Diana C. Taylor

A possible role for lysozyme in determining acute exacerbation in chronic bronchitis

The aggregation of non‐serotypable Haemophilus influenzae (NTHI) by whole saliva from patients with chronic obstructive lung disease (COLD) was investigated. Significant differences were observed between salivary aggregating activity of a control and COLD population (P < 0·001). Saliva from patients less prone to acute exacerbations had a greater capacity to aggregate bacteria compared with saliva from patients with a predilection to infection. The mechanism of saliva‐mediated aggregation of NTHI was investigated and shown to be related to lysozyme content. Lysozyme activity in saliva was measured by the turbidimetric technique and results showed that patients with chronic bronchitis had increased levels of salivary lysozyme, with a subpopulation within the non‐infection‐prone group having greater amounts. A significant difference was observed in salivary lysozyme between controls and non‐infection‐prone (P < 0·005) and infection‐prone (P < 0·05) patients, respectively: the non‐infection‐prone patients having significantly (P < 0·005) more than the infection‐prone patients. There was significant correlation (r= 0·742, P < 0·001) between salivary aggregation of NTHI and lysozyme activity. Chromatographically purified human lysozyme had a similar aggregation profile to that of saliva. There was no difference in serum and saliva lactoferrin concentrations between groups, but there was a significant increase (P < 0·05) in serum lysozyme concentration in the non‐infection‐prone group. This study suggests that the level of salivary lysozyme derived from macrophages may play an important role in determining resistance or susceptibility to acute bronchitis.

Measurement of lysozyme by an enzyme-linked immunosorbent assay.

In this study an enzyme-linked immunosorbent assay has been developed for the determination of lysozyme in saliva, serum and urine. The assay relies on the detection of specific protein rather than lytic activity, a property which has been shown to be most suitable for the quantitation of lysozyme in mucin containing substances. Our results indicate that no pretreatment is necessary for the immunochemical method. The assay is sensitive to concentrations as low as 1 microgram lysozyme/l. The intra-assay and inter-assay coefficients of variation were 5.9% and 15.8% respectively. The lysozyme level in whole saliva was 55.53 +/- 30.35 mg/l, in serum the level was 0.64 +/- 0.15 mg/l and in urine it was 0.17 +/- 0.22 mg/l. Comparisons between immunochemical determination and lytic assays showed a good correlation (serum, r = 0.79, P less than 0.01; saliva, r = 0.85, P less than 0.005; treated saliva, r = 0.96, P less than 0.001).

An alteration in the host-parasite relationship in subjects with chronic bronchitis prone to recurrent episodes of acute bronchitis.

Acute episodes of bronchitis have been shown to be unequally distributed within a population of subjects with chronic bronchitis. Two groups were identified based on incidence of acute bronchitis — subjects who were ‘infection‐prone’ (2–5 infections per year) and those who were ‘non‐infection‐ prone’ (0–1 infections per year). Minor differences in clinical parameters existed, except for smoking experience. The non‐infection‐prone group included more current smokers, and the total smoking experience (in ‘pack years’) was significantly greater in this group. Between‐year analysis demonstrated a stability of classification, established after a minimum of two years’ prospective observation. Parameters of the host‐parasite relationship were assessed in both groups. A significantly greater polybacterial colonization of the oropharynx was observed for chronic bronchitics, both infection‐prone (P < 0.0001) and non‐infection‐prone (P < 0.001), compared with control subjects. Infection‐prone chronic bronchitics had significantly greater total bacteria cultured from the oropharynx compared to the non‐in feet ion‐prone group (P < 0.05); adherence of indigenous microflora to buccal epithelial cells, in particular Gram‐positive cocci (P < 0.01) and in vitro adherence of non‐serotypable Haemophilus influenzae to buccal cells (P < 0.05) compared with the control and non‐infection‐prone groups. These studies suggest that an important variation in subjects with chronic bronchitis is the binding capacity of epithelial cells for bacteria, which when increased enhances susceptibility to colonization and clinical infection.

Acute on chronic bronchitis: A model of mucosal immunology

Acute bronchitis has been studied as a model of disturbed mucosal immunoregulation. A new hypothesis relating to the pathogenesis of acute bronchitis has been developed, based on altered host response as the prime mover. Infection‐prone subjects had low levels of lysozyme. Effective oral immunization, especially if early, reduced levels of bacterial colonization. Future attention focuses on intra bronchial inflammation and its link to the host‐parasite relationship.

Biotypes of Haemophilus parainfluenzae from the respiratory secretions in chronic bronchitis.

A total of 2401 isolates of Haemophilus parainfluenzae was isolated from respiratory secretions of 36 healthy adults and 128 patients with chronic bronchitis over a period of 1 year. The isolates were allocated to eight biotypes, by their production of indole, urease and ornithine decarboxylase. Biotypes I and II constituted most of the isolates of H. parainfluenzae from the oropharynx of controls (75%) and chronic bronchitics (c. 90%). Among the patients, there was no difference in the isolation rate between oropharyngeal swabs and sputum specimens. Biotypes III, IV, VI, VII and VIII were isolated less frequently, as was a new taxon defined here as biotype V which does not produce indole, urease or ornithine decarboxylase. Biotype III was isolated significantly less frequently from cases of chronic bronchitis than from controls, whereas biotype II was isolated somewhat more frequently from the patients, especially during acute episodes.

Detection of Antibody against Helicobacter pylori in the Saliva of Patients with Dyspepsia

There is a need to develop noninvasive assays to detect Helicobacter pylori infection in the gastric mucosa, Current dogma predicts that the presence of antibody within saliva should accurately reflect contemporary colonization of the gut mucosa. This study examined the clinical value of a saliva enzyme-linked immunoadsorbent assay (ELISA) for anti-H pylori antibody, compared with the serum ELISA assay, and found the sensitivity of the saliva assay was 89%, specificity 94%, accuracy 93%, positive predictive value 89% and negative predictive value 94%. Assessment following eradication therapy demonstrated that salivary antibody was a more sensitive indicator of colonization than was serum antibody. The immunoglobulin G antibody in saliva correlated best with colonization, and regression analysis was most consistent with a local production of antibody. These results indicate that detection of antibody in saliva contributes to diagnosis and management of H pylori infection.

Biotyping respiratory Haemophilus species with the microbact system

&NA; The biochemical characteristics of 114 respiratory Haemophilus isolates were examined by the Minitek and Microbact systems. The Microbact system was easy to use and read, although some of the less important reactions (glucose and xylose) were difficult to interpret on occasions. On the basis of the 3 crucial reactions – indole production, ornithine decarboxylase and urease activity – discrepancies between the two systems were minor. Given careful standardization of techniques the Microbact system is a suitable alternative to established techniques for the biotyping of H. influenzae and H. parainfluenzae.

Interaction of bacteria and the epithelial surface in chronic bronchitis

Subjects with chronic lung disease are prone to recurrent episodes of acute bronchitis due to a disturbance in the normal host-parasite relationship involving colonizing bacteria. Non-serotypable Haemophilus influenzae (NTHI) has been commonly associated with acute exacerbations of bronchitis [1]. A prospective study of a population with chronic bronchitis showed that while about one third of subjects have repeated episodes of acute bronchitis, others with a similar degree of chronic lung disease develop few or no episodes of infection (unpublished data). Parameters of both colonization by bacteria and indices of host resistance have been studied to investigate possible mechanisms that determine infection susceptibility in subjects with chronic bronchitis.

Evaluation of a selective medium for the isolation and differentiation of Haemophilus Influenzae and Haemophilus Parainfluenzae from the respiratory tract of chronic bronchitics

&NA; Respiratory tract specimens from chronic bronchitic patients were cultured for Haemophilus species on conventional chocolate agar and a modified sucrose medium in order to determine the accuracy of the new medium in differentiating Haemophilus influenzae from Haemophilus parainfluenzae strains. Haemophilus influenzae biotypes II and III and Haemophilus parainfluenzae biotypes I and II were found to be the predominant strains isolated from the respiratory tract. The modified sucrose medium was found to be a rapid and reliable means of differentiating Haemophilus influenzae from Haemophilus parainfluenzae by sucrose fermentation, on initial isolation.