Molecular epidemiology of tuberculosis in rural Matlab, Bangladesh.
OBJECTIVE
To characterise and classify clinical isolates collected from tuberculosis (TB) patients in rural Bangladesh and to investigate the mode of transmission.


METHODS
An epidemiological study using a combination of conventional and molecular methods was performed in a rural  population of Bangladesh. A total of 168 clinical isolates were collected from TB patients. Deletion analysis, used for rapid differentiation of members of the Mycobacterium tuberculosis complex, spoligotyping and variable number tandem repeats of mycobacterial interspersed repetitive  units (VNTR-MIRU) typing were used.


RESULTS
Deletion analysis identified all isolates as M. tuberculosis and further divided them into 109 strains (65%) carrying the M. tuberculosis deletion region 1 (TbD1-intact or 'ancestral' strains) and 59 strains (35%) lacking  this region (TbD1 or 'modern' strains). MIRU analyses showed that 149 strains (89%) had unique patterns, whereas 19 strains (11%) clustered into eight groups. The largest cluster comprised five TbD1 strains of the Beijing type. The rate of recent transmission was estimated to be  6.5%.


CONCLUSIONS
Our results suggest that TB in rural Bangladesh is caused primarily by reactivation of latent infections involving TbD1 intact strains, overlaid with the recent emergence of Beijing strain clusters that include multidrug-resistant isolates.
International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh. sbanu@icddrb.org
S
S
Banu
M K M
MK
Uddin
M R
MR
Islam
K
K
Zaman
T
T
Ahmed
A H
AH
Talukder
M T
MT
Rahman
Z
Z
Rahim
N
N
Akter
R
R
Khatun
R
R
Brosch
H P
HP
Endtz
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015373:Bacterial Typing Techniques / Q000379:methods; D001459:Bangladesh / Q000453:epidemiology; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D055985:Latent Tuberculosis / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000302:isolation & purification*; D012424:Rural Population; D020080:Tandem Repeat Sequences; D014376:Tuberculosis / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D018088:Tuberculosis, Multidrug-Resistant / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D055815:Young Adult