SETTING: The molecular diagnosis of tuberculosis (TB) in Viet Nam is often based on the detection of insertion sequence (IS) 6110 in Mycobacterium tuberculosis. However, 8-11% of M. tuberculosis strains in South-East Asia do not contain this target and this undermines the validity of these molecular tests. OBJECTIVE: We quantified the frequency of M. tuberculosis strains lacking IS6110 in rural Viet Nam and studied their epidemiological and clinical characteristics. DESIGN: Consecutively diagnosed adult TB patients in rural Southern Viet Nam submitted two sputum samples for culture, IS6110 restriction fragment length polymorphism (RFLP) spoligotyping and 15-loci variable number tandem repeat typing. Polymerase chain reaction (PCR) was performed to confirm the absence of IS6110 elements in strains lacking IS6110 hybridisation in RFLP. RESULTS: Among 2664 TB patient isolates examined, 109 (4.1%) had no IS6110 element. Compared to other strains, these no-copy strains were less often resistant to anti-tuberculosis drugs, particularly to streptomycin (adjusted OR 0.2, 95%CI 0.1-0.5), and showed significant geographic variation. No associations with TB history or demographic factors were found. CONCLUSIONS: Strains without the IS6110 target pose a problem in Viet Nam as regards false-negative molecular TB diagnosis in PCR. Compared to other strains circulating in Viet Nam, no-copy strains are more susceptible to anti-tuberculosis drugs.
SETTING: The molecular diagnosis of tuberculosis (TB) in Viet Nam is often based on the detection of insertion sequence (IS) 6110 in Mycobacterium tuberculosis. However, 8-11% of M. tuberculosis strains in South-East Asia do not contain this target and this undermines the validity of these molecular tests. OBJECTIVE: We quantified the frequency of M. tuberculosis strains lacking IS6110 in rural Viet Nam and studied their epidemiological and clinical characteristics. DESIGN: Consecutively diagnosed adult TB patients in rural Southern Viet Nam submitted two sputum samples for culture, IS6110 restriction fragment length polymorphism (RFLP) spoligotyping and 15-loci variable number tandem repeat typing. Polymerase chain reaction (PCR) was performed to confirm the absence of IS6110 elements in strains lacking IS6110 hybridisation in RFLP. RESULTS: Among 2664 TB patient isolates examined, 109 (4.1%) had no IS6110 element. Compared to other strains, these no-copy strains were less often resistant to anti-tuberculosis drugs, particularly to streptomycin (adjusted OR 0.2, 95%CI 0.1-0.5), and showed significant geographic variation. No associations with TB history or demographic factors were found. CONCLUSIONS: Strains without the IS6110 target pose a problem in Viet Nam as regards false-negative molecular TB diagnosis in PCR. Compared to other strains circulating in Viet Nam, no-copy strains are more susceptible to anti-tuberculosis drugs.
Authors: Donald G Catanzaro; Rebecca E Colman; Yvonne Linger; Sophia B Georghiou; Alexander V Kukhtin; Marva Seifert; Rebecca C Holmberg; Haifa Mshaiel; Peter Chiles; Naomi Hillery; Christopher G Cooney; Timothy C Rodwell Journal: J Clin Microbiol Date: 2020-10-21 Impact factor: 5.948
Authors: David S Boyle; Ruth McNerney; Hwee Teng Low; Brandon Troy Leader; Ailyn C Pérez-Osorio; Jessica C Meyer; Denise M O'Sullivan; David G Brooks; Olaf Piepenburg; Matthew S Forrest Journal: PLoS One Date: 2014-08-13 Impact factor: 3.240
Authors: Juliana Maria Azevedo de Lyra; Magda Maruza; Mirela Verza; Maria Madileuza Carneiro; Maria de Fátima Militão de Albuquerque; Maria Lúcia Rossetti; Ricardo Ximenes; Maria Cynthia Braga; Norma Lucena-Silva Journal: Mem Inst Oswaldo Cruz Date: 2014-08-29 Impact factor: 2.743
Authors: El Mehdi Bentaleb; Mohammed Abid; My Driss El Messaoudi; Brahim Lakssir; El Mostafa Ressami; Saaïd Amzazi; Hassan Sefrioui; Hassan Ait Benhassou Journal: BMC Infect Dis Date: 2016-09-27 Impact factor: 3.090