Clinical Microbiology and Antimicrobial Chemotherapy. 2023; 25(4):421-427
To conduct a comparative evaluation of the results of phenotypic and molecular genetic methods for testing drug resistance of Mycobacterium tuberculosis isolated from bone biopsies of patients with tuberculous spondylitis.
A retrospective cohort study was conducted on the case histories of patients diagnosed with tuberculous spondylitis who underwent surgical treatment in the period from 2016 to 2021. The main study subject was surgical material. Antimicrobial resistance patterns of MBT isolates was performed using phenotypic and molecular genetic methods.
The vast majority of Mycobacterium tuberculosis isolates possess at least multidrug-resistance (MDR): 92 of 104 isolates (88.5%) according to phenotypic methods, and 192 of 274 DNA samples (70.1%) according to molecular methods. For rifampicin, isoniazid and ofloxacin the results of phenotypic and molecular methods matched in 92.7%, 97.9%, and 92.6% of cases, respectively; for levofloxacin, moxifloxacin and kanamycin – in 78.3%, 77.1%, and 73.1% of cases; , for amikacin and capreomycin – only – in 52.2% and 57.7% of cases, respectively. For rifampicin and isoniazid, the dominant mutations associated with resistance were: serine replacement for leucine in the 531 codon of the rpoB gene for rifampicin and serine replacement for threonine in the 315 codon of the katG gene for isoniazid.
Data on the presence of mutations associated with resistance to rifampicin (rpoB gene), isoniazid (katG gene) and aminoglycosides/capreomycin (rrs gene) can be used when prescribing chemotherapy regimens. The presence of mutations associated with MBT resistance to fluoroquinolones and aminoglycosides/capreomycin (eis gene) is not always accompanied by phenotypic manifestation of resistance. For these antimicrobials it is necessary to confirm resistance by phenotypic methods.