Effect of age on adherence of Branhamella catarrhalis to buccal epithelial cells

Pulmonary thin-section CT findings in acute Moraxella catarrhalis pulmonary infection

OBJECTIVE

Moraxella catarrhalis is an important pathogen in the exacerbation of chronic obstructive pulmonary disease. The aim of this study was to assess the clinical and pulmonary thin-section CT findings in patients with acute M. catarrhalis pulmonary infection.

METHODS

Thin-section CT scans obtained between January 2004 and March 2009 from 292 patients with acute M. catarrhalis pulmonary infection were retrospectively evaluated. Clinical and pulmonary CT findings in the patients were assessed. Patients with concurrent infection including Streptococcus pneumoniae (n = 72), Haemophilus influenzae (n = 61) or multiple pathogens were excluded from this study.

RESULTS

The study group comprised 109 patients (66 male, 43 female; age range 28-102 years; mean age 74.9 years). Among the 109 patients, 34 had community-acquired and 75 had nosocomial infections. Underlying diseases included pulmonary emphysema (n = 74), cardiovascular disease (n = 44) or malignant disease (n = 41). Abnormal findings were seen on CT scans in all patients and included ground-glass opacity (n = 99), bronchial wall thickening (n = 85) and centrilobular nodules (n = 79). These abnormalities were predominantly seen in the peripheral lung parenchyma (n = 99). Pleural effusion was found in eight patients. No patients had mediastinal and/or hilar lymph node enlargement.

CONCLUSIONS

M. catarrhalis pulmonary infection was observed in elderly patients, often in combination with pulmonary emphysema. CT manifestations of infection were mainly ground-glass opacity, bronchial wall thickening and centilobular nodules.

Tissue culture adherence and haemagglutination characteristics of Moraxella (Branhamella) catarrhalis

The haemagglutination and tissue culture adherence properties of 20 isolates of Moraxella catarrhalis obtained from the sputum of elderly patients with lower respiratory tract infections were compared with those of 20 isolates of M. catarrhalis obtained from the nasopharynx of elderly persons colonised by the organism. Eighty percent of isolates from the infected group as opposed to 5% of isolates from the colonised group haemagglutinated human erythrocytes (P < 0.001), indicating that the haemagglutinin might be a marker of pathogenicity for M. catarrhalis. There was a significant difference in the adherence to HEp-2 cells of isolates from the infected group in comparison to isolates from the colonised group (P = 0.03). Haemagglutination and tissue culture adherence properties were unrelated, indicating that separate adhesin systems are involved. The adherence of M. catarrhalis to HEp-2 cells was unaffected following pronase and trypsin treatment, however, sodium periodate pre-treatment of the bacteria significantly reduced the tissue culture adherence index, indicating that the adhesin by which the bacteria bind to HEp-2 cells may have a carbohydrate moiety. Transmission electron microscopy studies revealed that adherence of M. catarrhalis to HEp-2 cells was mediated by trypsin-resistant 'tack-/spicule-like' structures protruding from the surface of the bacteria.

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.

Changes in adherence of respiratory pathogens to HEp-2 cells induced by subinhibitory concentrations of sparfloxacin, ciprofloxacin, and trimethoprim

Preincubation with subinhibitory concentrations of sparfloxacin, ciprofloxacin, and trimethoprim decreased the adherence of the respiratory pathogens Klebsiella pneumoniae, Haemophilus influenzae, and Moraxella (Branhamella) catarrhalis to human larynx carcinoma HEp-2 cells. Subinhibitory concentrations of sparfloxacin did not change the adherence of Pseudomonas aeruginosa or Streptococcus pneumoniae 15.62, but adhesion of S. pneumoniae 15.42 was significantly enhanced by subinhibitory antimicrobial concentrations.