Chadi M. El Saleeby

Respiratory Syncytial Virus Load, Viral Dynamics, and Disease Severity in Previously Healthy Naturally Infected Children

BACKGROUND Respiratory syncytial virus (RSV) disease severity was thought to be a result of host immunopathology but alternatively may be driven by high-level viral replication. The relationships between RSV load, viral clearance dynamics, and disease severity have not been carefully evaluated. METHODS Previously healthy RSV-infected children <2 years old were recruited. RSV load was measured in respiratory secretions by fresh quantitative culture over 3 hospital days. Measures of disease severity were hospital admission, duration of hospitalization, requirement for intensive care, and respiratory failure. RESULTS Multivariate logistic regression models revealed independent predictors of increased duration of hospitalization: male sex, lower weight, and higher viral load on any day. Viral loads at day 3 were more significantly associated with requirement for intensive care and respiratory failure than were viral loads at earlier time points. Faster RSV clearance was independently associated with shorter hospitalization. DISCUSSION These observations challenge the immunopathology-based pathogenesis paradigm. They also have major therapeutic implications, suggesting that application of antiviral agents early in the disease course, even at a time when viral replication is at its highest, might improve subsequent morbidity by significantly lowering viral load and direct viral cytopathic effects, and aborting the potential downstream immunopathology.

Risk factors for severe respiratory syncytial virus disease in children with cancer: the importance of lymphopenia and young age.

OBJECTIVE. We sought to determine the epidemiologic features of respiratory syncytial virus infection in immunocompromised pediatric patients and to identify the risk factors for severe disease. METHODS. We designed a retrospective study examining the experience with respiratory syncytial virus infection in pediatric patients with underlying malignancies and hematopoietic stem cell transplant recipients seen between 1997 and 2005. Clinical and laboratory data were extracted from patient records, and independent predictors of disease severity were investigated. RESULTS. Fifty-eight patients met the study criteria. Twenty-three patients (40%) had underlying diagnoses of acute lymphoblastic leukemia, 11 (19%) had solid tumors, and 24 (41%) were hematopoietic stem cell transplant recipients, had acute myeloid leukemia, or had severe combined immunodeficiency syndrome. Seventeen patients (29%) were <2 years of age. Overall, 16 patients (28%) developed lower respiratory tract infections. The frequency of lower respiratory tract infections was highest in patients with hematopoietic stem cell transplants, acute myeloid leukemia, or severe combined immunodeficiency syndrome (42%). Independent predictors of lower respiratory tract infections were profound lymphopenia, with absolute lymphocyte counts of <100 cells per mm3, and age of ≤2 years. Of all patients with lower respiratory tract infections, 31% died as a result of respiratory syncytial virus infection. The overall mortality rate was low (5 of 58 patients; 8.6%). All deaths occurred in patients with lower respiratory tract infections who were before or after hematopoietic stem cell transplants or were <2 years of age and receiving treatment for acute myeloid leukemia. Neutropenia was not a predictor of respiratory syncytial virus lower respiratory tract infection or death. CONCLUSIONS. This study identified profound lymphopenia and young age as independent predictors of respiratory syncytial virus-related lower respiratory tract infections in immunocompromised children. No association between neutropenia and respiratory syncytial virus-related morbidity or death was found. These findings can guide interventions for respiratory syncytial virus infection in high risk hosts.

Comparison of a Real-Time Reverse Transcriptase PCR Assay and a Culture Technique for Quantitative Assessment of Viral Load in Children Naturally Infected with Respiratory Syncytial Virus

ABSTRACT Respiratory syncytial virus (RSV) is the most common cause of lower respiratory infection of children. Understanding RSV pathogenesis and evaluating interventions requires quantitative RSV testing. Previous studies have used the plaque assay technique. Real-time reverse transcriptase PCR (RTrtPCR) offers possible greater sensitivity, stability after freeze/thaw, and lower cost, thus facilitating multicenter studies. We developed RTrtPCR assays based upon the RSV N and F genes. The N-gene assay detected greater RSV quantity and was further evaluated. Standard curves utilized both extractions from RSV culture supernatants of known quantity and cloned purified copies of the target DNA. In vitro, the ratio of RSV subgroup A (RSV-A) genome copies to PFU was 153:1. A total of 462 samples collected quantitatively from 259 children were analyzed in duplicate by RTrtPCR. Results were compared with those of RSV plaque assays performed on fresh aliquots from the same children. Duplicate RTrtPCR results were highly correlated (r2 = 0.9964). The mean viral load from nasal washes obtained on the first study day was 5.75 ± standard error of the mean 0.09 log PFU equivalents (PFUe)/ml. Viral load by RTrtPCR correlated with plaque assay results (r2 = 0.158; P < 0.0001). Within individuals, upper and lower respiratory tract secretions contained similar viral concentrations. RSV-A-infected children had 1.17 log PFUe higher viral loads than did those with RSV-B (P < 0.0001). RSV quantification by RTrtPCR of the N gene is precise and has significant, though limited, correlation with quantitative culture. The utility of the RTrtPCR quantification technique for clinical studies would be solidified after its correlation with RSV disease severity is established.

Surfactant Protein A2 Polymorphisms and Disease Severity in a Respiratory Syncytial Virus-Infected Population

OBJECTIVE To examine whether genetic variations within the surfactant protein A2 (SP-A2) gene are associated with respiratory syncytial virus (RSV) disease severity in infected children. STUDY DESIGN Naturally infected children aged < or =24 months were prospectively enrolled in 3 RSV seasons. SP-A2 genotyping was performed. Independent clinical predictors of disease severity were analyzed. The association of SP-A2 genetic diversity and disease severity was tested by using multivariate logistic regression models and 4 levels of disease gradation as outcome measures. RESULTS Homozygosity of the 1A(0) allele was protective against hospitalization (odds ratio [OR] = 0.15, P = .0010). This remained significant in African American patients (OR = 0.24, P = .042) and Caucasian patients (OR = 0.05, P = .021) after adjustment for other co-variates. Hospitalized children with the 1A(2) allele demonstrated significant protection from severe disease with univariate analyses, but only a trend for protection with multivariate analyses. Patients homozygous or heterozygous for an asparagine at amino acid position 9 were twice or more likely to need intensive care unit admission (OR = 2.15, P = .022), require intubation (OR = 3.04, P = .005), and have a hospitalization lasting > or =4 days (OR = 1.89, P = .02) compared with children homozygous for a threonine at this position. CONCLUSIONS SP-A2 polymorphisms are associated with the severity of RSV infection in infants.

Discordant Rise in Galactomannan Antigenemia in a Patient with Resolving Aspergillosis, Renal Failure, and Ongoing Hemodialysis

ABSTRACT We describe the case of a patient with improving invasive aspergillosis and paradoxically rising serum galactomannan levels in the presence of chronic renal failure and ongoing hemodialysis. Dialysate tested negative for galactomannan, demonstrating the inability of treatments such as hemodialysis to clear Aspergillus antigen from serum. In patients with renal failure and aspergillosis, rising serum galactomannan levels may not necessarily signify progressive infection.

Molecular detection and quantification of pertussis and correlation with clinical outcomes in children

Pertussis is an under-recognized serious infection. Conventional cultures are insensitive and of limited utility after antibiotic exposure. We corroborated the utility of real-time polymerase chain reaction (PCR) as a diagnostic tool in pertussis and investigated its role as a prognostic tool by evaluating its benefit in the quantification of pertussis bacterial load. All pertussis-positive PCR tests (n = 104) submitted over 5 years were collected for retrospective study. PCR cycle threshold was compared to quantitative culture in 43. Compared to PCR, the sensitivity of culture was 41%. Our PCR assay reliably quantified bacterial load and was quantitatively reproducible. Higher bacterial load correlated with longer duration of hospitalization (P = 0.0003), and multivariate logistic regression models demonstrated this association to be independent. The study confirmed PCR as a superior diagnostic tool in pertussis. PCR quantification of bacterial load at initial diagnosis predicts later clinical disease severity, suggesting a potential benefit of PCR as a prognostic tool in pertussis.

Case 39-2014

Dr. Michelle K. Trivedi (Pediatrics): A 9-year-old girl with Crohn’s disease was admitted to this hospital because of abdominal pain and diarrhea. The patient had been well until 7 years of age, when a diagnosis of Crohn’s disease was made after she presented with abdominal pain, diarrhea, weight loss (2.3 kg), and fevers. Laboratory testing revealed lactase deficiency and antibodies to outer membrane protein C (OmpC) IgA and bacterial flagellin (CBir1). Colonoscopic examination revealed multiple shallow ulcers throughout the colon, rectum, and cecum. Pathological examination of biopsy specimens obtained on upper and lower endoscopy revealed evidence of acute gastritis, a granuloma in the duodenal bulb, moderately active ileitis, and chronic active colitis, findings consistent with Crohn’s disease. Omeprazole (20 mg twice daily), balsalazide disodium (up to three 750-mg capsules twice daily), and azathioprine (up to 50 mg daily) were administered, and a modified specific carbohydrate diet (without nuts) was begun. Symptoms resolved, and 14 months before the current admission, a routine follow-up endoscopic examination and biopsy revealed no evidence of colitis. During the next 6 months, all medications were discontinued, and the patient remained asymptomatic while on a vegetarian diet. Approximately 5 weeks before the current admission (concurrent with the start of the school year), nonbloody diarrhea developed, occurring three or four times daily. Three weeks before admission, intermittent crampy periumbilical pain developed, radiating to both lower quadrants. Four days before admission, the patient had increased abdominal pain and diarrhea, decreased appetite, weight loss, arthralgias, and fever, with a temperature as high as 38.9°C. Two days before admission, she was seen in the gastroenterology clinic of this hospital. The patient rated the pain at 4 on a scale of 0 to 10, with 10 indicating the most severe pain. On examination, she was alert. While she was in a supine position, the blood pressure was 108/50 mm Hg and the pulse was 104 beats per minute, and while she was in a standing position, the blood pressure was 100/50 mm Hg and the pulse was 110 beats per minute. The abdomen was soft, with normal bowel sounds, and was tender in all four quadrants, without guarding or grimacing. Her stools were watery From the Departments of Pediatrics (B.A.N., J.L.K., C.M.E.S.), Radiology (M.T.L.), and Pathology (E.J.M.), Massa‐ chusetts General Hospital, and the De‐ partments of Pediatrics (B.A.N., J.L.K., C.M.E.S.), Radiology (M.T.L.), and Pathol‐ ogy (E.J.M.), Harvard Medical School — both in Boston.

Case 9-2013

Dr. Sarita U. Patil (Allergy and Immunology): A 9-year-old boy was admitted to this hospital because of fever, cough, respiratory distress, and chest pain. The patient had been well until 8 days before admission, when cough, red and watery eyes, and a temperature of 37.2°C developed. Two days later, on a winter holiday, he vomited and did not want to open his presents. The temperature rose to 38.9°C, and he became increasingly lethargic. The next day, he saw his pediatrician. On examination, the temperature was reportedly 39.4°C, the right periorbital region and cheek were erythematous, and a cervical lymph node on the left side was enlarged. A rapid screening test for streptococcal pharyngitis was negative; supportive care was advised, and the patient returned home. The next day, 4 days before admission, shortness of breath and tachypnea developed. The patient was seen in the emergency department at another hospital, where a chest radiograph was reportedly normal. A diagnosis of acute otitis media was made, and a 5-day course of azithromycin was prescribed. During the next 3 days, cough and occasional vomiting persisted. On the morning of admission, he returned to his pediatrician. The patient and his family reported that he had worsening cough, midsternal chest pain with deep inspiration, and weight loss of 1.8 kg in 1 week. On examination, the temperature was 40.3°C, and he appeared to be in respiratory distress. Acetaminophen was administered, and he was sent to this hospital. The patient’s family reported decreased cervical lymphadenopathy in the patient as compared with earlier in the week; however, cough and shortness of breath had worsened. He did not have diarrhea, jaundice, rash, tongue or lip swelling, or abdominal or joint pain. The patient had been delivered by cesarean section because of failure to progress after 42 weeks of uncomplicated gestation; umbilical-cord separation occurred in a normal time frame. Between the ages of 6 and 9 years, he had had five episodes of streptococcal pharyngitis, three episodes of otitis media, and four episodes of cellulitis (most recently, caused by methicillin-resistant Staphylococcus aureus, sensitive to trimethoprim–sulfamethoxazole). One year earlier, he had been evaluated in the pulmonary clinic at this hospital because of a cough of 3 months’ duration, which occurred during the day but not during sleep. At that time, the

Case 4-2011

From the Divisions of Pediatric Hospi tal Medicine and Infectious Diseases (C.M.E.S.), Pediatric Orthopedic Surgery (B.E.G.), and Pediatric Oncology (A.M.F.), Department of Pediatrics, and the Departments of Radiology (S.J.W.) and Pathology (A.R.S.), Massachusetts General Hospital; and the Departments of Pediatrics (C.M.E.S., A.M.F.), Surgery (B.E.G.), Radiology (S.J.W.), and Pathology (A.R.S.), Harvard Medical School — both in Boston.

Cardiovascular Effects of Continuous Dexmedetomidine Infusion Without a Loading Dose in the Pediatric Intensive Care Unit

Background: Use of dexmedetomidine in pediatric critical care is common, despite lack of prospective studies on its hemodynamic effects. Objective: To describe cardiovascular effects in critically ill children treated with a constant continuous infusion of dexmedetomidine without a loading dose at highest Food and Drug Administration-approved adult dose. Methods: Prospective, pilot study of 17 patients with dexmedetomidine infused at a rate of 0.7 μg/kg/h for 6 to 24 hours. Heart rate (HR) and blood pressure (BP) values over time were analyzed by a random effects mixed model. Results: Patients with median age of 1.6 years (1 month to 17 years) and median weight of 11.8 kg (2.8-84 kg) received an infusion for a mean of 16 ± 7.2 hours. There were no cardiac conduction abnormalities. One patient required discontinuation of infusion for predetermined low HR termination criteria at hour 13 of infusion; there was no clinical compromise and it coincided with planned extubation. Decreased HR of 20% from baseline was found in 35% of patients. The mean HR reduction was largest at hour 13 of infusion with a decrease of 13 ± 17 bpm from baseline, but HR changes over time were not statistically significant. Blood pressure effects included a decrease in 12% and an increase in 29%. There was a small but statistically significant increase in systolic BP of 0.4 mm Hg/h of infusion, P < .001. Conclusion: A continuous infusion of 0.7 μg/kg/h of dexmedetomidine without a loading dose for up to 24 hours in critically ill children had tolerable effects on HR and BP.