted characterization confirm the M75 strain as an appropriate choice for initial deployment in the CHIM, with the aim of safely and successfully causing pharyngitis in healthy adult volunteers.IMPORTANCE GAS (Streptococcus pyogenes) is a leading global cause of infection-related morbidity and mortality. A modern CHIM of GAS pharyngitis could help to accelerate vaccine development and drive pathogenesis research. Challenge strain selection is critical

Lemierre's syndrome is a rare and feared complication of pharyngitis, occurring most commonly in adolescents and young adults. It is typically defined by the constellation of septic internal jugular vein thrombophlebitis, pulmonary and other septic emboli, and sterilesite infection by Fusobacterium necrophorum. The rarity and severity of Lemierre's syndrome has made it an attractive subject for case reports but there is a paucity of evidence to inform areas of persistent uncertainty. In recent years, heightened attention and controversy has focused upon speculation that a purported rise in the incidence of Lemierre's syndrome is due to reduced antibiotic prescribing for respiratory tract infections, that F. necrophorum is an under-appreciated cause of acute tonsillopharyngitis and that testing and targeted treatment would prevent cases of Lemierre's syndrome.Copyright © 2017 The British Infection Association

Few studies are available to inform duration of intravenous antibiotics for children and when it is safe and appropriate to switch to oral antibiotics. We have systematically reviewed antibiotic duration and timing of intravenous to oral switch for 36 paediatric infectious diseases and developed evidence-graded recommendations on the basis of the review, guidelines, and expert consensus. We searched databases and obtained information from references identified and relevant guidelines. All eligible studies were assessed for quality. 4090 articles were identified and 170 studies were included. Evidence relating antibiotic duration to outcomes in children for some infections was supported by meta-analyses or randomised controlled trials; in other infections data were from retrospective series only. Criteria for intravenous to oral switch commonly included defervescence and clinical improvement with or without improvement in laboratory markers. Evidence suggests that intravenous to oral switch can occur earlier than previously recommended for some infections. We have synthesised recommendations for antibiotic duration and intravenous to oral switch to support clinical decision making and prospective research.Copyright © 2016 Elsevier Ltd

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Background: There is increasing recognition of the threat to neonatal patients from antibiotic resistance. There are limited data on antimicrobial prescribing practices for hospitalized neonates. We aimed to describe antimicrobial use in hospitalized Australian neonatal patients, and to determine its appropriateness. Method(s): Multicentre single-day hospital-wide point prevalence survey in 2012, in conjunction with the Antimicrobial Resistance and Prescribing in European Children study. The appropriateness of antimicrobial prescriptions was also assessed. All patients admitted at 8 am on the survey day, in 6 neonatal units in tertiary children's hospitals across 5 states, were included in an analysis of the quantity and quality of all antimicrobial prescriptions. Result(s): The point prevalence survey included 6 neonatal units and 236 patients. Of 109 patients (46%) receiving at least 1 antimicrobial, 66 (61%) were being treated for infection, with sepsis the most common indication. There were 216 antimicrobial prescriptions, 134 (62%) for treatment of infection and 82 (38%) for prophylaxis, mostly oral nystatin. Only 15 prescriptions were for targeted as opposed to empirical treatment. Penicillin and gentamicin were the most commonly prescribed antibiotics, with vancomycin third most common. Half of all treated patients were receiving combination antimicrobial therapy. There was marked variation in vancomycin and gentamicin dosing. Overall, few prescriptions (4%) were deemed inappropriate. Conclusion(s): This is the first Australia-wide point prevalence survey of neonatal antimicrobial prescribing in tertiary children's hospitals. The findings highlight positive practices and potential targets for quality improvement.Copyright © 2015 Wolters Kluwer Health, Inc.

Objectives: To describe antimicrobial use in hospitalised Australian children and to analyse the appropriateness of this antimicrobial use. Design: Multicentre single-day hospital-wide point prevalence survey, conducted in conjunction with the Antimicrobial Resistance and Prescribing in European Children study. Setting: Eight children's hospitals across five Australian states, surveyed during late spring and early summer 2012. Patients: Children and adolescents who were inpatients at 8 am on the day of the survey. Main outcome measures: Quantity and quality of antimicrobial prescribing. Results: Of 1373 patients, 631 (46%) were prescribed at least one antimicrobial agent, 198 (31%) of whom were < 1 year old. The highest antimicrobial prescribing rates were in haematology and oncology wards (76% [95/125]) and paediatric intensive care units (55% [44/80]). Of 1174 antimicrobial prescriptions, 550 (47%) were for community-acquired infections, 175 (15%) were for hospital-acquired infections and 437 (37%) were for prophylaxis. Empirical treatment accounted for 72% of antimicrobial prescriptions for community-acquired infections and 58% for hospital-acquired infections (395 and 102 prescriptions, respectively). A total of 915 prescriptions (78%) were for antibacterials; antifungals and antivirals were predominantly used for prophylaxis. The most commonly prescribed antibacterials were narrow-spectrum penicillins (18% [164 prescriptions]), beta-lactam-beta-lactamase inhibitor combinations (15% [136]) and aminoglycosides (14% [128]). Overall, 957 prescriptions (82%) were deemed appropriate, but this varied between hospitals (range, 66% [74/112]) to 95% [165/174]) and specialties (range, 65% [122/187] to 94% [204/217]). Among surgical patients, 65 of 187 antimicrobial prescriptions (35%) were deemed inappropriate, and a common reason for this was excessive prophylaxis duration. Conclusion: A point prevalence survey is a useful cross-sectional method for quantifying antimicro

Introduction/Aim: Pleural empyema is a serious complication of bacterial pneumonia. Affected children often require surgical intervention to drain purulent pleural fluid (PF) and empiric IV antibiotics. Identifying the bacterial cause of empyema by culturing this PF is unreliable, especially with prior antibiotic use. In most cases, the bacterial cause remains unidentified, necessitating prolonged empiric antibiotics, increasing risk of side-effects and antimicrobial resistance. We are developing a multiplex quantitative PCR assay (m-qPCR) to improve identification of the bacterial causes of empyema, to direct rational antibiotic therapy. Method(s): We are recruiting 150 paediatric empyema patients, across two tertiary hospitals in Melbourne, and testing PF using our m-qPCR assay. The m-qPCR targets the most common causes of empyema: Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus and Haemophilus influenzae. We will compare our m-qPCR assay's performance against identification by PF culture and assess its potential clinical impact. Result(s): We have recruited and tested PF from 50 empyema patients, aged between 1.5 months and 17 years old. Using our m-qPCR, we detected a bacterial species in 45/50 (90%), compared with 9/50 (18%) by PF culture. Our assay showed 100% concordance for target species with culture results. By m-qPCR, the most common pathogen was S. pneumoniae n=36 (72%), followed by S. pyogenes in n=6 (12%), H. influenzae in n=2 (4%) and S. aureus in n=1 (2%). Conclusion(s): Preliminary results show our m-qPCR is 5-fold more sensitive than PF culture in identifying the bacterial cause of pleural empyema. We will further assess the performance of our m-qPCR, and its potential clinical impact as a rapid, reliable diagnostic, enabling efficient antibiotic stewardship and improved clinical outcomes for patients.

Introduction/Aim: Pleural empyema is a serious complication of bacterial pneumonia. Affected children often require surgical intervention to drain purulent pleural fluid (PF) and empiric IV antibiotics. Identifying the bacterial cause of empyema by culturing this PF is unreliable, especially with prior antibiotic use. In most cases, the bacterial cause remains unidentified, necessitating prolonged empiric antibiotics, increasing risk of side-effects and antimicrobial resistance. We are developing a multiplex quantitative PCR assay (m-qPCR) to improve identification of the bacterial causes of empyema, to direct rational antibiotic therapy. Method(s): We are recruiting 150 paediatric empyema patients, across two tertiary hospitals in Melbourne, and testing PF using our m-qPCR assay. The m-qPCR targets the most common causes of empyema: Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus and Haemophilus influenzae. We will compare our m-qPCR assay's performance against identification by PF culture and assess its potential clinical impact. Result(s): We have recruited and tested PF from 50 empyema patients, aged between 1.5 months and 17 years old. Using our m-qPCR, we detected a bacterial species in 45/50 (90%), compared with 9/50 (18%) by PF culture. Our assay showed 100% concordance for target species with culture results. By m-qPCR, the most common pathogen was S. pneumoniae n=36 (72%), followed by S. pyogenes in n=6 (12%), H. influenzae in n=2 (4%) and S. aureus in n=1 (2%). Conclusion(s): Preliminary results show our m-qPCR is 5-fold more sensitive than PF culture in identifying the bacterial cause of pleural empyema. We will further assess the performance of our m-qPCR, and its potential clinical impact as a rapid, reliable diagnostic, enabling efficient antibiotic stewardship and improved clinical outcomes for patients.