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Background Gram-negative organisms are common causes of bloodstream infection (BSI) during the neonatal period and early childhood. Whilst several large studies have characterised these isolates in adults, equivalent data (particularly incorporating whole genome sequencing) is lacking in the paediatric population. Methods We perform an epidemiological and sequencing based analysis of Gram-negative bloodstream infections (327 isolates (296 successfully sequenced) from 287 patients) in children Results Here we show that the burden of infection lies predominantly in neonates and that most infections are caused by Escherichia coli, Klebsiella spp. and Enterobacter hormaechei. There is no evidence in our setting that the proportion of antimicrobial resistant isolates is increasing in the paediatric population although we identify some evidence of sub-breakpoint increases in gentamicin resistance. The population structure of E. coli BSI isolates in neonates and children mirrors that in adults with a predominance of STs 131/95/73/69 and the same proportions of O-antigen serotypes. In most cases in our setting there is no evidence of transmission/point-source acquisition and we demonstrate the utility of whole genome sequencing to refute a previously suspected outbreak. Conclusions Our findings support continued use of current empirical treatment guidelines and suggest that O-antigen targeted vaccines may have a role in reducing the incidence of neonatal sepsis.

ObjectiveTo describe the impact of the SARS-CoV-2 pandemic on the incidence of paediatric viral respiratory tract infection in Oxfordshire, UK.MethodsData on paediatric Emergency Department (ED) attendances (0-15 years inclusive), respiratory virus testing, vital signs and mortality at Oxford University Hospitals were summarised using descriptive statistics.ResultsBetween 1-March-2016 and 30-July-2021, 155,056 ED attendances occurred and 7,195 respiratory virus PCRs were performed. Detection of all pathogens was suppressed during the first national lockdown. Rhinovirus and adenovirus rates increased when schools reopened September-December 2020, then fell, before rising in March-May 2021. The usual winter RSV peak did not occur in 2020/21, with an inter-seasonal rise (32/1,000 attendances in 0-3yr olds) in July 2021. Influenza remained suppressed throughout. A higher Paediatric Early Warning Score (PEWS) was seen for attendees with adenovirus during the pandemic compared to pre-pandemic (p=0.04, Mann-Witney U test), no other differences in PEWS were seen.ConclusionsSARS-CoV-2 caused major changes in the incidence of paediatric respiratory viral infection in Oxfordshire, with implications for clinical service demand, testing strategies, timing of palivizumab RSV prophylaxis, and highlighting the need to understand which public health interventions are most effective for preventing respiratory virus infections.

ObjectivesGram-negative organisms are common causes of bloodstream infection (BSI) during the neonatal period and early childhood. Whilst several large studies have characterised these isolates in adults, equivalent data (particularly incorporating whole genome sequencing) is lacking in the paediatric population.MethodsWe performed an epidemiological and sequencing based analysis of Gram-negative bloodstream infections in children Results327 isolates (296 successfully sequenced) from 287 patients were included. The burden of infection was predominantly in neonates (124/327[38%]). Most infections were caused by Escherichia coli (149/327[46%])/Klebsiella spp. (69/327[21%]) and Enterobacter hormaechei (34/327[10%]). There was no evidence of an increasing incidence of E. coli BSIs (IRRy 0.96, 95%CI 0.90-1.30, p=0.30) and for Klebsiella spp. there was some evidence that the incidence decreased slightly (IRRy 0.91, 95%CI 0.83-1.00, p=0.06). Similarly the proportion of antimicrobial resistant (across all antimicrobial classes evaluated) isolates did not change over time, though we did identify some evidence of sub-breakpoint increases in gentamicin resistance IRRy 1.86, 95%CI 1.33-2.58, pheterogeneity=0.002. The population structure of E. coli BSI isolates in neonates and children mirrors that in adults with a predominance of STs 131/95/73/69 and the same proportion of O-antigen serotypes covered by the ExPEC-4V vaccine. In most cases there was no evidence of transmission/point-source acquisition and whole genome sequencing was able to refute a previously suspected Serratia marcescens outbreak.ConclusionOur findings support continued use of current empirical treatment guidelines and suggest that O-antigen targeted vaccines may have a role in reducing the incidence of neonatal sepsis.

Exanthems/rashes are common in childhood and account for a large number of consultations in primary care and attendances to the emergency department. They are typically caused by allergic reactions, by viruses and occasionally by severe life-threatening bacterial infections. A careful history (including prodrome, associated symptoms, exposure to infectious contact, foreign travel, animals and immunization status), examination of the rash (including distribution, morphology, nature and site) and generalized examination (including presence of conjunctivitis, genital lesions, enanthems, hepatosplenomegaly and lymphadenopathy) can inform diagnosis. Molecular testing has led to a cause being identified in approximately 50% of cases. Early diagnosis is particularly important in the context of severe systemic infection, in immunocompromised hosts and in pregnancy. This review outlines the most common infectious exanthems, including measles, rubella, varicella, erythema infectiosum, roseola infantum and enterovirus infection.

We describe the youngest case to date of a 2 year old child who developed central skull base osteomyelitis (SBO) initially presenting with a fever, vomiting and sore throat. An extremely rare complication of mastoiditis following otitis media in children is SBO which can present with non-specific symptoms. This report describes the first case of symptomatic ischaemic stroke secondary to SBO in an immunocompetent child. We review the literature of the management and the potential cerebrovascular complications of central SBO in children secondary to otolaryngological infection.

Loss-of-function mutations in DOCK8 are linked to hyper-IgE syndrome. Patients typically present with recurrent sinopulmonary infections, severe cutaneous viral infections, food allergies and elevated serum IgE. Although patients may present with a spectrum of disease-related symptoms, molecular mechanisms explaining phenotypic variability in patients are poorly defined. Here we characterized a novel compound heterozygous mutation in DOCK8 in a patient diagnosed with primary combined immunodeficiency which was not typical of classical DOCK8 deficiency. In contrast to previously identified mutations in DOCK8 which result in complete loss of function, the newly identified single nucleotide insertion results in expression of a truncated DOCK8 protein. Functional evaluation of the truncated DOCK8 protein revealed its hypomorphic function. In addition we found somatic reversion of DOCK8 predominantly in T cells. The combination of somatic reversion and hypomorphic DOCK8 function explains the milder and atypical phenotype of the patient and further broadens the spectrum of DOCK8-associated disease., Highlights • Whole exome sequencing identified the underlying defect in a patient with combined immunodeficiency. • A novel compound heterozygous DOCK8 mutation was identified. • Expression of a truncated DOCK8 protein with hypomorphic function was identified. • Somatic reversion of DOCK8 mainly in T cells was identified. • DOCK8 deficiency may present without severe viral infections and increased serum IgE levels.

A 28-month-old infant presented with fever, vomiting and encephalopathy. Magnetic resonance imaging findings and family history confirmed a diagnosis of recurrent familial acute necrotizing encephalopathy (ANE1). We believe that this is the first description implicating the H1N1 viral strain as a trigger and the second report of a T653I mutation in the RANBP2 gene described in relation to ANE1.

The proinflammatory transcription factor nuclear factor-kappaB (NF-κB) plays a central role in host defence against pneumococcal disease. Both rare mutations and common polymorphisms in the NFKBIA gene encoding the NF-κB inhibitor IκB-α associate with susceptibility to bacterial disease, but the possible role of polymorphisms within the related IκB-ζ gene NFKBIZ in the development of invasive pneumococcal disease has not previously been reported. To investigate this further, we examined the frequencies of 22 single-nucleotide polymorphisms spanning NFKBIZ in two case-control studies, comprising UK Caucasian (n=1008) and Kenyan (n=723) individuals. Nine polymorphisms within a single UK linkage disequilibrium block and all four polymorphisms within the equivalent, shorter Kenyan linkage disequilibrium block displayed either significant association with invasive pneumococcal disease or a trend towards association. For each polymorphism, heterozygosity was associated with protection from invasive pneumococcal disease when compared to the combined homozygous states (e.g. for rs600718, Mantel-Haenszel 2×2 χ2=7.576, P=0.006, OR=0.67, 95% CI for OR: 0.51-0.88; for rs616597, Mantel-Haenszel 2×2 χ2=8.715, P=0.003, OR=0.65, 95% CI: 0.49-0.86). We conclude that multiple NFKBIZ polymorphisms associate with susceptibility to invasive pneumococcal disease in humans. The study of multiple populations may aid fine-mapping of associations within extensive regions of strong linkage disequilibrium (‘transethnic mapping’).

Summary Background Streptococcus pneumonias is a major cause of morbidity and mortality in developed and developing countries. No common genetic determinants of susceptibility have been defined. Mannose-binding lectin (MBL) is a key mediator of innate host immunity that activates the complement pathway and directly opsonises some infectious pathogens. Mutations in three codons in the MBL gene have been identified, and individuals homozygous for a mutant genotype have very little or no serum MBL. We did a case-control study in the UK to assess whether these mutant genotypes were associated with invasive pneumococcal disease. Methods The frequencies of genotypes defined by the three mutations in codons 52, 54, and 57, and a functional promoter polymorphism at -221, were compared in a two-stage study of 337 patients with invasive pneumococcal disease and 1032 controls. All individuals were recruited from an ethnically homogeneous white population in Oxfordshire, UK. Patients had S pneumoniae isolated from a normally sterile site. Findings In our initial set of participants, 28 (12%) of 229 patients and 18 (5%) of 353 controls were homozygotes for MBL codon variants (odds ratio 2·59 [95% Cl 1·39–4·83], p=0·002). Neither heterozygosity for these codon variants nor the promoter polymorphism was associated with susceptibility. In a confirmatory study, 11 (10%) of 108 patients were MBL homozygotes compared with 36 (5%) of 679 controls (p=0·046). Interpretation Homozygotes for MBL codon variants, who represent about 5% of north Europeans and north Americans and larger proportions of populations in many developing countries, could be at substantially increased risk of invasive pneumococcal disease.

To investigate a putative link between genetically determined variations in Toll-like receptor 2 (TLR2) and the occurrence of severe Staphylococcus aureus infection, the functional Arg753Gln single-nucleotide polymorphism and the GT repeat microsatellite in the TLR2 gene were examined in a large case-control study. No associations with disease or mortality attributable to these features were found.

Skull base osteomyelitis is a rare condition in childhood and can be described according to whether it is associated with spread of infection from the middle ear (otogenic) or not (nonotogenic). Early recognition of this serious disease and prompt treatment are key to preventing extension to adjacent vascular and nervous system structures. Diagnosis can be challenging due to the variable presentation of the disease and potentially subtle radiological appearances. We present 2 cases of nonotogenic skull base osteomyelitis in childhood both affecting the clivus and review the 6 cases previously described. Both children presented with fever, headache and neck stiffness and responded well to medical management alone; detailed imaging was key to making a diagnosis.