Clinical, Genomic, and Immunological Characterization of RSV Surge in Sydney, Australia, 2022

OBJECTIVES

The 2022 seasonal respiratory syncytial virus (RSV) epidemic in Sydney, Australia saw an unprecedented number of RSV detections. We aimed to characterize genomic and immunologic factors associated with the surge in RSV cases.

METHODS

Whole genome sequences of RSV were generated from 264 RSV-infected infants and linked to case-matched clinical data from the 2022 southern hemisphere RSV season. We then performed an immunologic analysis of baseline RSV-specific humoral immunity in women of childbearing age before and throughout the coronavirus disease 2019 pandemic.

RESULTS

Clinical analysis revealed a high burden of disease across patients of all health backgrounds. More than one-half of RSV-related health care visits by infants resulted in hospitalization, and one-quarter required high-flow respiratory support or a higher level of care. Viral phylogenetic analyses revealed that 2022 Sydney RSV sequences were closely related to viruses that had been circulating globally since 2017, including those detected in recent US outbreaks. Nonsynonymous mutations within the palivizumab and nirsevimab binding sites were detected at low frequencies. There was no difference in baseline RSV-neutralizing antibody titers between 2020 and 2022.

CONCLUSIONS

Collectively, these findings suggest that neither the emergence of a novel RSV genotype nor hypothesized immune debt was associated with the surge of RSV cases and hospitalizations in 2022. Continued genomic and immunologic surveillance is required to further understand the factors driving outbreaks of RSV globally, and to inform guidelines for the rollout and ongoing use of recently developed immunotherapeutics and vaccines.

A single blinded, phase IV, adaptive randomised control trial to evaluate the safety of coadministration of seasonal influenza and COVID-19 vaccines (The FluVID study)

OBJECTIVES

We evaluated the frequency of moderate and severe adverse events following coadministration of seasonal influenza vaccine (SIV) versus placebo with COVID-19 vaccines among adults to support practice guidelines.

METHODS

FluVID is a participant-blinded, phase IV, randomised control trial. On the same day as the participant's scheduled COVID-19 vaccine, participants were randomised to receive SIV or saline placebo; those assigned placebo at visit one then received SIV a week later, and vice versa. Self-reported adverse events were collected daily for seven days following each visit. The primary endpoint was any solicited adverse event of at least moderate severity occurring up to seven days following receipt of SIV or placebo. This was modelled using a Bayesian logistic regression model. Analyses were performed by COVID-19 vaccine type and dose number.

RESULTS

Overall, 248 participants were enrolled; of these, 195 had received BNT162b2 and 53 had received mRNA1273 COVID-19 vaccines according to national guidelines. After randomisation, 119 were assigned to receive SIV and 129 were assigned to receive placebo at visit one. Adverse events were most frequently reported as mild (grade 1) in nature. Among 142 BNT162b2 booster dose one and 43 BNT162b2 booster dose two recipients, the posterior median risk difference for moderate/severe adverse events following SIV versus placebo was 13% (95% credible interval [CrI] -0.03 to 0.27) and 13% (95%CrI -0.37 to 0.12), respectively. Among 18 mRNA1273 booster dose one and 35 mRNA1273 booster dose two recipients, the posterior median risk difference of moderate/severe adverse events following influenza vaccine versus placebo was 6% (95%CrI -0.29 to 0.41) and -4% (95%CrI -0.30 to 0.23), respectively.

CONCLUSION

Adverse events following SIV and COVID-19 co-administration were generally mild and occurred with similar frequency to events following COVID-19 vaccine alone. We found no evidence to justify routine separation of SIV and COVID-19 vaccine doses.

CLINICAL TRIAL REGISTRATION

ACTRN12621001063808.

Successful Use of Cefiderocol to Treat a Multidrug-resistant Stenotrophomonas maltophilia Ventilator-associated Pneumonia in an Extremely Preterm Neonate

BACKGROUND

Ventilator-associated pneumonia (VAP) caries a morbidity and mortality risk in the preterm neonate, particularly in the context of rising global antimicrobial resistance driving infections due to multidrug-resistant Gram-negative bacteria. Cefiderocol, a siderophilic cephalosporin, has broad Gram-negative antimicrobial activity and central nervous system penetration and is used for the treatment of hospital-acquired pneumonia or VAP in adults. Scarce data exists on its use in neonates.

CASE

A female neonate born at 26 + 6 weeks developed VAP at 21 days of life. She was commenced on corticosteroids, vancomycin and ceftazidime but continued to deteriorate. Sputum cultures yielded Stenotrophomonas maltophilia resistant to trimethoprim/sulfamethoxazole, ciprofloxacin and ceftazidime, with potential susceptibility to cefiderocol. Cerebrospinal fluid showed an elevated white cell count. In view of worsening respiratory and hemodynamic status, antibiotic treatment was changed to cefiderocol monotherapy at 30 mg/kg/dose every 8 hours. Within 72 hours of commencing cefiderocol, the neonate was successfully extubated to variable-flow continuous positive airway pressure and showed ongoing clinical improvement.

CONCLUSIONS

Cefiderocol was integral for the care of our neonate without any immediate adverse safety consequences. We relied on dosing data from a conference abstract, due to the paucity of evidence on the use of novel antimicrobials. This lack of evidence is particularly concerning given preterm neonates are particularly vulnerable to infections with multidrug-resistant Gram-negative organisms due to their immature immune systems, prolonged hospital stay, repeated interventions and antimicrobial exposure.

Core protocol for the adaptive Platform Trial In COVID-19 Vaccine priming and BOOsting (PICOBOO)

BACKGROUND

The need for coronavirus 2019 (COVID-19) vaccination in different age groups and populations is a subject of great uncertainty and an ongoing global debate. Critical knowledge gaps regarding COVID-19 vaccination include the duration of protection offered by different priming and booster vaccination regimens in different populations, including homologous or heterologous schedules; how vaccination impacts key elements of the immune system; how this is modified by prior or subsequent exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and future variants; and how immune responses correlate with protection against infection and disease, including antibodies and effector and T cell central memory.

METHODS

The Platform Trial In COVID-19 priming and BOOsting (PICOBOO) is a multi-site, multi-arm, Bayesian, adaptive, randomised controlled platform trial. PICOBOO will expeditiously generate and translate high-quality evidence of the immunogenicity, reactogenicity and cross-protection of different COVID-19 priming and booster vaccination strategies against SARS-CoV-2 and its variants/subvariants, specific to the Australian context. While the platform is designed to be vaccine agnostic, participants will be randomised to one of three vaccines at trial commencement, including Pfizer's Comirnaty, Moderna's Spikevax or Novavax's Nuvaxovid COVID-19 vaccine. The protocol structure specifying PICOBOO is modular and hierarchical. Here, we describe the Core Protocol, which outlines the trial processes applicable to all study participants included in the platform trial.

DISCUSSION

PICOBOO is the first adaptive platform trial evaluating different COVID-19 priming and booster vaccination strategies in Australia, and one of the few established internationally, that is designed to generate high-quality evidence to inform immunisation practice and policy. The modular, hierarchical protocol structure is intended to standardise outcomes, endpoints, data collection and other study processes for nested substudies included in the trial platform and to minimise duplication. It is anticipated that this flexible trial structure will enable investigators to respond with agility to new research questions as they arise, such as the utility of new vaccines (such as bivalent, or SARS-CoV-2 variant-specific vaccines) as they become available for use.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ACTRN12622000238774. Registered on 10 February 2022.

Predicting the causative pathogen among children with pneumonia using a causal Bayesian network

BACKGROUND

Pneumonia remains a leading cause of hospitalization and death among young children worldwide, and the diagnostic challenge of differentiating bacterial from non-bacterial pneumonia is the main driver of antibiotic use for treating pneumonia in children. Causal Bayesian networks (BNs) serve as powerful tools for this problem as they provide clear maps of probabilistic relationships between variables and produce results in an explainable way by incorporating both domain expert knowledge and numerical data.

METHODS

We used domain expert knowledge and data in combination and iteratively, to construct, parameterise and validate a causal BN to predict causative pathogens for childhood pneumonia. Expert knowledge elicitation occurred through a series of group workshops, surveys and one-on-one meetings involving 6-8 experts from diverse domain areas. The model performance was evaluated based on both quantitative metrics and qualitative expert validation. Sensitivity analyses were conducted to investigate how the target output is influenced by varying key assumptions of a particularly high degree of uncertainty around data or domain expert knowledge.

RESULTS

Designed to apply to a cohort of children with X-ray confirmed pneumonia who presented to a tertiary paediatric hospital in Australia, the resulting BN offers explainable and quantitative predictions on a range of variables of interest, including the diagnosis of bacterial pneumonia, detection of respiratory pathogens in the nasopharynx, and the clinical phenotype of a pneumonia episode. Satisfactory numeric performance has been achieved including an area under the receiver operating characteristic curve of 0.8 in predicting clinically-confirmed bacterial pneumonia with sensitivity 88% and specificity 66% given certain input scenarios (i.e., information that is available and entered into the model) and trade-off preferences (i.e., relative weightings of the consequences of false positive versus false negative predictions). We specifically highlight that a desirable model output threshold for practical use is very dependent upon different input scenarios and trade-off preferences. Three commonly encountered scenarios were presented to demonstrate the potential usefulness of the BN outputs in various clinical pictures.

CONCLUSIONS

To our knowledge, this is the first causal model developed to help determine the causative pathogen for paediatric pneumonia. We have shown how the method works and how it would help decision making on the use of antibiotics, providing insight into how computational model predictions may be translated to actionable decisions in practice. We discussed key next steps including external validation, adaptation and implementation. Our model framework and the methodological approach can be adapted beyond our context to broad respiratory infections and geographical and healthcare settings.

The impact of climate change and biodiversity loss on the health of children: An ethical perspective

The reality of human induced climate change is no longer in doubt, but the concerted global action required to address this existential crisis remains inexcusably inert. Together with climate change, biodiversity collapse is increasingly driving the emergence and spread of infectious diseases, the consequences of which are inequitable globally. Climate change is regressive in its nature, with those least responsible for destroying planetary health at greatest risk of suffering the direct and indirect health consequences. Over half a billion of the world's children live in areas vulnerable to extreme weather events. Without immediate action, the health of today's children and future generations will be compromised. We consider the impact of biodiversity collapse on the spread of infectious diseases and outline a duty of care along a continuum of three dimensions of medical ethics. From a medical perspective, the first dimension requires doctors to serve the best interests of their individual patients. The second dimension considers the public health dimension with a focus on disease control and cost-effectiveness. The neglected third dimension considers our mutual obligation to the future health and wellbeing of children and generations to come. Given the adverse impact of our ecological footprint on current and future human health, we have a collective moral obligation to act.

Urinary tract infections in children: building a causal model-based decision support tool for diagnosis with domain knowledge and prospective data

BACKGROUND

Diagnosing urinary tract infections (UTIs) in children in the emergency department (ED) is challenging due to the variable clinical presentations and difficulties in obtaining a urine sample free from contamination. Clinicians need to weigh a range of observations to make timely diagnostic and management decisions, a difficult task to achieve without support due to the complex interactions among relevant factors. Directed acyclic graphs (DAG) and causal Bayesian networks (BN) offer a way to explicitly outline the underlying disease, contamination and diagnostic processes, and to further make quantitative inference on the event of interest thus serving as a tool for decision support.

METHODS

We prospectively collected data on children present to ED with suspected UTIs. Through knowledge elicitation workshops and one-on-one meetings, a DAG was co-developed with clinical domain experts (the Expert DAG) to describe the causal relationships among variables relevant to paediatric UTIs. The Expert DAG was combined with prospective data and further domain knowledge to inform the development of an application-oriented BN (the Applied BN), designed to support the diagnosis of UTI. We assessed the performance of the Applied BN using quantitative and qualitative methods.

RESULTS

We summarised patient background, clinical and laboratory characteristics of 431 episodes of suspected UTIs enrolled from May 2019 to November 2020. The Expert DAG was presented with a narrative description, elucidating how infection, specimen contamination and management pathways causally interact to form the complex picture of paediatric UTIs. Parameterised using prospective data and expert-elicited parameters, the Applied BN achieved an excellent and stable performance in predicting Escherichia coli culture results, with a mean area under the receiver operating characteristic curve of 0.86 and a mean log loss of 0.48 based on 10-fold cross-validation. The BN predictions were reviewed via a validation workshop, and we illustrate how they can be presented for decision support using three hypothetical clinical scenarios.

CONCLUSION

Causal BNs created from both expert knowledge and data can integrate case-specific information to provide individual decision support during the diagnosis of paediatric UTIs in ED. The model aids the interpretation of culture results and the diagnosis of UTIs, promising the prospect of improved patient care and judicious use of antibiotics.

Successful treatment of invasive carbapenemase-producing Enterobacteriaceae infections in children using carbapenem-aminoglycoside combination therapy: A case series

Multidrug-resistant infections present a treatment challenge for pediatric clinicians and these infections have been associated with increased morbidity and mortality. There are very limited published data to support safe and effective treatment regimens for carbapenemase-producing Enterobacteriaceae (CPE) infections, particularly in children. We report the successful treatment of three children with invasive CPE infections using a combination of extended-infusion meropenem and amikacin.

The potential of fosfomycin for multi-drug resistant sepsis: an analysis of in vitro activity against invasive paediatric Gram-negative bacteria

PURPOSE

Antimicrobial resistance (AMR) is of increasing global concern, threatening to undermine recent progress in reducing child and neonatal mortality. Repurposing older antimicrobials is a prominent strategy to combat multidrug-resistant sepsis. A potential agent is fosfomycin, however, there is scarce data regarding its in vitro activity and pharmacokinetics in the paediatric population.

METHODOLOGY

We analysed a contemporary, systematically collected archive of community-acquired (CA) and hospital-acquired (HA) paediatric Gram-negative bacteraemia isolates for their susceptibility to fosfomcyin. MICs were determined using agar serial dilution methods and validated by disk diffusion testing where breakpoints are available. Disk diffusion antimicrobial susceptibility testing was also conducted for current empirical therapies (ampicillin, gentamicin, ceftriaxone) and amikacin (proposed in the literature as a new combination empirical therapeutic option).

RESULTS

Fosfomycin was highly active against invasive Gram-negative isolates, including 90  % (202/224) of Enterobacteriaceae and 96  % (22/23) of Pseudomonas spp. Fosfomycin showed high sensitivity against both CA isolates (94 %, 142/151) and HA isolates (81 %, 78/96; P =0.0015). CA isolates were significantly more likely to be susceptible to fosfomycin than the current first-line empirical therapy (96  % vs 59  %, P <0.0001). Extended spectrum β-lactamases (ESBL) production was detected in 34  % (85/247) of isolates with no significant difference in fosfomycin susceptibility between ESBL-positive or -negative isolates [73/85 (86  %) vs 147/162 (91  %) respectively, P =0.245]. All isolates were susceptible to a fosfomycin-amikacin combination.

CONCLUSION

Gram-negative paediatric bacteraemia isolates are highly susceptible to fosfomycin, which could be combined with aminoglycosides as a new, carbapenem-sparing regimen to achieve excellent coverage to treat antimicrobial-resistant neonatal and paediatric sepsis.

Guidelines for the treatment of dysentery (shigellosis): a systematic review of the evidence

BACKGROUND

Shigella remains the primary cause of diarrhoea in paediatric patients worldwide and accounts for up to 40,000 deaths per year. Current guidelines for the treatment of shigellosis are based on data which are over a decade old. In an era of increasing antimicrobial resistance, an updated review of the appropriate empirical therapy for shigellosis in children is necessary, taking into account susceptibility patterns, cost and the risk of adverse events.

METHODS

A systematic review of the current published literature on the treatment of shigella dysentery was undertaken in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

RESULTS

The initial search produced 131 results, of which nine studies met the inclusion criteria. The quality of the studies was assessed as per the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines. International guidelines were also reviewed. There is a lack of current research regarding the clinical treatment of shigellosis in paediatric and adult patients, despite rising antimicrobial resistance worldwide. In particular, there is a lack of studies assessing the non-susceptibility of community-acquired strains, with almost all published research pertaining to microbiological data from hospital-based settings.

DISCUSSION

Current WHO guidelines support the use of fluoroquinolones (first-line), β-lactams (second-line) and cephalosporins (second-line) which accords with currently available evidence and other international guidelines, and there is no strong evidence for changing this guidance. Azithromycin is appropriate as a second-line therapy in regions where the rate of non-susceptibility of ciprofloxacin is known to be high, and research suggests that, from a cardiac point of view, azithromycin is safer than other macrolide antibiotics. Cefixime is also a reasonable alternative, although its use must be weighed against the risk of dissemination of extended-spectrum β-lactamase-producing organisms.

Guidelines for the management of paediatric cholera infection: a systematic review of the evidence

Background Vibrio cholerae is a highly motile Gram-negative bacterium which is responsible for 3 million cases of diarrhoeal illness and up to 100,000 deaths per year, with an increasing burden documented over the past decade. Current WHO guidelines for the treatment of paediatric cholera infection (tetracycline 12.5 mg/kg four times daily for 3 days) are based on data which are over a decade old. In an era of increasing antimicrobial resistance, updated review of the appropriate empirical therapy for cholera infection in children (taking account of susceptibility patterns, cost and the risk of adverse events) is necessary. Methods A systematic review of the current published literature on the treatment of cholera infection in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was undertaken. International clinical guidelines and studies pertaining to adverse effects associated with treatments available for cholera infection were also reviewed. Results The initial search produced 256 results, of which eight studies met the inclusion criteria. Quality assessment of the studies was performed as per the Grading of Recommendations Assessment, Development and Evaluation guidelines. Conclusions In view of the changing non-susceptibility rates worldwide, empirical therapy for cholera infection in paediatric patients should be changed to single-dose azithromycin (20 mg/kg), a safe and effective medication with ease of administration. Erythromycin (12.5 mg/kg four times daily for 3 days) exhibits similar bacteriological and clinical success and should be listed as a second-line therapy. Fluid resuscitation remains the cornerstone of management of paediatric cholera infection, and prevention of infection by promoting access to clean water and sanitation is paramount.

Guidelines for the treatment of severe acute malnutrition: a systematic review of the evidence for antimicrobial therapy

Background Severe acute malnutrition (SAM) affects nearly 20 million children worldwide and is responsible for up to 1 million deaths per year in children under the age of 5 years. Current WHO guidelines recommend oral amoxicillin for children with uncomplicated malnutrition and parenteral benzylpenicillin and gentamicin for those with complicated malnutrition. Because of cost pressures and increasing antimicrobial resistance, the administration of empirical antibiotics for children with SAM has recently been debated. Methods A systematic review of the current published literature was undertaken to assess the efficacy, safety, cost-effectiveness and pharmacokinetics of antimicrobial treatment of children with SAM in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Results The initial search found 712 papers, eight of which met the inclusion criteria. Quality assessment of the studies was performed as per the Grading of Recommendations Assessment, Development and Evaluation guidelines. International guidelines and clinical data registries were also reviewed which identified inconsistencies in current first- and second-line therapies and dosing regimens. Conclusion Current evidence supports the continued use of broad-spectrum oral amoxicillin for treating children with uncomplicated SAM as outpatients. There is no strong evidence to justify changing the current parenteral therapy guidelines for children admitted with complicated SAM, although they should be clarified to harmonise the dosage regimen of amoxicillin for the treatment of SAM to 40 mg/kg twice daily, and to continue parenteral antimicrobials beyond 2 days if indicated by the clinical condition.

Antimicrobial resistance among children in sub-Saharan Africa

Antimicrobial resistance is an important threat to international health. Therapeutic guidelines for empirical treatment of common life-threatening infections depend on available information regarding microbial aetiology and antimicrobial susceptibility, but sub-Saharan Africa lacks diagnostic capacity and antimicrobial resistance surveillance. We systematically reviewed studies of antimicrobial resistance among children in sub-Saharan Africa since 2005. 18 of 1075 articles reviewed met inclusion criteria, providing data from 67 451 invasive bacterial isolates from inconsistently defined populations in predominantly urban tertiary settings. Among neonates, Gram-negative organisms were the predominant cause of early-onset neonatal sepsis, with a high prevalence of extended-spectrum β-lactamase-producing organisms. Gram-positive bacteria were responsible for a high proportion of infections among children beyond the neon atal period, with high reported prevalence of non-susceptibility to treatment advocated by the WHO therapeutic guidelines. There are few up-to-date or representative studies given the magnitude of the problem of antimicrobial resistance, especially regarding community-acquired infections. Research should focus on differentiating resistance in community-acquired versus hospital-acquired infections, implementation of standardised reporting systems, and pragmatic clinical trials to assess the efficacy of alternative treatment regimens.

Malaria prevention in Sub-Saharan Africa: a field study in rural Uganda

Malaria, a completely preventable and treatable disease, remains one of the biggest killers in Sub-Saharan Africa today. The objectives of this study were to describe the impact of malaria on a small rural community in Uganda (Bufuula) and to implement and evaluate a malaria prevention program (subsidised insecticide treated nets with an accompanying education session). In January 2006, a survey of 202 households (100% response rate) was conducted, and meetings held with the Village Council, which revealed that malaria was the community's major cause of morbidity and mortality, and showed there was a lack of access to preventative measures. Furthermore, 34% of each household's income was allocated to the burden of malaria. A malaria education and mosquito net distribution session was held in January 2006, which was attended by over 500 villagers who purchased 480 heavily-subsidised long lasting insecticide treated nets (LLINs). Home visits were conducted 1 week later to ensure the LLINs were hung correctly. A follow-up survey was conducted in January 2007. There was a rise in net ownership following the program (18% to 51%, P < 0.0001) and lower rates of childhood malaria prevalence (14%) than reported in Ugandan national statistics (40%). However, only half the nets owned were being used correctly by those most vulnerable to the illness. The findings suggest that mosquito nets must be provided with an effective education program and may be more successful if conducted in whole districts simultaneously rather than on a per-community basis. The evidence for super-targeting strategies for those most vulnerable is also considered. These findings provide important lessons and considerations for other wide-scale malaria prevention programs.