Genotype and phenotype relationships and transmission analysis of drug-resistant tuberculosis in Singapore.
METHODS
The small urban country of Singapore.


OBJECTIVE
To investigate the relationships between Mycobacterium tuberculosis genotypes and drug-resistant phenotypes and to analyse the transmission of drug-resistant tuberculosis (DR-TB).


METHODS
A 29-month population-based study comparing drug-resistant and drug-susceptible M. tuberculosis isolates.


RESULTS
We found that multidrug-resistant (MDR) isolates (n = 41, OR 2.66, 95%CI 1.28-5.50), rifampicin-resistant isolates (n = 48, OR 2.88, 95%CI 1.44-5.76), and streptomycin (SM) resistant isolates (n = 103, OR 3.35, 95%CI 1.99-5.62) were more common among Beijing genotype strains than among non-Beijing strains, while SM-resistant isolates were less common in East-African-Indian (EAI) genotype strains than in non-EAI strains (OR 0.30, 95%CI 0.14-0.64). Based on clustering analysis and drug-resistant patterns, 22 of 230 drug-resistant isolates were found to have likely resulted from recent transmission. The estimated transmission rate of DR-TB was 9.6% and that of MDR-TB was 7.7%. The transmission rate of DR-TB was significantly higher among Beijing genotype strains than non-Beijing strains (12.9% vs. 4.4%; P = 0.034).


CONCLUSIONS
Compared to other genotypes, Beijing genotype strains are associated with a higher frequency of drug resistance, including multidrug resistance, and are more transmissible. However, the overall transmission rate of DR-TB in Singapore is low.
Sun
Y-J
YJ
Infectious Disease Research Laboratory, Department of Infectious Diseases, TTSH Medical Centre, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433. yong_jiang_sun@ttsh.com.sg
Lee
A S G
AS
Wong
S-Y
SY
Heersma
H
H
Kremer
K
K
van Soolingen
D
D
Paton
N I
NI
D000995:Antitubercular Agents / Q000494:pharmacology; D016000:Cluster Analysis; D006801:Humans; D018598:Minisatellite Repeats; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D012846:Singapore / Q000453:epidemiology; D018088:Tuberculosis, Multidrug-Resistant / Q000235:genetics* / Q000635:transmission*
D000995:Antitubercular Agents