Abstract:
The spread of multidrug-resistant (MDR) strains of Mycobacterium
tuberculosis has become a major public health concern since these
bacteria often cause incurable disease, even when expensive second- and
third-line drugs are available.
This study aimed to identify M. tuberculosis among suspected
tuberculous patients in Khartoum State by using conventional methods
also to identify rifampicin resistance M. tuberculosis by amplifying (rpo
B) gene, using polymerase chain reaction (PCR).
128 sputum samples were collected from suspected tuberculosis patients.
Direct smears were performed by using ZN stains, the results showed that
36 (21.7%) were positive for AFB while 92 (78.3) were negative. All
sputum samples were inoculated on Lowenstein Jensen medium and
incubated aerobically at 37°C,the isolates showed obvious growth in 46
(36%) whereas 82 (64%) showed no growth.
Selected biochemical tests were performed to all Mycobacterium
tuberculosis complex (MTC) isolates, the results revealed that all isolates
were sensitive to Para-nitro benzoic acid ( growth was inhibited by PNB),
resistant to Thiophene - 2 - Carboxylic Acid Hydrazide (TCH), positive
for nitrate reduction and were Catalase negative at 68°C.
All the forty six isolates that showed typical growth of MTC on LJ
medium were subjected to PCR to amplify (IS 6110) gene .The results
indicate clearly that all isolates showed positive results for (IS 6110),
123bp.
Drug sensitivity tests were performed to all isolates, the results showed
that 26 (56.5%) as MDR-TB, 16 (34.8%) as sensitive to rifampicin,
Isoniazid, Ethambutol and streptomycin, 2 (4.4%) as resistance to
streptomycin, and 2(4.4%) as triple resistance to Isoniazid, Ethambutol
and streptomycin.
The thirty resistant isolates were subjected to PCR searching for
rifampicin resistance gene (rpoB) with band equal to 193bp in size, the
results showed existence of this band in (86.7%). Due to the low
sensitivity of ZN technique and the long time required to conduct Drug
susceptibility Test (DST) through conventional method, the results
concluded the PCR is evaluable, rapid and sensitive technique which can
replace conventional method.
