ABSTRACT
The complement phenotypes of Moraxella catarrhalis isolates obtained from adult patients with acute laryngitis were investigated using a microliter serum bactericidal assay and compared with those of other donor groups. Laryngitis isolates had a higher proportion (57%) of complement-resistant strains than did carrier strains from healthy 8- to 13-year-old schoolchildren (16%). The difference between these groups was statistically significant (chi2 [3 x 2 table] = 21.55; P < .001). The relatively frequent occurrence of the complement-resistant (virulence-associated) phenotype in adults with acute laryngitis supports the theory of an active role of M. catarrhalis in the pathogenesis of acute laryngitis.
Subject(s)
Complement System Proteins/chemistry , Laryngitis/microbiology , Moraxella catarrhalis/pathogenicity , Virulence/genetics , Adolescent , Adult , Child , Child, Preschool , Complement System Proteins/genetics , Complement System Proteins/physiology , Humans , Moraxella catarrhalis/isolation & purification , PhenotypeABSTRACT
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.
Subject(s)
Complement System Proteins/metabolism , Moraxella catarrhalis/immunology , Moraxella catarrhalis/pathogenicity , Adolescent , Adult , Blood Bactericidal Activity , Carrier State/microbiology , Child , Child, Preschool , Humans , Moraxella catarrhalis/isolation & purification , Neisseriaceae Infections/microbiology , Nose/microbiology , Pharynx/microbiology , Sputum/microbiology , Virulence/immunologyABSTRACT
Resistance of microorganisms to antimicrobial agents is an increasing problem in the treatment of infectious diseases. In mixed infections, an interesting development can arise when one organism protects another from being killed by an antibiotic. Unfortunately, in the case of respiratory tract infections, experimental evidence of this development is poor. In this study, mice intranasally infected with a lethal number of pneumococci and treated with a curative dose of penicillin or amoxicillin died from pneumococcal pneumonia when they were coinoculated with beta-lactamase-producing Moraxella catarrhalis. beta-lactamase-negative M. catarrhalis did not show a similar indirect pathogenic effect. Treatment with a combination of amoxicillin and the beta-lactamase inhibitor clavulanic acid was not affected by beta-lactamase-producing M. catarrhalis. These findings help explain antibiotic failure in respiratory tract infections, even though the causative microorganism is sensitive to the antibiotic in vitro.
Subject(s)
Moraxella catarrhalis/enzymology , Neisseriaceae Infections/microbiology , Penicillins/therapeutic use , Pneumonia, Pneumococcal/drug therapy , beta-Lactamases/metabolism , Amoxicillin/therapeutic use , Amoxicillin-Potassium Clavulanate Combination , Animals , Clavulanic Acids/therapeutic use , Drug Therapy, Combination/therapeutic use , Male , Mice , Mice, Inbred BALB C , Neisseriaceae Infections/complications , Organ Specificity , Penicillin Resistance , Pneumonia, Pneumococcal/complications , Pneumonia, Pneumococcal/microbiology , Streptococcus pneumoniae/drug effectsABSTRACT
The efficacy, as oral vaccines, of hepta- and mono-valent, Klebsiella-containing bacterial lysates and a number of control preparations was tested in mice. The preparations were administered during two periods of four days each, interrupted by an interval of 3 days. Fourteen days after the first dose, the animals were challenged either intraperitoneally (i.p.; peritonitis/sepsis model) or intranasally (i.n.; pneumonia model). Animals treated with low doses of Klebsiella lysate, in the form of either a 7-valent lysate or a Klebsiella monolysate, showed enhanced survival in both the peritonitis/sepsis and the pneumonia models. Hexa- and tetra-valent preparations without Klebsiella were not protective in the models tested. Furthermore, it was found that the protection is accompanied by priming for Klebsiella-specific IgG responsiveness (probably at the T cell level) and by significant IgA anti-Klebsiella serum antibody levels in about one third of the animals. The oral efficacy of Klebsiella-containing lysates suggests the presence of an adjacent component that directs Klebsiella antigen(s) to follow a selective intestinal pathway which renders them immunogenic. The identity of this component is under investigation.
