Rifampicin resistance in Mycobacterium tuberculosis in Iran: a two-centre study

Area of Science:

• Microbiology
• Infectious Diseases
• Public Health

Background:

• Multidrug-resistant tuberculosis (MDR-TB) presents a persistent global health challenge.
• Rifampicin resistance is a key indicator of MDR-TB and necessitates effective diagnostic strategies.
• Timely diagnosis of rifampicin resistance is crucial to prevent treatment delays and reduce morbidity.

Purpose of the Study:

• To determine the incidence of rifampicin (RIF)-resistant *Mycobacterium tuberculosis* in pulmonary specimens.
• To evaluate the performance of the GeneXpert MTB/RIF assay for detecting RIF resistance in a large cohort.
• To assess the utility of rapid diagnostics in managing tuberculosis (TB).

Main Methods:

• A retrospective, two-center study was conducted in Tehran, Iran, analyzing 6624 pulmonary samples from TB patients between May 2014 and July 2018.
• The GeneXpert MTB/RIF assay was used for the primary detection of RIF resistance.
• Conventional drug susceptibility testing (DST) was employed for phenotypic confirmation of RIF resistance in isolates identified by GeneXpert.

Main Results:

• Out of 96 positive *M. tuberculosis* cases identified, 5 (5.3%) exhibited rifampicin resistance.
• All RIF-resistant and sensitive isolates detected by the GeneXpert assay were confirmed through phenotypic DST.
• The GeneXpert MTB/RIF assay demonstrated its capability for rapid identification of RIF-resistant TB.

Conclusions:

• The GeneXpert MTB/RIF assay is a reliable and rapid tool for diagnosing rifampicin-resistant tuberculosis.
• Implementing rapid diagnostic methods like GeneXpert can significantly decrease diagnostic delays.
• Reduced diagnostic delays have the potential to lower morbidity associated with mistreatment and prolonged illness.