Severe Community-Acquired Pneumonia with Disseminated Infection Caused by Highly Virulent Pseudomonas aeruginosa: Successful Treatment of a Case.

PURPOSE: Pseudomonas aeruginosa (P. aeruginosa) is a Gram-negative pathogen with strong colonization ability and multidrug resistance. Disseminated infection complicated by secondary organizing pneumonia is extremely uncommon.

PATIENTS AND

METHODS

We describe a rare case of severe community-acquired pneumonia due to highly virulent P. aeruginosa, complicated by endophthalmitis, ecthyma gangrenosum, and secondary organizing pneumonia. Clinical features, microbiological results, histopathology, and treatment were analyzed.

RESULTS

A 61-year-old woman developed a disseminated infection caused by highly virulent P. aeruginosa, presenting with persistent high fever, impaired consciousness, ocular involvement, mucocutaneous erosions, and widespread erythematous papules. The diagnosis was confirmed by consistent isolation of P. aeruginosa from sputum, blood, and ocular pus, and detection in bronchoalveolar lavage fluid by metagenomic sequencing. Whole-genome sequencing of the ocular isolate identified multiple virulence factors, including Type III secretion system effectors ExoS, ExoT, and ExoY, reflecting the pathogen's capacity for systemic dissemination. Lung biopsy revealed extensive necrosis with fibrinoid exudation and granulation tissue, consistent with secondary organizing pneumonia. The patient received combined antimicrobial and anti-inflammatory therapy targeting both the disseminated infection and the organizing pneumonia, resulting in rapid defervescence, restoration of consciousness and oral intake, and clinical improvement. She was subsequently discharged in stable condition.

CONCLUSION

This case highlights the disseminated potential of highly virulent P. aeruginosa and underscores the need for vigilance regarding secondary organizing pneumonia in such infections. Timely recognition, together with a treatment strategy combining appropriate antimicrobial and anti-inflammatory therapy, is crucial to improving patient outcomes.