科研之友
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摘要
objective: to compare four laboratory methods in the diagnosis of pulmonary tuberculosis. methods: respiratory secretion specimens were collected from 160 patients suspected of having pulmonary tuberculosis. direct testing for mycobacterium tuberculosis was carried out using ziehl-neelsen and auramine staining. in addition, culture in lˋwenstein-jensen (lj) medium and polymerase chain reaction (pcr) were used. the strains isolated were identified by means of a radiometric method using p-nitro-alpha-acetylamino-beta-hydroxypropiophenone (nap) and classical methods. the sensitivity of the methods was compared to the gold standard for the diagnosis of pulmonary tuberculosis, based on clinical, radiological and microbiological criteria. results: of the 160 patients, 142 were diagnosed with pulmonary tuberculosis according to the gold standard. the sensitivity of ziehl-neelsen staining, auramine staining, culture in lj medium and pcr was 54.2%, 58.4%, 67.6% and 77.5%, respectively, when compared with the diagnostic criterion adopted. all four methods presented 100% specificity. in the identification of mycobacteria, there was high (96.8%) concordance between pcr and the radiometric method using nap. the sensitivity of pcr was 50.8% in samples with negative sputum smear microscopy results and 98.8% in those with positive results. the sensitivity of pcr was lower in specimens with negative results in sputum smear microscopy and culture than in those with positive results (25.6% and 99.0%, respectively). conclusions: we found pcr to be a promising method for the diagnosis of pulmonary tuberculosis, even in paucibacillary specimens. simultaneous identification and faster results are additional advantages of this method.
