Background. Pseudomonas aeruginosa (P. aeruginosa) is an important pathogen causing nosocomial infections and is associated with a high morbidity and a mortality rate. The aim of this study was to find out the impact of virulence factors of P. aeruginosa strains, isolated from different clinical material, on clinical course of disease.
Material and Methods. A retrospective data analysis of medical records of patients with P. aeruginosa infection, treated in tertiary health care setting, was performed. P. aeruginosa virulence factors were evaluated by strain ability to produce biofilms, resistance to bactericidal serum activity, carbapenem resistance. The susceptibility testing was performed by the E-test method. Detected minimal inhibitory concentrations were evaluated according to EUCAST breakpoints.
Results. 33 (46.5%) of P. aeruginosa isolates were carbapenem-resistant, 37 (52.1%) of strains were multidrug resistant. All the strains isolated from the patients with trophic ulcers were carbapenem-sensitive (6 versus 0, P=0.033) and those, isolated from burns were more often carbapenem-resistant (6 versus 1, P=0.016). Biofilm producers cause more offen pneumonia then non-biofilm producers (76.2%, n=16 and 35.7%, n=5, respectively P=0.033). 68.4% (n=13) of non-biofilm producers were able to induce macroorganism systemic response to infection and 72.2% (n=13) of biofilm-producers were not, respectively P=0.006. Lethal outcome was more often in age group >65 years, intensive unit patients and in patients with pneumonia diagnosis.
Conclusions. P. aeruginosa resistance to carbapenems is associated with resistance to other antimicrobial classes. P. aeruginosa biofilm producfion helps the strains to survive and is important in chronic wound infections and hospital acquired pneumonia cases.