Genotype and phenotype relationships and transmission analysis of drug-resistant tuberculosis in Singapore

• Published in: The international journal of tuberculosis and lung disease Vol. 11; no. 4; pp. 436 - 442
• Main Authors: SUN, Y-J, LEE, A. S. G, WONG, S-Y, HEERSMA, H, KREMER, K, VAN SOOLINGEN, D, PATON, N. I
• Format: Journal Article
• Language: English
• Published: Paris, France IUATLD 01.04.2007; Union internationale contre la tuberculose et les maladies respiratoires
• Subjects: Antitubercular Agents - pharmacology; Bacterial diseases; Beijing Genotype; Biological and medical sciences; Cluster Analysis; Drug-Resistant Tuberculosis; Human bacterial diseases; Humans; Infectious diseases; Medical sciences; Minisatellite Repeats; Miscellaneous; Molecular Epidemiology; Mycobacterium tuberculosis - drug effects; Mycobacterium tuberculosis - genetics; Pneumology; Polymorphism, Restriction Fragment Length; Prevention and actions; Public health. Hygiene; Public health. Hygiene-occupational medicine; Resistant Phenotype; Singapore - epidemiology; Tuberculosis and atypical mycobacterial infections; Tuberculosis, Multidrug-Resistant - genetics; Tuberculosis, Multidrug-Resistant - transmission; Asia; Singapore; Human; Treatment resistance; Typing; Transmission; Genotype; Mycobacterial infection; Beijing genotype; drug-resistant tuberculosis; Infection; Phenotype; Tuberculosis; resistant phenotype; Bacteriosis; Molecular epidemiology; Pneumology
• ISSN: 1027-3719; 1815-7920

SETTING: The small urban country of Singapore. OBJECTIVES: To investigate the relationships between Mycobacterium tuberculosis genotypes and drug-resistant phenotypes and to analyse the transmission of drug-resistant tuberculosis (DR-TB). DESIGN: 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.