Phenotypic and genotypic characterization of pyrazinamide resistance among multidrug-resistant Mycobacterium tuberculosis isolates in Zhejiang, China.

To explore the phenotypic and genotypic characterization of pyrazinamide (PZA) resistance among multidrug-resistant Mycobacterium tuberculosis (MDR-TB) isolates in Zhejiang province, a total of 274 MDR-TB isolates were collected. Drug susceptibility testing and spoligotyping were performed on all clinical isolates. In addition, the mutated features of PZA-resistant loci, including pncA and rpsA, were also analyzed by DNA sequencing. Our results showed that the prevalence of PZA resistance among MDR-TB strains in Zhejiang province was 43.07% and that PZA resistance was associated with concomitant resistance to streptomycin. The majority of PZA-resistant MDR-TB isolates belonged to the Beijing family. Mutations within pncA, not rpsA, constituted the primary mechanism of PZA resistance. Among 118 PZA-resistant isolates, 53 different mutations were observed in pncA, and most of them were point mutations. Compared with the phenotypic data, DNA sequencing of pncA has sensitivity and specificity of 77.97% and 96.79%, respectively. Analysis of pncA provided a robust tool for rapid detection of PZA drug resistance.

[Application of quantitative polymerase chain reaction in the differentiation of sarcoidosis and proliferative tuberculosis].

OBJECTIVE: To evaluate the role of mycobacterial infection in the pathogenesis of sarcoidosis by examination of mycobacterial DNA in tissue samples of sarcoidosis and tuberculosis, and to examine the value of quantitative real-time polymerase chain reaction (PCR) in the differentiation of the two diseases. METHODS: Mycobacterium tuberculosis DNA was measured by quantitative real-time PCR from formalin-fixed and paraffin-embedded sections of biopsy samples of lymph nodes and lung tissues from 31 patients with sarcoidosis, 30 patients with tuberculosis and 15 patients with other diseases (as the control samples) in Shanghai Pulmonary Hospital from January 1998 to December 2003. Lung tissues from 15 normal embryonic mice served as the negative control. RESULTS: The positive rate of mycobacterial DNA in the tuberculosis samples (30/30) was higher than that of the sarcoidosis samples (6/31) and of the control samples (2/15). The difference between sarcoidosis and normal samples showed no statistical significance. The absolute and relative copies of mycobacterial DNA in the tuberculosis samples were significantly higher than those in the sarcoidosis and the control samples; while there was no statistical difference between the sarcoidosis and the control samples. There was no positive result in the lung tissues of the embryonic mice. CONCLUSIONS: The results do not show any relationship between mycobacterial infection and sarcoidosis. Quantitative PCR may be a reliable method for the differentiation of sarcoidosis from tuberculosis.

[Analysis of drug resistance to antituberculosis drugs of the first time retreated pulmonary tuberculosis patients in Shanghai].

OBJECTIVE: To investigate antituberculosis drug resistance among the first time retreated pulmonary tuberculosis patients in Shanghai, and therefore to provide evidence for establishing retreatment regimen. METHODS: Analysis was conducted retrospectively on drug susceptibility tests to isoniazid, rifampin, streptomycin, ethambutol and para-aminosalicylates of the first time retreated pulmonary tuberculosis patients with a positive sputum culture in Shanghai Center for Disease Control from January 2002 to December 2004. RESULTS: The total drug resistance rate was 39.6%. The drug resistance rate in male and female patients was 38.5% and 44.4% respectively, the difference being not significant. The drug resistance rate in the young age group, the middle age group and the old age group were 50.0%, 41.6% and 34.6% respectively, the difference being not significant. The total drug resistance rates in the treatment failure group with standard initial chemotherapy and in the relapse group with standard regimen were both higher than in the relapse group with non-standard regimen (70.0%, 47.5%, 28.2%). So do the drug resistance rates of more than two drugs (70.0%, 18.3%, 6.4%). The multi-drug resistance rate of the failures with standard regimen was 70.0%, much higher than the relapses with standard regimen and the relapses with non-standard regimen. In relapses with non-standard initial therapy, the drug resistance rate of patients who received medications > or = 12 months was 55.0%, significantly higher than those treated for 1 - 5 months (13.0%). The drug resistance rate of patients who were treated with one to two drugs was lower than those treated with > or = 3 drugs, but no significant difference was observed (24.4% and 30.8%). CONCLUSION: Drug resistance rate varies in different types of the first time retreated pulmonary tuberculosis patients due to the history of drug use, which indicates that the current standard retreatment regimen is probably ineffective for some patients.