CHARACTERIZATION OF BIOLOGICAL PROPERTIES OF NOSOCOMIAL PSEUDOMONAS AERUGINOSA STRAINS

Aim. To assess the biological properties of P.aeruginosa strains depending on profilization of hospital and the studied clinical material. Materials and methods. 143 P. aeruginosa strains isolated from patients of large surgical hospitals of the city of Perm and 20 strains of polyclinic patients were studied. Hemolytic and phospholipase activity was determined in all the cultures. Pyocyanine and pyoverdin production was assessed using spectrophotometric method according to Deziel E. et al (2001). Results. Phenotypic patterns of Pseudomonas aeruginosa population did not differ at the units of different profiles of surgical hospitals. Qualitative comparative analysis permitted to detect a weak reliable correlation between presence of phospholipase and “pulmonary” origin of the isolate (φ=0,285; p =0,0006) as well as between pyocyanine production and culture excretion from the wound (φ=0,2374; p =0,00470). When carrying out quantitative estimation of the level of pigment production, statistically significant difference between their synthesis with nosocomial and out-of-hospital isolates ( U -test, p <0,001) as well as its absence, depending on the excreted material ( p <0,05) was shown. Conclusions. It may be assumed that patients hospitalized to Resuscitation and Intensive Therapy Units become the reason for propagation of high-virulent strains when being transferred to the other units of medical institutions. Probably, the studied characters are the dominant ones and are met in the overwhelming majority of natural P. aeruginosa strains, but their manifestation at the level of modification variability depends on environmental conditions that is expressed by phenotypic heterogeneity of P. aeruginosa bacillus.

Pseudomonas aeruginosa, nosocomial isolate, pathogenic factors, pyocyanine, pyoverdin