ABSTRACT
<I>M. tuberculosis</I> strains were isolated from clinically and bacteriologically confirmed patients to evaluate the susceptibility of clinical <I>M. tuberculosis</I> isolates to fluoroquinolone and to obtain molecular epidemiological information in Zambia,. The pathogens were subjected to susceptibility testing with isoniazid, rifampicin, ethambutol and streptomycin. The minimum inhibitory concentrations to ciprofloxacin, sparfloxacin and levofloxacin were also evaluated. The <I>gyrA</I>, fluoroquinolone resistance-determining region (QRDR), was sequenced and analysed. As a result, three of the 16 strains examined were resistant to isoniazid, rifampicin and⁄or streptomycin. All of the strains were susceptible to ciprofloxacin, levofloxacin and sparfloxacin. However, a unique <I>gyrA</I> gene variation of<I> M. tuberculosis</I> was identified in the isolates. One strain had a mutation (T73A) in QRDR. Additionally, 81.25% (13⁄16) of the strains tested had Thr at codon 88. Several variations of <I>gyrA</I> gene have been reported in relation to drug resistance. The <I>gyrA</I> variation data will be useful as epidemiological information. It may be important to monitor fluoroquinolone susceptibility even in developing countries for use against resistant <I>M. tuberculosis</I> infection, even though no fluoroquinolone resistance was observed in this study.
ABSTRACT
Two egg-based culture media were evaluated for detection of mycobacteria with Löwenstein-Jensen (L-J) as a gold standard. The conventional culture method was modified to improve laboratory diagnosis of tuberculosis in resource scarce countries by employing an inexpensive but sensitive and specific culture method. Sputum samples were collected from pulmonary tuberculosis suspects who visited the chest clinic at the University Teaching Hospital in Zambia. These samples were processed using three different sample treating procedures (with or without sample concentration) and cultured on L-J and Ogawa media for mycobacteria isolation. A total of 276 sputum samples were collected from 138 pulmonary tuberculosis suspects. When the L-J result was used as a standard, the sensitivity of Ogawa and modified Ogawa was 81.7% and 90.3% respectively. Similarly, the specificities of those methods were 96.7% and 92.3% respectively. In total, 90 samples (32.6%) were smear positive and 108 (39.1%) were culture positive. The positivity of each culture method was as follows: 93 (33.7%) in L-J, 98 (35.5%) in modified Ogawa, and 82 (29.7%) in original Ogawa. The contamination rate was 1.1%, 5.1%, and 9.8% for L-J, Ogawa and modified Ogawa respectively. The Ogawa culturing method is economical, simple and quick. Its low sensitivity was overcome by employing the concentration method, the sensitivity significantly improving from 81.7% to 90.3%. Ogawa techniques are ideal in overburdened TB laboratories with poor resources in developing countries.