摘要
Background: Molecular diagnosis based on the detection of mutations conferring genetic drug resistance is useful for early diagnosis and treatment of Pre-XDR and XDR-TB patients. However, the study of mutation as a marker to predict Pre-XDR and XDR-TB is rare. Methods: Thirty-four Mycobacterium tuberculosis (MTB) isolates from MDR, Pre-XDR and XDR-TB patients in the upper north of Thailand, who had been identified for drug susceptibility using the indirect agar proportion method from 2005-2012, were examined for genetic site mutations of katG, inhA, and ahpC for isoniazid (INH) drug resistance, rpoB for rifampicin (RIF) drug resistance, gyrA for ofloxacin (OFX), and rrs for kanamycin (KAN). Associations between resistant genes and Pre-XDR and XDR-TB in the MDR patients were performed using exact probability tests. Univariable logistic regression was used to quantify the strength of association between the gene mutation with Mycobacterium tuberculosis and the prevalence of Pre-XDR and XDR-TB in the MDR patients. Results: The mutations in the region of the rpoB gene at codon 445 (C445T) in the Pre-XDR or XDR-TB patients were significantly 20.6 times more prevalent among the MDR-TB patients. The inhA gene mutation at codon 114 (T114G) was also significantly 8.1 times more prevalent. Conclusion: The findings can be used to predict the odds of Pre-XDR and XDR-TB in MDR-TB patients, as a guide for prevention and treatments.
Background: Molecular diagnosis based on the detection of mutations conferring genetic drug resistance is useful for early diagnosis and treatment of Pre-XDR and XDR-TB patients. However, the study of mutation as a marker to predict Pre-XDR and XDR-TB is rare. Methods: Thirty-four Mycobacterium tuberculosis (MTB) isolates from MDR, Pre-XDR and XDR-TB patients in the upper north of Thailand, who had been identified for drug susceptibility using the indirect agar proportion method from 2005-2012, were examined for genetic site mutations of katG, inhA, and ahpC for isoniazid (INH) drug resistance, rpoB for rifampicin (RIF) drug resistance, gyrA for ofloxacin (OFX), and rrs for kanamycin (KAN). Associations between resistant genes and Pre-XDR and XDR-TB in the MDR patients were performed using exact probability tests. Univariable logistic regression was used to quantify the strength of association between the gene mutation with Mycobacterium tuberculosis and the prevalence of Pre-XDR and XDR-TB in the MDR patients. Results: The mutations in the region of the rpoB gene at codon 445 (C445T) in the Pre-XDR or XDR-TB patients were significantly 20.6 times more prevalent among the MDR-TB patients. The inhA gene mutation at codon 114 (T114G) was also significantly 8.1 times more prevalent. Conclusion: The findings can be used to predict the odds of Pre-XDR and XDR-TB in MDR-TB patients, as a guide for prevention and treatments.
