COMPLICATIONS OF KLEBSIELLA PNEUMONIA - CT EVALUATION

Objective: To evaluate the CT features of complicated Klebsiella pneum onia. Materials and Methods: We retrospectively reviewed 15 CT examina tions from 11 consecutive patients with complicated Klebsiella pneumon ia with special attention to internal architecture of pneumonic consol idation and its changes on follow-up CT. On plain radiography, abscess or cavitation was suspected in all patients. The diagnosis was establ ished by isolation of Klebsiella pneumoniae from blood in six patients , from sputum in two, and from both in three. Five patients underwent follow-up CT due to progression (one) or incomplete resolution (four) of the disease despite antimicrobial therapy. Results: In all patients pneumonic consolidation was composed of two intermingled components: enhancing homogeneous areas and poorly marginated low-density areas wi th multiple small air cavities, suggesting necrotizing pneumonia. In n ine patients scattered enhancing structures probably due to atelectati c lung and pulmonary vessels were noted within necrotic areas of conso lidated lung. In eight patients pleural complications such as effusion (all) or diffuse pleural enhancement (five) were seen. In two patient s with multilobar disease and delayed treatment, multiple small absces s cavities coalesced to form a large cavity with sloughing of lung tis sue, suggesting pulmonary gangrene and lung abscess formation on 18 an d 45 day follow-up CT, respectively. In three other patients necrotizi ng pneumonia resolved slowly from the periphery to the center with res idual fibrosis on follow-up CT at 2-3 months. Conclusion: The most com mon CT manifestation of complicated Klebsiella pneumonia was necrotizi ng pneumonia associated with pleural abnormalities. In extensive cases , pulmonary gangrene or lung abscess was a rare complication.