Sensitivity to avian and human PPD in Brisbane school children

Gastroesophageal Reflux Disease, Acid Suppression, and Mycobacterium avium Complex Pulmonary Disease

BACKGROUND

Weekly symptoms of gastroesophageal reflux disease (GERD) occur in 20% of the population, and GERD has been implicated in the pathophysiology of many respiratory diseases. Microaspiration of contaminated water is a potential portal of entry for Mycobacterium avium complex (MAC) organisms into the respiratory tract, and acid-suppression therapy may enhance the survival of mycobacteria in the stomach. This study aimed to assess the prevalence of GERD, swallowing disorders, reflux symptoms, and acid-suppression therapy in patients with MAC lung disease (MAC positive [MAC+]), and to compare these patients to control subjects without MAC lung disease (MAC negative [MAC-]).

METHODS

Clinical information was collected on 58 MAC+ patients and 58 age- and sex-matched MAC- patients who were asked to complete a DeMeester questionnaire of reflux symptoms and to identify any acid-suppressive medication consumed.

RESULTS

A clinical diagnosis of GERD was documented in 23 of 52 MAC+ patients (44.2%), compared to 16 MAC- patients (27.6%) [p = 0.019]. MAC+ patients consumed significantly more histamine type 2 receptor antagonists and prokinetic agents, and MAC- patients consumed more antacids. The mean DeMeester questionnaire score (+/- SD) for MAC+ patients was 1.39 +/- 1.8, and for MAC- patients was 0.88 +/- 1.4. (p = 0.098). Aspiration was suspected in nine MAC+ patients (15.5%), compared to three MAC- patients (5.2%) [p = 0.032]. There was no association between GERD and radiologic presentation of MAC disease. Consolidation and nodules > 5 mm were more common in those receiving acid suppression than those who were not.

CONCLUSIONS

GERD, acid suppression, and clinically suspected aspiration are more common in patients with MAC lung disease than in similar patients without MAC disease.

A meta-analysis of the effect of Bacille Calmette Guérin vaccination on tuberculin skin test measurements

BACKGROUND

The accurate diagnosis of latent tuberculosis infection (LTBI) is an important component of any tuberculosis control programme and depends largely on tuberculin skin testing. The appropriate interpretation of skin test results requires knowledge of the possible confounding factors such as previous BCG vaccination. Uncertainty about the effect of BCG vaccination on tuberculin skin testing and the strength with which recommendations are made to individual patients regarding treatment of LTBI have identified a need to analyse the available data on the effect of BCG on skin testing. A meta-analysis of the evidence for the effect of BCG vaccination on tuberculin skin testing in subjects without active tuberculosis was therefore performed.

METHODS

Medline was searched for English language articles published from 1966 to 1999 using the key words "BCG vaccine", "tuberculin test/PPD", and "skin testing". Bibliographies of relevant articles were reviewed for additional studies that may have been missed in the Medline search. Articles were considered for inclusion in the meta-analysis if they had recorded tuberculin skin test results in subjects who had received BCG vaccination more than 5 years previously and had a concurrent control group. Only prospective studies were considered. The geographical location, number of participants, type of BCG vaccine used, type of tuberculin skin test performed, and the results of the tuberculin skin test were extracted.

RESULTS

The abstracts and titles of 980 articles were identified, 370 full text articles were reviewed, and 26 articles were included in the final analysis. Patients who had received BCG vaccination were more likely to have a positive skin test (5 TU PPD: relative risk (RR) 2.12 (95% confidence interval (CI)1.50 to 3.00); 2 TU RT23: 2.65 [corrected] (95% CI 1.83 to 3.85). The effect of BCG vaccination on PPD skin test results was less after 15 years. Positive skin tests with indurations of >15 mm are more likely to be the result of tuberculous infection than of BCG vaccination.

CONCLUSIONS

In subjects without active tuberculosis, immunisation with BCG significantly increases the likelihood of a positive tuberculin skin test. The interpretation of the skin test therefore needs to be made in the individual clinical context and with evaluation of other risk factors for infection. The size of the induration should also be considered when making recommendations for treatment of latent infection.

Tuberculin hypersensitivity following BCG vaccination in Brisbane school children

Seven hundred and fifty Brisbane school children were tuberculin tested, in paired groups, with purified protein derivatives of Mycobacterium tuberculosis, bovis, BCG and avium. Reaction to avian PPD were stronger than to any of the others used. This finding may be of some importance in interpreting the variation in protection afforded by BCG vaccination.

The role of nontuberculous mycobacterial skin test antigens in the diagnosis of mycobacterial infections

A retrospective study of 212 patients with mycobacterial infection was conducted to determine intradermal reactivity to five tuberculin units (TU) of purified protein derivative of Mycobacterium tuberculosis (PPD-S), and purified protein derivatives (PPDs) derived from non-tuberculous mycobacteria. PPDs B, Y, A, G, and F were used. The study included 138 patients with Mycobacterium tuberculosis infection, and 74 with proved nontuberculous mycobacterial infection. Eight possible patterns of skin test reactivity were discerned using PPD-S, PPD-B, and PPD-Y. In this population, selection of the largest skin test reaction within any one pattern correlated with the infecting organism in 87 per cent of the cases. Use of PPD-A, PPD-G, and PPD-F did not increase diagnostic capability. We conclude that differential skin testing with PPD-S, PPD-B and PPD-Y, is useful in the diagnosis of mycobacterial disease.