Detection of mutations in the katG gene among isoniazid-resistant Mycobacterium tuberculosis isolates from Lebanon and Syria

Infection of Mycobacterium tuberculosis (MTB) is one of the most common infections in humans. However, the detection rate is only 37% of estimated patients. Currently, Tuberculosic bacteria (TB) are becoming more serious with many TB strains developing multi-drug resistance, and particularly, in case of co-infection with TB and HIV/AIDS. The izoniazid resistant TB strains (INH) also resistant to the other anti-TB antibiotics. The molecular biology methods have allowed rapid and accurate diagnosis of patients infected with drug-resistant TB bacteria. In this study, we used primers katG-F and katG-R designed for amplication of a fragment of 684 bp in katG gene in 7 strains of TB bacteria collected in Pham Ngoc Thach - Ho Chi Minh city and Hue Central hospitals. Sequence analysis of the katG gene fragments showed that 5 samples had substitution mutations at codon 315 (point mutation G to C), leading to the change of amino acid from Serine to Threonine (S315T). In the 5th sample there appeared another mutation at codon 324, changing amino acid Aspartic (D) to Glycine (G) (D324G). In the sample DA1, no mutation has been found in any codon in the katG gene fragment studied. The results obtained in this study may have important implications in changing the treatment regimen and control of tuberculosis in a country with high number of TB patients as in Vietnam.

Download Full-text

Detection of mutations associated with isoniazid resistance in multidrug-resistant Mycobacterium tuberculosis clinical isolates

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dku161 ◽

2014 ◽

Vol 69 (9) ◽

pp. 2369-2375 ◽

Cited By ~ 32

Author(s):

Tomasz Jagielski ◽

Zofia Bakuła ◽

Katarzyna Roeske ◽

Michał Kamiński ◽

Agnieszka Napiórkowska ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Multidrug Resistant ◽

Clinical Isolates ◽

Isoniazid Resistance ◽

Detection Of Mutations

Download Full-text

Evaluation of a Bacteriophage-Based Assay (Phage Amplified Biologically Assay) as a Rapid Screen for Resistance to Isoniazid, Ethambutol, Streptomycin, Pyrazinamide, and Ciprofloxacin among Clinical Isolates of Mycobacterium tuberculosis

Journal of Clinical Microbiology ◽

10.1128/jcm.37.11.3528-3532.1999 ◽

1999 ◽

Vol 37 (11) ◽

pp. 3528-3532 ◽

Cited By ~ 30

Author(s):

I. J. Eltringham ◽

S. M. Wilson ◽

F. A. Drobniewski

Keyword(s):

Mycobacterium Tuberculosis ◽

Rapid Determination ◽

Low Cost ◽

Resistance Ratio ◽

Clinical Isolates ◽

Rapid Screening ◽

Ratio Method ◽

Predictive Values ◽

Molecular Assays ◽

Detection Of Mutations

Rapid molecular assays for the detection of mutations associated with rifampin resistance in Mycobacterium tuberculosis are commercially available. However, they are complex and expensive and have predictive values of 90 to 95%. Molecular assays for other drugs are less predictive of resistance. Ideally, assays based on phenotypic markers should be used for susceptibility testing, but these can take weeks to complete. We previously described a rapid phenotypic assay, the phage amplified biologically (PhaB) assay, for the rapid determination of rifampin and isoniazid susceptibility in clinical isolates of M. tuberculosis. In this study, we extended the assay to the study of ethambutol, pyrazinamide, streptomycin, and ciprofloxacin. After the optimization of antibiotic concentrations and incubation conditions, the assay was applied to each drug for a total of 157 isolates. The correlations between the results of the PhaB assay and the resistance ratio method were 94% for isoniazid, 96% for streptomycin, 100% for ciprofloxacin, 88% for ethambutol, and 87% for pyrazinamide. For ciprofloxacin, ethambutol, and pyrazinamide, significantly better correlations were found when a 90% reduction in plaque count was used as the cutoff. Turnaround times for the PhaB assay were 2 to 3 days, compared with 10 days for the resistance ratio method. We believe that this low-cost assay may have widespread applicability for the rapid screening of drug resistance in M. tuberculosis isolates, especially in developing countries.

Download Full-text

Characterization of Mutations Conferring Extensive Drug Resistance to Mycobacterium tuberculosis Isolates in Pakistan

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.05101-11 ◽

2011 ◽

Vol 55 (12) ◽

pp. 5654-5659 ◽

Cited By ~ 31

Author(s):

Asho Ali ◽

Rumina Hasan ◽

Kauser Jabeen ◽

Nusrat Jabeen ◽

Ejaz Qadeer ◽

...

Keyword(s):

Drug Resistance ◽

Mycobacterium Tuberculosis ◽

Hot Spot ◽

East African ◽

Content Type ◽

Diagnostic Assays ◽

Asian Strain ◽

Central Asian ◽

Extensive Drug Resistance ◽

Detection Of Mutations

ABSTRACTThe increasing incidence of extensively drug-resistant (XDR)Mycobacterium tuberculosisin high-tuberculosis-burden countries further highlights the need for improved rapid diagnostic assays. An increasing incidence of XDRM. tuberculosisstrains in Pakistan has been reported, but drug resistance-associated mutations in these strains have not been evaluated previously. We sequenced the “hot-spot” regions ofrpoB,katG,inhA,ahpC,gyrA,gyrB, andrrsgenes in 50 XDRM. tuberculosisstrains. It was observed that 2% of rifampin, 6% of isoniazid, 24% of fluoroquinolone, and 32% of aminoglycoside/capreomycin resistance in XDRM. tuberculosisstrains would be undetected if only these common hot-spot regions were tested. The frequencies of resistance-conferring mutations were found to be comparable among all XDRM. tuberculosisstrain families present, including the Central Asian Strain, Beijing, and East African Indian genogroups and the Unique isolates. Additional genetic loci need to be tested for detection of mutations conferring fluoroquinolone, aminoglycoside, and capreomycin resistance in order to improve molecular diagnosis of regional XDRM. tuberculosisstrains.

Download Full-text