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Background RSV remains a leading cause for hospitalization of infants. The mechanisms associated with the ability of RSV to suppress the induction of an adequate immune response are not well understood and represent a challenge for vaccine development. Myeloid-derived-suppressor cells (MDSCs) have been shown to suppress CD8+ T cells in patients with malignancies. These immature myeloid cells are divided into three groups: granulocytic, monocytic, and undifferentiated. Of those, monocytic MDSCs (M-MDSCs) are considered to be key regulators of inflammatory responses during acute infections. Their potential role in the immunopathogenesis of RSV infection in infants is yet to be defined. Methods Single-center, prospective cohort study in previously healthy infants hospitalized with severe RSV lower respiratory tract infection (LRTI) and age-matched healthy controls (HC). Nasopharyngeal swabs for RSV detection and blood samples for cell immunophenotyping were analyzed at enrollment (D1), 1-month (D30), and 6-months (D180) follow-up visits. Disease severity was assessed using a clinical disease severity score (CDSS), duration of supplemental O2, and duration of hospitalization. Results We enrolled 39 infants with RSV LRTI (median [IQR] age: 3.3 [1.5–5.2] months) and 5 HC (5.9 [4.5–7.2] months). Infants with RSV infection demonstrated an expansion of M-MDSCs during the acute infection (D1) that resolved to numbers comparable to those in HC at follow-up visits (Figure 1A). In addition, numbers of CD8+ T cells were significantly reduced during the acute infection (D1) in RSV-infected infants, but also returned to the HC baseline on D30 and D180 (Figure 1B). Finally, the increase in M-MDSCs numbers and decrease in CD8+ T-cell numbers were associated with worse clinical outcomes as defined by duration of supplemental oxygen (>1 day), hospitalization (>48 hours), and clinical disease severity score (CDSS, > 9) (Figure 2). Conclusion These findings suggest that an expansion of M-MDSCs may play a role in T-cell suppression in children with severe RSV disease. As new vaccines are being developed, it is critical to elucidate the immune suppressive mechanisms associated with RSV infection. Disclosures Octavio Ramilo, MD, Bill & Melinda Gates Foundation: Research Grant; Janssen: Research Grant; Merck: Advisory Board; NIH: Research Grant; Ohio Children’s Hospital Association (OCHA): Research Grant; Pfizer: Advisory Board, Consultant, Lectures; Sanofi/Medimmune: Advisory Board.

Summary Bronchiolitis is the leading cause of hospitalization of infants and young children worldwide. Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis in infants. Studies conducted using molecular diagnostic assays confirmed that RSV accounts for over 50% of bronchiolitis in young children requiring hospitalization. Those studies demonstrate that it is common to identify RSV in association with a second viral agent but it is yet unclear whether the simultaneous detection of two or even three viruses is associated with increased disease severity. Despite extensive efforts, a vaccine for prevention of RSV infection is not yet available. Palivizumab a humanized monoclonal antibody directed against the F protein of RSV is the only agent licensed to prevent severe RSV disease in high-risk children. Among the new antivirals being developed for treatment of RSV infections, an RNA-interference based agent has demonstrated promising results for treatment of lung transplant recipients with acute RSV infection.

Summary Blood represents a reservoir and a migration compartment of cells of the immune system. Traditional microbiologic diagnostic tests relied on laboratory identification of the pathogen causing the infection. However, this approach is less than optimal for a variety of reasons: pathogen's slow growth, resistance to cultivation in vitro or insufficient proof to establish causality when a pathogen is identified. An alternative approach to the pathogen-detection strategy is based on a comprehensive analysis of the host response to the infection by analysis of blood leukocytes gene expression profiles. This strategy has been successfully applied to distinguish and classify children and adults with acute infections caused by different pathogens. Molecular distance to health (MDTH) is a genomic score that measures the global transcriptional perturbation in each individual patient compared to healthy controls. Studies indicate that MDTH is a promising biomarker to help classifying patients according to clinical severity.

Resumen: La infección por Staphylococcus aureus resistente a meticilina asociado a la comunidad (SARM-AC) es un problema creciente en nuestro país. La daptomicina es un antibiótico bactericida con actividad frente al SARM-AC. Presentamos a 3 pacientes pediátricos con SARM-AC diseminado que recibieron daptomicina a dosis altas, con buena respuesta microbiológica y clínica. Abstract: Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are an increasing problem in our country. Daptomycin is a bactericidal antibiotic with activity against CA-MRSA. Experience using high-dose daptomycin is reviewed in three paediatric patients with severe-disseminated CA-MRSA infection with a favourable microbiological and clinical response.

Respiratory syncytial virus (RSV) remains a significant cause of morbidity and mortality in infants and young children, immunocompromised patients and the elderly. Despite the high disease burden, an effective and safe vaccine is lacking, although several candidates are currently in development. Current treatment for RSV infection remains largely supportive and RSV-specific options for prophylaxis are limited to palivizumab. In the past few years, novel therapeutic options including nanobodies, polyclonal and monoclonal antibodies have emerged and there are several products in preclinical and Phase-I, -II or -III clinical trials. The major target for antiviral drug development is the surface fusion (F) glycoprotein, which is crucial for the infectivity and pathogenesis of the virus. Solving the structures of the two conformations of the RSV F protein, the prefusion and postfusion forms, has revolutionized RSV research. It is now known that prefusion F is highly superior in inducing neutralizing antibodies. In this section we will review the stages of development and availability of different antibodies directed against RSV for the prevention and also for treatment of acute RSV infections. Some of these newer anti-RSV agents have shown enhanced potency, are being explored through alternative routes of administration, have improved pharmacokinetic profiles with an extended half-life, and may reduce design and manufacturing costs. Management strategies will require targeting not only high-risk populations (including adults or immunocompromised patients), but also previously healthy children who, in fact, represent the majority of children hospitalized with RSV infection. Following treated patients longitudinally is essential for determining the impact of these strategies on the acute disease as well as their possible long-term benefits on lung morbidity.

SUMMARYThe impact of human metapneumovirus (HMPV) in children aged >5 years and the risk factors associated with disease severity for all ages have not been well characterized. A retrospective cohort study of 238 children aged 0–15 years hospitalized over a 3-year period was performed. Medical records were reviewed for demographic information, clinical parameters and outcomes. Multivariable analyses were performed to identify independent factors associated with worse disease severity assessed by length of hospital stay (LOS), need for ICU care, respiratory support, and a disease severity score. Pulmonary diseases were associated with all outcomes of care, while congenital heart disease (CHD) and neuromuscular disorders were associated with longer LOS, and CHD and trisomy 21 were associated with worse severity scores independent of other covariables. Fever, retractions, use of steroids and albuterol were also associated with enhanced disease severity. Understanding the determinants of HMPV disease in children may help design targeted preventive strategies.

Respiratory viral infections in episodes of fever and neutropenia (FN) in children with cancer are not well characterized. We compared the clinical outcome of infections caused by different respiratory viruses (RVs) and by RV coinfection in this population.Children with cancer and FN at 3 hospitals in Chile were prospectively evaluated by clinical examination, blood cultures and detection of 17 RVs using multiplex polymerase chain reaction (nasopharyngeal samples). Clinical characterization and outcome variables were determined and compared by the type of RV detected.A total of 1044 episodes of FN in 525 children were included. At least 1 RV was detected in 46%. In 350 of 1044 (34%) episodes, we detected only RVs, of which 284 (81%) were classified as a single-RV infection and 66 (19%) as a viral coinfection. Respiratory symptoms were present at admission in 65% of the episodes with any detected RV. Median age was 6 years (interquartile range, 3-10), and 51% were women. The most common RVs detected were rhinovirus, respiratory syncytial virus, parainfluenza, influenza, adenovirus and human metapneumovirus. Episodes caused by different types of RVs had no differences in the clinical outcome (days of hospitalization, days of fever, O2 requirement, admission to the intensive care unit and death) and when comparing single and viral coinfection.To our knowledge, this is the largest report comparing clinical outcome in FN episodes caused by different RVs in children with cancer. A positive polymerase chain reaction for RV at admission was significantly associated with the presence of respiratory symptoms. Our data showed a favorable outcome in all episodes with RV detection, including single and viral coinfections.

Work in humans and mice highlights the role of tryptophan metabolism in the immunopathogenesis of typhoid fever, offering novel insight into clinical disease., Enteric fever, caused by Salmonella enterica serovar Typhi, is an important public health problem in resource-limited settings and, despite decades of research, human responses to the infection are poorly understood. In 41 healthy adults experimentally infected with wild-type S. Typhi, we detected significant cytokine responses within 12 h of bacterial ingestion. These early responses did not correlate with subsequent clinical disease outcomes and likely indicate initial host–pathogen interactions in the gut mucosa. In participants developing enteric fever after oral infection, marked transcriptional and cytokine responses during acute disease reflected dominant type I/II interferon signatures, which were significantly associated with bacteremia. Using a murine and macrophage infection model, we validated the pivotal role of this response in the expression of proteins of the host tryptophan metabolism during Salmonella infection. Corresponding alterations in tryptophan catabolites with immunomodulatory properties in serum of participants with typhoid fever confirmed the activity of this pathway, and implicate a central role of host tryptophan metabolism in the pathogenesis of typhoid fever.

BACKGROUND Human adenovirus (HAdV), especially species C (HAdV-C), can be detected incidentally by polymerase chain reaction in nasopharyngeal (NP) samples, making it difficult to interpret clinical significance of a positive result. We classified patients into groups based on HAdV culture positivity from respiratory specimens and the presence of an identified co-pathogen. We hypothesized that HAdV-C would be over-represented and viral burden would be lower in patients most likely to have incidental detection (ie, with a negative viral culture and documented co-pathogen). METHODS Immunocompetent children with HAdV + nasopharyngeal specimens were classified into 4 groups: group I (HAdV culture (+) and no co-infection), group II (culture (+) and co-infection), group III (culture (-) and no co-infection) and group IV (culture (-) and co-infection). Viral burden (cycle threshold) and species were compared among groups. RESULTS Of 483 nasopharyngeal specimens, HAdV was isolated in culture in 252 (52%); co-infection was found in 265 (55%) patients. Group I (most consistent with acute disease) had significantly lower cycle thresholds (median 23.9; interquarile range 22.2-28.1) compared with group IV (most consistent with incidental detection; median 37.3; interquarile range 35.3-38.9; P < 0.0001). HAdV-C accounted for 41% samples of group I and 83% of group IV (P < 0.0001). We identified a subset of 22 patients with bacterial or fungal co-pathogens, 18 of whom had no growth on viral culture (group IV) with a median cycle threshold of 37.4 (interquarile range 33.9-39.2). CONCLUSIONS Species identification and viral burden may assist in interpretation of a positive HAdV result. Low viral burden with HAdV-C may be consistent with incidental detection.

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection (LRTI) in young children worldwide and an increasingly recognized cause of death in developing countries [1, 2]. Despite that selected groups of infants have increased risk for severe disease and mortality, the majority of children hospitalized with RSV LRTI are previously healthy with no known risk factors for severe disease [3, 4]. Of those hospitalized infants, 10%–20% will develop a disease severe enough to require admission to the pediatric intensive care unit (PICU) [5, 6]. It has been proposed that the combination of both viral factors and the host immune response probably contribute to the severity of RSV disease [7–11]. The importance of the innate immune response in the pathogenesis of severe RSV disease is being increasingly recognized. To date, however, studies addressing the role of innate immunity cytokines on RSV disease severity have been focused on determining concentrations of blood and respiratory cytokines, with inconsistent results [10–13]. Studies in critically ill patients with bacterial sepsis suggest that innate immune hyporesponsiveness, defined by decreased whole blood tumor necrosis factor α (TNF-α) production after ex vivo lipopolysaccharide (LPS) stimulation, is associated with worse clinical outcomes [14, 15]. Whether the functional capacity of the innate immune response is impaired in children with severe RSV disease, and how it correlates with plasma concentrations of innate immunity cytokines has not been characterized. The overall aims of this study were to determine whether patients with severe RSV bronchiolitis admitted to the PICU had decreased whole blood functional innate immune responses and to evaluate the relationships between innate immune dysfunction and disease outcomes.

Background. Human adenovirus (HAdV) infection mimics Kawasaki disease (KD) but can also be detected in KD patients. Evidence suggests that HAdV-C species can persist in pediatric adenoids and/or tonsils. We sought to determine (1) the frequency of HAdV detection by real-time polymerase chain reaction in KD patients, (2) the differences in HAdV semiquantitative nasopharyngeal viral loads between KD patients with detectable HAdV vs those with HAdV disease, and (3) whether nasopharyngeal HAdV-C shedding is occurring in KD. Methods. From August 2009 through April 2011, HAdV-positive patients were identified in 1 of the following groups: group I, complete or incomplete KD as defined by the American Heart Association (AHA); group II, treated for incomplete KD but not fulfilling AHA criteria; and group III, otherwise healthy children with some KD-like features ultimately diagnosed with HAdV disease. Results. Among 77 KD patients diagnosed, 8.8% (5/57) of group I and 25% (5/20) of group II KD patients had HAdV detected. Viral loads were significantly lower in group I (n = 5) vs group III (n = 26; P = .034). Of the 13 specimens available for HAdV typing, 7 of 7 group III and 1 of 3 group II specimens were determined to be HAdV-B using viral culture. The remaining 5 KD samples were unable to be cultured and molecular typing showed either HAdV-C (n = 3) or were nontypeable (n = 2). Conclusions. In KD, molecular-based HAdV detection is not uncommon, may represent persistence of HAdV-C, and should be interpreted with caution. Together, quantitative polymerase chain reaction and HAdV typing may aid in distinguishing HAdV disease mimicking KD from KD with concomitant HAdV detection.

Airway epithelial cells (AECs) provide the first line of defense in the respiratory tract and are the main target of respiratory viruses. Here, using oligonucleotide and protein arrays, we analyze the infection of primary polarized human AEC cultures with influenza virus and respiratory syncytial virus (RSV), and we show that the immune response of AECs is quantitatively and qualitatively virus specific. Differentially expressed genes (DEGs) specifically induced by influenza virus and not by RSV included those encoding interferon B1 (IFN-B1), type III interferons (interleukin 28A [IL-28A], IL-28B, and IL-29), interleukins (IL-6, IL-1A, IL-1B, IL-23A, IL-17C, and IL-32), and chemokines (CCL2, CCL8, and CXCL5). Lack of type I interferon or STAT1 signaling decreased the expression and secretion of cytokines and chemokines by the airway epithelium. We also observed strong basolateral polarization of the secretion of cytokines and chemokines by human and murine AECs during infection. Importantly, the antiviral response of human AECs to influenza virus or to RSV correlated with the infection signature obtained from peripheral blood mononuclear cells (PBMCs) isolated from patients with acute influenza or RSV bronchiolitis, respectively. IFI27 (also known as ISG12) was identified as a biomarker of respiratory virus infection in both AECs and PBMCs. In addition, the extent of the transcriptional perturbation in PBMCs correlated with the clinical disease severity. Our results demonstrate that the human airway epithelium mounts virus-specific immune responses that are likely to determine the subsequent systemic immune responses and suggest that the absence of epithelial immune mediators after RSV infection may contribute to explaining the inadequacy of systemic immunity to the virus.

Influenza A virus (IAV) and influenza B virus (IBV) cause substantial morbidity and mortality during annual epidemics. Two distinct lineages of IBV are distinguished, based on variation in hemagglutinin (HA): B/Victoria/2/87-like (B/Vic) and B/Yamagata/16/88-like (B/Yam). Here, we show that, in humans, primary IBV infection with either lineage induces HA-specific antibody-dependent cellular cytotoxicity (ADCC)-mediating antibodies. IBV infection induced antibodies specific to the HA head and stalk, but only HA stalk-specific antibodies mediated ADCC efficiently and displayed cross-reactivity with IBV of both lineages. This corresponds to recent findings that 2 points of contact between the effector and target cell (ie, HA and sialic acid, respectively, and the fragment crystallizable [Fc] domain and Fcγ receptor IIIα, respectively) are required for efficient ADCC activity and that antibodies specific for the receptor-binding site located in the head domain of HA therefore fail to mediate ADCC. Potentially, ADCC-mediating antibodies directed to the HA stalk of IBV contribute to cross-protective immunity to IBV of both lineages.

Background Almost all children are infected with RSV by 2 yrs of age, yet

Infections in infants continue to be an important cause of morbidity and mortality worldwide. Understanding the immune mechanisms that operate in infants is necessary for the development of new approaches to improve the health of infants around the world.

Objective To determine the risk of serious bacterial infections (SBIs) in young febrile infants with and without viral infections. Study design Planned secondary analyses of a prospective observational study of febrile infants 60 days of age or younger evaluated at 1 of 26 emergency departments who did not have clinical sepsis or an identifiable site of bacterial infection. We compared patient demographics, clinical, and laboratory findings, and prevalence of SBIs between virus-positive and virus-negative infants. Results Of the 4778 enrolled infants, 2945 (61.6%) had viral testing performed, of whom 1200 (48.1%) were virus positive; 44 of the 1200 had SBIs (3.7%; 95% CI, 2.7%-4.9%). Of the 1745 virus-negative infants, 222 had SBIs (12.7%; 95% CI, 11.2%-14.4%). Rates of specific SBIs in the virus-positive group vs the virus-negative group were: UTIs (33 of 1200 [2.8%; 95% CI, 1.9%-3.8%] vs 186 of 1745 [10.7%; 95% CI, 9.2%-12.2%]) and bacteremia (9 of 1199 [0.8%; 95% CI, 0.3%-1.4%] vs 50 of 1743 [2.9%; 95% CI, 2.1%-3.8%]). The rate of bacterial meningitis tended to be lower in the virus-positive group (0.4%) than in the viral-negative group (0.8%); the difference was not statistically significant. Negative viral status (aOR, 3.2; 95% CI, 2.3-4.6), was significantly associated with SBI in multivariable analysis. Conclusions Febrile infants ≤60 days of age with viral infections are at significantly lower, but non-negligible risk for SBIs, including bacteremia and bacterial meningitis.

Background Macrolide-resistant Mycoplasma pneumoniae (MRMp) has emerged in the last 2 decades, with rates as high as 93% in Asia. Rates in the United Stated vary from 3.5 to 13.2%. By sequencing we identified our local resistance rate of 1.8% (9/477) in isolates collected from October 2015 to December 2017. Previous reports described increased morbidity in patients with MRMp. We evaluated the clinical characteristics of children infected with MRMp in Central Ohio. Methods Of the 9 MRMp isolates identified, clinical data were available in 7 cases. We performed a case–control (1:3) analysis, where Mp patients were matched by month and year of presentation. Retrospective analysis of electronic health records (HER) was performed to identify clinical and treatment characteristics. Continuous variables are shown as medians and inter-quartile ranges (IQR), and categorical variables as percentages. For comparisons T, Mann–Whitney U, and Fisher’s exact tests were used as appropriate. Results Both groups had similar demographics with no differences in age and gender. Median age (IQR) was 8.5 years (6–17) for the MRMp and 8 (IQR 3.5–11.5) for the Macrolide-susceptible Mp (MSMp). Duration of symptoms at presentation was similar, median (IQR) of 11 (4–14) days for MRMp, and 8 (6.25–13.25) days for MSMp (P = 0.7). All patients with MRMp had fever compared with 17 (81%) of the MSMp (P = 0.07). Tmax was similar in both groups (P = 0.11). All patients (100%) had cough. There were no differences in the frequency of oxygen requirement, fatigue, shortness of breath, sore throat, nasal congestion, rash, headache and chest radiographic findings. There were similar rates of hospitalization with 4 (57%) in the MRMp and 8 (38%) in the MSMp (P = 0.42). Among hospitalized children, there were no differences in duration hospitalization, median (IQR) 6 (1.25–21.25) days for MRMp and 2 (1–2.75) for MSMp (P = 0.31). None required invasive ventilation. One MRMp patient had encephalitis; this was the only patient requiring intensive care compared with none MSMp (P = 0.25). All patients were initially treated with azithromycin, but 2 (12%) of the MRMp were switched to levofloxacin (P = 0.06). Conclusion We did not identify significant differences in clinical characteristics between patients with MRMp and MSMp. This could be related to our low local rate of MRMp. Disclosures O. Ramilo, Janssen Scientific Affairs, LLC: Consultant, Consulting fee. Sanofi: Scientific Advisor, Consulting fee. Merck: Scientific Advisor, Consulting fee and Speaker honorarium. Janssen: Grant Investigator and Scientific Advisor, Consulting fee, Grant recipient and Speaker honorarium. Pfizer: Consultant, Consulting fee and Speaker honorarium. A. Leber, Nationwide Children’s Hospital: Research Contractor, Research support.

Tuberculosis (TB), caused by infection with Mycobacterium tuberculosis, is a major cause of morbidity and mortality worldwide. Efforts to control it are hampered by difficulties with diagnosis, prevention and treatment. Most people infected with M. tuberculosis remain asymptomatic, termed latent TB, with a 10% lifetime risk of developing active TB disease. Current tests, however, cannot identify which individuals will develop disease. The immune response to M. tuberculosis is complex and incompletely characterized, hindering development of new diagnostics, therapies and vaccines. Here we identify a whole-blood 393 transcript signature for active TB in intermediate and high-burden settings, correlating with radiological extent of disease and reverting to that of healthy controls after treatment. A subset of patients with latent TB had signatures similar to those in patients with active TB. We also identify a specific 86-transcript signature that discriminates active TB from other inflammatory and infectious diseases. Modular and pathway analysis revealed that the TB signature was dominated by a neutrophil-driven interferon (IFN)-inducible gene profile, consisting of both IFN-gamma and type I IFN-alphabeta signalling. Comparison with transcriptional signatures in purified cells and flow cytometric analysis suggest that this TB signature reflects changes in cellular composition and altered gene expression. Although an IFN-inducible signature was also observed in whole blood of patients with systemic lupus erythematosus (SLE), their complete modular signature differed from TB, with increased abundance of plasma cell transcripts. Our studies demonstrate a hitherto underappreciated role of type I IFN-alphabeta signalling in the pathogenesis of TB, which has implications for vaccine and therapeutic development. Our study also provides a broad range of transcriptional biomarkers with potential as diagnostic and prognostic tools to combat the TB epidemic.

Background: Community-acquired pneumonia (CAP), a leading cause of mortality, mainly affects children in developing countries. The harsh circumstances experienced by refugees include various factors associated with respiratory pathogen transmission, and clinical progression of CAP. Consequently, the etiology of CAP in humanitarian crisis situations may differ to that of settled populations, which would impact appropriate case management. Therefore, the Pneumonia Etiology Among Refugees and the Lebanese population (PEARL) study was initiated with the objective of identifying the causal pathogenic microorganisms in the respiratory tract of children and adults from both the refugee and host country population presenting with signs of CAP during a humanitarian crisis. Methods: PEARL, a prospective, multicentric, case-control study, will be conducted at four primary healthcare facilities in Tripoli and the Bekaa valley over 15 months (including two high-transmission seasons/winters). Sociodemographic and medical data, and biological samples will be collected from at least 600 CAP cases and 600 controls. Nasopharyngeal swabs, sputum, urine and blood samples will be analyzed at five clinical pathology laboratories in Lebanon to identify the bacterial and viral etiological agents of CAP. Transcriptomic profiling of host leukocytes will be performed. Conclusions: PEARL is an original observational study that will provide important new information on the etiology of pneumonia among refugees, which may improve case management, help design antimicrobial stewardship interventions, and reduce morbidity and mortality due to CAP in a humanitarian crisis.

Oseltamivir, an orally bioavailable neuraminidase inhibitor, is licensed in the United States for treatment and chemoprophylaxis of influenza in children ≥1 year of age.1 Another neuraminidase inhibitor, zanamivir, also is licensed for use in children ≥7 years of age for treatment and ≥5 years of age for chemoprophylaxis.1 It is delivered via an inhaler device that is difficult for younger children to use. In a prospective, randomized, blinded, placebo-controlled study in influenza-infected children 1 to 12 years of age, a 5-day treatment course of oseltamivir was associated with a median reduction in overall clinical illness of 36 hours and a reduction in fever of 25 hours.2 Additionally, the incidence of acute otitis media was reduced by 44% compared with placebo recipients. A significant decrease in viral shedding was also noted in treated children, with few treated children still shedding virus on day 4 of therapy. The most common adverse drug effect was vomiting (14% of oseltamivir-treated subjects vs. 8% of placebo recipients).2 The safety of oseltamivir therapy in infants younger than 12 months of age is a potential concern. The oseltamivir package insert states that use of oseltamivir in this age group is not indicated,3 based on preclinical findings in juvenile rats.4 A single 1000 mg/kg dose of oseltamivir (about 250 times the recommended dose in children) in 7-day-old rats resulted in excess deaths in association with unusually high exposure to both the active metabolite of oseltamivir and the prodrug. Concentrations of the prodrug in juveniles were approximately 1500 times greater than those seen in adult animals, suggesting that these adverse outcomes may be related to an immature blood-brain barrier or to immaturity of conversion of prodrug to active metabolite in juvenile animals. While the applicability of these rat studies to human infants is questionable due to significant differences in oseltamivir metabolism between the 2 species and the extremely high doses employed in the animal trials, caution is warranted until appropriate pediatric studies can be conducted. Reassuringly, a retrospective study of infants younger than 1 year of age in Japan did not find an association between use of oseltamivir and either mortality or encephalopathy.5 Despite the wording of the package insert, off-label use of oseltamivir in infants less than 12 months of age occurs in the United States, particularly in infants who are seriously ill or considered to be at high risk of complications from influenza infection or in those who present with severe disease. To assess potential neurologic adverse effects of oseltamivir in infants, a retrospective chart review was performed in North America by the National Institute of Allergy and Infectious Diseases (NIAID) Collaborative Antiviral Study Group (CASG) of infants less than 12 months of age who received oseltamivir compared with either of the adamantanes (amantadine or rimantadine).

Inflammatory mediators play a major role in the pathogenesis of respiratory syncytial virus (RSV) infection. The objective of this study was to evaluate the effect of i.v. dexamethasone on cytokine concentrations in tracheal aspirates (TA) of children with severe RSV disease and to correlate them with disease severity. Twenty-five cytokines were measured in TA obtained from children

Influenza virus and respiratory syncytial virus (RSV) are among the most common viruses causing infections of the lower respiratory tract in young children. Although there are important differences in the immunopathogenesis of these 2 viral pathogens, little is known about how they affect antigen-presenting cells in children with acute infections.To characterize the immune cells that are mobilized to the respiratory tract by influenza virus and RSV, we analyzed nasal wash and blood samples obtained from children hospitalized with acute respiratory infections.Influenza virus and RSV mobilize immune cells, including myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs), to the nasal mucosa. Patients with influenza virus infection had greater numbers of mDCs, pDCs, and monocytes in nasal wash samples than did patients with RSV infection. The frequencies of respiratory tract and blood T cell subsets were not affected by infection with influenza virus or RSV. Monocyte chemoattractant protein-1 concentrations in nasal wash samples were significantly increased in patients with influenza virus infection but not in those with RSV infection. RANTES (regulated on activation, normally T cell expressed and secreted) concentrations were increased only in the blood of patients with influenza virus infection.Infection with influenza virus or RSV mobilizes antigen-presenting cells to the respiratory tract. The differences in antigen-presenting cell numbers and cytokine concentrations suggest that there are distinctive, early immune responses to these 2 viruses.

The development of novel human vaccines would be greatly facilitated by the development of in vivo models that permit preclinical analysis of human immune responses. Here, we show that nonobese diabetic severe combined immunodeficiency (NOD/SCID) β2 microglobulin−/− mice, engrafted with human CD34+ hematopoietic progenitors and further reconstituted with T cells, can mount specific immune responses against influenza virus vaccines. Live attenuated trivalent influenza virus vaccine induces expansion of CD8+ T cells specific to influenza matrix protein (FluM1) and nonstructural protein 1 in blood, spleen, and lungs. On ex vivo exposure to influenza antigens, antigen-specific CD8+ T cells produce IFN-γ and express cell-surface CD107a. FluM1-specific CD8+ T cells can be also expanded in mice vaccinated with inactivated trivalent influenza virus vaccine. Expansion of antigen-specific CD8+ T cells is dependent on reconstitution of the human myeloid compartment. Thus, this humanized mouse model permits preclinical testing of vaccines designed to induce cellular immunity, including those against influenza virus. Furthermore, this work sets the stage for systematic analysis of the in vivo functions of human DCs. This, in turn, will allow a new approach to the rational design and preclinical testing of vaccines that cannot be tested in human volunteers.

The mechanisms contributing to hypoxic respiratory failure (HRF) in term infants are multifactorial. Recent evidence suggests a potential pathogenetic role for inflammation. Nitric oxide (NO), a pulmonary vasodilator, is inhibited by inflammatory mediators that are upregulated in the presence of placental inflammation.To examine the relationship between histological chorioamnionitis and/or funisitis, serum concentrations of inflammatory mediators and severity of HRF.Prospective observational study involving term neonates with HRF and normal controls. Blood samples were taken at birth from mixed cord blood, at 6 h and 30 h for cytokines and CRP, and at 72 h and 96 h for CRP. Placentas were examined for chorioamnionitis. The primary outcome was the administration of inhaled nitric oxide (iNO) therapy. Data were analysed using analysis of variance and chi(2) analysis.32 neonates with hypoxic respiratory failure and 25 controls were enrolled. 14/32 (44%) neonates with HRF required iNO, 9/32 (28%) required high-frequency ventilation and 3/32 (9%) required ECMO; 2/32 (6%) died. Neonates with HRF had more than threefold higher cord levels of interleukin 8 (IL8) than the controls (p0.05). At 6 h and 30 h, serum IL6, IL8 and CRP wereor =2.2-fold higher in neonates who received iNO (p0.003). 23/32 (72%) infants with HRF had evidence of histological chorioamnionitis and/or funisitis compared with 5/25 (20%) controls (p0.001).Severe HRF, as defined by the need for iNO, is associated with raised blood levels of proinflammatory mediators and increased occurrence of histological chorioamnionitis and funisitis, suggesting that inflammation contributes to the severity of hypoxic failure.

Background: Staphylococcus aureus remains the most common etiologic agent of acute osteomyelitis in children. Recently, methicillin-resistant S. aureus (MRSA) has emerged as a major pathogen. Methods: Records of all children admitted with acute osteomyelitis from January 1999 to December 2003 were reviewed. For the comparative analysis, the study population was evenly distributed in 2 periods: period A, January 1999 to June 2001; n= 113; and period B, July 2001 to December 2003; n = 177. In addition, clinical findings of MRSA osteomyelitis were compared with non-MRSA osteomyelitis, including methicillin-sensitive S. aureus infections. Results: Two hundred ninety children (60% male subjects) with acute osteomyelitis were identified. Median (25th-75th percentile) age at diagnosis was 6 years (range, 2-11 years). Significant clinical findings included the following: localized pain (84%), fever (67%), and swelling (62%). Affected bones included the following: foot (23%), femur (20%), tibia (16%), and pelvis (7%). Thirty-seven percent of blood cultures were positive, and a bacterial isolate was obtained in 55% of cases. Bacteria most frequently isolated included the following: methicillin-sensitive S. aureus (45%) (57% in period A vs 40% in period B), MRSA (23%) (6% in A vs 31% in B; P < 0.001), Streptococcus pyogenes (6%), and Pseudomonas aeruginosa (5%). Children with MRSA compared with those with non-MRSA osteomyelitis had significantly greater erythrocyte sedimentation rate and C-reactive protein values on admission and increased length of hospital stay, antibiotic therapy, and overall rate of complications. We observed significant changes in antibiotic therapy related to increased use of agents with activity against MRSA. Conclusions: Methicillin-resistant S. aureus was isolated more frequently in the second study period and was associated with worse clinical outcomes.

SummaryThe analysis of patient blood transcriptional profiles offers a means to investigate the immunological mechanisms relevant to human diseases on a genome-wide scale. In addition, such studies provide a basis for the discovery of clinically relevant biomarker signatures. We designed a strategy for microarray analysis that is based on the identification of transcriptional modules formed by genes coordinately expressed in multiple disease data sets. Mapping changes in gene expression at the module level generated disease-specific transcriptional fingerprints that provide a stable framework for the visualization and functional interpretation of microarray data. These transcriptional modules were used as a basis for the selection of biomarkers and the development of a multivariate transcriptional indicator of disease progression in patients with systemic lupus erythematosus. Thus, this work describes the implementation and application of a methodology designed to support systems-scale analysis of the human immune system in translational research settings.

RSV is a major cause of morbidity and mortality worldwide. Although no treatment or vaccine currently exists, RSV therapeutics and preventative strategies are being evaluated in clinical trials, including phase 3 trials. Despite great prospects, the regulatory pathways of novel RSV therapeutics have been defined insufficiently. Here we report the results from the ReSViNET 2nd High–level expert meeting 2016 on RSV therapeutics, which was held in Zeist, the Netherlands on March 2nd and 3rd. This meeting was organized to advance discussion on regulatory pathways, clinical development, clinical trials, and health technology models in the RSV therapeutics field. During this meeting regulators, public health specialists, academia, non–governmental organizations and pharmaceutical companies openly discussed and addressed the needs for the successful development of RSV therapeutics and prophylaxis.

Risk factors for severe respiratory syncytial virus (RSV) disease include prematurity, congenital heart disease, chronic lung disease, and immunocompromised states. There is no consensus concerning the most effective therapy for severe RSV infection in high-risk patients. Palivizumab is approved for prevention of RSV disease, and ribavirin is approved for treatment of RSV infections but its efficacy in high-risk patients has not been conclusively established.Retrospective chart review of RSV infected children treated with intravenous palivizumab and ribavirin in a pediatric hospital from 2001 to 2005.: Twenty male and 11 female patients with a median age of 23.4 months, hospitalized for RSV infection were treated with intravenous palivizumab from October 2001 through July 2005. Mean dose was 14.93 (SD = 0.68) mg/kg. Twenty-five patients (80%) also received ribavirin, 22 of whom by aerosolization. Common baseline diagnoses were malignancy (n = 15), congenital heart disease (n = 5), and prematurity (n = 5). Included above are 1 cardiac and 6 hematopoietic stem cell transplant recipients. Eighteen (58%) patients had signs of lower respiratory tract infection, 17 were hypoxemic, 10 required intensive care unit (ICU) admission, and 5 were intubated. Twenty-nine (93.6%) patients survived and 2 died. No adverse events attributed to intravenous palivizumab or ribavirin administration were observed.Treatment of RSV-infected high-risk children with intravenous palivizumab alone or in combination with ribavirin was well tolerated and associated with decreased mortality compared with previous reports.

Drug rash with eosinophilia and systemic symptoms (DRESS Syndrome) associated with nevirapine treatment has not been previously reported in children. These findings can mimic other common illnesses, and treatment options are limited. We describe a 12-year-old girl infected with human immunodeficiency virus who developed hypersensitivity to nevirapine therapy. She was successfully treated with intravenous immune globulin.

Author(s): Kanegaye, John T; Jones, Jefferson M; Burns, Jane C; Jain, Sonia; Sun, Xiaoying; Jimenez-Fernandez, Susan; Berry, Erika; Pancheri, Joan M; Jaggi, Preeti; Ramilo, Octavio; Tremoulet, Adriana H | Abstract: BackgroundImportant therapeutic decisions are made based on the presence or absence of fever in patients with Kawasaki disease (KD), yet no standard method or threshold exists for temperature measurement during the diagnosis and treatment of these patients. We sought to compare surface and internal (rectal or oral) routes of temperature measurement for the detection of fever as a marker of treatment resistance.MethodsFrom a randomized, placebo-controlled trial of infliximab as an adjunct to primary intravenous immunoglobulin treatment for acute KD, we collected concurrent (within 5 minutes) axillary and internal temperature measurements and performed receiver-operating characteristic and Bland-Altman analyses. We also determined the ability of surface temperatures to detect treatment resistance defined by internal temperature measurements.ResultsAmong 452 oral-axillary and 439 rectal-axillary pairs from 159 patients, mean axillary temperatures were 0.25 and 0.43 °C lower than oral and rectal temperatures and had high receiver-operating characteristic areas under curves. However, axillary temperatures ≥ 38.0 °C had limited sensitivity to detect fever defined by internal temperatures. Axillary thresholds of 37.5 and 37.2 °C provided maximal sensitivity and specificity to detect oral and rectal temperatures ≥ 38.0 °C, respectively.ConclusionsAxillary temperatures are an insensitive metric for fevers defining treatment resistance. Clinical trials should adopt temperature measurement by the oral or rectal routes for adjudication of treatment resistance in KD.

Background Airway diseases are highly prevalent in infants and cause significant morbidity. We aimed to determine the incidence and risk factors for respiratory morbidity in a Spanish cohort of moderate-to-late preterm (MLP) infants prospectively followed during their first year of life. Methods SAREPREM is a multicenter, prospective, longitudinal study. Preterm infants born at 32–35 weeks of gestation with no comorbidities were enrolled within 2 weeks of life and followed at 2–4 weeks, 6, and 12 months of age. Multivariate mixed-models were performed to identify independent risk factors associated with (i) development of bronchiolitis, (ii) recurrent wheezing, or (iii) related hospital admissions. Results Overall, 977 preterm infants were included, and 766 (78.4%) completed follow-up. Of those, 365 (47.7%) developed bronchiolitis during the first year, 144 (18.8%) recurrent wheezing, and 48 (6.3%) were hospitalized. While low birthweight, day care attendance (DCA) and school-age siblings were significantly and independently associated with both the development of bronchiolitis and recurrent wheezing, lower maternal age increased the risk for bronchiolitis and respiratory-related hospitalizations. Lastly, mechanical ventilation was associated with a higher risk of bronchiolitis and history of asthma in any parent increased the likelihood of developing recurrent wheezing. Conclusions In this study, several non-modifiable parameters (family history of asthma, low birthweight, need for mechanical ventilation) and modifiable parameters (young maternal age, DCA, or exposure to school-age siblings) were identified as significant risk factors for the development of bronchiolitis and recurrent wheezing during the first year of life in MLP infants.

Background: The relationship between KD type and outcomes is not well described. We sought to describe the incidence of KD outcomes based on type of KD presentation. Methods: Using an electronic medical record, we prospectively recorded clinical data for each KD encounter (initial treatment, 2 and 6 week follow up visits) for all pts treated with IVIG at our hospital and followed in our KD clinic from 11/2012-9/2014. Pts were grouped by KD type as determined on the day of treatment - Complete, Incomplete, or questionable KD (qKD), defined as incomplete KD and < 3 supplemental lab criteria. Late treatment was defined as IVIG given at > 10 days of fever. The correlation of KD type with outcomes of persistent fever requiring repeat IVIG, development of periungual peeling (PP), and coronary abnormalities (CAA) was assessed using chi-square. Results: We studied 109 pts treated with IVIG; 95 were treated within 10 days of fever onset (14 late). Late treatment was most common in qKD (9/19=47%) compared to Incomplete (4/22=18%) and Complete (1/68=1.5%), p Conclusions: The incidence of CAA was not statistically different between KD types, though no qKD pts developed CAA despite a higher incidence of late treatment with IVIG. In most pts who developed CAA, the initial echocardiogram showed either CAA or a pericardial effusion. PP was least common in qKD. In qKD, failure of initial IVIG should prompt re-evaluation of the diagnosis of KD.

Background: The diagnosis of Kawasaki disease (KD) is often difficult to distinguish from HAdV. Objective: 1) To characterize the specific transcriptional profiles of KD patients versus acute HAdV infection 2) To determine whether the molecular distance to health (MDTH) score (a molecular score that reflects the perturbation derived from whole genome transcriptional analysis) correlates with response to therapy. Methods: Whole blood RNA samples collected in Tempus tubes were analyzed using Illumina chips and GeneSpring software 7.4 from 76 pediatric patients with complete KD, 13 with incomplete KD, and 19 patients with HadV, and 20 age- and sex-matched healthy controls (HC). We used class comparison algorithms (Mann-Whitney p< 0.01, Benjamini-Hochberg, and 1.25- fold change filter) and modular analysis to define the KD profiles; class prediction algorithm was used to identify genes that best differentiate KD and HAdV. Results: Statistical group comparisons identified 7,899 genes differentially expressed in 39 complete KD patients versus HC (KD biosignature). This signature was validated in another 37 patients with complete KD and in 13 patients with incomplete KD. Modular analysis in children with complete KD demonstrated overexpression of inflammation, neutrophils, myeloid cell, coagulation cascade, and cell cycle genes. The class prediction algorithm identified 25-classifier genes that differentiated children with KD vs HAdV infection in two independent cohorts of patients with 92% (95% CI [73%-99%]) sensitivity and 90% [67%-98%] specificity. MDTH scores in KD patients significantly correlated with the baseline c-reactive protein (R=0.29, p=0.008) and was four fold higher than in children with HAdV (p Conclusion: Transcriptional signatures can be used as a tool to discriminate between KD and HAdV infection, and may also provide prognostic information.

Respiratory syncytial virus (RSV) remains a significant cause of morbidity and mortality in infants, immunocompromised patients and the elderly. Despite the high disease burden, an effective vaccine or specific therapy are lacking which is largely due to our limited understanding of the immune response to RSV and how it relates to clinical disease severity. Current treatment for RSV remains largely supportive and RSV-specific options for prophylaxis and/or treatment are limited to palivizumab and ribavirin. There are a number of promising compounds currently under development, including new monoclonal antibodies and small molecules. These newer antivirals have the potential to impact both the prevention and treatment of RSV disease in the main target populations.

Resumen Introducción Las infecciones virales respiratorias son causa de importante morbimortalidad en recién nacidos prematuros. Hemos realizado un estudio prospectivo en nuestra unidad de cuidados intensivos neonatales (UCIN) para determinar la incidencia de infecciones respiratorias, su impacto, epidemiología y pronóstico en neonatos de alto riesgo. Pacientes y métodos Estudio prospectivo realizado entre septiembre del 2011 y mayo del 2013 entre todos los recién nacidos < 32 semanas de edad gestacional y aquellos niños cuya patología pudiera dar lugar a pensar en un ingreso superior a las 2 semanas. Se recogieron aspirados nasofaríngeos (ANF) el primer día de vida y semanalmente hasta el alta para estudio virológico mediante reacción en cadena de polimerasa. En los casos en los que los niños presentaban síntomas respiratorios, se procedió a recoger un nuevo ANF. El pediatra cumplimentó un cuestionario con los datos clínicos. Resultados Se estudió a 60 niños; 30 (50%) de ellos con una edad gestacional < 32 semanas y 36 (60%) con un peso < 1.500 g. Se recogió un total de 256 ANF, 24 de los cuales resultaron positivos (9,3%). Estas 24 muestras positivas correspondieron solo a 13 niños (21,6% de los pacientes). De ellos, 9 resultaron sintomáticos y presentaron 11 episodios de infección (2 pacientes experimentaron 2 episodios diferentes con control negativo entre ellos). El virus más frecuentemente identificado —el 79% de las muestras (19)— fue el rinovirus (RV). El dato clínico más frecuente fue la presencia o incremento de apneas (75%) y la necesidad de oxigenoterapia. Conclusiones Las infecciones por RV son frecuentes en la UCIN y los recién nacidos pretérmino tienen un alto riesgo de presentar infecciones de relevancia clínica.

HIV-associated encephalopathy (HIV-AE) is a severe neurologic condition that affects HIV-infected children. The potential benefit of antiretroviral (ARV) agents with good cerebrospinal fluid (CSF) penetration remains to be defined. Abacavir (ABC) achieves good CSF concentrations and studies of high-dose ABC showed benefit in adults with HIV dementia. The present study evaluated the safety and virologic, immunologic and neuropsychological responses of an ARV regimen including high-dose ABC in children with HIV-AE.Children between 3 months and 18 years old and abacavir-naive with HIV-AE and virologic failure were eligible.: Seventeen children (16 ARV-experienced) were enrolled and 14 children completed 48 weeks of therapy. The overall tolerability was good; 2 children had a possible hypersensitivity reaction. At week 48, 53% and 59% of the children achieved HIV RNA levels below the limit of quantitation in plasma and CSF, respectively. The median (25%-75% range) change of HIV RNA from baseline to week 48 was -2.29 (-0.81 to -2.47) log10 copies/mL in plasma and -0.94 (0 to -1.13) log10 copies/mL in CSF. The mean increases in CD4 (+/-standard error of mean) cell count and CD4% were 427 (+/-169) cells/mm and 8% (+/-2), respectively. Concentrations of soluble tumor necrosis factor receptor II were reduced in plasma and CSF. Children less than 6 years of age demonstrated significant neuropsychological improvement at week 48.In the present study with a limited number of children, highly active ARV therapy including high-dose ABC showed a safety profile similar to standard dose ABC and provided clinical, immunologic and virologic response in children with HIV-AE at week 48. Children less than 6 years of age also demonstrated significant neuropsychological improvement.

Several guidelines are available to guide the initiation of highly active antiretroviral therapy (HAART) in human immunodeficiency virus (HIV)-infected children. The recommendations in these guidelines show significant variability. Because there is no well-established evidence on when to start HAART, it is left to the discretion of the pediatrician which guidelines to follow. We conducted a survey concerning the indications for starting antiretroviral therapy among pediatricians involved in the treatment of HIV-infected patients in Europe and the United States. We compared the results of this survey with the guidelines available at the time, the recently adapted guidelines and literature evidence. Our results indicate that in clinical practice HAART was initiated at higher viral loads and lower CD4 counts than recommended by the guidelines. American guidelines recommended and still recommend more aggressive treatment than the European guidelines, and this is reflected in clinical practice. Until recently all guidelines were based on long term risk analyses of progression to acquired immunodeficiency syndrome (AIDS) and death performed in cohort data. A recent short term risk analysis makes it possible to calculate the 6 or 12-month risk for progression to AIDS or death for an individual child. Because viral load and CD4 count are typically measured every 3 months, one can argue that it is clinically more relevant to base the decision of when to start HAART on the short term probability of disease progression. Guidelines in Europe are now based on this type of analysis. The American guidelines only adopted the thresholds for CD4 and viral load. The short term risk analysis also shows that the risk for developing AIDS varies markedly with age. This should be reflected in all guidelines. Determining the acceptable risk of disease progression is difficult and influenced by patient-, doctor- and culture-related factors. The controversy over whether or not to treat asymptomatic infants is unresolved as well. All infants have a very high risk of disease progression regardless of their viral load or CD4 count, but lifelong treatment with a potential for significant toxicities and risk of developing resistance is also not an appealing option. We recommend an attempt to achieve a consensus among the different working groups to reduce the number of different guidelines, which should be based on the literature evidence. Because all risk analyses are based on information from the pre-HAART era, a head-to-head trial comparing early versus deferred HAART would be useful. This may be difficult to accomplish. The first step could be an analysis of retrospective data from collaborative cohort data.

Despite almost half a century of active research into the pathogenesis of respiratory syncytial virus (RSV)-induced acute and chronic airway disease, many questions remain unresolved. Experimental studies have demonstrated that interventions that reduced viral replication resulted in improvement of acute disease severity and long-term pulmonary abnormalities. The stage is ready for clinical studies to determine the potential benefit of new strategies for prevention and treatment of RSV infections.