title: Complications of Klebsiella pneumonia: CT evaluation.
abstract: OBJECTIVE
  To evaluate the CT features of complicated Klebsiella pneumonia.
  
  
  METHODS
  We retrospectively reviewed 15 CT examinations from 11 consecutive patients with complicated Klebsiella pneumonia with special attention to internal architecture of pneumonic consolidation and its changes on follow-up CT. On plain radiography, abscess or cavitation was suspected in all patients. The diagnosis was established 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 with multiple small air cavities, suggesting necrotizing pneumonia. In nine patients scattered enhancing structures probably due to atelectatic lung and pulmonary vessels were noted within necrotic areas of consolidated lung. In eight patients pleural complications such as effusion (all) or diffuse pleural enhancement (five) were seen. In two patients with multilobar disease and delayed treatment, multiple small abscess cavities coalesced to form a large cavity with sloughing of lung tissue, suggesting pulmonary gangrene and lung abscess formation on 18 and 45 day follow-up CT, respectively. In three other patients necrotizing pneumonia resolved slowly from the periphery to the center with residual fibrosis on follow-up CT at 2-3 months.
  
  
  CONCLUSIONS
  The most common CT manifestation of complicated Klebsiella pneumonia was necrotizing pneumonia associated with pleural abnormalities. In extensive cases, pulmonary gangrene or lung abscess was a rare complication.
authors.affiliation: Department of Radiology, College of Medicine, Seoul National University, Republic of Korea.
authors.forename: W K
authors.initials: WK
authors.lastname: Moon
authors.forename: J G
authors.initials: JG
authors.lastname: Im
authors.forename: K M
authors.initials: KM
authors.lastname: Yeon
authors.forename: M C
authors.initials: MC
authors.lastname: Han
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007710:Klebsiella Infections / Q000150:complications / Q000000981:diagnostic imaging*; D007711:Klebsiella pneumoniae; D008169:Lung Abscess / Q000000981:diagnostic imaging / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D010996:Pleural Effusion / Q000000981:diagnostic imaging / Q000209:etiology; D018410:Pneumonia, Bacterial / Q000150:complications / Q000000981:diagnostic imaging*; D013902:Radiography, Thoracic; D014057:Tomography, X-Ray Computed