Temporal evolution of bacterial species and their antimicrobial resistance characteristics in wound infections of war-related injuries in Ukraine from 2014 to 2023.

BACKGROUND: This study continues surveillance of antimicrobial resistance associated with combat injuries in Ukraine. AIM: To compare species composition, antibiotic resistance profiles, and emergence of new resistance genes between 2014-2020 and 2022-2023. METHODS: Retrospective multicentre microbiological survey in Ukrainian hospitals. Antibiotic susceptibility, whole genome sequencing, and MLST typing were conducted on 154 organisms obtained from 125 casualties from 2022-2023. FINDINGS: The data reveals a predominance of gram-negative bacteria, particularly Acinetobacter baumannii (35.7%), Pseudomonas aeruginosa (14.9%), and Klebsiella pneumoniae (20.7%). High levels of carbapenem resistance was observed among A. baumannii (meropenem 72,2% [(39/54) 95% CI 58.4-83.5], imipenem 66.7% [(36/54) 95% CI 52.5-78.9]), Klebsiella (meropenem 90.6% [(29/32) 95% CI 75.0-98.0], imipenem 81.2% [(26/32) 95% CI 63.6-92.8]), and P. aeruginosa (meropenem 47.8% [(11/23) 95% CI 26.8-69.4], imipenem 60.8% [(14/23) 95% CI 38.5-80.3]) strains. A. baumannii ST-78 and ST-400 were prevalent from 2014 to 2020, while 5 strains of ST-1077 were newly identified. Pseudomonas aeruginosa strains showed diversity across 16 sequence types (STs), with ST-773 increasing in frequency and new STs emerging, but lacking carbapenemase genes. K. pneumoniae exhibited increased genetic diversity over time, with three STs from 2014 to 2020 and six new STs, including blaNDM-1, blaOXA-48, and blaKPC2 carriers, in recent years. CONCLUSION: There is a growing prevalence of multidrug resistant isolates from globally distributed sequence types.

BIOFILM FORMING ACTIVITY OF NON-FERMENTING GRAM-NEGATIVE BACTERIA.

OBJECTIVE: The aim: To study the influence of chemical, physical factors on the biofilm forming activity of P. aeruginosa, A. baumannii. PATIENTS AND METHODS: Materials and methods: Biofilm forming activity of P. aeruginosa (10 isolates) and A. baumannii (10 isolates) was studied in nutrient media of different composition. There was used the method in 96-well crystalline violet staining plates with spectrophotometry (STAT FAX®4300, wavelength of 620 nm). RESULTS: Results: Results showed that in standard medium (trypto-soy broth), strains of P. aeruginosa (90%) and A. baumannii (60%) obtained high biofilm forming activity. A. baumannii formed biofilms even in sterile water. Biofilm forming activity of urease positive P. aeruginosa increased in the medium with 1.0% urea. Both Acinetbacteria and Pseudomonas intensively produced their biofilms in the presence of 5% serum or sub-bacteriostatic concentrations of levofloxacin in the media. High concentrations of sodium chloride inhibited their biofilm activity. CONCLUSION: Conclusions: Isolates of Acinetobacter and Pseudomonas obtain the protective biofilm-forming ability under such adverse environmental conditions as insufficient nutrients, high osmotic pressure, the presence of antibiotics but at high concentrations sodium chloride biofilm-formation is stimulated only in the first bacteria and suppressed in the second one.