Branhamella catarrhalis colonization in preschool asthmatics

Infection in severe asthma exacerbations and critical asthma syndrome

In chronic persistent asthma and severe acute exacerbations of bronchial asthma, infectious agents are the predominant triggers that drive disease and airway pathobiology. In acute exacerbations of bronchial asthma (AEBA) including near fatal and fatal asthma, viral agents, particularly human rhinovirus-C, respiratory syncytial virus and influenza A appear to be the more prevalent and recurring threats. Both viral, and to a lesser extent bacterial agents, can play a role, and co-infection may also be present and worsen prognosis in hospitalized patients, placing a portion at risk for critical asthma syndrome. During severe acute exacerbations, infectious agents must be treated empirically, but the initial treatment regimens can vary and viral coverage may also vary based on seasonality and patient age. Early treatment with ceftriaxone and azithromycin, along with oseltamivir in winter months, should be initiated with all cases of severe exacerbations where infection is suspected, and definitely in critical asthma syndrome until infection is excluded by appropriate diagnostic testing. In this manuscript we will outline the impact of the major viral agents on severe asthma including the data from the 2009 H1N1 influenza pandemic. The role of bacterial infections in acute exacerbations of asthma will also be reviewed as well as the benefit of empiric antibiotics and the role of macrolides in both acute and chronic asthma.

The role of bacterial infections in asthma

In summary, bacterial organisms are clinically relevant contributors to asthma exacerbations, and have received much less attention than viruses in this process. Streptococcus pneumoniae, Hemophilus influenzae, and Moraxella catarrhalis have been linked to asthma exacerbations, particularly when sinusitis is present. Treatment therefore should be directed toward these organisms if a bacterial cause is suspected. The atypical bacteria--specifically, C. pneumoniae and M. pneumoniae--deserve special attention. Data suggest a link between these organisms and the exacerbation of asthma, as well as suggest that these organisms may be causative in asthma development. The existing data are not conclusive, but are suggestive enough to drive studies evaluating them as a possible mechanism in asthma pathogenesis. An animal model evaluating M. pneumoniae and C. pneumoniae would be ideal, but at present no model exists in which chronic infection with these organisms results in bronchial hyperresponsiveness. There is active work in this area, however. Alternative investigations include continued evaluation of these organisms by several modalities, including culture, serology, and PCR, along with evaluation of the host response. Many questions remain, but the ground is fertile for continued investigation.

Examen virologique des sécrétions nasopharyngées et examen cytobactériologique de l'expectoration

Les sécrétions nasopharyngées et bronchiques se prêtent à différents examens bactériologiques, virologiques et autres. Assez courants à l'hôpital, ils sont beaucoup moins utilisés en pédiatrie ambulatoire. Néanmoins, pour que leurs résultats soient interprétables et utiles au diagnostic, la technique de prélèvement doit être soigneuse. L'intérêt pratique de ces examens mérite également d'être précisé pour que les demandes soient justifiées.

Moraxella catarrhalis: clinical significance, antimicrobial susceptibility and BRO beta-lactamases

Moraxella catarrhalis is an important pathogen of humans. It is a common cause of respiratory infections, particularly otitis media in children and lower respiratory tract infections in the elderly. Colonisation of the upper respiratory tract appears to be associated with infection in many cases, although this association is not well understood. Nosocomial transmission is being increasingly documented and the emergence of this organism as a cause of bacteremia is of concern. The widespread production of a beta-lactamase enzyme renders Moraxella catarrhalis resistant to the penicillins. Cephalosporins and beta-lactamase inhibitor combinations are effective for treatment of beta-lactamase producers, and the organism remains nearly universally susceptible to the macrolides, fluoroquinolones, tetracyclines and the combination of trimethoprim and sulfamethoxazole. Two major beta-lactamase forms, BRO-1 and BRO-2, have been described on the basis of their isoelectric focusing patterns. The BRO-1 enzyme is found in the majority of beta-lactamase-producing isolates and confers a higher level of resistance to strains than BRO-2. The BRO enzymes are membrane associated and their production appears to be mediated by chromosomal determinants which are transmissible by an unknown mechanism. The origin of these novel proteins is unknown.

Clinical utility of flexible bronchoscopy and bronchoalveolar lavage in young children with recurrent wheezing

OBJECTIVE

The objective of this study was to determine in young children with recurrent wheezing poorly responsive to bronchodilator therapy whether flexible bronchoscopy (FB) and bronchoalveolar lavage (BAL) provide clinically useful information, whether age-specific differences are present in bronchoscopic and BAL fluid (BALF) findings, and whether differential cellular analysis of BALF is useful in suggesting an infectious or inflammatory process.

DESIGN

This was a retrospective case series with descriptive and analytical components. The study population included children referred to a large tertiary care children's hospital subspecialty service for further evaluation of recurrent wheezing. Clinical and demographic data and findings of FB and BALF studies were collected from chart review. For purposes of data analysis patients were divided into 0- to 6-, 7- to 12-, and 13- to 18-month age groups.

RESULTS

Thirty otherwise healthy children, 0 to 18 months of age with recurrent wheezing, who had undergone FB were identified; and 28 were found to have positive diagnostic findings. Airway abnormalities were found in 17 (57%) and tended to be more common in the 0- to 6-month age group. In the 27 who also had BAL performed, 3 (11%) had a positive bacterial culture, 9 (33%) a positive viral culture, and 5 (19%) an elevated lipid-laden macrophage index suggesting aspiration. Differential cellular analysis was abnormal in 11 (41%), a finding that was significantly associated with a positive bacterial culture, a positive viral culture, or an elevated lipid-laden macrophage index.

CONCLUSIONS

In this population of young children with recurrent wheezing poorly responsive to bronchodilator therapy, FB and BAL yielded useful diagnostic findings in most children studied. In addition, in the presence of an infectious or inflammatory process, differential cellular analysis of BALF revealed an increased percentage of neutrophils.

Bronchopulmonary infection with Moraxella catarrhalis in infants requiring extracorporeal membrane oxygenation

Moraxella (formerly Branhamella) catarrhalis is now a well-recognized pathogen of the upper and lower respiratory tract. Four pediatric cases of life-threatening pneumonia requiring extracorporeal membrane oxygenation are presented. M. Catarrhalis was isolated within 48 hours of admission in three of the cases and within 24 hours of an acute deterioration in the fourth. We conclude that M. catarrhalis is either a significant pathogen in its own right, a marker of severe disease, or a secondary invader.