Monica I. Ardura

A Modular Analysis Framework for Blood Genomics Studies: Application to Systemic Lupus Erythematosus

The 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.

Blood leukocyte microarrays to diagnose systemic onset juvenile idiopathic arthritis and follow the response to IL-1 blockade

Systemic onset juvenile idiopathic arthritis (SoJIA) represents up to 20% of juvenile idiopathic arthritis. We recently reported that interleukin (IL) 1 is an important mediator of this disease and that IL-1 blockade induces clinical remission. However, lack of specificity of the initial systemic manifestations leads to delays in diagnosis and initiation of therapy. To develop a specific diagnostic test, we analyzed leukocyte gene expression profiles of 44 pediatric SoJIA patients, 94 pediatric patients with acute viral and bacterial infections, 38 pediatric patients with systemic lupus erythematosus (SLE), 6 patients with PAPA syndrome, and 39 healthy children. Statistical group comparison and class prediction identified genes differentially expressed in SoJIA patients compared with healthy children. These genes, however, were also changed in patients with acute infections and SLE. An analysis of significance across all diagnostic groups identified 88 SoJIA-specific genes, 12 of which accurately classified an independent set of SoJIA patients with systemic disease. Transcripts that changed significantly in patients undergoing IL-1 blockade were also identified. Thus, leukocyte transcriptional signatures can be used to distinguish SoJIA from other febrile illnesses and to assess response to therapy. Availability of early diagnostic markers may allow prompt initiation of therapy and prevention of disabilities.

Changing trends in acute osteomyelitis in children: impact of methicillin-resistant Staphylococcus aureus infections.

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 Avs 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. Level of Evidence: II. Retrospective study.

Daptomycin therapy for invasive Gram-positive bacterial infections in children.

Background: Clinical improvement is often delayed among children with invasive infections caused by multidrug resistant Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) despite use of standard antimicrobial therapy. Daptomycin, a bactericidal lipopeptide antibiotic, may prove useful for treatment of these infections in children, but clinical experience is lacking. Methods: Retrospective review of medical records of hospitalized children who received daptomycin for treatment of invasive Gram-positive bacterial infections at Children’s Medical Center Dallas from December 2003 to March 2007. Bacterial isolates were tested for susceptibility to daptomycin and characterized by pulsed-field gel electrophoresis and polymerase chain reaction for staphylococcal cassette chromosome mec A. Results: Sixteen children (10 male; median age, 6.5 years) received daptomycin. Fifteen (94%) children had invasive staphylococcal disease (14, MRSA, of which 13 were community-associated; 1, methicillin-susceptible S. aureus), and 1 had urinary tract infection caused by VRE. Twelve children with disseminated staphylococcal disease had bacteremia for 2–10 days despite therapy with 2 or more of the following: vancomycin, clindamycin, rifampin, aminoglycoside, or linezolid. The addition of daptomycin resulted in bacteriologic cure in 6 of 7 evaluable patients with persistent bacteremia. No adverse events were attributed to daptomycin. Overall, 14 patients improved and were discharged home, and 2 died of complications of their underlying medical conditions. Conclusions: The majority of patients demonstrated clinical improvement after addition of daptomycin to conventional antimicrobial therapy. Further studies are needed to assess the pharmacokinetics, pharmacodynamics, safety, and effectiveness of daptomycin in infants and children.

Host immune transcriptional profiles reflect the variability in clinical disease manifestations in patients with Staphylococcus aureus infections.

Staphylococcus aureus infections are associated with diverse clinical manifestations leading to significant morbidity and mortality. To define the role of the host response in the clinical manifestations of the disease, we characterized whole blood transcriptional profiles of children hospitalized with community-acquired S. aureus infection and phenotyped the bacterial strains isolated. The overall transcriptional response to S. aureus infection was characterized by over-expression of innate immunity and hematopoiesis related genes and under-expression of genes related to adaptive immunity. We assessed individual profiles using modular fingerprints combined with the molecular distance to health (MDTH), a numerical score of transcriptional perturbation as compared to healthy controls. We observed significant heterogeneity in the host signatures and MDTH, as they were influenced by the type of clinical presentation, the extent of bacterial dissemination, and time of blood sampling in the course of the infection, but not by the bacterial isolate. System analysis approaches provide a new understanding of disease pathogenesis and the relation/interaction between host response and clinical disease manifestations.

Enhanced monocyte response and decreased central memory T cells in children with invasive Staphylococcus aureus infections.

Staphylococcus aureus has emerged as a significant pathogen causing severe invasive disease in otherwise healthy people. Despite considerable advances in understanding the epidemiology, resistance mechanisms, and virulence factors produced by the bacteria, there is limited knowledge of the in vivo host immune response to acute, invasive S. aureus infections. Herein, we report that peripheral blood mononuclear cells from patients with severe S. aureus infections demonstrate a distinctive and robust gene expression profile which is validated in a distinct group of patients and on a different microarray platform. Application of a systems-wide modular analysis framework reveals significant over-expression of innate immunity genes and under-expression of genes related to adaptive immunity. Simultaneous flow cytometry analyses demonstrated marked alterations in immune cell numbers, with decreased central memory CD4 and CD8 T cells and increased numbers of monocytes. CD14+ monocyte numbers significantly correlated with the gene expression levels of genes related to the innate immune response. These results demonstrate the value of applying a systems biology approach that reveals the significant alterations in the components of circulating blood lymphocytes and monocytes in invasive S. aureus infections.

Management of Single‐Ventricle Patients With Berlin Heart EXCOR Ventricular Assist Device: Single‐Center Experience

There are minimal data regarding chronic management of single-ventricle ventricular assist device (VAD) patients. This study aims to describe our centers multidisciplinary team management of single-ventricle patients supported long term with the Berlin Heart EXCOR Pediatric VAD. Patient #1 was a 4-year-old with double-outlet right ventricle with aortic atresia, L-looped ventricles, and heart block who developed heart failure 1 year after Fontan. She initially required extracorporeal membrane oxygenation support and was transitioned to Berlin Heart systemic VAD. She was supported for 363 days (cardiac intensive care unit [CICU] 335 days, floor 28 days). The postoperative course was complicated by intermittent infection including methicillin-resistant Staphylococcus aureus, intermittent hepatic and renal insufficiencies, and transient antithrombin, protein C, and protein S deficiencies resulting in multiple thrombi. She had a total of five pump changes over 10 months. Long-term medical management included anticoagulation with enoxaparin, platelet inhibition with aspirin and dipyridamole, and antibiotic prophylaxis using trimethoprim/sulfamethoxazole. She developed sepsis of unknown etiology and subsequently died from multiorgan failure. Patient #2 was a 4-year-old with hypoplastic left heart syndrome who developed heart failure 2 years after bidirectional Glenn shunt. At systemic VAD implantation, he was intubated with renal insufficiency. Post-VAD implantation, his renal insufficiency resolved, and he was successfully extubated to daytime nasal cannula and biphasic positive airway pressure at night. He was supported for 270 days (CICU 143 days, floor 127 days). The pump was upsized to a 50-mL pump in May 2011 for increased central venous pressures (29 mm Hg). Long-term medical management included anticoagulation with warfarin and single-agent platelet inhibition using dipyridamole due to aspirin resistance. He developed increased work of breathing requiring intubation, significant anasarca, and bleeding from the endotracheal tube. The family elected to withdraw support. Although both patients died prior to heart transplantation, a consistent specialized multidisciplinary team approach to the medical care of our VAD patients, consisting of cardiothoracic surgeons, heart transplant team, hematologists, pharmacists, infectious disease physicians, psychiatrists, specialty trained bedside nursing, and nurse practitioners, allowed us to manage these patients long term while awaiting heart transplantation.

2009 pandemic influenza a (H1N1) virus infection in pediatric oncology and hematopoietic stem cell transplantation patients

Pediatric oncology and hematopoietic stem cell transplantation (HSCT) patients are at high risk for influenza infection and its associated complications. Little is known about infection with novel 2009 influenza A (H1N1) in this population.

Central Catheter–Associated Bloodstream Infection Reduction With Ethanol Lock Prophylaxis in Pediatric Intestinal Failure: Broadening Quality Improvement Initiatives From Hospital to Home

IMPORTANCE Children with intestinal failure are at high risk for developing central catheter-associated bloodstream infections (CCABSIs) owing to childrens chronic dependence on central venous catheters for parenteral nutrition. OBJECTIVE To evaluate the effectiveness and safety of the addition of ethanol lock prophylaxis to a best-practice CCABSI prevention bundle on hospital and ambulatory CCABSI rates in children with intestinal failure. DESIGN, SETTING, AND PARTICIPANTS Quality improvement and statistical process control analysis that took place at a tertiary care pediatric hospital and patient homes. Participants included children who were 18 years or younger with intestinal failure requiring a central venous catheter. INTERVENTIONS Central catheter-associated bloodstream infection prevention bundle that included daily ethanol lock prophylaxis. MAIN OUTCOMES AND MEASURES Central catheter-associated bloodstream infection rates and safety outcomes (central catheter insertions, repairs, and hospitalizations) before (January 1, 2011-January 31, 2012) and after (February 1, 2012-December 31, 2013) ethanol lock prophylaxis bundle implementation. RESULTS Twenty-four children with intestinal failure received the ethanol lock prophylaxis CCABSI prevention bundle for a median of 266 days (range, 12-635 days). Rates of CCABSI decreased from 6.99 CCABSIs per 1000 catheter days at baseline to 0.42 CCABSI per 1000 catheter days after ethanol lock prophylaxis bundle implementation, despite an increase in the total number of catheter days. A subset of 14 children who received prolonged ethanol lock prophylaxis (≥3 months) had fewer median (range) central catheter insertions 0 (0-2) vs 3 (0-6); P = .001. The pre-ELP intervention CCABSI rates in this subset was 7.01 per 1000 catheter days vs 0.64 per 1000 catheter days for post-ELP intervention (P = .004). There were no significant differences in the total number of hospital admissions; however, there were fewer hospitalizations for fever and CCABSI (P = .003). CONCLUSIONS AND RELEVANCE A best-practice CCABSI prevention bundle that included ethanol lock prophylaxis in both the hospital and home was successfully implemented, well tolerated, and demonstrated a significant and sustained reduction in preventable harm in the form of CCABSIs in children with intestinal failure.

Persistence of herpes simplex virus DNA in cerebrospinal fluid of neonates with herpes simplex virus encephalitis

Objective:The significance of detecting herpes simplex virus (HSV) DNA in the cerebrospinal fluid (CSF) of infants with HSV encephalitis after receipt of prolonged therapy with high-dose (60 mg kg−1 day−1) acyclovir is unknown. We report the clinical and laboratory characteristics, neuroimaging studies and outcomes of four neonates with HSV encephalitis who had persistence of CSF HSV DNA, by polymerase chain reaction (PCR) after 15 to 21 days of high-dose acyclovir therapy.Study Design:Retrospective chart review.Results:All four infants had abnormal neuroimaging studies and subsequently experienced severe developmental delay or death.Conclusion:A persistently positive CSF HSV PCR in neonates may be another risk factor for worse neurodevelopmental outcome. Prospective studies are needed to document how often HSV DNA persists in CSF, elucidate whether it represents an initially high CSF viral load, ongoing viral replication or viral resistance, and determine its possible association with neurodevelopmental impairment.