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The rate of recovery and time to the detection of mycobacteria from clinical specimens were measured for biphasic (MB-Check; Nippon Roche Co., Ltd., Tokyo, Japan) and radiometric (BACTEC; Nippon Becton Dickinson Co., Ltd., Tokyo, Japan) liquid-based culture systems and egg-based media (3% Ogawa and Ogawa K). From the 245 sputum specimens processed, a total of 86 (35.1%) mycobacterial isolates were detected. Of these, 81 (94.2%) and 80 (93.01%) isolates were detected with the MB-Check and BACTEC systems, respectively, and 65 (75.6%) isolates were detected with the 3% Ogawa egg method. The difference in the percentages of positive cultures between the two systems based on liquid media and the 3% Ogawa egg method was significant (P < 0.01). This difference was even greater among smear-negative specimens. The detection time was shorter with the liquid-based systems. The mean times to the detection of the Mycobacterium tuberculosis complex were 19.1 days with the MB-Check system, 13.4 days with the BACTEC system, and 21.7 days with the 3% Ogawa egg method. These results indicate that both the MB-Check and the BACTEC systems, based on liquid media, are efficient for the recovery of mycobacteria.

A high rate of double point mutations in gyrA (56% of 87 ofloxacin-resistant Mycobacterium tuberculosis clinical isolates) indicates the emergence of fluoroquinolone resistance. This is the first report to describe denaturing high-pressure liquid chromatography analysis of mutations in gyrA of M. tuberculosis in a large number of clinical isolates.Up to the present, fluoroquinolones have been studied as a first-line treatment for tuberculosis (9). However, fluoroquinolone resistance among Mycobacterium tuberculosis strains is emerging, with important implications for treatment (4, 6). Fluoroquinolones have been widely used for tuberculosis treatment in China for more than 10 years and have been given routinely as monotherapy for the empirical treatment of numerous outpatient infections. Thus, China may be one of the countries with the highest rate of fluoroquinolone abuse and resistance in the world. The goal of this work was to identify quinolone resistance-determining regions (QRDRs) of gyrA in ofloxacin-resistant isolates from China by denaturing highpressure liquid chromatography (DHPLC) and DNA sequencing methods.( All the isolates contain a naturally occurring polymorphism, codon 95 AGC3ACC. Seventy-three (84%) of the 87 ofloxacin-resistant clinical isolates were found to carry a codon 94 mutation, and 49 (56%) were found to harbor a double point mutation. 4566on May 9, 2018 by guest

To gain a better understanding of the pathological role of interferon-y (IFN-y) in specific granuloma formation, IFN-y gene-deficient mice (BALB/c and C57BL/6) were produced. The IFN-y gene in embryonic stem (ES) cells was disrupted by inserting the P-galactosidase gene (IacZ) and the neomycin resistance gene ( m u ) at the translation initiation site in exon 1 by homologous recombination. Six-week-old IFN-y-deficient and wild-type mice were inoculated with lo3 -10' bacilli of various strains of Mycobacteriurn tuberculosis (Kurono, H37Rv, H37Ra and BCG Pasteur) through their tail veins. The mice were examined 7 weeks later for granuloma formation. The avirulent BCG Pasteur and H37Ra strains (lo3-lo4 bacilli/ml) induced granulomas in the spleen, liver and lungs of IFN-y-deficient mice. The granulomas consisted of epithelioid macrophages and Langhans multinucleate giant cells, but lacked caseous necrosis. The virulent Kurono and H37Rv strains induced disseminated abscesses but not granulomas in various organs of IFN-y-deficient mice and Mac-3-positive macrophages were not detected in the abscess lesions. These results suggest that IFN-y may be primarily responsible for macrophage activation and that other factor(s) may be involved in the granuloma formation mechanism.