title: Complement resistance is a virulence factor of Branhamella (Moraxella) catarrhalis.
abstract: The purpose of this study was to investigate complement resistance in Branhamella (Moraxella) catarrhalis isolated from healthy schoolchildren or sputum-producing adult patients. Two techniques were used: a serum bactericidal assay as the gold standard and an easier 'culture and spot' test. Children (age 4-13; n = 303) and patients (n = 1047) showed high colonization/infection rates with B. catarrhalis (31% and 19%, respectively). Complement resistance or intermediate sensitivity occurred frequently in patient isolates (62% and 27%, respectively) and less often in children (33% and 8.5%, respectively; P << 0.0001). In young children (age 4-5 years), the proportion of complement-resistant strains was around 50%. Complement resistance in B. catarrhalis is associated with illness and may hence be considered a virulence factor.
authors.affiliation: Eijkman-Winkler Institute for Medical and Clinical Microbiology, University Hospital, Utrecht, The Netherlands.
authors.forename: C
authors.initials: C
authors.lastname: Hol
authors.forename: C M
authors.initials: CM
authors.lastname: Verduin
authors.forename: E E
authors.initials: EE
authors.lastname: Van Dijke
authors.forename: J
authors.initials: J
authors.lastname: Verhoef
authors.forename: A
authors.initials: A
authors.lastname: Fleer
authors.forename: H
authors.initials: H
authors.lastname: van Dijk
mesh_terms: D000293:Adolescent; D000328:Adult; D001770:Blood Bactericidal Activity; D002353:Carrier State / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D003165:Complement System Proteins / Q000378:metabolism*; D006801:Humans; D001936:Moraxella catarrhalis / Q000276:immunology* / Q000302:isolation & purification / Q000472:pathogenicity*; D016870:Neisseriaceae Infections / Q000382:microbiology; D009666:Nose / Q000382:microbiology; D010614:Pharynx / Q000382:microbiology; D013183:Sputum / Q000382:microbiology; D014774:Virulence / Q000276:immunology
chemical_list: D003165:Complement System Proteins