ABSTRACT
Frequency of bacterial co-infections among patients with COVID-19 is not high, and over-prescribing of antibiotics may contribute the selection of resistant strains of enterobacteria and gram-negative non-fermenting bacteria. The aim of the study was to assess the local features of antibiotic resistance of K. pneumoniae and its genetic mechanisms against background of the COVID-19 infection pandemic. Material and methods. There was selected 37 carbapenem-resistant K. pneumoniae strains isolated in 2016, 2017 and 2020 from hospitalized patients, including 15 strains, isolated from patients with COVID-19 infection. Minimal inhibitory concentrations (MICs) of meropenem and colistin were determined by broth microdilution method. Determination of MICs of eravacycline, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/relebactam was performed using Sensititre diagnostic system on EUMDROXF plates. Susceptibility to 11 combinations of 2 antibiotics was detected by modified method of multiply combination bactericidal testing. For 4 K. pneumoniae strains high-throughput sequencing was performed, followed with the subsequent search for determinants of antibiotic resistance and virulence, assessment of plasmid profiles. Results. All strains were resistant to meropenem (MIC50 32 mg/l, MIC90 128 mg/l) and produced KPC and OXA-48 carbapenemases. Strains isolated in 2016-2017 were susceptible to colistin (MIC <=2 mg/l), in 2020 only 26.7% of the strains retained their susceptibility (MIC50 64 mg/l, MIC90 256 mg/l). Susceptibility to combinations of two antibiotics with colistin included reduced from 84.6-100% in 2016-2017 till 26.6-66.7% in 2020. The strains isolated in 2020 retained their susceptibility to ceftazidime/avibactam (MIC <=1 mg/l). 5 strains resistant to cefiderocol with a MIC 8 mg/l were identified. Strains 2564 and 3125 isolated in 2020 from sputum of patients with COVID-19 infection belonged to different sequence-types (ST12 and ST23) and contained the blaOXA-48 carbapenemase gene, additionally strain 2564 contained the blaKPC-27carbapenemase gene. Resistance to colistin was caused by inactivation of the mgrB genes due to insertion of IS1 and IS5-like transposons. Conclusion. The performed genetic studies demonstrate a diversity of mechanisms of antibiotic resistance in K. pneumoniae leading to the formation of resistance including to antibiotics that haven't been used in Belarus till now.Copyright © 2021 Geotar Media Publishing Group. All Rights Reserved.
ABSTRACT
Frequency of bacterial co-infections among patients with COVID-19 is not high, and over-prescribing of antibiotics may contribute the selection of resistant strains of enterobacteria and gram-negative non-fermenting bacteria. The aim of the study was to assess the local features of antibiotic resistance of K. pneumoniae and its genetic mechanisms against background of the COVID-19 infection pandemic. Material and methods. There was selected 37 carbapenem-resistant K. pneumoniae strains isolated in 2016, 2017 and 2020 from hospitalized patients, including 15 strains, isolated from patients with COVID-19 infection. Minimal inhibitory concentrations (MICs) of meropenem and colistin were determined by broth microdilution method. Determination of MICs of eravacycline, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/relebactam was performed using Sensititre diagnostic system on EUMDROXF plates. Susceptibility to 11 combinations of 2 antibiotics was detected by modified method of multiply combination bactericidal testing. For 4 K. pneumoniae strains high-throughput sequencing was performed, followed with the subsequent search for determinants of antibiotic resistance and virulence, assessment of plasmid profiles. Results. All strains were resistant to meropenem (MIC50 32 mg/l, MIC90 128 mg/l) and produced KPC and OXA-48 carbapenemases. Strains isolated in 2016–2017 were susceptible to colistin (MIC ≤2 mg/l), in 2020 only 26.7% of the strains retained their susceptibility (MIC50 64 mg/l, MIC90 256 mg/l). Susceptibility to combinations of two antibiotics with colistin included reduced from 84.6–100% in 2016–2017 till 26.6–66.7% in 2020. The strains isolated in 2020 retained their susceptibility to ceftazidime/avibactam (MIC ≤1 mg/l). 5 strains resistant to cefiderocol with a MIC 8 mg/l were identified. Strains 2564 and 3125 isolated in 2020 from sputum of patients with COVID-19 infection belonged to different sequence-types (ST12 and ST23) and contained the blaOXA-48 carbapenemase gene, additionally strain 2564 contained the blaKPC-27carbapenemase gene. Resistance to colistin was caused by inactivation of the mgrB genes due to insertion of IS1 and IS5-like transposons. Conclusion. The performed genetic studies demonstrate a diversity of mechanisms of antibiotic resistance in K. pneumoniae leading to the formation of resistance including to antibiotics that haven’t been used in Belarus till now. © 2021 Geotar Media Publishing Group. All Rights Reserved.