We aimed at evaluating the relationship between microbial etiology and
chest radiograph appearance in various types of pneumonia. In a prosp
ective study, the radiographic findings in 479 cases of acute pneumoni
a in children were compared with viral etiology and growth of potentia
l bacterial pathogens in nasopharyngeal secretion. As the basis for vi
ral etiology was most conclusive, the material was here classified acc
ording to the viral findings. The patients were divided into three age
groups: 0-2, 3-5 and 6-15 years. The chest radiograms were analyzed b
lindly for the presence of hyperinflation and interstitial, alveolar a
nd mixed interstitial-alveolar infiltrates. There was a statistically
significant relationship between low age and occurrence of hyperinflat
ion and interstitial infiltrates, and between high age and alveolar in
filtrates. No unequivocal relationship was found between type of infil
trates or presence of atelectasis and proven viral etiology. We conclu
de that chest radiographs are not a useful indicator of microbial etio
logy in childhood pneumonia.