Fran Balamuth

Distinct Patterns of Membrane Microdomain Partitioning in Th1 and Th2 Cells

Here we show that activated Th1 and Th2 cells have distinct patterns of membrane compartmentalization into lipid rafts. TCR complex members are recruited efficiently to rafts and aggregate with rafts at the site of MHC/peptide contact in Th1 cells but not Th2 cells. TCR/raft association in Th1 cells is deficient in the absence of CD4, suggesting that CD4 aids recruitment of the TCR to rafts. We show differential utilization of rafts in Th1 and Th2 cells by cholesterol depletion studies, which alters calcium signaling in Th1 but not Th2 cells. Furthermore, Th2 cells have a decreased ability to respond to low-affinity peptide stimulation. These studies indicate that components of membrane microdomains are differentially regulated in functionally distinct CD4 T cells.

Delayed antimicrobial therapy increases mortality and organ dysfunction duration in pediatric sepsis.

Objectives: Delayed antimicrobials are associated with poor outcomes in adult sepsis, but data relating antimicrobial timing to mortality and organ dysfunction in pediatric sepsis are limited. We sought to determine the impact of antimicrobial timing on mortality and organ dysfunction in pediatric patients with severe sepsis or septic shock. Design: Retrospective observational study. Setting: PICU at an academic medical center. Patients: One hundred thirty patients treated for severe sepsis or septic shock. Interventions: None. Measurements and Main Results: We determined if hourly delays from sepsis recognition to initial and first appropriate antimicrobial administration were associated with PICU mortality (primary outcome); ventilator-free, vasoactive-free, and organ failure–free days; and length of stay. Median time from sepsis recognition to initial antimicrobial administration was 140 minutes (interquartile range, 74–277 min) and to first appropriate antimicrobial was 177 minutes (90–550 min). An escalating risk of mortality was observed with each hour delay from sepsis recognition to antimicrobial administration, although this did not achieve significance until 3 hours. For patients with more than 3-hour delay to initial and first appropriate antimicrobials, the odds ratio for PICU mortality was 3.92 (95% CI, 1.27–12.06) and 3.59 (95% CI, 1.09–11.76), respectively. These associations persisted after adjustment for individual confounders and a propensity score analysis. After controlling for severity of illness, the odds ratio for PICU mortality increased to 4.84 (95% CI, 1.45–16.2) and 4.92 (95% CI, 1.30–18.58) for more than 3-hour delay to initial and first appropriate antimicrobials, respectively. Initial antimicrobial administration more than 3 hours was also associated with fewer organ failure–free days (16 [interquartile range, 1–23] vs 20 [interquartile range, 6–26]; p = 0.04). Conclusions: Delayed antimicrobial therapy was an independent risk factor for mortality and prolonged organ dysfunction in pediatric sepsis.

Pediatric severe sepsis in U.S. children's hospitals.

Objectives: To compare the prevalence, resource utilization, and mortality for pediatric severe sepsis identified using two established identification strategies. Design: Observational cohort study from 2004 to 2012. Setting: Forty-four pediatric hospitals contributing data to the Pediatric Health Information Systems database. Patients: Children 18 years old or younger. Measurements and Main Results: We identified patients with severe sepsis or septic shock by using two International Classification of Diseases, 9th edition, Clinical Modification–based coding strategies: 1) combinations of International Classification of Diseases, 9th edition, Clinical Modification codes for infection plus organ dysfunction (combination code cohort); 2) International Classification of Diseases, 9th edition, Clinical Modification codes for severe sepsis and septic shock (sepsis code cohort). Outcomes included prevalence of severe sepsis, as well as hospital and ICU length of stay, and mortality. Outcomes were compared between the two cohorts examining aggregate differences over the study period and trends over time. The combination code cohort identified 176,124 hospitalizations (3.1% of all hospitalizations), whereas the sepsis code cohort identified 25,236 hospitalizations (0.45%), a seven-fold difference. Between 2004 and 2012, the prevalence of sepsis increased from 3.7% to 4.4% using the combination code cohort and from 0.4% to 0.7% using the sepsis code cohort (p < 0.001 for trend in each cohort). Length of stay (hospital and ICU) and costs decreased in both cohorts over the study period (p < 0.001). Overall, hospital mortality was higher in the sepsis code cohort than the combination code cohort (21.2% [95% CI, 20.7–21.8] vs 8.2% [95% CI, 8.0–8.3]). Over the 9-year study period, there was an absolute reduction in mortality of 10.9% (p < 0.001) in the sepsis code cohort and 3.8% (p < 0.001) in the combination code cohort. Conclusions: Prevalence of pediatric severe sepsis increased in the studied U.S. children’s hospitals over the past 9 years, whereas resource utilization and mortality decreased. Epidemiologic estimates of pediatric severe sepsis varied up to seven-fold depending on the strategy used for case ascertainment.

CD4 Raft Association and Signaling Regulate Molecular Clustering at the Immunological Synapse Site

T cell activation is associated with the partitioning of TCRs and other signaling proteins, forming an immunological synapse. This study demonstrates a novel function for the CD4 coreceptor in regulating molecular clustering at the immunological synapse site. We show using transgenic mouse and retroviral reconstitution studies that CD4 is required for TCR/protein kinase C (PKC) θ clustering. Specifically, we demonstrate that CD4 palmitoylation sequences are required for TCR/PKCθ raft association and subsequent clustering, indicating a particular role for raft-associated CD4 molecules in regulating immune synapse organization. Although raft association of CD4 is necessary, it is not sufficient to mediate clustering, as cytoplasmic tail deletion mutants are able to localize to rafts, but are unable to mediate TCR/PKCθ clustering, indicating an additional requirement for CD4 signaling. These studies suggest that CD4 coreceptor function is regulated not only through its known signaling function, but also by posttranslational lipid modifications which regulate localization of CD4 in lipid rafts.

American College of Critical Care Medicine Clinical Practice Parameters for Hemodynamic Support of Pediatric and Neonatal Septic Shock

Objectives: The American College of Critical Care Medicine provided 2002 and 2007 guidelines for hemodynamic support of newborn and pediatric septic shock. Provide the 2014 update of the 2007 American College of Critical Care Medicine “Clinical Guidelines for Hemodynamic Support of Neonates and Children with Septic Shock.” Design: Society of Critical Care Medicine members were identified from general solicitation at Society of Critical Care Medicine Educational and Scientific Symposia (2006–2014). The PubMed/Medline/Embase literature (2006–14) was searched by the Society of Critical Care Medicine librarian using the keywords: sepsis, septicemia, septic shock, endotoxemia, persistent pulmonary hypertension, nitric oxide, extracorporeal membrane oxygenation, and American College of Critical Care Medicine guidelines in the newborn and pediatric age groups. Measurements and Main Results: The 2002 and 2007 guidelines were widely disseminated, translated into Spanish and Portuguese, and incorporated into Society of Critical Care Medicine and American Heart Association/Pediatric Advanced Life Support sanctioned recommendations. The review of new literature highlights two tertiary pediatric centers that implemented quality improvement initiatives to improve early septic shock recognition and first-hour compliance to these guidelines. Improved compliance reduced hospital mortality from 4% to 2%. Analysis of Global Sepsis Initiative data in resource rich developed and developing nations further showed improved hospital mortality with compliance to first-hour and stabilization guideline recommendations. Conclusions: The major new recommendation in the 2014 update is consideration of institution—specific use of 1) a “recognition bundle” containing a trigger tool for rapid identification of patients with septic shock, 2) a “resuscitation and stabilization bundle” to help adherence to best practice principles, and 3) a “performance bundle” to identify and overcome perceived barriers to the pursuit of best practice principles.

CTLA-4 Differentially Regulates the Immunological Synapse in CD4 T Cell Subsets

Primary murine Th1 and Th2 cells differ in the organization of the immunological synapse, with Th1 cells, but not Th2 cells, clustering signaling molecules at the T cell/B cell synapse site. We sought to determine whether differential costimulatory signals could account for the differences observed. We found that Th2 cells express higher levels of CTLA-4 than Th1 cells, and demonstrated that Th2 cells lacking CTLA-4 are now able to cluster the TCR with the same frequency as Th1 cells. Furthermore, reconstitution of CTLA-4 into CTLA-4-deficient Th2 cells, or into Th1 cells, inhibits the clustering of the TCR. We have also shown that Th2 cells, but not Th1 cells, show variations in the organization of the immunological synapse depending on levels of expression of CD80/CD86 on the APC. These studies demonstrate a unique role for CTLA-4 as a critical regulator of Th2 cells and the immunological synapse.

Association of clinical practice guidelines with emergency department management of febrile infants ≤56 days of age

BACKGROUND Differences among febrile infant institutional clinical practice guidelines (CPGs) may contribute to practice variation and increased healthcare costs. OBJECTIVE Determine the association between pediatric emergency department (ED) CPGs and laboratory testing, hospitalization, ceftriaxone use, and costs in febrile infants. DESIGN Retrospective cross-sectional study in 2013. SETTING Thirty-three hospitals in the Pediatric Health Information System. PATIENTS Infants aged ≤56 days with a diagnosis of fever. EXPOSURES The presence and content of ED-based febrile infant CPGs assessed by electronic survey. MEASUREMENTS Using generalized estimating equations, we evaluated the association between CPG recommendations and rates of urine, blood, cerebrospinal fluid (CSF) testing, hospitalization, and ceftriaxone use at ED discharge in 2 age groups: ≤28 days and 29 to 56 days. We also assessed CPG impact on healthcare costs. RESULTS We included 9377 ED visits; 21 of 33 EDs (63.6%) had a CPG. For neonates ≤28 days, CPG recommendations did not vary and were not associated with differences in testing, hospitalization, or costs. Among infants 29 to 56 days, CPG recommendations for CSF testing and ceftriaxone use varied. CSF testing occurred less often at EDs with CPGs recommending limited testing compared to hospitals without CPGs (adjusted odds ratio: 0.5, 95% confidence interval: 0.3-0.8). Ceftriaxone use at ED discharge varied significantly based on CPG recommendations. Costs were higher for admitted and discharged infants 29 to 56 days old at hospitals with CPGs. CONCLUSIONS CPG recommendations for febrile infants 29 to 56 days old vary across institutions for CSF testing and ceftriaxone use, correlating with observed practice variation. CPGs were not associated with lower healthcare costs.

Protocolized Treatment Is Associated With Decreased Organ Dysfunction in Pediatric Severe Sepsis.

Objectives: To determine whether treatment with a protocolized sepsis guideline in the emergency department was associated with a lower burden of organ dysfunction by hospital day 2 compared to nonprotocolized usual care in pediatric patients with severe sepsis. Design: Retrospective cohort study. Setting: Tertiary care children’s hospital from January 1, 2012, to March 31, 2014. Subjects: Patients older than 56 days old and younger than 18 years old with international consensus defined severe sepsis and who required PICU admission within 24 hours of emergency department arrival were included. Measurements and Main Results: The exposure was the use of a protocolized emergency department sepsis guideline. The primary outcome was complete resolution of organ dysfunction by hospital day 2. One hundred eighty nine subjects were identified during the study period. Of these, 121 (64%) were treated with the protocolized emergency department guideline and 68 were not. There were no significant differences between the groups in age, sex, race, number of comorbid conditions, emergency department triage level, or organ dysfunction on arrival to the emergency department. Patients treated with protocolized emergency department care were more likely to be free of organ dysfunction on hospital day 2 after controlling for sex, comorbid condition, indwelling central venous catheter, Pediatric Index of Mortality-2 score, and timing of antibiotics and IV fluids (adjusted odds ratio, 4.2; 95% CI, 1.7–10.4). Conclusions: Use of a protocolized emergency department sepsis guideline was independently associated with resolution of organ dysfunction by hospital day 2 compared to nonprotocolized usual care. These data indicate that morbidity outcomes in children can be improved with the use of protocolized care.

Comparison of Two Sepsis Recognition Methods in a Pediatric Emergency Department

OBJECTIVES The objective was to compare the effectiveness of physician judgment and an electronic algorithmic alert to identify pediatric patients with severe sepsis/septic shock in a pediatric emergency department (ED). METHODS This was an observational cohort study of patients older than 56 days with fever or hypothermia. All patients were evaluated for potential sepsis in real time by the ED clinical team. An electronic algorithmic alert was retrospectively applied to identify patients with potential sepsis independent of physician judgment. The primary outcome was the proportion of patients correctly identified with severe sepsis/septic shock defined by consensus criteria. Test characteristics were determined and receiver operating characteristic (ROC) curves were compared. RESULTS Of 19,524 eligible patient visits, 88 patients developed consensus-confirmed severe sepsis or septic shock. Physician judgment identified 159 and the algorithmic alert identified 3,301 patients with potential sepsis. Physician judgment had sensitivity of 72.7% (95% confidence interval [CI] = 72.1% to 73.4%) and specificity of 99.5% (95% CI = 99.4% to 99.6%); the algorithmic alert had sensitivity of 92.1% (95% CI = 91.7% to 92.4%) and specificity of 83.4% (95% CI = 82.9% to 83.9%) for severe sepsis/septic shock. There was no significant difference in the area under the ROC curve for physician judgment (0.86, 95% CI = 0.81 to 0.91) or the algorithm (0.88, 95% CI = 0.85 to 0.91; p = 0.54). A combination method using either positive physician judgment or an algorithmic alert improved sensitivity to 96.6% and specificity to 83.3%. A sequential approach, in which positive identification by the algorithmic alert was then confirmed by physician judgment, achieved 68.2% sensitivity and 99.6% specificity. Positive and negative predictive values for physician judgment versus algorithmic alert were 40.3% versus 2.5% and 99.88% versus 99.96%, respectively. CONCLUSIONS The electronic algorithmic alert was more sensitive but less specific than physician judgment for recognition of pediatric severe sepsis and septic shock. These findings can help to guide institutions in selecting pediatric sepsis recognition methods based on institutional needs and priorities.

Improving Adolescent Pelvic Inflammatory Disease Follow-up From the Emergency Department: Randomized Controlled Trial With Text Messages

STUDY OBJECTIVE Centers for Disease Control and Prevention guidelines recommend follow-up within 72 hours of diagnosis of pelvic inflammatory disease because patients with inadequate treatment are at increased risk of acute and chronic complications. Follow-up rates in adolescents after diagnosis range between 10% and 16%. The primary objective is to assess the effect of text message reminders to adolescent patients receiving a diagnosis of pelvic inflammatory disease on obtaining follow-up care within 72 hours of emergency department (ED) discharge. METHODS This was a single-blinded randomized controlled trial of adolescents receiving a diagnosis of pelvic inflammatory disease in the ED. Patients received standard discharge instructions or standard discharge instructions plus text message reminders. Patients in the text message group received daily, tailored text messages for 4 days, with a reminder to schedule and attend primary care provider follow-up. The primary outcome was follow-up within 72 hours of ED discharge. RESULTS Ninety-five patients (48 standard; 47 text message) were randomized. Three patients were excluded, leaving 92 patients (46 standard; 46 text message) for analysis. Baseline characteristics were similar between treatment groups. Follow-up was 15.2% in the standard group and 43.5% in the text message group. Patients receiving text message reminders were more likely to follow up compared with the standard group (relative risk 2.9; 95% confidence interval [CI] 1.4 to 5.7). The absolute efficacy difference was 28.3% (95% CI 9.5% to 46.9%), yielding number needed to treat of 4 (95% CI 2.2 to 9.5). CONCLUSION Personalized text message reminders were efficacious in improving follow-up for adolescents after ED diagnosis of pelvic inflammatory disease.