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Objective: The purpose of this study was to explore the association between tuberculin reaction size in contacts with positive tuberculin skin test results and a variety of contact and index patient variables., Patients and Methods: We reviewed the contact investigation records for tuberculosis patients identified by the Tuberculosis Prevention and Control Center of Lleida, Spain, over a period of 7 years. Patients with pulmonary and/or extrapulmonary disease were included. Tuberculosis infection had been diagnosed using the Mantoux skin test with 2 tuberculin units of purified protein derivative RT-23, and tuberculosis disease had been detected on the basis of clinical data, chest radiographs, and cultures. We examined the association between tuberculin reaction size and contact age, close contact with index patients with positive sputum smears, and diagnosis of tuberculosis disease in contacts. Associations were analyzed using the chi(2) test for linear trend., Results: Tuberculin reaction size was 10 mm or greater in 85.9% of the 768 contacts analyzed and 15 mm or greater in 63.8%. The percentage of contacts under 15 years of age (P=.006) who had close contact with an index patient with a positive sputum smear (P=.013) and who were diagnosed with tuberculosis disease (P=.029) increased with tuberculin reaction size., Conclusions: We found that larger tuberculin reaction size in contacts with positive tuberculin skin test results was most frequently associated with recent infections in the contact, close contact with an index patient with a positive sputum smear, and diagnosis of tuberculosis disease in the contact.

Unlabelled: Tuberculous infection in adults is not a well known entity in our country, despite its epidemiological importance. We have designed an observational study in a homogeneous group of adult civil servants of Catalonia (n = 8,202) from 20 to 54 years old that were submitted to a health examination which included a tuberculin test, in order to study the tuberculous infection in these people and to evaluate the factors associated with this infection., Results: The global prevalence of reactivity in tuberculin test was 22.36% and the prevalence of the tuberculous infection was 14.76%. The factors related to the tuberculous infection were the following: age, male sex, background of exposure to sources of contagion, and previous BCG vaccination., Conclusions: The prevalence of tuberculous infection in adults has declined, and is currently greater in men than women, among patients who recognize previous contact with a tuberculous patient, and among patients with previous BCG vaccination.

Background: The increase of the atopical disorders can be partially explained by two factors, the infectious disease in developed and developing countries, and the changes in immunization programs, infections such as measles, whooping cough or tuberculosis can modify the immune response. Recent studies have demonstrated that an inverse relation could exist between the response to late cutaneus hypersensitivity to Mycobacterium tuberculosis and atopic condition. Also, a strong positive response has been associated with low levels of IgE and Th1 cytokines. However some authors have not found positivity between low prevalence in allergic diseases and PPD., Objective: To determine the reaction to PPD in children vaccinated with BCG at birth and its disorders., Material and Method: The study sample included male and female children from 2 to 7 years old, vaccinated with BCG at birth, this fact was corroborated with the post vaccination scar. They had all been diagnosed with allergic disease with clinical compatible data, positive Prick test, elevated serum IgE, and absence of any associated immune deficiency., Results: A total of 50 patients, with a mean age of 4.7 years (2.0 to 7.7 years) were studied. 72% (36) were males and 28% (14) females. Twenty-two percent had diagnosis of asthma, 8% allergic rhinitis, and 62% both diagnosis. The average diameter of tuberculin induration was of 5 mm; 5 patients (10%) had positive reaction (+10 mm); 23 patients (46%) were between 5-9 mm; 8 patients (16%) between 1-4 mm, and 14 of the patients (28%) without reactivity., Conclusion: We demonstrated that the vaccination with BCG do not protect against the development of allergy, and the negative tuberculin response may mean a reduced cell response. So, it is necessary to assess the cell immunity and revaccination with BCG, with determination of immunological markers, before and after, such as IL 4, IL 2, INF and allergy symptoms.

Background: The aim of this study was to ascertain the positive tuberculin prevalence among the nursing students at the beginning of their studies; to assess the annual tuberculin conversion rate during their studies; to obviate the possibility of false conversions, studying the booster effect., Patients and Methods: Cohort study, prospective, 3 groups not parallels (n = 316), 32 months follow-up in all students. Mean age 21 years (SD = 4; range = 17-39). First phase: before beginning clinical practice, a tuberculin test was undertaken by Mantoux technique with PPD type RT-23 with Tween 80 of 2 TU; this was repeated after 7-10 days, to BCG vaccinated and PPD negative on the first one, to study the booster effect. Second phase: at 18 months we repeated the tuberculin test to PPD negatives including the vaccinates with booster effect but PPD negative. The end of the study was at 32 months, repeating the test to PPD negatives at the end of their nursing studies., Results: Tuberculin prevalence of 12% (38/316); CI 95%: 8.4%-15.6%. There were no significant differences of prevalence between vaccinated and unvaccinated nurse students. The prevalence in women was 8.9% (24/267) and 28.6% (14/49) in men. The only variables with statistical significance for being tuberculin positive were, age (p = 0.002) and sex (p = 0.003). 3/42 vaccinated with BCG (7%) had initial PPD (+); 2/39 of the remaining (5%) showed to be tuberculin positive after the booster effect and 37 tuberculin negative and booster negative. In the conversion study there were 259 valid students at the end of 3 years; there were 14 (5.4%) converters in the second year and 9 (3.5%) in the third year. Tuberculin conversion annual rate was 3.8 per 100 people/year., Conclusions: The tuberculous infection prevalence in nursing students was 12% (38/316). The annual frequency of tuberculin conversion (3.8 per 100 people/year) was higher in our students than in the general population, reinforcing the suitability of making periodical tuberculin control tests in PPD negative student nurses with continuous hospital contact.

The aim of this study is to demonstrate the transference of PPD hypersensibility in an in vitro model, with dialysable colostral leukocyte extract (DCLE) of PPD+ and PPD-mothers, through measurements of leukocyte migration inhibition factor activity (LIF) from blood obtained of the umbilical cord of newborns from PPD+ mothers. The results show that DCLE PPD+ incubated with leukocytes of newborns from PPD- mothers had inhibition of leukocyte migration compared with migration of leukocytes incubated with DCLE PPD-. These results suggest that in this in vitro model, DCLE transfers hypersensibility to PPD.

We analyze serum samples from 70 patients with pulmonary tuberculosis and 50 healthy individuals. The antigenic activity (IgG) against protein purified antigen (PPD) and antigen 60 (A60) from M. tuberculosis. Thirteen patients were also HIV infected, and three patients had AIDS defined by the presence of disseminated tuberculosis. The test using antigen alone showed a 77% sensitivity and 74% specificity when PPD is used. When A60 was used, both values improved (81% sensitivity, 94% specificity). The use of a combined test (PPD and A60) improves the sensitivity (89%) but reduces the specificity (82%). The HIV infected patients showed similar responses to those of other patients. The combined use of different antigens might be useful for diagnosing tuberculosis.

To assess the usefulness of enzyme immunoassay as a rapid method of diagnosing tuberculosis, a study was conducted of 687 serum samples from 271 children and 416 adults. With 55 sera from nontuberculous children as controls, the specificity was 0.98, and with 137 controls from the adult population, 0.93. Prior vaccination with BCG did not influence the level of detectable anti-PPD antibody. The results were similar in healthy PPD-positive and negative adults. The test differentiated mycoses and nontuberculous mycobacterioses from tuberculosis. The sensitivity rates in 49 children and 200 adults diagnosed with bacteriologically confirmed pulmonary and extrapulmonary tuberculosis were calculated at 0.51 and 0.69, respectively. In those tuberculosis cases not bacteriologically confirmed or at other sites, the test was positive in 28.1% of 114 children and in 48.6% of 35 adults. The cost, speed, and availability of reagents for this test were comparable to those for direct microscopic examination. Both methods were positive for 49% of the tuberculosis cases confirmed by culture, and a total of 84% of those cases were found positive using one method or the other. It is concluded that enzyme immunoassay can be especially useful in the rapid diagnosis of nonbacilliferous pulmonary, extrapulmonary, and childhood tuberculosis.

An enzyme-linked immunosorbent assay (ELISA) for the diagnosis of bovine tuberculosis through the detection of specific seric antibodies has recently been developed in our laboratory. In order to assess its reproducibility and select the most adequate antigen, four bovine PPDs from different sources were evaluated in parallel: PPD M. bovis strain AN5, CEPANZO standard (CPZ), PPD M. bovis strain AN5, European Economic Community standard (EEC), PPD M. bovis strain AN5, prepared from non heated bacilli, killed by phenol (P) and PPD. M. bovis BCG strain prepared at the Pasteur Institute, Paris (BCG). Sera from 22 healthy cattle from tuberculosis free area and 20 bacteriologically confirmed tuberculous animals were employed in simultaneous assays. Antibody mean and standard deviations from healthy cattle expressed as optical density (OD) values were 45 +/- 22 when CPZ was used as antigen, 24 +/- 10 with EEC, 103 +/- 56 with P and 56 +/- 20 with BCG. Mean O.D. from tuberculous cattle were 588 +/- 158, 510 +/- 234, 782 +/- 138 and 441 +/- 189 with antigens CPZ, EEC, P and BCG respectively. A close correlation was observed when results obtained with EEC and P were compared with that of CPZ (r: 0.97 and 0.94 respectively). A lower specificity was achieved when BCG was used as antigen being also lower its correlation with the results obtained with CPZ (r: 0.87). It is concluded that our ELISA would achieve similar sensitivity and specificity if CPZ, EEC and P were used as antigens. On the other hand, BCG would not be suitable for this assay.