Introduction. The selective effect on microorganisms due to the use of antimicrobial drugs leads to the expansion of the spectrum of pathogens and the growth of pathogen resistance. The phenomenon of antibiotic resistance is characterized by the fact that pathogens of many diseases acquire resistance to antibiotic drugs (ABP) due to resistance genes and their ability to be horizontally transferred to other microorganisms. Effective treatment of patients with infectious processes, including leukemia patients, requires clarification of the nature of antibiotic resistance of bacteria and the development of new ABPs. This, first of all, concerns the microorganisms listed in the WHO list as priority.

Aim. To characterize the antibiotic resistance of pathogens of infectious and inflammatory complications that were isolated from patients with various nosological forms of leukemia during the period 2002-2020.

Materials and methods. In patients with acute myeloid (AML), acute lymphoid (ALL), chronic lymphoid (CLL) and chronic myeloid leukemia (CML) during 2002-2020, 4,612 strains of microorganisms were isolated and identified from the biotopes of the upper respiratory tract (UPR) and intestines, which belonged to different taxonomic groups. Among the selected cultures, 496 isolates were recognized as factors of infectious and inflammatory complications (IIC). The study of the sensitivity of bacterial pathogens of IU to 60 ABPs of different classification groups was carried out by the disk diffusion method on Muller-Hinton agar and Sabouraud agar. All clinical bacterial isolates (338 cultures) were divided into MDR, XDR and PDR groups according to the International classification of bacterial resistance to antibiotics.

Results. Monitoring of antibiotic resistance of microorganisms of the genus Staphylococcus, the causative agents of IU in patients with leukemia, made it possible to determine that 83.9% of isolates were characterized by varying degrees of resistance to ABP of known classification groups: in total, 42.9% of strains were classified as MDR, 38.4% as XDR microorganisms, and 2.0% – to PDR panresistant cultures. Analysis of antibiotic resistance of clinical strains of S. aureus showed that 58.8% and 47.1% of methicillin-resistant S. aureus (MRSA) cultures were found in patients with AL and HL, respectively. As for vancomycin, 46.2% of cultures isolated from patients with AL and 42.1% of strains from CL were resistant. It was established that the vast majority of strains of Enterococcus sp. in AML it belonged to XDR microorganisms (73.0%), while 18.9% had all the signs of PDR cultures. Strains of Enterococcus sp., which were isolated from patients with ALL, are classified as XDR bacteria. In chronic variants of leukemia, 16 isolates of Enterococcus sp. turned out to be factors of IIC, among which: 42.8% of strains were recognized as XDR microorganisms, 28.6% of cultures showed signs of MDR and PDR bacteria. Of the 37 strains of Enterococcus sp. isolated in AML, 67.6% were classified as vancomycin-resistant (VRE); in patients with CLL, 71.4% were characterized as VRE. Based on the results of the antibiotic resistance study, it was established that representatives of Moraxella catarrhalis had a high degree of resistance to most antibiotics of all classification groups: 90.0% of cultures showed signs of XDR strains, and 10.0% were classified as PDR bacteria. The analysis of antibiotic resistance of 25 strains of representatives of the Enterobacteriacae family and 12 cultures of Pseudomonas aeruginosa allowed us to establish that 54.1% of isolates were characterized as pathogens with multiple hospital resistance MDR, 13.5% of strains with significant hospital resistance XDR, and 5.4% of cultures as panresistant PDR, that is, resistant to all known classes of ABP.

Conclusions. During the period 2002-2020, 4,612 strains of microorganisms were isolated and identified in patients with AML, ALL, CLL, and CML from biotopes of the upper respiratory tract, intestines, wound surfaces, and blood cultures, among which 496 cultures were recognized as factors of infectious and inflammatory complications. Antibiotic resistance of pathogens of infectious and inflammatory processes that were isolated from patients with various forms of leukemia was characterized, taking into account the international criteria of MDR, XDR, PDR. The obtained results will contribute to the optimization of empiric antibacterial therapy of patients with hemoblastosis.

Keywords: leukemia patients, microorganisms, antibiotic resistance.