Rapid Detection of Streptomycin‑Resistant Mycobacterium tuberculosis by rpsL‑Restriction Fragment Length Polymorphism

Molecular methods for the detection of drug‑resistant tuberculosis (DR‑TB) are potentially more rapid than conventional culture‑based drug susceptibility testing, facilitating the commencement of appropriate treatment for patients with DR‑TB. The aim of this study was to evaluate and develop polymerase chain reaction‑restriction fragment length polymorphism (PCR‑RFLP) assays for the detection of mutations within rpsL, and for the determination of streptomycin (STR) resistance in Mycobacterium tuberculosis.

Clinical specimens were collected from individuals with suspected TB referred to the TB Center of Isfahan‚ from which 205 M. tuberclosis were isolated and identified by conventional phenotypic methods. The minimum inhibitory concentration of STR for all isolates was determined using the proportion method and 10 isolates were recognized as STR resistant M. tuberculosis. The effect of genetic alterations in the rpsL gene for these resistant isolates were investigated by PCR‑RFLP method.

Three (30%) isolates showed point mutation at codon 43 by RLFP analysis.

Our results suggest that RFLP analysis of the rpsL gene is useful for the rapid prediction of STR resistant strains of M. tuberculosis.