Differentiation of bacterial and non-bacterial community-acquired pneumonia by thin-section computed tomography.
OBJECTIVE
The management of community-acquired pneumonia (CAP) depends, in part, on the identification of the causative agents. The objective of this study was to determine the potential of thin-section computed tomography (CT) in differentiating bacterial and non-bacterial pneumonia.


METHODS
Thin-section CT studies were prospectively examined in hospitalized CAP patients within 2 days of admission, followed by retrospective assessment by two pulmonary radiologists. Thin-section CT findings on the pneumonias caused by each pathogen were examined, and two types of pneumonias were compared. Using multivariate logistic regression analyses, receiver operating characteristic (ROC) curves were produced.


RESULTS
Among 183 CAP episodes (181 patients, 125 men and 56 women, mean age+/-S.D.: 61.1+/-19.7) examined by thin-section CT, the etiologies of 125 were confirmed (94 bacterial pneumonia and 31 non-bacterial pneumonia). Centrilobular nodules were specific for non-bacterial pneumonia and airspace nodules were specific for bacterial pneumonia (specificities of 89% and 94%, respectively) when located in the outer lung areas. When centrilobular nodules were the principal finding, they were specific but lacked sensitivity for non-bacterial pneumonia (specificity 98% and sensitivity 23%). To distinguish the two types of pneumonias, centrilobular nodules, airspace nodules and lobular shadows were found to be important by multivariate analyses. ROC curve analysis discriminated bacterial pneumonia from non-bacterial pneumonia among patients without underlying lung diseases, yielding an optimal point with sensitivity and specificity of 86% and 79%, respectively, but was less effective when all patients were analyzed together (70% and 84%, respectively).


CONCLUSIONS
Thin-section CT examination was applied for the differentiation of bacterial and non-bacterial pneumonias. Though showing some potential, this examination at the present time would not be applicable for patients with underlying lung diseases, severe conditions of pneumonia, or immunocompromised conditions.
Ito
Isao
I
Department of Respiratory Medicine, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki 710-8602, Japan. isaoito@kuhp.kyoto-u.ac.jp
Ishida
Tadashi
T
Togashi
Kaori
K
Niimi
Akio
A
Koyama
Hiroshi
H
Ishimori
Takayoshi
T
Kobayashi
Hisataka
H
Mishima
Michiaki
M
D003428:Cross Infection / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000145:classification / Q000000981:diagnostic imaging*; D013902:Radiography, Thoracic / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*