IMC Journal of Medical Science
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Ibrahim Medical College Journal of Medical ScienceMd. MohiuddinJ. Ashraful Haq https://www.imcjms.com/registration/journal_full_text/69
2016-08-02 12:06:05Original ArticleIbrahim Med. Coll. J. 2014; 8(2): 41-46
0.05).
Table-7: Rate of
isolation of MDR-TB from untreated and treated pulmonary tuberculosis cases
Table-9: Rate of
concomitant resistance of RIF / INH / ETH /SM sensitive M. tuberculosis to
corresponding drugs
Table-9 shows the concomitant resistance rate
of M. tuberculosis to any three first line anti-TB drugs which were
sensitive to RIF, INH, ETH or SM. Rate of resistance to three other drugs
ranged from 34.78% to 43.21% among RIF, INH, ETH or SM sensitive isolates.
Discussion
Monitoring of drug resistance pattern, early
diagnosis and initiating prompt treatment has been the mainstay to interrupt
the transmission of tuberculosis. In this context, the present study was
designed to determine the drug resistance pattern of mycobacterium. In the
present study, about 70.0% sputum samples yielded positive culture results on
L-J media. Various authors have reported similar culture positivity rate in L-J
media which ranged from 59.72 to 87.2%.8-11 However, the culture positivity rate was only
44.0% in lymph node aspirate samples. The failure to isolate mycobacteria in
about 30-56% sputum and lymph node aspirates was due to contamination of media
or damage to organisms during decontamination process. Previous studies
reported the contamination rate from 1.2% to 27.2%.9-13 Therefore, the isolation
rate of mycobacteria can be increased if contamination is prevented and sample
processing procedure is further improved. Out of the 200 isolates of
mycobacteria, 96.0% were M. tuberculosis and 4.0% were MOTT. Earlier, a
study in Dhaka by Miah et al. reported 95.3% isolates as M.
tuberculosis and 4.7% as MOTT.3
The resistance pattern of first line
anti-tubercular drugs observed in the present study among untreated cases was
almost similar to the resistance pattern reported previously in 2000 and 2007.3,4 Almost similar rate of
resistance was observed in other neighboring countries.14,15
In the present study, out of 30 RIF resistant M.
tuberculosis, 83.3% were also concomitantly or cross resistant to other
three first line anti-tubercular drugs (p<0.05; Table-8). On the other hand,
of the 50 INH resistant M. tuberculosis, 64.0% were concomitantly or
cross resistant to other three first line anti tubercular drugs (p>0.05)
while for ETH and SM the rate was 74.3% and 55.5% respectively. Resistance to
RIF in M. tuberculosis occurs in a high frequency and mono resistance to
RIF is rare, whereas mono resistance to INH is common.17 It has been proposed that
resistance to RIF can be used as a surrogate marker for MDR-TB as nearly 90% of
the RIF resistant strains are also INH resistant.17,18 It is to be noted that only
43.21% M. tuberculosis isolates which were sensitive to RIF, was
concomitantly resistant to other 3 drugs (Table-9). This indicates that a
sensitive M. tuberculosis isolates (sensitive to RIF, INH, ETH and SM)
could be resistant to any of the three other first line anti-TB drugs and it
could not therefore, predict that if an isolate sensitive to any single first
line drug would simultaneously be sensitive to other three drugs.
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