title: Branhamella (Moraxella) catarrhalis: pathogenic significance in respiratory infections.
abstract: OBJECTIVE
  To assess the pathogenic significance of Branhamella catarrhalis isolates in patients with respiratory infections and to define the clinical characteristics of such patients.
  
  
  METHODS
  Respiratory specimens were assessed in a three-year prospective study performed in a Brisbane metropolitan hospital. Assessment of the pathogenic significance of isolates of B. catarrhalis was based on four predetermined criteria: (i) clinical evidence of respiratory infection based on history, examination and chest x-ray; (ii) isolation of B. catarrhalis as the sole potential pathogen; (iii) absence of antibiotic treatment in the previous two weeks; and (iv) subsequent clinical response to an antibiotic to which the isolate was sensitive.
  
  
  RESULTS
  B. catarrhalis was identified in 118 respiratory samples, 92 (78%) being from patients less than 10 years old. Infection with B. catarrhalis was more commonly seen in winter months and was community-acquired in two-thirds of cases. Isolation of this organism was associated with a broad variety of upper and lower respiratory tract syndromes. Isolates were considered to be of pathogenic significance (all four above criteria satisfied) in 35% of cases and of possible significance (the first and fourth criteria satisfied) in a further 15% of cases. Isolates were more likely to be of pathogenic significance in older patients and in those with pre-existing cardiorespiratory disease; however, a number of serious infections were observed in previously-well children. Expectorated sputum and tracheal aspirates were more likely to yield a clinically significant isolate than nasopharyngeal aspirates. Production of beta-lactamase was demonstrated in 88% of isolates.
  
  
  CONCLUSIONS
  B. catarrhalis causes respiratory infection more frequently than is generally appreciated. Isolation of this organism from the respiratory tract had pathogenic significance or possible pathogenic significance in 50% of our patients. If therapy is indicated in patients with respiratory infection caused by this organism, traditional beta-lactam regimens cannot be relied upon, as shown by the high rate of beta-lactamase production in this study; a tetracycline, erythromycin, a second or third generation cephalosporin, or the combination of a penicillin derivative and beta-lactamase inhibitor should be considered.
authors.affiliation: University of Queensland Department of Medicine, Mater Misericordiae Hospital, South Brisbane.
authors.forename: F M
authors.initials: FM
authors.lastname: Boyle
authors.forename: P R
authors.initials: PR
authors.lastname: Georghiou
authors.forename: M H
authors.initials: MH
authors.lastname: Tilse
authors.forename: J G
authors.initials: JG
authors.lastname: McCormack
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001424:Bacterial Infections / Q000150:complications*; D002648:Child; D002675:Child, Preschool; D003428:Cross Infection / Q000382:microbiology / Q000635:transmission; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D001936:Moraxella catarrhalis / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism / Q000472:pathogenicity*; D009305:Nasopharynx / Q000382:microbiology; D011446:Prospective Studies; D012141:Respiratory Tract Infections / Q000382:microbiology*; D012621:Seasons; D013183:Sputum / Q000382:microbiology; D014132:Trachea / Q000382:microbiology; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D001618:beta-Lactamases