title: Sequence Analysis of Fluoroquinolone Resistance-Associated Genes gyrA and gyrB in Clinical Mycobacterium tuberculosis Isolates from Patients Suspected of Having Multidrug-Resistant Tuberculosis in New Delhi, India.
abstract: Fluoroquinolones (FQs) are broad-spectrum antibiotics recommended for the treatment of multidrug-resistant tuberculosis (MDR-TB) patients. FQ resistance, caused by mutations in the gyrA and gyrB genes of Mycobacterium tuberculosis, is increasingly reported worldwide; however, information on mutations occurring in strains from the Indian subcontinent is scarce. Hence, in this study, we aimed to characterize mutations in the gyrA and gyrB genes of acid-fast bacillus (AFB) smear-positive sediments or of M. tuberculosis isolates from AFB smear-negative samples from patients in India suspected of having MDR-TB. A total of 152 samples from patients suspected of having MDR-TB were included in the study. One hundred forty-six strains detected in these samples were characterized by sequencing of the gyrA and gyrB genes. The extracted DNA was subjected to successive amplifications using a nested PCR protocol, followed by sequencing. A total of 27 mutations were observed in the gyrA genes of 25 strains, while no mutations were observed in the gyrB genes. The most common mutations occurred at amino acid position 94 (13/27 [48.1%]); of these, the D94G mutation was the most prevalent. The gyrA mutations were significantly associated with patients with rifampin (RIF)-resistant TB. Heterozygosity was seen in 4/27 (14.8%) mutations, suggesting the occurrence of mixed populations with different antimicrobial susceptibilities. A high rate of FQ-resistant mutations (17.1%) was obtained among the isolates of TB patients suspected of having MDR-TB. These observations emphasize the need for accurate and rapid molecular tests for the detection of FQ-resistant mutations at the time of MDR-TB diagnosis.
authors.affiliation: Mycobacteriology and Pharmacokinetics Laboratories, National Jewish Health, Denver, Colorado, USA National Reference Laboratory and Centre of Excellence (WHO), Department of Microbiology, National Institute of Tuberculosis and Respiratory Diseases, New Delhi, India.
authors.forename: Ritu
authors.initials: R
authors.lastname: Singhal
authors.affiliation: Department of Academic Affairs, National Jewish Health, Denver, Colorado, USA Department of Pediatrics, National Jewish Health, Denver, Colorado, USA.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Reynolds
authors.affiliation: Mycobacteriology and Pharmacokinetics Laboratories, National Jewish Health, Denver, Colorado, USA.
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Marola
authors.affiliation: Center for Genes, Environment, and Health, National Jewish Health, Denver, Colorado, USA.
authors.forename: L Elaine
authors.initials: LE
authors.lastname: Epperson
authors.affiliation: National Reference Laboratory and Centre of Excellence (WHO), Department of Microbiology, National Institute of Tuberculosis and Respiratory Diseases, New Delhi, India.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Arora
authors.affiliation: Department of Tuberculosis and Chest Diseases, National Institute of Tuberculosis and Respiratory Diseases, New Delhi, India.
authors.forename: Rohit
authors.initials: R
authors.lastname: Sarin
authors.affiliation: National Reference Laboratory and Centre of Excellence (WHO), Department of Microbiology, National Institute of Tuberculosis and Respiratory Diseases, New Delhi, India tbmicro@gmail.com salfingerm@njhealth.org.
authors.forename: Vithal Prasad
authors.initials: VP
authors.lastname: Myneedu
authors.affiliation: Center for Genes, Environment, and Health, National Jewish Health, Denver, Colorado, USA Computational Bioscience Program, University of Colorado, Denver, Colorado, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Strong
authors.affiliation: Mycobacteriology and Pharmacokinetics Laboratories, National Jewish Health, Denver, Colorado, USA Department of Medicine, National Jewish Health, Denver, Colorado, USA tbmicro@gmail.com salfingerm@njhealth.org.
authors.forename: Max
authors.initials: M
authors.lastname: Salfinger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000995:Antitubercular Agents / Q000494:pharmacology*; D002648:Child; D027081:DNA Gyrase / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D018088:Tuberculosis, Multidrug-Resistant / Q000382:microbiology*; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D004269:DNA, Bacterial; D024841:Fluoroquinolones; D027081:DNA Gyrase