Clinical risk factors, antimicrobial therapy, and virulence-associated mortality in patients with extensively drug-resistant or pan-drug-resistant (XDR/PDR) Pseudomonas aeruginosa pulmonary infections.

OBJECTIVES

To identify independent predictors for mortality in patients with extensively drug-resistant or pan-drug-resistant (XDR/PDR) Pseudomonas aeruginosa pulmonary infections and to explore the association between bacterial virulence characteristics and patient mortality.

METHODS

Multivariate logistic regression analysis was conducted to identify independent predictors associated with XDR/PDR-P. aeruginosa pulmonary infections. The virulence characteristics of XDR/PDR-P. aeruginosa were evaluated through biofilm formation measurement, human serum killing assay, and a Galleria mellonella infection model. Whole-genome sequencing was employed to investigate the virulence-associated genes of XDR/PDR-P. aeruginosa.

RESULTS

Among 57 patients with XDR/PDR-P. aeruginosa pulmonary infections, 30-day mortality was significantly associated with a history of respiratory diseases (P = 0.016) and cardiovascular diseases (P = 0.017). The use of cefoperazone-sulbactam was independently associated with reduced 7- and 30-day mortality. Isolates from nonsurvivors demonstrated significantly higher biofilm formation and serum resistance than those from survivors (P < 0.05). G. mellonella infected with ExoU⁺/ExoS⁺ strains exhibited higher mortality than those infected with ExoU⁺/ExoS⁻ strains (P = 0.0194), indicating the enhanced virulence of co-expressing strains.

CONCLUSION

Respiratory diseases and cardiovascular diseases are independent risk factors for 30-day mortality in patients with XDR/PDR-P. aeruginosa pulmonary infections. Virulence characteristics such as strong biofilm formation and low serum killing ability were significantly associated with 30-day mortality, suggesting their critical role in disease progression.