Anne M. Stack

Human Monoclonal Antibodies Directed against Toxins A and B Prevent Clostridium difficile-Induced Mortality in Hamsters

ABSTRACT Clostridium difficile is the leading cause of nosocomial antibiotic-associated diarrhea, and recent outbreaks of strains with increased virulence underscore the importance of identifying novel approaches to treat and prevent relapse of Clostridium difficile-associated diarrhea (CDAD). CDAD pathology is induced by two exotoxins, toxin A and toxin B, which have been shown to be cytotoxic and, in the case of toxin A, enterotoxic. In this report we describe fully human monoclonal antibodies (HuMAbs) that neutralize these toxins and prevent disease in hamsters. Transgenic mice carrying human immunoglobulin genes were used to isolate HuMAbs that neutralize the cytotoxic effects of either toxin A or toxin B in cell-based in vitro neutralization assays. Three anti-toxin A HuMAbs (3H2, CDA1, and 1B11) could all inhibit the enterotoxicity of toxin A in mouse intestinal loops and the in vivo toxicity in a systemic mouse model. Four anti-toxin B HuMAbs (MDX-1388, 103-174, 1G10, and 2A11) could neutralize cytotoxicity in vitro, although systemic toxicity in the mouse could not be neutralized. Anti-toxin A HuMAb CDA1 and anti-toxin B HuMAb MDX-1388 were tested in the well-established hamster model of C. difficile disease. CDA1 alone resulted in a statistically significant reduction of mortality in hamsters; however, the combination treatment offered enhanced protection. Compared to controls, combination therapy reduced mortality from 100% to 45% (P < 0.0001) in the primary disease hamster model and from 78% to 32% (P < 0.0001) in the less stringent relapse model.

Intranasal Immunization with Killed Unencapsulated Whole Cells Prevents Colonization and Invasive Disease by Capsulated Pneumococci

ABSTRACT A whole-cell killed unencapsulated pneumococcal vaccine given by the intranasal route with cholera toxin as an adjuvant was tested in two animal models. This vaccination was highly effective in preventing nasopharyngeal colonization with an encapsulated serotype 6B strain in mice and also conferred protection against illness and death in rats inoculated intrathoracically with a highly encapsulated serotype 3 strain. When the serotype 3 challenge strain was incubated in the sera of immunized rats, it was no longer virulent in an infant-rat sepsis model, indicating that the intranasal immunization elicited protective systemic antibodies. These studies suggest that killed whole-cell unencapsulated pneumococci given intranasally with an adjuvant may provide multitypic protection against capsulated pneumococci.

Role of interferon gamma in the pathogenesis of primary respiratory syncytial virus infection in BALB/c mice.

Immunologic mechanisms are thought to contribute to the pathogenesis of respiratory syncytial virus (RSV) bronchiolitis in humans. RSV‐infected BALB/c mice exhibit tachypnea and signs of outflow obstruction, similar to symptoms in humans. Interferon gamma (IFNγ) has been found to be the predominant cytokine produced in humans and mice with RSV infection. We therefore undertook this study to evaluate the role of IFNγ in the development of respiratory illness in RSV‐infected mice. BALB/c mice were infected with RSV, and lung function was assessed by plethysmography. Bronchoalveolar lavage (BAL) fluids were analyzed for the concentration of interferon gamma (IFNγ) and the presence of inflammatory cells, and lung tissue sections were examined for histopathologic changes. The role of IFNγ was further addressed in studies of IFNγ knock‐out mice (IFNγ−/−) and of mice depleted of IFNγ by in vivo administration of a neutralizing antibody. After infection, mice developed respiratory symptoms that were strongly associated with the number of inflammatory cells in BAL, as well as with the concentrations of IFN‐γ. Both IFN‐γ−/− mice and mice treated with anti‐IFNγ developed more extensive inflammation of the airways than control mice. However mice lacking IFNγ exhibited less severe signs of airway obstruction. Together these data suggest a protective role of IFNγ in RSV infection in terms of limiting viral replication and inflammatory responses but also a pathogenic role in causing airway obstruction. J. Med. Virol. 62:257–266, 2000.

Heterotrimeric G proteins physically associated with the lipopolysaccharide receptor CD14 modulate both in vivo and in vitro responses to lipopolysaccharide.

Septic shock induced by lipopolysaccharide (LPS) triggering of cytokine production from monocytes/macrophages is a major cause of morbidity and mortality. The major monocyte/macrophage LPS receptor is the glycosylphosphatidylinositol (GPI)-anchored glycoprotein CD14. Here we demonstrate that CD14 coimmunoprecipitates with Gi/Go heterotrimeric G proteins. Furthermore, we demonstrate that heterotrimeric G proteins specifically regulate CD14-mediated, LPS-induced mitogen-activated protein kinase (MAPK) activation and cytokine production in normal human monocytes and cultured cells. We report here that a G protein binding peptide protects rats from LPS-induced mortality, suggesting a functional linkage between a GPI-anchored receptor and the intracellular signaling molecules with which it is physically associated.

Effective Discharge Communication in the Emergency Department

Communication at discharge is an important part of high-quality emergency department (ED) care. This review describes the existing literature on patient understanding and implementation of discharge instructions, discusses previous interventions aimed at improving the discharge process, and recommends best practices and future research. MEDLINE and Cochrane databases were searched, using combinations of key terms. Literature from both the adult and pediatric ED populations was reviewed. Multiple reports have shown deficient comprehension at discharge, with patients or parents frequently unable to report their diagnosis, management plan, or reasons to return. Interventions to improve discharge communication have been, at best, moderately successful. Patients need structured content, presented verbally, with written and visual cues to enhance recall. Written instructions need to be provided in the patients language and at an appropriate reading level. Understanding should be confirmed before the patient leaves the ED. Further research is needed to describe the optimal content, channel, and timing for the ED discharge process and the relationship between discharge process and outcomes.

Pneumomediastinum in childhood asthma.

The objective of this study was to examine the presentation and clinical course of patients with asthma and pneumomediastinum (PNMD). A retrospective chart review was performed from a computer-generated list of all patients discharged from an urban childrens hospital between 1981 and 1991 with the diagnoses of asthma and PNMD. Thirty cases and 30 controls with asthma, matched for age and sex, were identified. The incidence of PNMD and asthma was 0.3%. Mean age was 11.8 years with a male:female ratio of 1.15:1. Chest pain was reported in 27% of patients and 13% of controls (P=0.17). There was no difference in presenting respiratory rate, heart rate, or systolic blood pressure between cases and controls, nor was there a difference in respiratory distress by modified Wood-Downes scale. Fifty percent of patients had room air oxygen saturation measured at presentation. There was a significant difference in mean oxygen saturation between those with PNMD and those without (90.4 vs 94.1 %; P=0.03). Subcutaneous emphysema was detected in 73% of cases versus none in controls (P<0.001; positive predictive value (PPV)=100%). Sixty-seven percent of patients with PNMD had repeat radiographs during hospitalization. Of these x-rays, 85% showed no change in, improvement, or complete resolution of the PNMD. Three patients (15%) developed a small increase in the PNMD. No patient developed pneumothorax, pneumopericardium, or deterioration in cardiovascular status. PNMD is a rare complication of asthma. Subcutaneous emphysema was the most useful predictor of PNMD in asthma. Chest pain and diminished oxygen saturation should heighten suspicion. Further complications of PNMD were exceedingly rare, and all patients recovered uneventfully, suggesting that attention to excellent treatment for the acute exacerbation may be sufficient in most instances of PNMD.

Incidence of bacteremia in infants and children with fever and petechiae

OBJECTIVE We determined the incidence of serious invasive bacteremia caused by Neisseria meningitidis and other organisms in febrile infants and children with a petechial rash. Further, we studied the diagnostic value of laboratory and clinical finding in these patients. STUDY DESIGN We conducted this prospective cohort study in the emergency department of an urban pediatric teaching hospital, during an 18-month period, and enrolled consecutive patients with temperature of 38 degrees C or higher and petechiae. Our measures included (1) laboratory tests (leukocyte count, coagulation profile, blood culture, and cerebrospinal fluid bacterial culture); (2) a questionnaire requesting clinical data including general appearance, number and location of petechiae, and presence or absence of purpura; and (3) a follow-up telephone survey documenting health status. RESULTS A total of 411 patients were enrolled, with 57.7% between 3 and 36 months of age. Eight patients (1.9%) had bacteremia or clinical sepsis. Six had serious invasive bacteremia: N. meningitidis (two patients), group A streptococcus (one), or sepsis with negative culture results (three). Two had occult bacteremia caused by Streptococcus pneumoniae and no evidence of sepsis. No patient had a positive cerebrospinal fluid culture result. None of the 357 well-appearing patients (95% confidence interval: 0.0%, 1.0%) had serious invasive bacteremia. Fifty-three patients appeared ill, including all six with serious invasive bacteremia. Ill appearance of the child had a sensitivity of 1.00 (95% confidence interval: 0.60, 1.00), and a leukocyte count of 15,000 or greater, or of less than 5000, had a sensitivity of 1.0 (95% confidence interval: 0.53, 1.00) for detecting serious invasive bacteremia. All children with meningococcemia had purpura. CONCLUSIONS Invasive bacteremia occurred less frequently in our study than in previous series and was identified by clinical criteria. Our data support the treatment of selected well-appearing children with fever and petechiae as outpatients.

Improving Adherence to PALS Septic Shock Guidelines

BACKGROUND AND OBJECTIVES: Few studies have demonstrated improvement in adherence to Pediatric Advanced Life Support guidelines for severe sepsis and septic shock. We sought to improve adherence to national guidelines for children with septic shock in a pediatric emergency department with poor guideline adherence. METHODS: Prospective cohort study of children presenting to a tertiary care pediatric emergency department with septic shock. Quality improvement (QI) interventions, including repeated plan-do-study-act cycles, were used to improve adherence to a 5-component sepsis bundle, including timely (1) recognition of septic shock, (2) vascular access, (3) administration of intravenous (IV) fluid, (4) antibiotics, and (5) vasoactive agents. The intervention focused on IV fluid delivery as a key driver impacting bundle adherence, and adherence was measured using statistical process control methodology. RESULTS: Two-hundred forty-two patients were included: 126 subjects before the intervention (November 2009 to March 2011), and 116 patients during the QI intervention (October 2011 to May 2013). We achieved 100% adherence for all metrics, including (1) administration of 60 mL/kg IV fluid within 60 minutes (increased from baseline adherence rate of 37%), (2) administration of vasoactive agents within 60 minutes (baseline rate of 35%), and (3) 5-component bundle adherence (baseline rate of 19%). Improvement was sustained over 9 months. The number of septic shock cases between each death from this condition increased after implementation of the QI intervention. CONCLUSIONS: Using QI methodology, we have demonstrated improved adherence to national guidelines for severe sepsis and septic shock.

The Effect of Hospital Bed Occupancy on Throughput in the Pediatric Emergency Department

STUDY OBJECTIVE Although it has been suggested that high hospital occupancy leads to emergency department (ED) overcrowding and impedes ED throughput, there are limited data defining this relationship. The objective of this study is to examine whether high inpatient hospital occupancy negatively affects throughput in a pediatric ED. METHODS This cross-sectional analysis evaluated patient visits to an urban pediatric ED and hospital occupancy rates. Data were collected from a 347-bed pediatric tertiary care hospital in Boston, MA, between January and December 2006. Primary outcome measure was ED length of stay; secondary outcomes were percentages of patients who left without being seen or had a hallway bed used for treatment. RESULTS Throughout the study period, there were 56,335 patient visits to the pediatric ED; 9,687 (17%) patients were hospitalized. High hospital occupancy directly correlated with longer length of stay for all patients treated in the ED. When inpatient occupancy was at or more than 80% capacity, every 5% increase in hospital occupancy was associated with an increase in length of stay of 17.7 minutes for discharged patients (95% confidence interval [CI] 2.2 to 33.2 minutes) and 34.3 minutes for admitted patients (95% CI 11.4 to 57.2 minutes). With the same 5% increase in inpatient occupancy, there were increases in the odds of either a patient leaving without being seen (odds ratio 1.21; 95% CI 1.12 to 1.31) or being treated in a hallway bed (odds ratio 1.18; 95% CI 1.15 to 1.22). CONCLUSION High hospital occupancy has a significant and quantifiable negative influence on ED throughput, affecting patients both discharged and hospitalized.

Impact of a Bronchiolitis Guideline on ED Resource Use and Cost: A Segmented Time-Series Analysis

OBJECTIVE: Bronchiolitis is a major cause of infant morbidity and contributes to millions of dollars in health care costs. Care guidelines may cut costs by reducing unnecessary resource utilization. Through the implementation of a guideline, we sought to reduce unnecessary resource utilization and improve the value of care provided to infants with bronchiolitis in a pediatric emergency department (ED). METHODS: We conducted an interrupted time series that examined ED visits of 2929 patients with bronchiolitis, aged 1 to 12 months old, seen between November 2007 and April 2013. Outcomes were proportion having a chest radiograph (CXR), respiratory syncytial virus (RSV) testing, albuterol or antibiotic administration, and the total cost of care. Balancing measures included admission rate, returns to the ED resulting in admission within 72 hours of discharge, and ED length of stay (LOS). RESULTS: There were no significant preexisting trends in the outcomes. After guideline implementation, there was an absolute reduction of 23% in CXR (95% confidence interval [CI]: 11% to 34%), 11% in RSV testing (95% CI: 6% to 17%), 7% in albuterol use (95% CI: 0.2% to 13%), and 41 minutes in ED LOS (95% CI: 16 to 65 minutes). Mean cost per patient was reduced by