Pathogenic characteristics of Pseudomonas aeruginosa bacteraemia isolates in a high-endemicity setting for ST175 and ST235 high-risk clones

AbstractMultidrug-resistant (MDR)Pseudomonas aeruginosa represents a major clinical concern. The interplay between antimicrobial resistance and virulence ofP. aeruginosa was investigated in in vitro and in vivo studies. Thirty-eight well-characterized (21 MDR and 17 non-MDR)P. aeruginosa strains from patients with bacteraemia were analysed. Resistance phenotype, carbapenemase production, clonal relatedness, type III secretion system genotype, O-antigen serotype, cytotoxicity (ability to lyse cells) on A549 cells, and virulence (lethality in nematodes) in aCaenorhabditis elegans model were investigated. MDR strains showed lower cytotoxicity (35.4 ± 21.30% vs. 45.0 ± 18.78 %;P = 0.044) and virulence (66.7% vs. 100%;P = 0.011) than non-MDR strains. However, the pathogenicity of MDR high-risk clones varied broadly, with ST235 and ST175 clones being the most and least cytotoxic (51.8 ± 10.59% vs. 11.0 ± 1.25%;P< 0.0001) and virulent ([100% vs. 73.1;P = 0.075] and [0% vs. 93.9%;P< 0.0001], respectively). The pathogenicity of the ST235 clone was similar to that of non-MDR strains, and its ability to lyse cells and high virulence were related with theexoU-positive genotype. Furthermore, the O11 serotype was more frequent among the ST235 clone andexoU-positive genotype strains and was also essential for the pathogenicity ofP. aeruginosa. Our data suggest that the pathogenicity of MDR high-risk clones is the result not only of the resistance phenotype but also of the virulenc...
Source: European Journal of Clinical Microbiology and Infectious Diseases - Category: Microbiology Source Type: research