Clinical Microbiology and Antimicrobial Chemotherapy. 2024; 26(4):462-469
Conduct a comparative assessment of the frequency and spectrum of antimicrobial resistance of Mycobacterium avium isolated from patients of a phthisiopulmonology clinic in the pre-Covid period (2018–2019) and during the COVID-19 pandemic (2020–2023).
The antimicrobial sensitivity of M. avium isolates was determined to 8 antimicrobial drugs: amikacin, clarithromycin, linezolid, moxifloxacin, ciprofloxacin, doxycycline, rifabutin, rifampicin. Drug susceptibility testing was performed using serial broth microdilution method according to published CLSI guidelines, M24S, 2023. Interpretation of the results, classifying M. avium into one of three categories: sensitive, intermediate, resistant, was carried out based on a comparison of the values of the minimum inhibitory concentrations (MIC) of antimicrobial drugs with the breakpoint values of these parameters published in the CLSI M24S, 2023. M. avium complex breakpoints were used for amikacin, clarithromycin, linezolid, and moxifloxacin. For ciprofloxacin, doxycycline, rifabutin, rifampicin, breakpoints for other slow-growing non-tuberculous mycobacteria (NTM) (M. kansasii and M. marinum) were used according to the rules in section CLSI M24S, 2023 “Non-species related breakpoints”.
A comparative analysis of antimicrobial resistance of M. avium in the pre-Covid period (2018– 2019) and during the COVID-19 pandemic (2020–2023) showed an increase in the proportion of M. avium isolates resistant to clarithromycin (from 1.1% to 20.1%, p < 0.0001), moxifloxacin (from 11.0% to 29.2%, p = 0.0007) and an increase in the proportion of isolates with intermediate drug sensitivity to clarithromycin (from 5.6% to 17.6%, p = 0.0080) during the COVID-19 pandemic. The opposite trend is noteworthy – an increase in the proportion of M. avium isolates sensitive to amikacin during the COVID-19 pandemic (from 55.5% to 79.6%, p < 0.0001) and a decrease in the proportion of isolates resistant to amikacin (from 36% to 4.4%, p < 0.0001). In addition, there was a decrease in the proportion of isolates with intermediate drug sensitivity to ciprofloxacin (from 18.8% to 9.7%, p = 0.0288) and to linezolid (from 27.7% to 17.2%, p = 0.039).
The data obtained in this work on the increase in the frequency of occurrence of M. avium isolates resistant to main and reserve antimicrobials during the COVID-19 pandemic requires the search for new antimicrobials that are effective against infection caused by M. avium. It is necessary to expand data on the MIC breakpoint values of new and existing antimicrobials for M. avium and to develop a reasonable criterion for establishing clinical categories of sensitivity and resistance, as well as to revise recommendations and expand the group of antimicrobials tested for drug susceptibility of NTM to determine treatment regimens.