Molecular characteristics of antimicrobial resistance and biofilm formation of bloodstream infection pathogens isolated from pediatric patients in Ukraine

• The study found that Klebsiella pneumoniae strains show high resistance to key antibiotics. • A high prevalence of biofilm-associated genes was observed in clinical isolates. • Most strains had low in vitro biofilm formation, indicating a need for more research. • The study aids in understanding resistance genes prevalence in Ukraine. • The results highlight the importance of modern molecular techniques. To determine antimicrobial resistance and biofilm-associated genes among clinical isolates of bloodstream infection pathogens in Ukraine. A total of 35 clinical strains of Klebsiella pneumonia and 50 clinical strains of Staphylococcus spp. were isolated from patients from Ukrainian tertiary-level children`s hospitals during 2023 with bloodstream infections including central venous catheter-associated infections. Antimicrobial susceptibility testing was conducted following the European Committee on Antimicrobial Susceptibility Testing methodology. Capacity to form biofilms was assessed using a microtiter plate assay. Amplification of the variable resistance genes ( blaNDM-1, blaKPC, OXA-48, blaCTX-M-1, blaTEM, qnrB, gyrA, mecA ) and biofilm-associated genes ( clfA, fnbpA, icaA, fimH, mrkA, matBecp) was performed by polymerase chain reaction. |Overall, 96% (n = 46/50) of all Staphylococcus spp. strains expressed icaA, 94% (n = 47/50) of strains expressed fnbpA and 92% (n = 45/50) expressed clfA genes. In total, 32% (n = 16/50) of strains were resistant to methicillin, and all of the strains expressed mecA. All K. pneumoniae strains expressed matBecp , and 97% (n = 34/35) expressed fimH and mrkA genes. All of K. pneumonia were resistant to third-generation cephalosporins, 74.3% (n = 25/35) of isolates expressed CTX and 80% (n = 28/35) expressed blaTEM gene, 71.4% (n = 25/35) strains expressed both genes. In total, 80% (n = 28/35) of K. pneumoniae were resistant to carbapenems, 60.7% (n = 17/28) expressed blaNDM-1 , 64.3% (n = 18/28) expressed OXA-48 and all 28 strains expressed blaKPC . A total of 90% (n = 18/20) of K. pneumoniae were resistant to fluoroquinolones, 88.9% (n = 16/18) expressed qnrB and none of the isolates expressed gyrA gene. Very high prevalence of genes associated with biofilm formation was observed in clinical isolates of Staphylococcus spp. and K. pneumoniae . High-level resistance to all antimicrobials was observed in K. pneumoniae strains.