In-vivo and human evidence for potential efficacy of therapeutic polyclonal RSV neutralizing antibodies for palivizumab-resistant RSV infections

BACKGROUND

Monoclonal antibody (palivizumab), intravenous immune globulin (IGIV), or respiratory syncytial virus (RSV)-polyclonal-hyperimmune-globulin (RSV-IG as Respigam®, RI-001, RI-002) are used with ribavirin in RSV-infected immunocompromised patients, with debated efficacy. Palivizumab-resistance (PR) can arise during treatment of persistent infections in this population. RSV-IG may confer benefit in PR-RSV infection.

METHODS

RSV-IG [RI-001] was provided for an immunocompromised infant with RSV-pneumonitis refractory to ribavirin and palivizumab. RSV-neutralizing antibody, respiratory RSV load (qPCR), and F-gene-sequence-detection of PR was determined. Prophylactic RSV-IG [RI-002] or palivizumab was administered in a cotton-rat model infected with wild-type and PR-RSV. Lung RSV load and neutralizing antibody were measured.

RESULTS

As protective RI-001-neutralizing antibody titers waned in the infant, a subpopulation of PR-escape mutants were detected with a fatal RSV-burden in the lungs. In PR-RSV-infected cotton rats, prophylactic RI-002 reduced RSV-load in the lungs (2.45 vs 0.28 log10 PFU/g lung-tissue reduction, respectively, p < 0.05) and provided protective RSV-neutralizing antibody.

CONCLUSIONS

RSV-IG and ribavirin use in immunocompromised patients requires further study.

Two Distinct Illnesses Consistent With MIS-C in a Pediatric Patient

Multisystem inflammatory syndrome in children (MIS-C) is a severe inflammatory response described in children after infection with severe acute respiratory syndrome coronavirus 2. We present a case of a 9-year-old African American boy with 2 distinct illnesses that were both consistent with MIS-C. He first presented in the early stages of our understanding of MIS-C with predominantly neurologic and gastrointestinal symptoms and demonstrated elevated inflammatory markers consistent with MIS-C. He was treated with intravenous immunoglobulin with complete resolution of signs and symptoms. After 7 months of good health, he returned with a second, distinct illness characterized by fever, rash, gastrointestinal symptoms, and elevated inflammatory markers that met the criteria for MIS-C. In addition, we identified new dilatation of the left anterior descending coronary artery. He improved rapidly after treatment with intravenous immunoglobulin, aspirin, and steroids. Our report highlights the need to achieve a better understanding of this entity's pathogenesis and clinical course and to improve anticipatory guidance for children with MIS-C.

Analysis of Community-Acquired Urinary Tract Infection Treatment in Pediatric Patients Requiring Hospitalization: Opportunity for Use of Narrower Spectrum Antibiotics

Background: The most narrow-spectrum antibiotic possible should be used for empiric and definitive treatment of pediatric urinary tract infections (UTIs). Objectives: The objectives of this study were to determine an appropriate narrow-spectrum antibiotic for empiric UTI treatment, factors differentiating empiric first-generation cephalosporin (FGC) versus third-generation cephalosporin (TGC) coverage, and factors associated with unnecessarily broad-spectrum definitive antibiotic treatment. Methods: This was a retrospective chart review of children admitted from 2013 to 2015 who were diagnosed with a UTI and received treatment. Multivariable logistic regression assessed independent factors associated with our outcomes. Results: Of 568 diagnosed UTIs, 88.6% received empiric TGC treatment. Empiric coverage among cultured organisms was only 5.4% lower in FGC versus TGC. Adolescent age group (odds ratio [OR] = 8.83, 95% confidence interval [CI] = 1.47-53.11), uncircumcised males (OR = 4.52, 95% CI = 1.27-16.08), Hispanic ethnicity (OR = 4.37, 95% CI = 1.14-16.82), and hospitalization within the preceding 3 months (OR = 4.73, 95% CI = 1.38-16.23) were associated with FGC nonsusceptibility among TGC susceptible Enterobacteriaceae pathogens. De-escalation occurred in 55.8% of diagnosed UTIs eligible for de-escalation at discharge. Urine white blood cell (WBC) count >5 (OR = 2.89, 95% CI = 1.14-7.21), serum WBC count (OR = 1.04, 95% CI = 1.01-1.07), and having only one narrow-spectrum treatment option (OR = 5.1, 95% CI = 2.43-10.66) were associated with unnecessarily broad-spectrum definitive treatment. Conclusion and Relevance: FGC would be an appropriate narrow-spectrum empiric agent for UTIs at our institution. The factors associated with FGC nonsusceptibility can further stratify empiric treatment decisions. The factors associated with unnecessarily broad-spectrum definitive treatment illustrate areas for educational efforts and future research regarding UTI treatment.

Cytomegalovirus in pediatric inflammatory bowel disease patients with acute severe colitis

BACKGROUND

The prevalence and significance of cytomegalovirus (CMV) colitis in pediatric acute severe colitis is unknown. The aim of this study was to determine the prevalence of CMV in colonic mucosa of children with acute severe refractory colitis and compare the clinical characteristics and outcomes of CMV positive and negative patients.

METHODS

In a case-control study, colonic biopsy specimens from children with severe refractory colitis were tested for CMV, and matched with non-refractory IBD controls. We characterized CMV positive patients by assessing laboratory values, concurrent medications, and need for surgery as compared with CMV negative refractory colitis patients.

RESULTS

Colonic biopsies from 96 patients were evaluated for CMV; 48 with severe refractory colitis, and 48 non-refractory controls. There was an increased prevalence of CMV in severe refractory colitis [7/48 (14.6%), P < 0.0001]; all were previously CMV negative. Viral DNA burden on immunohistochemistry was not predictive of response to antiviral therapy or need for surgery at 12 months. Lymphopenia was seen in all CMV positive patients, but this did not demonstrate statistical significance (P = 0.09). We did not see an association between azathioprine or infliximab use and the need for surgery at 12 months.

CONCLUSIONS

There is an increased prevalence of CMV in colonic biopsies of pediatric patients with severe refractory colitis. Viral burden does not predict clinical outcomes or subsequent need for colectomy.

A Culture Change: Impact of a Pediatric Antimicrobial Stewardship Program Based on Guideline Implementation and Prospective Audit with Feedback

Reports analyzing the impact of pediatric antimicrobial stewardship programs (ASP) over long periods of time are lacking. We thus report our ASP experience in a pediatric tertiary referral center over a long-term period from 2011 to 2018. Our ASP was implemented in 2011. The program was based primarily on guideline development with key stakeholders, engaging and educating providers, followed by prospective audit with feedback (PAF). Monitored antibiotics included meropenem, piperacillin–tazobactam, and cefepime, followed by the addition of ceftriaxone, ceftazidime, cefotaxime, ciprofloxacin, levofloxacin, linezolid, and vancomycin at various time points. Specifically, the program did not implemented the core strategy of formulary restriction with prior authorization. Process- and outcome-related ASP measures were analyzed. We saw a 32% decrease in overall antibiotic utilization, a 51% decrease in the utilization of antibiotics undergoing PAF, and a 72% reduction in the use of broad-spectrum antibiotics such as meropenem. There was a concomitant increase in organism susceptibility and a reduction in yearly drug purchasing costs of over USD 560,000 from baseline without changes in sepsis-related mortality. Our study highlights that a pediatric ASP based primarily on the principles of guideline development and PAF can improve antibiotic utilization and institutional bacterial susceptibilities without a detrimental impact on patient outcomes by changing the culture of antimicrobial utilization within the institution.

Mediastinal Lymphadenopathy in Children With Histoplasmosis

BACKGROUND

Mediastinal lymphadenopathy (ML) in children can arise from malignancy, infection, or rheumatic illness among others, and may be found incidentally on imaging or during workup for a variety of symptoms. Our aim was to describe the clinical presentation and natural history of histoplasmosis in children who present to a tertiary care center with ML in an endemic area of the country.

METHODS

After institutional review board approval, a retrospective study of all children (aged < 21 y) presenting with proven (positive serologies) or suspected histoplasmosis (negative serologies, negative tuberculosis testing, and benign outcomes in follow-up) over a 5-y period was done. Seventy-four patients were tested; those with another diagnosis (n = 6) or without ML (n = 26) were excluded, for a total cohort of 44 patients. Demographics, clinical presentation, symptoms, laboratory data, treatment course, radiography studies, and inpatient and outpatient visits were examined.

RESULTS

Of the 44 patients with ML, 27 had proven histoplasmosis, and 19 had suspected histoplasmosis. The median follow-up by imaging or clinical examination was 6.9 mo (0.3-73.2 mo). Sixteen patients received antifungal therapy with itraconazole, and 15 patients received at least one course of steroids, nearly all for respiratory symptoms; 11 patients (24%) received both. There was no difference in readmission rate (n = 5 versus 2, P = 0.7) or recurrence of symptoms (n = 2 versus 5, P = 0.4) between patients who received an antifungal and those that did not. Receiving steroid therapy was associated with airway narrowing and a higher readmission rate (n =6 versus 2 who were not treated with steroids, P = 0.04), but not with symptom recurrence. Nine lymph node or mass biopsies were performed; however, the pathology only confirmed nonspecific infection in three and was nondiagnostic in the remaining six patients. Twenty-seven patients had at least one confirmatory laboratory test positive for histoplasmosis. Thirty-nine of the 44 patients (84%) with a diagnosis of histoplasmosis (proven or suspected) were asymptomatic by 1-2 mo follow up, with the remainder having intermittent chest pain or reactive airway disease.

CONCLUSIONS

ML because of proven or suspected histoplasmosis is usually a self-limiting disease that can be managed with treatment of the child's symptoms. Antifungals and steroids are of unclear benefit and may not alter the natural course of the disease. Biopsies are rarely diagnostic in the setting of ML, and invasive procedures should be avoided.

Pneumococcal Polysaccharide Vaccination in Pediatric Inflammatory Bowel Disease

According to current recommendations, in addition to 13-valent pneumococcal conjugate vaccine (PCV13) series, all children with inflammatory bowel disease (IBD) aged ≥2 years, with planned or current immunosuppression, should receive pneumococcal polysaccharide vaccine (PPSV23). The primary aim was to determine the PPSV23 immunization rates in our pediatric IBD patients. The secondary aim was to determine the incidence of invasive pneumococcal disease in these patients. The IBD database at Le Bonheur Children’s Hospital was retrospectively reviewed to identify all cases diagnosed from 2003 to 2015. Out of 190 IBD patients, 106 on immunosuppressive drugs, whose immunization records could be obtained from the state database, were included in the study. Medical records were reviewed to determine infections seen in these patients from the time of diagnosis to date. IBD patients in our study ranged from age 2 to 18 years. Only 4 of 106 (3.7%) patients had received PPSV23 vaccine. Only 1 patient (0.9%) had probable pneumococcal disease and none with invasive pneumococcal disease. Clostridium difficile (11 patients) and Cytomegalovirus colitis (4 patients) were more commonly encountered. All our patients received the recommended PCV13 vaccine. The majority of our pediatric IBD patients did not receive PPSV23 vaccine. Fortunately, we did not see a high rate of invasive pneumococcal disease in our patients suggesting that they may be protected by the primary PCV13 vaccine series. Non-pneumococcal infections were more common in this population.

Disseminated histoplasmosis in pediatric kidney transplant recipients-A report of six cases and review of the literature

BACKGROUND

We report a case series of histoplasmosis in KTx patients in a children's hospital in an endemic area.

METHODS

All KTx cases from January 1, 2002, to August 31, 2016, were reviewed to identify those with disseminated histoplasmosis.

RESULTS

The attack rate of histoplasmosis among our KTx patients was 6.9 per 100 cases. The median age at the time of diagnosis was 16 years (11-18). Comorbidities included glomerulosclerosis (3), medullary cystic disease (1), and obstructive uropathy (2) and HIV (1). There were 5 deceased and 1 living-related donor transplants, and no patient had a history of rejection prior to histoplasmosis. Median time from transplant to histoplasmosis was 14.8 months (IQR 2.2-38.3) and 33% occurred in the first year after transplant. Urine and/or serum antigens were positive in all patients. They were either treated with amphotericin B and transitioned to an azole or received azole monotherapy. Most (83%) received chronic suppression with itraconazole. No patients died and relapse occurred in 1 patient after repeat transplant.

CONCLUSIONS

KTx patients in endemic areas are at risk for disseminated histoplasmosis. Further study is needed to determine which factors portend the need for fungal prophylaxis in this subset of patients.

Intracranial pathologies associated with central diabetes insipidus in infants

Background Idiopathic central diabetes insipidus (CDI) has been associated with intracranial pathologies that do not involve the structural pituitary gland or hypothalamus. The objective was to study the association between non-structural hypothalamic/pituitary intracranial pathologies (NSHPIP) with CDI and to review etiologies that may be contributory to the development of CDI. Methods A retrospective query of our intra-institutional database from 2006 to 2015. Children admitted diagnosed with diabetes insipidus (DI) (ICD-9 253.5) between the ages of 0-1 year were included. Patient charts were reviewed to include those who have a documented diagnosis of CDI, hypernatremia (>145 mmol/L), high serum osmolality (>300 mOsm/kg), low urine osmolality (<300 mOsm/kg), and brain imaging reports. Diagnoses of nephrogenic DI were excluded. Results Twenty-three infant patients were diagnosed with CDI. Eleven subjects (48%) had NSHPIP. Of those, 18% had cerebral infarction, 27% had intracranial injury and hemorrhage due to traumatic brain injury, 18% had isolated intraventricular hemorrhage, and 27% had meningitis. Hospital prevalence for NSHPIP, age 0-1 year, ranged from 0.05% to 0.3%. Conclusions Rates of NSHPIP in those with CDI are higher than expected hospital rates (p<0.001), suggesting a possible association between CDI and NSHPIP.

Unrecognized prolonged viral replication in the pathogenesis of human RSV infection

BACKGROUND

Respiratory symptoms in RSV persist long after the virus is no longer detected by culture. Current concepts of RSV pathogenesis explain this by RSV inducing a long-lasting pathogenic immune cascade. We alternatively hypothesized that prolonged unrecognized RSV replication may be responsible and studied this possibility directly in a human wild-type RSV experimental infection model.

OBJECTIVE

The objective of the current report was to define the duration of true human RSV replication by studying it directly in immunocompetent adults experimentally infected with a clinical strain of RSV utilizing this previously established safe and reproducible model.

STUDY DESIGN

35 healthy adult volunteers were inoculated with RSV-A (Memphis-37, a low11 passage clinical strain virus, manufactured from a hospitalized bronchiolitic infant) and evaluated over 12 days. Viral load by culture, parallel quantitative PCR (genomic, message) and RSV-specific IgA, were measured twice daily from serially collected nasal washes.

RESULTS

After inoculation, 77% (27/35) of volunteers became RSV infected. As expected, culture-detectable RSV ceased abruptly by the 5-6 t h 15 infection day. However, infected volunteers demonstrated prolonged RSV presence by both genomic and message PCR. RSV-specific IgA rose within respiratory secretions of infected volunteers during same time frame.

CONCLUSIONS

RSV replication appears to continue in humans far longer than previously thought. The rise in nasal RSV-specific IgA shortly after infection likely neutralizes culture detectable virus producing misleadingly short durations of infection. Prolonged viral replication helps explain RSV's extended disease manifestations and increases the potential utility of antivirals.

Angiostrongylus cantonensis Eosinophilic Meningitis in an Infant, Tennessee, USA

Angiostrongylus cantonensis, the rat lungworm, is the most common infectious cause of eosinophilic meningoencephalitis worldwide. This parasite is endemic to Southeast Asia and the Pacific Islands, and its global distribution is increasing. We report A. cantonensis meningoencephalitis in a 12-month-old boy in Tennessee, USA, who had not traveled outside of southwestern Tennessee or northwestern Mississippi.

Respiratory Syncytial Virus Disease Is Mediated by Age-Variable IL-33

Respiratory syncytial virus (RSV) is the most common cause of infant hospitalizations and severe RSV infections are a significant risk factor for childhood asthma. The pathogenic mechanisms responsible for RSV induced immunopathophysiology remain elusive. Using an age-appropriate mouse model of RSV, we show that IL-33 plays a critical role in the immunopathogenesis of severe RSV, which is associated with higher group 2 innate lymphoid cells (ILC2s) specifically in neonates. Infection with RSV induced rapid IL-33 expression and an increase in ILC2 numbers in the lungs of neonatal mice; this was not observed in adult mice. Blocking IL-33 with antibodies or using an IL-33 receptor knockout mouse during infection was sufficient to inhibit RSV immunopathogenesis (i.e., airway hyperresponsiveness, Th2 inflammation, eosinophilia, and mucus hyperproduction); whereas administration of IL-33 to adult mice during RSV infection was sufficient to induce RSV disease. Additionally, elevated IL-33 and IL-13 were observed in nasal aspirates from infants hospitalized with RSV; these cytokines declined during convalescence. In summary, IL-33 is necessary, either directly or indirectly, to induce ILC2s and the Th2 biased immunopathophysiology observed following neonatal RSV infection. This study provides a mechanism involving IL-33 and ILC2s in RSV mediated human asthma.

Respiratory syncytial virus disease is mediated by age-variable IL-33 and innate lymphoid cells (INC1P.347)

Respiratory syncytial virus (RSV) is the most common cause of infant hospitalizations and represents an enormous health burden worldwide. Severe RSV infections are a significant risk factor for childhood asthma, but the pathogenic mechanisms responsible for RSV induced airway disease remain elusive. We and others have shown that age at time of initial infection is a crucial determinant of RSV immunopathogenesis (i.e., Th2 inflammation, eosinophilia, airway hyperresponsiveness, mucus). Using an age-appropriate mouse model of RSV that phenotypically recapitulates severe Th2-biased RSV seen in human infants, we show that this age-related disparity in immunopathogenesis is related to enhanced IL-33 production and increased group 2 innate lymphoid cells (ILC2s) in lungs of neonatal mice compared to adult mice. In nasal aspirates from RSV-infected human infants, IL-33 was elevated in the youngest of patients which further indicates age-variable regulation in response to RSV infection. These data provide a previously unknown mechanism involving ILC2s and IL-33 in RSV mediated human asthma, and represent the first evidence of differential ILC2/IL-33 regulation with respect to very early age.

Comparing influenza and RSV viral and disease dynamics in experimentally infected adults predicts clinical effectiveness of RSV antivirals

BACKGROUND

Antivirals reduce influenza viral replication and illness measures, particularly if initiated early, within 48 h of symptom onset. Whether experimental antivirals that reduce respiratory syncytial virus (RSV) load would also reduce disease is unknown. This study compares viral and disease dynamics in humans experimentally infected with influenza or RSV.

METHODS

Clinical strains of RSV-A and influenza A were inoculated intranasally into 20 and 17 healthy volunteers, respectively, on day 0. Symptom scores and nasal washes were performed twice daily, and daily mucus weights were collected. Viral loads in nasal washes were quantified by culture (plaque assay in HEp-2 cells for RSV and by end point dilution in Madin-Darby canine kidney cells for influenza).

RESULTS

After influenza inoculation, influenza viral load and illness markers increased simultaneously until day 2. Within individual subjects, peak influenza load occurred 0.4 days (95% CI -0.4, 1.3) before peak symptoms. Influenza viral load and disease declined thereafter. After RSV inoculation, a longer incubation period occurred prior to viral detection and symptom onset. RSV load and disease increased together until day 5. Within individual subjects, peak RSV loads occurred 0.2 days (95% CI -0.7, 1.05) before peak symptoms, after which both illness measures and viral load declined together.

CONCLUSIONS

Viral and disease dynamics in experimental human infections suggest that reducing RSV load, if timed similarly to clinically-effective influenza antivirals, might be expected to have a similar or greater window of opportunity for reducing clinical RSV disease.