RESUMO
SETTING: Urban public teaching and referral hospital in Espirito Santo, Brazil. OBJECTIVE: To assess whether rates of infection and progression to active tuberculosis (TB) differed between household contacts of patients with multidrug-resistant (MDR) and drug susceptible (DS) pulmonary tuberculosis. DESIGN: Household contacts were assessed for evidence of TB infection and disease by purified protein derivative (PPD) skin testing, physical examination, chest X-ray, and sputum smear and culture. RESULTS: Among 133 close contacts of patients with MDR-TB, 44% were PPD-positive (> or =10 mm) compared to 37% of 231 contacts of the DS-TB cases (P = 0.18, chi2 test, OR 1.2, 95%CI 0.8-2). In a multivariate logistic regression analysis, after allowance for between-household variation in PPD responses, PPD positivity among household contacts of patients with MDR-TB remained comparable to PPD positivity in contacts of patients with DS-TB (OR 2.1, 95%CI 0.7-6.5). Respectively six (4%) and 11 (4%) contacts of the MDR- and DS-TB cases were found to have active TB at the time of initial evaluation or during follow-up (P = 0.78, chi2 test). Five of six contacts of MDR-TB cases and nine of nine contacts of DS-TB cases who developed TB, and for whom drug susceptibility test results were available, had the same bacterial susceptibility profiles as their index cases. DNA fingerprinting analysis of Mycobacterium tuberculosis isolates was identical between household contacts with active TB and the index MDR or DS-TB case for all 14 pairs compared. CONCLUSION: Our data suggest that the prevalence of tuberculous infection and progression to active TB among household contacts exposed to DS and MDR-TB cases is comparable, despite a longer duration of exposure of contacts to the index case in patients with MDR-TB.
Assuntos
Transmissão de Doença Infecciosa/estatística & dados numéricos , Tuberculose Resistente a Múltiplos Medicamentos/diagnóstico , Tuberculose Resistente a Múltiplos Medicamentos/transmissão , Adolescente , Adulto , Distribuição por Idade , Brasil/epidemiologia , Estudos de Coortes , Intervalos de Confiança , Progressão da Doença , Características da Família , Feminino , Hospitais de Ensino , Humanos , Controle de Infecções , Masculino , Radiografia Pulmonar de Massa , Pessoa de Meia-Idade , Razão de Chances , Exame Físico , Prevalência , Fatores de Risco , Distribuição por Sexo , Escarro/microbiologia , Teste Tuberculínico , Tuberculose Resistente a Múltiplos Medicamentos/epidemiologia , Tuberculose Pulmonar/diagnóstico , Tuberculose Pulmonar/epidemiologia , Tuberculose Pulmonar/transmissão , População UrbanaRESUMO
An enzyme-linked immunosorbent assay (ELISA) was evaluated as a serodiagnostic test for active tuberculosis in La Paz, Bolivia. ELISA was compared with sputum smear in 277 persons presenting to the Instituto de Torax and was used for screening in 1,458 military personnel. The test was performed under field conditions on 4-microliter samples of capillary blood obtained by finger prick. ELISA was found to have a sensitivity of 69% and a specificity of 88%. Sputum smear had a sensitivity of 79% and a specificity of 100%. ELISA was found to have undiminished sensitivity and specificity in patients who were sputum-negative, and the two tests could be combined to achieve a sensitivity of 92% and specificity of 88%. Positive and negative predictive values were highest for populations with tuberculosis prevalences in the range of that seen among patients presenting to the Instituto de Torax in Bolivia, but ELISA also led to the diagnosis of tuberculosis in 5 of 1,458 soldiers tested in the screening program.
Assuntos
Ensaio de Imunoadsorção Enzimática , Tuberculose Pulmonar/diagnóstico , Adolescente , Adulto , Bolívia , Diagnóstico Diferencial , Ensaio de Imunoadsorção Enzimática/métodos , Estudos de Avaliação como Assunto , Feminino , Humanos , Masculino , Militares , Mycobacterium tuberculosis/isolamento & purificação , Escarro/microbiologiaRESUMO
Mycobacterium tuberculosis antigen 5 is a protein antigen limited in distribution to M. tuberculosis and M. bovis and capable of eliciting typical delayed tuberculin skin test reactions in humans. A single large batch of this antigen was purified by immunoabsorbent affinity chromatography and used to skin test patients with tuberculosis and other mycobacterial infections and healthy persons in general populations in geographic areas where nonspecific tuberculin reactivity is frequently encountered. Antigen 5 was found to be no more specific as a tuberculin antigen than PPD. If the available data are accepted, then either a disparity in antigen recognition by antibody and T lymphocytes may exist or the widely accepted hypothesis attributing nonspecific tuberculin reactivity to antigenic cross reactivity with other mycobacteria may be incorrect.