Antimicrobial resistance of clinical isolates of Klebsiella pneumoniae and Escherichia coli in Russian hospitals: results of a multicenter epidemiological study

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Objective. To study the prevalence and mechanisms of antibiotic resistance, including carbapenemase production, in clinical isolates of Klebsiella pneumoniae and Escherichia coli isolated in different regions of Russia as part of the sentinel multicenter surveillance study in 2020–2021, and to explore the population structure of K. pneumoniae and the impact of “high-risk clones” on antibiotic resistance. Materials and Methods. Consecutive, non-duplicate isolates of K. pneumoniae (n = 2503) and E. coli (n = 2055) isolated from various specimens (blood, cerebrospinal fluid, respiratory samples, urine, wound secretions, etc.) of hospitalized patients with clinical signs of infection in 55 hospitals of 29 cities of Russia were studied. Species identification of isolates was performed by matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF MS). Antibiotic susceptibilities were determined by serial broth microdilution or, in the case of fosfomycin, by agar dilution method, and results were interpreted according to EUCAST v13 MIC breakpoints. Carbapenemase production was determined phenotypically by carbapenem inactivation method (CIM), the presence of genes of the most common serine carbapenemases (KPC, OXA-48) and metallo-β-lactamases (VIM, IMP, NDM) was determined by real-time PCR. K. pneumoniae clinical isolates were genotyped and assigned to the known clonal complexes (CC) and sequence types (ST) using SNP typing and multilocus sequencing typing (MLST) methods. K- and O-serotypes, acquired resistance and virulence genes, and plasmids carrying these genes were characterized using whole-genome sequencing of selected isolates (n = 215). Results. The resistance rates of nosocomial/community-acquired isolates of K. pneumoniae were as follows: amoxicillin-clavulanate – 88.63⁄57.99%, piperacillin-tazobactam – 82.92⁄45.49%, cefotaxime – 87.74⁄56.97%, ceftazidime – 84.76⁄53.07%, cefepime – 81.43⁄49.18%, aztreonam – 1.63⁄53.28%, ceftazidime-avibactam – 30, 88⁄9.22%, ceftolozan-tazobactam – 70.06/31.35%, ertapenem – 72.10⁄28.69%, meropenem – 49.60⁄15.16%, imipenem – 44.54⁄13.73%, gentamicin – 60.82⁄30.33%, amikacin – 42.06/17.21%, ciprofloxacin – 85.10⁄49.39%; trimethoprimsulfamethoxazole – 74.38⁄48.16%, colistin – 5.96⁄2.25%. The resistance of nosocomial/outpatient isolates of E. coli were: ampicillin – 84.93⁄67.67%, amoxicillin-clavulanate – 57.37⁄39.73%, piperacillin-tazobactam – 19.48⁄8.70%, cefotaxime – 63.83⁄34.19%, ceftazidime – 45.32⁄20.34%, cefepime – 35.95⁄16.61%, aztreonam – 51.78⁄26.11%, ceftazidime-avibactam – 5.71⁄0.80%, ceftolozane-tazobactam – 11, 95⁄2.22%, ertapenem – 8.18⁄1.42%, meropenem – 5.17⁄0.53%, imipenem – 4.95⁄0.36%, gentamicin – 24.54⁄13.68%, amikacin – 5.49⁄1.42%, ciprofloxacin – 54, 14⁄32.50%, trimethoprim-sulfamethoxazole – 52.21⁄38.54%, fosfomycin – 2.48⁄1.43%, colistin – 1.60⁄1.07%, tigecycline – 6.35⁄3.11%. The frequency of carbapenemase production among K. pneumoniae nosocomial isolates was 65.32% (OXA-48 – 40.75%, NDM – 30.28%, KPC – 8.74%, OXA-48 + NDM – 10.62%, OXA-48 + KPC – 2.98%, NDM + KPC – 0.45%, OXA-48 + NDM + KPC – 0.20%). More than 70% of nosocomial isolates of K. pneumoniae belonged to only 7 major genetic lineages known as “high-risk international clones”: CC395 – 37.40%, CC23 – 9.59%, CC307 – 8.64%, CC147 – 7.61%, CC15 – 2.95%, CC258 – 2.92%, and CC11 – 2.41%. The population of community-acquired K. pneumoniae was characterized by significantly greater genetic diversity (Simpson diversity index: D = 0.919; 95% CI: 0.904 to 0.933) compared with the population of nosocomial strains (Simpson diversity index: D = 0.815; 95% CI: 0.802 to 0.827). Strains of the “hypervirulent” genetic lineage of K. pneumoniae CC23 were more common in community-acquired infections. Conclusions. The extremely high frequency of resistance to cephalosporins in K. pneumoniae (> 80%) and E. coli (> 60%), as well as the high frequency of combined resistance to aminoglycosides and fluoroquinolones precludes their empirical use for the treatment of serious nosocomial infections caused by these pathogens. K. pneumoniae shows a rapid increase in resistance to carbapenems, mainly due to the spread of carbapenemases of three major groups: OXA-48, NDM and KPC. The overall increase in the frequency of carbapenemase production is accompanied by the growing diversity of carbapenemases, the increasing prevalence of strains producing NDM and KPC enzymes and those co-producing multiple carbapenemases simultaneously. In community-acquired infections, the high prevalence of resistance to cephalosporins in E. coli (> 30%) and K. pneumoniae (> 50%) remains the most important problem.