Limits...
Genotypic detection of rifampicin and isoniazid resistant Mycobacterium tuberculosis strains by DNA sequencing: a randomized trial.

Abdelaal A, El-Ghaffar HA, Zaghloul MH, El Mashad N, Badran E, Fathy A - Ann. Clin. Microbiol. Antimicrob. (2009)

Bottom Line: Direct sequencing of Kat G gene revealed point mutation in 24/26 (92.3%) and the remaining 2/26 (7.7%) had wild type KatG i.e. no evidence of mutation with a high statistical significant difference between them (P < 0.001).We can conclude that rifampicin resistance could be used as a useful surrogate marker for estimation of multidrug resistance.In addition, Genotypic method was superior to that of the traditional phenotypic method which is time-consuming taking several weeks or longer.

View Article: PubMed Central - HTML - PubMed

Affiliation: Clinical Pathology Department, Faculty of Medicine, Mansoura University, Mansoura, Egypt. Amina_abdelaal@yahoo.com

ABSTRACT

Background: Tuberculosis is a growing international health concern. It is the biggest killer among the infectious diseases in the world today. Early detection of drug resistance allows starting of an appropriate treatment. Resistance to drugs is due to particular genomic mutations in specific genes of Mycobacterium tuberculosis(MTB). The aim of this study was to identify the presence of Isoniazid (INH) and Rifampicin(RIF) drug resistance in new and previously treated tuberculosis (TB) cases using DNA sequencing.

Methods: This study was carried out on 153 tuberculous patients with positive Bactec 460 culture for acid fast bacilli.

Results: Of the 153 patients, 105 (68.6%) were new cases and 48 (31.4%) were previously treated cases. Drug susceptibility testing on Bactec revealed 50 resistant cases for one or more of the first line antituberculous. Genotypic analysis was done only for rifampicin resistant specimens (23 cases) and INH resistant specimens (26 cases) to detect mutations responsible for drug resistance by PCR amplification of rpoB gene for rifampicin resistant cases and KatG gene for isoniazid resistant cases. Finally, DNA sequencing was done for detection of mutation within rpoB and KatG genes. Genotypic analysis of RIF resistant cases revealed that 20/23 cases (86.9%) of RIF resistance were having rpoB gene mutation versus 3 cases (13.1%) having no mutation with a high statistical significant difference between them (P < 0.001). Direct sequencing of Kat G gene revealed point mutation in 24/26 (92.3%) and the remaining 2/26 (7.7%) had wild type KatG i.e. no evidence of mutation with a high statistical significant difference between them (P < 0.001).

Conclusion: We can conclude that rifampicin resistance could be used as a useful surrogate marker for estimation of multidrug resistance. In addition, Genotypic method was superior to that of the traditional phenotypic method which is time-consuming taking several weeks or longer.

Show MeSH

Related in: MedlinePlus

rpoB gene mutations detected by DNA sequencing in RIF resistant cases.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2654859&req=5

Figure 2: rpoB gene mutations detected by DNA sequencing in RIF resistant cases.

Mentions: The commonest point mutation (table 9 & figure 2) was found at codon 531 in 9/20 (45%) with serine-->leucine substitution (TCG-->TTG). The second type of mutation was detected at codon 526 in 6/20 (30%) with histidine -->aspartate substitution (CAC-->GAC), followed by codon 516 in 4/20 (20%) with aspartate--> valine substitution (GAC-->GTC). The lowest point mutation was found at codon 522 in 1/20 (5%) with serine--> leucine substitution (TCG-->TTG). These results were similar to Kim et al.[22] in Korea, who found high-mutation frequencies of codon 526 (37.8%) and codon 531 (24.4%) in rifampin-resistant strains. Also, these findings were more or less in agreement with those results of the United States[23,24], Japan[25,26], Australia[27], Asia [28]Brazil and France,[29] China,[30] and in Netherlands[31].


Genotypic detection of rifampicin and isoniazid resistant Mycobacterium tuberculosis strains by DNA sequencing: a randomized trial.

Abdelaal A, El-Ghaffar HA, Zaghloul MH, El Mashad N, Badran E, Fathy A - Ann. Clin. Microbiol. Antimicrob. (2009)

rpoB gene mutations detected by DNA sequencing in RIF resistant cases.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2654859&req=5

Figure 2: rpoB gene mutations detected by DNA sequencing in RIF resistant cases.
Mentions: The commonest point mutation (table 9 & figure 2) was found at codon 531 in 9/20 (45%) with serine-->leucine substitution (TCG-->TTG). The second type of mutation was detected at codon 526 in 6/20 (30%) with histidine -->aspartate substitution (CAC-->GAC), followed by codon 516 in 4/20 (20%) with aspartate--> valine substitution (GAC-->GTC). The lowest point mutation was found at codon 522 in 1/20 (5%) with serine--> leucine substitution (TCG-->TTG). These results were similar to Kim et al.[22] in Korea, who found high-mutation frequencies of codon 526 (37.8%) and codon 531 (24.4%) in rifampin-resistant strains. Also, these findings were more or less in agreement with those results of the United States[23,24], Japan[25,26], Australia[27], Asia [28]Brazil and France,[29] China,[30] and in Netherlands[31].

Bottom Line: Direct sequencing of Kat G gene revealed point mutation in 24/26 (92.3%) and the remaining 2/26 (7.7%) had wild type KatG i.e. no evidence of mutation with a high statistical significant difference between them (P < 0.001).We can conclude that rifampicin resistance could be used as a useful surrogate marker for estimation of multidrug resistance.In addition, Genotypic method was superior to that of the traditional phenotypic method which is time-consuming taking several weeks or longer.

View Article: PubMed Central - HTML - PubMed

Affiliation: Clinical Pathology Department, Faculty of Medicine, Mansoura University, Mansoura, Egypt. Amina_abdelaal@yahoo.com

ABSTRACT

Background: Tuberculosis is a growing international health concern. It is the biggest killer among the infectious diseases in the world today. Early detection of drug resistance allows starting of an appropriate treatment. Resistance to drugs is due to particular genomic mutations in specific genes of Mycobacterium tuberculosis(MTB). The aim of this study was to identify the presence of Isoniazid (INH) and Rifampicin(RIF) drug resistance in new and previously treated tuberculosis (TB) cases using DNA sequencing.

Methods: This study was carried out on 153 tuberculous patients with positive Bactec 460 culture for acid fast bacilli.

Results: Of the 153 patients, 105 (68.6%) were new cases and 48 (31.4%) were previously treated cases. Drug susceptibility testing on Bactec revealed 50 resistant cases for one or more of the first line antituberculous. Genotypic analysis was done only for rifampicin resistant specimens (23 cases) and INH resistant specimens (26 cases) to detect mutations responsible for drug resistance by PCR amplification of rpoB gene for rifampicin resistant cases and KatG gene for isoniazid resistant cases. Finally, DNA sequencing was done for detection of mutation within rpoB and KatG genes. Genotypic analysis of RIF resistant cases revealed that 20/23 cases (86.9%) of RIF resistance were having rpoB gene mutation versus 3 cases (13.1%) having no mutation with a high statistical significant difference between them (P < 0.001). Direct sequencing of Kat G gene revealed point mutation in 24/26 (92.3%) and the remaining 2/26 (7.7%) had wild type KatG i.e. no evidence of mutation with a high statistical significant difference between them (P < 0.001).

Conclusion: We can conclude that rifampicin resistance could be used as a useful surrogate marker for estimation of multidrug resistance. In addition, Genotypic method was superior to that of the traditional phenotypic method which is time-consuming taking several weeks or longer.

Show MeSH
Related in: MedlinePlus