ABSTRACT: Defining RNA Transcriptional Biosignatures to Distinguish Febrile Infants 60 Days of Age and Younger with Bacterial vs Non-Bacterial Infections
Project description:The use of microbiological cultures for diagnosing bacterial infections in young febrile infants have substantial limitations, including false positive and false negative cultures, and non-ideal turn-around times. Analysis of host genomic expression patterns (âRNA biosignaturesâ) in response to the presence of specific pathogens, however, may provide an alternate and potentially improved diagnostic approach. This study was designed to define bacterial and non-bacterial RNA biosignatures to distinguish these infections in young febrile infants. A total of 279 febrile infants and 19 healthy afebrile control infants aged 0-6 months (for a total of 298 samples) for microarray analysis. For analytic purposes, we classified patients into two groups, those with bacterial infections (n=89) and those with non-bacterial infections (n=190). 144 of the samples were run on Illumina HT12 V4 R1 chips. Of these, there were 34 bacterial infections, 105 non-bacterial infections, and 5 healthy afebrile controls. 154 of the samples were run on Illumina HT12 V4 R2 chips. Of these, there were 55 bacterial infections, 85 non-bacterial infections, and 14 healthy afebrile controls.
Project description:The use of microbiological cultures for diagnosing bacterial infections in young febrile infants have substantial limitations, including false positive and false negative cultures, and non-ideal turn-around times. Analysis of host genomic expression patterns (“RNA biosignatures”) in response to the presence of specific pathogens, however, may provide an alternate and potentially improved diagnostic approach. This study was designed to define bacterial and non-bacterial RNA biosignatures to distinguish these infections in young febrile infants.
Project description:Viral infections are among the most common causes for fever without an apparent source (FWS) in young children; however, many febrile children are treated with antibiotics despite the absence of bacterial infection. Adenovirus, human herpesvirus 6 (HHV-6) and enterovirus are detected in children with FWS more often than other viral species. Virus and bacteria interact with pattern recognition receptors in circulating blood leukocytes and trigger specific host transcriptional programs that mediate immune response, and unique transcriptional signatures may be ascertained to discriminate between viral and bacterial causes for children with FWS. Microarray analyses were conducted on peripheral blood samples obtained from 51 pediatric patients with confirmed adenovirus, human herpesvirus 6 (HHV-6), enterovirus or bacterial infection. Whole blood transcriptional profiles could clearly distinguish febrile children from healthy controls, and febrile children with viral infections from afebrile children carrying the same virus. Molecular pathways regulating host immune response were the most affected in febrile children with infection. Pattern recognition programs were prominently activated in all febrile children with infection, while differential activation of transcriptional programs was observed among viral species. Interferon signaling pathway was uniquely activated in children with febrile viral infection, while a different set of pathways was uniquely activated in children with bacterial infection. Transcriptional signatures were identified and classified febrile children with viral or bacterial infection with 87% overall accuracy, an improvement from the current clinical practice of deducing from white blood cell (WBC) count status. Similar degree of accuracy was observed when we validated the signature probes on data sets from an independent study with different microarray platforms. The current study confirms the clinical utility of blood transcriptional analysis, suggests the composition of transcriptional signatures which can be used to ascertain the infectious etiology of febrile young children without an apparent source, thus limit the overuse of antibiotics on febrile children presenting with this common clinical complaint. Total RNA samples extracted from whole blood of young children were processed for hybridization onto Illumina Human-HT12 version 4 beadchips, and differential expression of the transcripts was analyzed between sick children with either viral or bacterial infection and healthy children.
Project description:Viral infections are among the most common causes for fever without an apparent source (FWS) in young children; however, many febrile children are treated with antibiotics despite the absence of bacterial infection. Adenovirus, human herpesvirus 6 (HHV-6) and enterovirus are detected in children with FWS more often than other viral species. Virus and bacteria interact with pattern recognition receptors in circulating blood leukocytes and trigger specific host transcriptional programs that mediate immune response, and unique transcriptional signatures may be ascertained to discriminate between viral and bacterial causes for children with FWS. Microarray analyses were conducted on peripheral blood samples obtained from 51 pediatric patients with confirmed adenovirus, human herpesvirus 6 (HHV-6), enterovirus or bacterial infection. Whole blood transcriptional profiles could clearly distinguish febrile children from healthy controls, and febrile children with viral infections from afebrile children carrying the same virus. Molecular pathways regulating host immune response were the most affected in febrile children with infection. Pattern recognition programs were prominently activated in all febrile children with infection, while differential activation of transcriptional programs was observed among viral species. Interferon signaling pathway was uniquely activated in children with febrile viral infection, while a different set of pathways was uniquely activated in children with bacterial infection. Transcriptional signatures were identified and classified febrile children with viral or bacterial infection with 87% overall accuracy, an improvement from the current clinical practice of deducing from white blood cell (WBC) count status. Similar degree of accuracy was observed when we validated the signature probes on data sets from an independent study with different microarray platforms. The current study confirms the clinical utility of blood transcriptional analysis, suggests the composition of transcriptional signatures which can be used to ascertain the infectious etiology of febrile young children without an apparent source, thus limit the overuse of antibiotics on febrile children presenting with this common clinical complaint.
Project description:DNA samples were derived from dried blood spots taken for newborn screening when infants were several days of age, after obtaining permission from the participants when they were aged 18 years, or from their parents if they were younger than 18 years.
Project description:RNA sequencing data from children with febrile illness and multisystem inflammatory syndrome in children (MIS-C). Samples used were Whole Blood. Febrile illness controls include children with bacterial and viral infections and healthy controls. This dataset contains samples from patients recruited into the DIAMONDS study.
Project description:Bacterial-derived immune training agents are a showing promise in clinical studies for prevention of lower respiatory infections in high-risk infants but underlying mechanisms of this protective effect are unclear. To address this, we employed a systems-level analysis of transcriptional responses to immune stimuli (LPS and PolyI:C) in infants who participated in a clinical trial of one such agent called OM85 which was clinically effective. We identified key protected innate immune changes using a series of analytical approaches such as reduced inflammatory responses to LPS and enhanced antibacterial interferon responses potentially mediated through IRF7. We posit that immune training agents exemplified by OM85 potentially protect against infant severe lower respiratory infection principally via effects on innate immune responses targeting the bacterial components of the mixed respiratory viral/bacterial infections which are characteristic of this age group.
Project description:Background: Non-malaria febrile illnesses such as bacterial bloodstream infections (BSI) are a leading cause of disease and mortality in the tropics. However, there are no reliable, simple diagnostic tests for identifying BSI or other severe non-malaria febrile illnesses. We hypothesized that different infectious agents responsible for severe febrile illness would impact on the host metabololome in different ways, and investigated the potential of plasma metabolites for diagnosis of non-malaria febrile illness. </p> Methodology: We conducted a comprehensive mass-spectrometry based metabolomics analysis of the plasma of 61 children with severe febrile illness from a malaria-endemic rural African setting. Metabolite features characteristic for non-malaria febrile illness, BSI, severe anemia and poor clinical outcome were identified by receiver operating curve analysis. </p> Principal Findings: The plasma metabolome profile of malaria and non-malaria patients revealed fundamental differences in host response, including a differential activation of the hypothalamic-pituitary-adrenal axis. A simple corticosteroid signature was a good classifier of severe malaria and non-malaria febrile patients (AUC 0.82, 95% CI: 0.70-0.93). Patients with BSI were characterized by upregulated plasma bile metabolites; a signature of two bile metabolites was estimated to have a sensitivity of 98.1% (95% CI: 80.2-100) and a specificity of 82.9% (95% CI: 54.7-99.9) to detect BSI in children younger than 5 years. This BSI signature demonstrates that host metabolites can have a superior diagnostic sensitivity compared to pathogen-detecting tests to identify infections characterized by low pathogen load such as BSI. </p> Conclusions: This study demonstrates the potential use of plasma metabolites to identify causality in children with severe febrile illness in malaria-endemic settings.
Project description:This project analyzes peripheral blood profiles of patients of age 90 or above and aims to detect profiles that distinguish them from younger controls.
Project description:Non-specific clinical presentation and lack of sensitive acute-phase diagnostic reagents hinder early recognitiion and manangement of systemic infections. To identify pathogen-specific features of the acute host response to infection we examined genome-wide patterns of whole blood gene expression in febrile patients with well-defined bacterial and viral infections (n=49), as well as health controls (n=12)