The role of type III secretion system in the development of nosocomial infections, caused by multiresistant Pseudomonas aeruginosa strains

Abstract

Type III Secretion System (TTSS) is a key pathogenicity factor of Pseudomonas aeruginosa. The suppression of the activity of TTSS would potentially allow block the infection independently on the presence of antimicrobial resistance. To study the role of TTSS P. аeruginosa in the development of nosocomial infections we characterized genes coding TTSS effector proteins and the activity of its secretion in vitro in 75 P. аeruginosa isolates. Genes of TTSS effectors were detected in all studied isolates with exoS+-genotype being the predominant one (80%). Isolates with exoU+-genotype were revealed twice more frequent from urine and blood than from respiratory material: 26.5% vs 12.8%. The presence of functional TTSS during the induction by low calcium concentrations was observed for 60.4% of isolates. At the same time 76.6% of strains were highly cytotoxic in vitro. Exploring the relation of TTSS-genotypes with resistance to particular groups of antimicrobials has shown higher resistance rates to gentamicin and ciprofloxacin in exoU+-genotype. Overall we can conclude that TTSS is a potentially interesting target for control of infections caused by multi-resistant P. аeruginosa strains.

Keywords

• pseudomonas aeruginosa
• type iii secretion system
• ttss effectors
• cytotoxicity
• antimicrobial resistance