Research on the formation of Pseudomonas aeruginosa biofilms as a factor in the development of antibiotic resistance in fatal pneumonias

Abstract. Background and aim: Antibiotic resistance of community-acquired pneumonia pathogens and the emergence of multiresistant bacteria is a problem of global importance. Determining the ability to form biofilms will provide an opportunity to develop new ways to overcome bacterial resistance to antimicrobial drugs. Thus, this study aimed to determine Pseudomonas aeruginosa isolates antibiotic resistance and to study the architecture of its biofilms. Methods: 22 fatal cases of secondary pneumonia due to gunshot trauma for the period from 2022 to 2023 during the war in Ukraine were studied. Isolation and identification of pure culture were provided using Micro-la-test kits. The sensitivity to antimicrobial drugs was studied using «SENSILAtest G-I, G-II» and Kirby-Bauer Disk Diffusion Susceptibility Test. To form biofilms bacteria was grown on the surface of coverslips in the 35 mm Petri dishes for 24 h. Biofilm formation was assessed by laser scanning confocal microscopy and scanning electron microscopy. Results: Examination of biological samples revealed 22 strains of microorganisms. Gram-negative microorganisms predominated among pathogens (63.6%) and Pseudomonas aeruginosa isolates were 50%. Determining the sensitivity established that to antimicrobial drugs took place in 71.4% of cases (5 strains), and poly-resistantance was found in 28.6% of cases (2 strains). Conclusions: the study of structural and functional features of biofilm formation showed that biofilms were formed according to classical stages. Dense biofilms determined the phenotypic variability of Pseudomonas aeruginosa with the development of antibiotic resistance to antimicrobial drugs, which is a barrier to the use of antimicrobial therapy. (www.actabiomedica.it)