Molecular identification of mutations conferring resistance to rifampin, isoniazid and pyrazinamide among Mycobacterium tuberculosis isolates from Iran

Abstract

Here, we aimed to determine the susceptibility of 70 Mycobacterium tuberculosis isolates obtained from different regions of the country to 8 anti-tuberculosis (anti-TB) drugs and possible underlying mechanisms causing resistance to rifampin, isoniazid, and pyrazinamide. The susceptibility of 70 isolates of M. tuberculosis to anti-TB drugs was tested using proportion method. Strains showing resistance to the first line anti-TB drugs were subjected to PCR amplification and sequencing of the rpoB, katG, ahpC, pncA genes, inhA promoter and oxyR-ahpC intergenic regions to detect resistance conferring mutations. Overall, 77.1% and 77.1% of isolates were resistant to at least one of the tested first- and second-line drugs, respectively. Within the rpoB gene the highest rate of mutation was found in codons 531(450) (56.3%), and 533(452) (12.5%). Also, codons 315 (42.4%) of katG, positions -48, -72 and -77 of oxyR-ahpC (total= 3, 9.1%) and -15 of inhA promoter region (33.3%) were the most altered positions in isoniazid resistant isolates. Only a single mutation was detected for pncA among resistant isolates. High prevalence of resistance to essential anti-TB drugs among M. tuberculosis strains isolated from retreated tuberculosis cases is alarming issue necessitating immediate action to prevent the spread of drug resistant isolates in the country.

Keywords:

• Mycobacterium tuberculosis
• Drug resistance
• MDR
• XDR
• Rifampin
• Isoniazid
• Pyrazinamide

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Tehran University of Medical Sciences (Project No. 27579)

Notes on contributors

Ahad Ali Haratiasl

Ahad Ali Haratiasl contributed to planning the study, collecting and analyzing the data and participated in writing the article. Gholamreza Hamzelou and Sirus Amini provided the bacterial samples and contributed to the performance of the bacterial identification tests and drug susceptibility testing. Jalil Kardan-Yamchi and Mehri Haeili participated in sequence analysis and manuscript editing. Mohammad Mehdi Feizabadi designed the experiments and wrote the manuscript.

Ahad Ali Harati Asl is Ph.D. student in bacteriology at the International Campus of Tehran University of Medical Sciences. He is currently a faculty member of Islamic Azad University in Iran and has many years of experience in teaching microbiology and related laboratories in biology departments. His research interests include various fields of microbiology such as drug resistance and new diagnostic methods in bacteria.

Gholamreza Hamzelou

Gholamreza Hamzehloo is a DCLS (Doctor of Clinical Laboratory Sciences), MPH candidate of Tehran University of Medical Sciences. His affiliation is; Director of Regional Reference Laboratory for Tuberculosis of Public Health, Tehran University of Medical Sciences. His work focuses specifically on the Quality System Management, Quality Assurance in Medical laboratory, HIV & Hepatitis and bacterial pathogens. His favorite place to do research is the Mycobacteriology Lab.

Sirus Amini

Sirus Amini is a Laboratory Expert affiliated at Tehran Regional Reference Laboratory for Tuberculosis, Tehran, Iran. He has many years of experiences in the diagnosis and drug susceptibility testing of Mycobacterium tuberculosis complex and his research interests is in the Mycobacteriology area.

Jalil Kardan-Yamchi

Jalil Kardan-Yamchi is a PhD candidate of Medical Bacteriology at Tehran University of Medical Sciences. His affiliation is; Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences. His work focuses specifically on the diagnosis, drug resistance and resistance mechanisms, and also molecular epidemiology of bacterial pathogens. His favorite place to do research is the Mycobacteriology Lab.

Mehri Haeili

Mehri Haeili, PhD in Microbiology, serves as assistant professor at the University of Tabriz. Her research interests are focused on molecular mechanisms of antibiotic resistance in bacteria. Her laboratory is currently working on unraveling molecular determinants of resistance to last-hope antibacterials including colistin, carbapenems and tigecycline. Her Affiliation is Department of Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran.

Fereshteh Heidari

Fereshteh Heidari Tajabadi is a Post-doc fellow at Department of Microbiology Tehran University of Medical Sciences. She is familiar with the techniques, methods and procedures used in the plant pathology laboratories, Extensive knowledge of the methods and materials used in isolate bacteria from soil, rhizosphere and human body and select the best biocontrol bacteria. Her work focuses specifically on the isolation, diagnosis and efficiency of predatory bacteria, BALOs, against gram negative bacteria in vitro and in vivo.

Mohammad Mehdi Feizabadi

Mohammad Mehdi Feizabadi holds DVM and PhD degrees in Veterinary Medicine and Medical Microbiology. He is a Professor in Medical Microbiology at Tehran University of Medical Sciences. His interests is molecular mechanism of drug resistance in bacterial pathogens particularly Mycobacteria. He is teaching Microbiology to both undergraduate and postgraduate students at Tehran.