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IL-1R antagonist (IL-1Ra) is required for adequate host defense in invasive pneumococcal disease (IPD). The minor allele of an IL1RN gene (C/T) promoter polymorphism (rs4251961) has been shown to be associated with decreased IL-1Ra production in healthy adults. We genotyped 299 children with IPD, and examined 19 IL1RN haplotype-tagging single-nucleotide polymorphisms. Human embryonic kidney HEK293(T) cells were transfected with the promoter reporter plasmid pGL3p containing either allelic variant C (pGL3pCC) or T (pGL3pTT) with or without cotransfection with an expression construct overexpressing the globin transcription factor GATA-1. Plasma IL-1Ra concentrations were significantly higher in nonsurvivors compared with survivors (p < 0.0005), and the C allele of rs4251961 was associated with a significant increase in plasma IL-1Ra concentrations (p = 0.01) during the acute illness of IPD. These findings were validated in a cohort of 276 treatment-naive HIV-infected adults, with borderline significance (p = 0.058). Functional analyses demonstrated that the activity of the promoter constructs containing the T allele increased ~6-fold as compared with basal activity, and that containing the C allele by ~9-fold (p < 0.001) in the presence of GATA-1. Our findings suggest that the IL-1Ra single-nucleotide polymorphism rs4251961 plays a key role in the pathophysiology of IPD and in other human infections.

Streptococcus pneumoniae (the pneumococcus) is estimated to cause approximately 1 million deaths per year in children in the developing world.1 The pneumococcus is the primary cause of pneumonia and meningitis in children in the developing world1 and is the leading cause of community-acquired bacteremia in children in sub-Saharan Africa.2 The burden of invasive pneumococcal disease (IPD) has increased in areas with a high prevalence of HIV infection.3 In South Africa, the disease incidence in children younger than 2 years of age has been shown to be 73 per 100,000 children per year in HIV-uninfected children compared with 3036 per 100,000 children per year in HIV-infected children.4 Chemokines (or chemoattractant cytokines) are subdivided into 4 distinct subfamilies (CC, CXC, CX3C, and C) depending on the arrangement and number of the conserved N-terminal cysteine molecules. The CC chemokines (also called β chemokines) have the first 2 cysteine molecules adjacent, include regulated on activation normal T cells expressed and secreted (RANTES or CCL5), monocyte chemotactic protein-1 (MCP-1 or CCL2), macrophage inflammatory protein-1α (MIP-1α or CCL3) and MIP-1β (CCL4), and they preferentially attract monocytes and/or macrophages and eosinophils. The CXC chemokines (also called α chemokines) have the first 2 cysteine molecules separated by an amino acid, which includes interleukin (IL)-8 (or CXCL8), growth-related oncogene (GROα or CXCL1), and epithelial cell–derived neutrophil activating peptide (ENA-78 or CXCL5), and they preferentially attract neutrophils.5,6 Interferon-γ (IFNγ) has been demonstrated to modulate the release of chemokines in pneumococcal cell wall–stimulated mouse microglia differentially, supporting the view that activated microglia are a major intrinsic source of central nervous system (CNS) chemokine production and that IFNγ potentially regulates this microglial chemokine response pattern.7 Because chemokines are specific for particular cell types, the ratio and concentration of different chemokines in different body compartments determine the composition of the different cell types within the particular compartment. To understand the host response, IPD, more fully, it is important to gain insight into the production and regulation of chemokines at local sites of inflammation. The HIV coreceptor CCR5 also acts as a receptor for CCL3, CCL4, and CCL5, and receptor binding and CCR5-dependent inhibition of HIV infection are induced by CCL8.8 CCR2b, the receptor for CCL2 (and CCL7, CCL8, and CCL13) is also a coreceptor for HIV and is expressed on peripheral blood lymphocytes and monocytes and/or macrophages.9 In HIV infection, CC chemokines induce an inflammatory response attracting noninfected target cells to the site of active viral replication and also induce intracellular signaling that enhances viral replication.10 The aims of this study were to investigate the chemokine response to IPD in children with pneumonia and meningitis and to examine the influence of HIV infection on the chemokine response, pneumococcal bacterial loads, and outcome.

Of 176 invasive Streptococcus pneumoniae isolates from children in Malawi, common serotypes were 1 (23%), 6A/B (18%), 14 (6%), and 23F (6%). Coverage with the 7-valent pneumococcal conjugate vaccine (PCV) was 39%; PCV10 and PCV13 increased coverage to 66% and 88%, respectively. We found chloramphenicol resistance in 27% of isolates and penicillin nonsusceptibility in 10% (by using meningitis breakpoints); all were ceftriaxone susceptible.

Of 176 invasive Streptococcus pneumoniae isolates from children in Malawi, common serotypes were 1 (23%), 6A/B (18%), 14 (6%), and 23F (6%). Coverage with the 7-valent pneumococcal conjugate vaccine (PCV) was 39%; PCV10 and PCV13 increased coverage to 66% and 88%, respectively. We found chloramphenicol resistance in 27% of isolates and penicillin nonsusceptibility in 10% (by using meningitis breakpoints); all were ceftriaxone susceptible.

Background Accurate data on childhood pneumonia aetiology are essential especially from regions where mortality is high, in order to inform case-management guidelines and the potential of prevention strategies such as bacterial conjugate vaccines. Yield from blood culture is low, but lung aspirate culture provides a higher diagnostic yield. We aimed to determine if diagnostic yield could be increased further by polymerase chain reaction (PCR) detection of bacteria (Streptococcus pneumoniae and Haemophilus influenzae b) and viruses in lung aspirate fluid. Methods A total of 95 children with radiological focal, lobar or segmental consolidation had lung aspirate performed and sent for bacterial culture and for PCR for detection of bacteria, viruses and Pneumocystis jirovecii. In children with a pneumococcal aetiology, pneumococcal bacterial loads were calculated in blood and lung aspirate fluid. Results Blood culture identified a bacterial pathogen in only 8 patients (8%). With the addition of PCR on lung aspirate samples, causative pathogens (bacterial, viral, pneumocystis) were identified singly or as co-infections in 59 children (62%). The commonest bacterial organism was S.pneumoniae (41%), followed by H. influenzae b (6%), and the commonest virus identified was adenovirus (16%), followed by human bocavirus (HBoV) (4%), either as single or co-infection. Conclusions In a select group of African children, lung aspirate PCR significantly improves diagnostic yield. Our study confirms a major role of S.pneumoniae and viruses in the aetiology of childhood pneumonia in Africa.

Introduction Severe sepsis is a disease of the microcirculation, with endothelial dysfunction playing a key role in its pathogenesis and subsequent associated mortality. Angiogenesis in damaged small vessels may ameliorate this dysfunction. The aim of the study was to determine whether the angiogenic factors (vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), and angiopoietin-1 (Ang-1) and -2 (Ang-2)) are mortality indicators in Malawian children with severe bacterial infection. Methods In 293 children with severe bacterial infection, plasma VEGF, PDGF, FGF, and Ang-1 and Ang-2 were measured on admission; in 50 of the children with meningitis, VEGF, PDGF, and FGF were also measured in the CSF. Healthy controls comprised children from some of the villages of the index cases. Univariable and multivariable logistic regression analyses were performed to develop a prognostic model. Results The median age was 2.4 years, and the IQR, 0.7 to 6.0 years. There were 211 children with bacterial meningitis (72%) and 82 (28%) with pneumonia, and 154 (53%) children were HIV infected. Mean VEGF, PDGF, and FGF concentrations were higher in survivors than in nonsurvivors, but only PDGF remained significantly increased in multivariate analysis (P = 0.007). Mean Ang-1 was significantly increased, and Ang-2 was significantly decreased in survivors compared with nonsurvivors (6,000 versus 3,900 pg/ml, P = 0.03; and 7,700 versus 11,900 pg/ml, P = 0.02, respectively). With a logistic regression model and controlling for confounding factors, only female sex (OR, 3.95; 95% CI, 1.33 to 11.76) and low Ang-1 (OR, 0.23; 95% CI, 0.08 to 0.69) were significantly associated with mortality. In children with bacterial meningitis, mean CSF VEGF, PDGF, and FGF concentrations were higher than paired plasma concentrations, and mean CSF, VEGF, and FGF concentrations were higher in nonsurvivors than in survivors (P = 0.02 and 0.001, respectively). Conclusions Lower plasma VEGF, PDGF, FGF, and Ang-1 concentrations and higher Ang-2 concentrations are associated with an unfavorable outcome in children with severe bacterial infection. These angiogenic factors may be important in the endothelial dysregulation seen in severe bacterial infection, and they could be used as biomarkers for the early identification of patients at risk of a poor outcome.

Background Early recognition and prompt and appropriate antibiotic treatment can significantly reduce mortality from serious bacterial infections (SBI). The aim of this study was to evaluate the utility of five markers of infection: C-reactive protein (CRP), procalcitonin (PCT), soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), CD163 and high mobility group box-1 (HMGB1), as markers of SBI in severely ill Malawian children. Methodology and Principal Findings Children presenting with a signs of meningitis (n = 282) or pneumonia (n = 95), were prospectively recruited. Plasma samples were taken on admission for CRP, PCT, sTREM-1 CD163 and HMGB1 and the performance characteristics of each test to diagnose SBI and to predict mortality were determined. Of 377 children, 279 (74%) had SBI and 83 (22%) died. Plasma CRP, PCT, CD163 and HMGB1 and were higher in HIV-infected children than in HIV-uninfected children (p

Background Streptococcus pneumoniae (pneumococcus) is responsible for over one million deaths per year, with young children, the elderly and immunocompromised individuals being most at risk. Approximately half of East African children have been reported to be asymptomatic carriers of pneumococcus with invasive infection occurring after the disruption of the respiratory membrane which is believed to be caused by the host immune response. Racial incidence of invasive pneumococcal disease (IPD) is higher in certain populations even after adjusting for environmental factors suggesting a genetic component to disease susceptibility. The nitric oxide synthase 2A (NOS2A) gene is responsible for the production of nitric oxide under pathological conditions including host defence against bacterial infection. Nitric oxide is a modulator of apoptotic and inflammatory cascades and endothelial permeability. We hypothesised that genetic variants within this gene may predispose to disease risk and survival. Methods A cohort of 299 children with IPD (221 meningitis, 41 pneumonia and 37 with bacteraemia) and 931 age matched controls from Malawi were used in this study. We investigated nine haplotype tagging single nucleotide polymorphisms within the NOS2A gene and compared the presence or absence of the minor alleles in cases and controls and survivors and non-survivors within the cases. Results We observed no significant associations between cases and controls or with survival in either all IPD cases or in the separate analysis of meningitis cases. A near significant association was obtained for the comparison of rs8078340 in cases and controls (p-value, 0.078). However, results were unadjusted for multiple testing. Conclusion Our results suggest that polymorphic variation within the NOS2A gene does not influence invasive pneumococcal disease susceptibility or survival.

The pneumococcus is a major cause of meningitis and severe pneumonia in the developing world. The burden of invasive pneumococcal disease (IPD) has increased in areas with a high prevalence of HIV infection.1 In The Gambia (with a low HIV prevalence rate), the incidence of IPD has been estimated to be 240/100,000/yr in children less than 5 years and 554/100,000/yr in children less than 1 year of age.2 By contrast, in South Africa (with a high HIV prevalence rate) the incidence of IPD in children under 2 years was found to be 73/100,000/yr in HIV-uninfected children and 3036/100,000/yr in HIV-infected children.3 The increased susceptibility of HIV-infected children to IPD is predominantly because of their increased susceptibility to disease caused by pediatric serotypes (serotypes 6, 9, 14, 19, 23). Tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), IL-6, IL-8, macrophage inflammatory protein-1α, monocyte chemoattractant protein-1 and nitric oxide have been shown to be elevated in murine models of pneumococcal pneumonia.4–6 IL-10 appears to down-regulate pathophysiologic changes in pneumococcal meningitis and this may be mediated by interfering with the production of reactive nitrogen intermediates.7 It is now recognized that the net biologic response of pro- and antiinflammatory cytokines may affect the outcome of certain inflammatory diseases.8 An improved understanding of the critical mediators in the host response to IPD is an important step in developing new therapeutic strategies. In children with bacteremia owing to Haemophilus influenzae or Streptococcus pneumoniae, high bacterial counts (greater than 100 organisms per milliliter of blood), at presentation, based on quantitative blood culture methods, were shown to be highly predictive of the development of serious invasive disease, such as epiglottitis or meningitis.9 This was confirmed in another study which demonstrated that the magnitude of bacteremia correlated with the severity of infection.10 Patients with H. influenzae meningitis with greater than or equal to 107 colony forming units of H. influenzae type b per milliliter of CSF had a significantly greater frequency of neurologic sequelae.11 In children the magnitude of bacteremia is usually higher than that in adults, the level of bacteremia being inversely correlated with the patients age.12 We used a modification of a multiplex real-time PCR assay13 to detect and quantify pneumococcal DNA in blood, CSF and lung aspirate samples, and to determine the relationship between bacterial loads, cytokine concentrations, disease presentation and outcome.

In a malaria-endemic area of Africa, rabies was an important cause of fatal central nervous system infection, responsible for 14 (10.5%) of 133 cases. Four patients had unusual clinical manifestations, and rabies was only diagnosed postmortem. Three (11.5%) of 26 fatal cases originally attributed to cerebral malaria were due to rabies.