PREDISPOSING CONDITIONS TO BACTERIAL-INFECTIONS IN CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

In normal airways, invasion of small numbers of pathogenic bacteria will not give rise to injury or local colonization. In chronic obstructive pulmonary disease, however, local conditions are changed, which may impair local defense systems and facilitate infection. These include: (I)factors promoting bacterial adherence and growth like the observed damaged airway epithelium in chronic bronchitis. The consequent changes in the composition of the epithetial lining fluid and impaired mucociliary clearance may be the most important pathophysiologic airway sequele in this respect; (2) aggravating generalized airway obstruction including mucus secretion, increase in mucus viscosity, and proliferation of submucosal smooth muscles, resulting in significant changes in airway geometry. This may change local conditions dramatically and so sustain factors promoting bacterial infections; (3) subversion of normally protective defense mechanisms into damaging host tissue at the mucosal level. Activated epithelial cell layers induce increased submucosal vascular leakage, edema, and inflammatory cell infiltration with subsequent tissue injury by locally produced cell products like free elastase Specific bacterial products but also generally produced bacterial endotoxins may induce a local immune response resulting in the local production of high concentrations of antibodies and an invasion of specific effector cells. The role of these reactive cells or proteins may even be a primary one, in that they attack on (cellular) proteins, which increase their susceptibility for dysfunction in the defense line. For the clinicians, the new insights in the role of these aggravating factors in the development of recurrent bacterial airway infections in chronic bronchitis may be of major importance. The effectiveness of antibiotic regimens will depend very much on the success achieved in diminishing these co-existing factors by longterm inhaled corticosteroids

Immune selection for antigenic drift of major outer membrane protein P2 of Haemophilus influenzae during persistence in subcutaneous tissue cages in rabbits.

During persistence of nonencapsulated Haemophilus influenzae in the respiratory tracts of patients with chronic bronchitis, the major outer membrane proteins (MOMPs) P2 and P5 show antigenic drift. The hypothesis that appearance of antigenic variants is the consequence of antibody-dependent selection was tested in a rabbit model. Persistence of H. influenzae d1 was achieved in subcutaneous tissue cages for up to 948 days. During persistence in the rabbits, similar changes in MOMP P2 of H. influenzae occurred, as observed in isolates from chronic bronchitis patients. In rabbits vaccinated with strain d3 and in nonvaccinated rabbits, antigenic drift occurred later than in rabbits vaccinated with strain d1. High titers of antibodies against H. influenzae were measured in tissue cage fluid and serum. Vaccination of the rabbits with H. influenzae d1 or d3, an antigenic variant of strain d1, resulted neither in eradication of H. influenzae d1 nor in increased antibody titers in serum and tissue cage fluid. The sera of nonvaccinated rabbits during persistence had no strain d1-specific bactericidal activity in the presence of complement. Vaccination with H. influenzae d1 induced serum bactericidal activity against strain d1 in the presence of complement. However, a variant of strain d1 appearing in the tissue cages was not killed by this serum bactericidal activity. We conclude that immunological pressure leads to the selection of MOMP variants of H. influenzae and that these variants escape the antibody-mediated strain-specific bactericidal activity against H. influenzae

MULTIPLE HAEMOPHILUS-INFLUENZAE STRAINS AND STRAIN VARIANTS COEXIST IN THE RESPIRATORY-TRACT OF PATIENTS WITH CYSTIC-FIBROSIS

To investigate the epidemiology of nontypeable Haemophilus influenzae in the respiratory tract of cystic fibrosis (CF) patients, H. influenzae isolates from sputum specimens of 40 CF patients were analyzed longitudinally for 2 years. The isolates were characterized by analysis of the major outer membrane protein (MOMP) patterns. MOMP variant H. influenzae strains were discriminated from distinct strains by randomly amplified polymorphic DNA analysis of genomic DNA. Multiple H. influenzae strains and MOMP variant strains were isolated from single sputum specimens of 29 patients. In 22 patients, a distinct H. influenzae strain persisted over time (median persistence, 8 months; range, 2-24). In general, the appearance of MOMP variant strains did not coincide with the occurrence of exacerbations

GENOMIC DNA-FINGERPRINTING OF CLINICAL HAEMOPHILUS-INFLUENZAE ISOLATES BY POLYMERASE CHAIN-REACTION AMPLIFICATION - COMPARISON WITH MAJOR OUTER-MEMBRANE PROTEIN AND RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS

Non-capsulate strains of Haemophilus influenzae were genotyped by analysis of variable DNA segments obtained by amplification of genomic DNA with the polymerase chain reaction (PCR fingerprinting). Discrete fragments of 100-2000 bp were obtained. The reproducibility of the procedure was assessed by comparing: (i) the fingerprints of 16 colonies of a single H. influenzae strain; (ii) isolates obtained from individual sputum samples (a total of 57 H. influenzae isolates from three cystic fibrosis patients); and (iii) 17 isolates collected during an outbreak of H. influenzae infection in a local pulmonary rehabilitation centre. The discriminatory power of the method was demonstrated by showing that the PCR fingerprints of eight unrelated H. influenzae strains from sputum samples of patients with chronic obstructive pulmonary disease (COPD) and 32 strains from cystic fibrosis patients were all different. These 40 isolates' also differed with respect to their restriction fragment length polymorphisms (RFLP) and major outer-membrane protein (MOMP) composition. Twelve MOMP antigenic strain variants from sputum samples of five COPD patients had identical PCR fingerprints and RFLPs. It was concluded that PCR fingerprinting is a reliable and reproducible method for genotyping non-capsulate strains of H. influenzae. The discriminatory power of PCR fingerprinting was similar to that of RFLP analysis, but the results of PCR fingerprinting were easier to interpret