Genetic characteristics of antimicrobial resistance mechanisms in Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii isolated from blood and cerebrospinal fluid of children

Objective. To assess antimicrobial susceptibility, presence of resistance genes and determine the phenotypic groups of K. pneumoniae, P. aeruginosa and A. baumannii isolated from blood and cerebrospinal fluid of children with nosocomial infections in intensive care units from 2014 to 2020. Materials and Methods. Minimum inhibitory concentrations of antibiotics were determined using the serial broth microdilution method. The identification of genes encoding the production of carbapenemases was carried out using hybridization fluorescence detection. Results. A total of 63 isolates of K. рneumoniae, 23 isolates of P. aeruginosa and 14 isolates of A. baumannii were tested in this study. K. pneumoniae was detected in 10.3%. P. aeruginosa was isolated at a frequency of 3.5%. A. baumannii accounted for 2.3%. The proportion of carbapenemresistant K. pneumoniae strains to meropenem and imipenem was 33% and 37%, respectively, of all isolates. Resistance to colistin and polymyxin in K. pneumoniae isolates was 33% and 24%, respectively. The production of carbapenemases OXA-48 was detected in 25 (89%) isolates. The presence of NDM, VIM, KPC carbapenemases was not detected. Among P. aeruginosa, 65% were resistant to meropenem, and 74% to imipenem. The highest activity against P. aeruginosa in vitro was exhibited by polymyxins. There were no strains that were insensitive to colistin. The detection rate of metallo-β-lactamases (MBL) in P. aeruginosa strains was 48%. Only VIM-type MBLs were identified. No other types of MBL have been found. A. baumannii was non-susceptible to meropenem in 64% and to imipenem in 71%. The highest in vitro activity against A. baumannii was shown by polymyxin. Rate of colistin resistance was 29%. The OXA-40 and OXA-23 genes were detected in 5 and 3 isolates, respectively. Conclusions. There were high resistance rates to most antimicrobials among K. pneumoniae, P. aeruginosa и A. baumannii isolated from blood and cerebrospinal fluid in children with nosocomial infections. The increase in carbapenem resistance rates was also observed. Carbapenem resistance was due to OXA48 carbapenemases in K. pneumoniae, VIM-type MBLs in P. aeruginosa, and OXA-40 and OXA-23 carbapenemases in A. baumannii.