Molecular epidemiology and evolutionary genetics of Mycobacterium tuberculosis in Taipei.
BACKGROUND
The control of tuberculosis in densely populated cities is complicated by close human-to-human contacts and potential transmission of pathogens from multiple sources. We conducted a molecular epidemiologic analysis of 356 Mycobacterium tuberculosis (MTB) isolates from patients presenting pulmonary tuberculosis in metropolitan Taipei. Classical antibiogram studies and genetic characterization, using mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) typing and spoligotyping, were applied after culture.


METHODS
A total of 356 isolates were genotyped by standard spoligotyping and the strains were compared with in the international spoligotyping database (SpolDB4). All isolates were also categorized using the 15 loci MIRU-VNTR typing method and combin with NTF locus and RD deletion analyses.


RESULTS
Of 356 isolates spoligotyped, 290 (81.4%) displayed known spoligotypes and 66 were not identified in the database. Major spoligotypes found were Beijing lineages (52.5%), followed by Haarlem lineages (13.5%) and EAI plus EAI-like lineages (11%). When MIRU-VNTR was employed, 140 patterns were identified, including 36 clusters by 252 isolates and 104 unique patterns, and the largest cluster comprised 95 isolates from the Beijing family. The combination of spoligotyping and MIRU-VNTR revealed that 236 (67%) of the 356 isolates were clustered in 43 genotypes. Strains of the Beijing family was more likely to be of modern strain and a higher percentage of multiple drug resistance than other families combined (P = 0.08). Patients infected with Beijing strains were younger than those with other strains (mean 58.7 vs. 64.2, p = 0.02). Moreover, 85.3% of infected persons younger than 25 years had Beijing modern strain, suggesting a possible recent spread in the young population by this family of TB strain in Taipei.


CONCLUSIONS
Our data on MTB genotype in Taipei suggest that MTB infection has not been optimally controlled. Control efforts should be reinforced in view of the high prevalence of the Beijing strain in young population and association with drug resistance.
Dou
Horng-Yunn
HY
Division of Clinical Research, National Health Research Institutes, Zhunan, Taiwan, Republic of China. hydou@nhri.org.tw
Tseng
Fan-Chen
FC
Lin
Chih-Wei
CW
Chang
Jia-Ru
JR
Sun
Jun-Ren
JR
Tsai
Wen-Shing
WS
Lee
Shi-Yi
SY
Su
Ih-Jen
IJ
Lu
Jang-Jih
JJ
D015373:Bacterial Typing Techniques; D004269:DNA, Bacterial / Q000032:analysis; D024881:Drug Resistance, Bacterial; D019143:Evolution, Molecular; D005260:Female; D006801:Humans; D008297:Male; D018598:Minisatellite Repeats; D017720:Molecular Epidemiology; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000302:isolation & purification*; D011933:Reagent Kits, Diagnostic; D013624:Taiwan / Q000453:epidemiology; D014376:Tuberculosis / Q000453:epidemiology*; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology
D004269:DNA, Bacterial; D011933:Reagent Kits, Diagnostic