Christoph Aebi

Viral etiology of acute respiratory infections with cough in infancy: a community-based birth cohort study

Background: Acute respiratory infections (ARI) are a major cause of morbidity in infancy worldwide, with cough and wheeze being alarming symptoms to parents. We aimed to analyze in detail the viral aetiology of ARI with such symptoms in otherwise healthy infants, including rhinoviruses and recently discovered viruses such as human metapneumovirus (HMPV), coronavirus NL63 and HKU1, and human bocavirus (HBoV). Methods: We prospectively followed 197 unselected infants during their first year of life and assessed clinical symptoms by weekly standardized interviews. At the first ARI with cough or wheeze, we analyzed nasal swabs by sensitive individual real time polymerase chain reaction assays targeting 16 different respiratory viruses. Results: All 112 infants who had an ARI had cough, and 39 (35%) had wheeze. One or more respiratory viruses were found in 88 of 112 (79%) cases. Fifteen (17%) dual and 3 (3%) triple infections were recorded. Rhino- (23% of all viruses) and coronaviruses (18%) were most common, followed by parainfluenza viruses (17%), respiratory syncytial virus (RSV) (16%), HMPV (13%), and HBoV (5%). Together rhinoviruses, coronaviruses, HMPV, and HBoV accounted for 60% (65 of 109) of viruses. Although symptom scores and need for general practitioner (GP) consultations were highest in infants infected with RSV, they were similar in infants infected with other viruses. Viral shedding at 3 weeks occurred in 20% of cases. Conclusions: Rhinoviruses, coronaviruses, HMPV, and HBoV are common pathogens associated with respiratory symptoms in otherwise healthy infants. They should be considered in the differential diagnosis of the aetiology of ARI in this age group.

Influenza-Associated Myositis in Children

Abstract.Background:Influenza-associated myositis (IAM) is an infrequent and poorly known complication of influenza virus infection in children. The aim of this study was to describe five cases of IAM and to review the literature on IAM in children.Patients and Methods:We conducted a retrospective analysis of cases of IAM diagnosed at two university children’s hospitals in Switzerland during two consecutive influenza seasons. Findings were compared with 39 individual case reports and five publications summarizing an additional 272 cases identified by a medical online library (MEDLINE) search.Results:Overall, 316 cases were analyzed. IAM typically occurred in school-aged children with a 2:1 male predominance. Influenza B and A viruses were identified in 76% and 24% of cases, respectively. The median interval between onset of influenza and onset of IAM was 3 days (range 0–18). The calf muscles were involved alone or together with other muscle groups in 69% and 31% of cases, respectively. Blood creatine phosphokinase (CPK) concentration was invariably elevated. Median duration to clinical recovery was 3 days (range 1–30). Rhabdomyolysis occurred in ten of 316 patients (3%), was more common in girls (80%), more often associated with influenza A (86%), and led to renal failure in eight patients (80%).Conclusion:Clinical and laboratory findings of IAM are highly characteristic and allow a rapid diagnosis during the influenza season.

Predicting Adverse Events in Children With Fever and Chemotherapy-Induced Neutropenia: The Prospective Multicenter SPOG 2003 FN Study

PURPOSE To develop a score predicting the risk of adverse events (AEs) in pediatric patients with cancer who experience fever and neutropenia (FN) and to evaluate its performance. PATIENTS AND METHODS Pediatric patients with cancer presenting with FN induced by nonmyeloablative chemotherapy were observed in a prospective multicenter study. A score predicting the risk of future AEs (ie, serious medical complication, microbiologically defined infection, radiologically confirmed pneumonia) was developed from a multivariate mixed logistic regression model. Its cross-validated predictive performance was compared with that of published risk prediction rules. Results An AE was reported in 122 (29%) of 423 FN episodes. In 57 episodes (13%), the first AE was known only after reassessment after 8 to 24 hours of inpatient management. Predicting AE at reassessment was better than prediction at presentation with FN. A differential leukocyte count did not increase the predictive performance. The score predicting future AE in 358 episodes without known AE at reassessment used the following four variables: preceding chemotherapy more intensive than acute lymphoblastic leukemia maintenance (weight = 4), hemoglobin > or = 90 g/L (weight = 5), leukocyte count less than 0.3 G/L (weight = 3), and platelet count less than 50 G/L (weight = 3). A score (sum of weights) > or = 9 predicted future AEs. The cross-validated performance of this score exceeded the performance of published risk prediction rules. At an overall sensitivity of 92%, 35% of the episodes were classified as low risk, with a specificity of 45% and a negative predictive value of 93%. CONCLUSION This score, based on four routinely accessible characteristics, accurately identifies pediatric patients with cancer with FN at risk for AEs after reassessment.

Serum concentrations of lectin-pathway components in healthy neonates, children and adults: mannan-binding lectin (MBL), M-, L-, and H-ficolin, and MBL-associated serine protease-2 (MASP-2).

To cite this article: Sallenbach S, Thiel S, Aebi C, Otth M, Bigler S, Jensenius JC, Schlapbach LJ, Ammann RA. Serum concentrations of lectin‐pathway components in healthy neonates, childrens and adults: mannan‐binding lectin (MBL), M‐, L‐, and H‐ficolin, and MBL‐associated serine protease‐2 (MASP‐2).Pediatr Allergy Immunol 2011;: 424–430.

Real-Time Quantitative Broad-Range PCR Assay for Detection of the 16S rRNA Gene Followed by Sequencing for Species Identification

ABSTRACT Here we determined the analytical sensitivities of broad-range real-time PCR-based assays employing one of three different genomic DNA extraction protocols in combination with one of three different primer pairs targeting the 16S rRNA gene to detect a panel of 22 bacterial species. DNA extraction protocol III, using lysozyme, lysostaphin, and proteinase K, followed by PCR with the primer pair Bak11W/Bak2, giving amplicons of 796 bp in length, showed the best overall sensitivity, detecting DNA of 82% of the strains investigated at concentrations of ≤102 CFU in water per reaction. DNA extraction protocols I and II, using less enzyme treatment, combined with other primer pairs giving shorter amplicons of 466 bp and 342 or 346 bp, respectively, were slightly more sensitive for the detection of gram-negative but less sensitive for the detection of gram-positive bacteria. The obstacle of detecting background DNA in blood samples spiked with bacteria was circumvented by introducing a broad-range hybridization probe, and this preserved the minimal detection limits observed in samples devoid of blood. Finally, sequencing of the amplicons generated using the primer pair Bak11W/Bak2 allowed species identification of the detected bacterial DNA. Thus, broad-spectrum PCR targeting the 16S rRNA gene in the quantitative real-time format can achieve an analytical sensitivity of 1 to 10 CFU per reaction in water, avoid detection of background DNA with the introduction of a broad-range probe, and generate amplicons that allow species identification of the detected bacterial DNA by sequencing. These prerequisites are important for its application to blood-containing patient samples.

Prospective surveillance of hospitalisations associated with varicella-zoster virus infections in children and adolescents

Our goal was to determine the epidemiology of severe varicella-zoster virus (VZV) infections in hospitalised paediatric patients. Admissions associated with VZV infection of patients aged 0–16 years were reported by all 38 paediatric units in Switzerland to the Swiss Paediatric Surveillance Unit (SPSU) during 3 consecutive years (4/2000–3/2003). We verified completeness of reporting by capture-recapture analysis with patient records identified by ICD-10 codes. Outcome of illness was assessed 6 months after hospitalisation. A total of 335 cases (235 identified by SPSU reports, 100 by ICD-10 code) were included in this study. Mean age of patients was 4.1 years (median 3.5 years, range 0–16 years); 54% were male. Some 293 (87%) patients presented with chickenpox, 42 (13%) with herpes zoster and 291 (87%) patients were not immunocompromised. A total of 319 complications occurred in 237 (71%) patients: secondary bacterial infections (n =109); central nervous system involvement (n =76); VZV pneumonitis (n =7); others (n =127). Eleven (3%) patients required intensive care and three died. On follow-up, 303 (96%) of 315 patients had completely recovered; sequelae were present in 12 (4%) patients. The calculated hospitalisation rate was 13 per 104 cases. Conclusion:This study describes a sizeable hospitalisation and complication rate of varicella-zoster virus infections and provides a solid basis for future immunisation recommendations in Switzerland.

Acute Community-Acquired Diarrhea Requiring Hospital Admission in Swiss Children

In order to ascertain the prevalence of agents that cause childhood diarrheal illness, stool specimens of 312 consecutive children with community-acquired diarrhea requiring admission were evaluated. Pathogens were detected in 166 (53%) of the 312 children (>/=2 pathogens in 28 children): Rotavirus (n=75), Salmonella spp. (n=37), Campylobacter spp. (n=24), Shigella spp. (n=5), Giardia spp. (n=4), Yersinia spp. (n=2), Aeromonas spp. (n=15), Cryptosporidium (n=15), enteropathogenic Escherichia coli (n=13), enterotoxigenic E. coli (n=7), and enterohemorrhagic E. coli (n=5). In conclusion, acute childhood diarrheal illness pathogens, such as Aeromonas, Cryptosporidium, and diarrheagenic E. coli, account for a large proportion of patients with a microbiologically positive stool specimen.

The UspA2 Protein of Moraxella catarrhalis Is Directly Involved in the Expression of Serum Resistance

ABSTRACT Many strains of Moraxella catarrhalis are resistant to the bactericidal activity of normal human serum. Previous studies have shown that mutations involving the insertion of an antibiotic resistance cartridge into the M. catarrhalis uspA2 gene resulted in the conversion of a serum-resistant strain to a serum-sensitive phenotype. In the present study, the deletion of the entire uspA2 gene from the serum-resistant M. catarrhalis strain O35E resulted in a serum-sensitive phenotype and did not affect either the rate of growth or the lipooligosaccharide expression profile of this mutant. Inactivation of the classical complement pathway in normal human serum with Mg2+ and EGTA resulted in the survival of this uspA2 mutant. In contrast, blocking of the alternative complement pathway did not protect this uspA2 mutant from complement-mediated killing. To determine whether the UspA2 protein is directly involved in serum resistance, transformation and allelic exchange were used to replace the uspA2 gene in the serum-resistant strain O35E with the uspA2 gene from the serum-sensitive M. catarrhalis strain MC317. The resultant O35E transformant exhibited a serum-sensitive phenotype. Similarly, when the uspA2 gene from the serum-resistant strain O35E was used to replace the uspA2 gene in the serum-sensitive strain MC317, the MC317 transformant acquired serum resistance. The use of hybrid O35E-MC317 uspA2 genes showed that the N-terminal half of the O35E protein contained a 102-amino-acid region that was involved in the expression of serum resistance. In addition, when the uspA2 genes from strains O35E and MC317 were cloned and expressed in Haemophilus influenzae DB117, only the O35E UspA2 protein caused a significant increase in the serum resistance of the H. influenzae recombinant strain. These results prove that the UspA2 protein is directly involved in the expression of serum resistance by certain M. catarrhalis strains.

The outer membrane proteins UspA1 and UspA2 of Moraxella catarrhalis are highly conserved in nasopharyngeal isolates from young children

UspA1 and UspA2 of Moraxella catarrhalis are vaccine candidates. The aims of this study were to determine: (1) the frequencies of occurrence and (2) the degrees of conservation of two surface-exposed epitopes of the uspA1 and uspA2 genes and their respective gene products in 108 nasopharyngeal isolates from young children. The uspA1 and uspA2 genes were detected in 107 (99%) and 108 (100%) isolates, respectively. Twenty-three of 108 uspA2 genes (21%) were identified as the variant gene uspA2H. One-hundred and five isolates (97%) expressed the mAb17C7-reactive epitope shared by UspA1 and UspA2, and 103 isolates (95%) reacted with the UspA1-specific mAb24B5. The only isolate which lacked a uspA1 gene demonstrated reduced adherence to HEp-2 cells and complement sensitivity. The data indicate that both uspA genes and the expression of at least two surface-exposed epitopes are virtually ubiquitous in isolates from a population at risk for otitis media. A vaccine capable of inducing a bactericidal immune response against the mAb17C7- and/or mAb24B5-reactive epitopes appears promising.

A Reservoir of Moraxella catarrhalis in Human Pharyngeal Lymphoid Tissue

BACKGROUND Early exposure of infants and long-term immunity suggest that colonization with Moraxella catarrhalis is more frequent than is determined by routine culture. We characterized a reservoir of M. catarrhalis in pharyngeal lymphoid tissue. METHODS Tissue from 40 patients (median age, 7.1 years) undergoing elective tonsillectomy and/or adenoidectomy was analyzed for the presence of M. catarrhalis by culture, real-time DNA and RNA polymerase chain reaction (PCR), immunohistochemical analysis (IHC), and fluorescent in situ hybridization (FISH). Histologic sections were double stained for M. catarrhalis and immune cell markers, to characterize the tissue distribution of the organism. Intracellular bacteria were identified using confocal laser scanning microscopy (CLSM). RESULTS Twenty-nine (91%) of 32 adenoids and 17 (85%) of 20 tonsils were colonized with M. catarrhalis. Detection rates for culture, DNA PCR, RNA PCR, IHC, and FISH were 7 (13%) of 52, 10 (19%) of 52, 21 (41%) of 51, 30 (61%) of 49, and 42 (88%) of 48, respectively (P<.001). Histologic analysis identified M. catarrhalis in crypts, intraepithelially, subepithelially, and (using CLSM) intracellularly. M. catarrhalis colocalized with macrophages and B cells in lymphoid follicles. CONCLUSIONS Colonization by M. catarrhalis is more frequent than is determined by surface culture, because the organism resides both within and beneath the epithelium and invades host cells.