[Eight cases of infection caused by the Streptococcus milleri group--significance of serum antibody titer and a comparative investigation of the backgrounds and factors of infections caused by Streptococcus milleri and Streptococcus pneumoniae].

Eight cases of infection caused by Streptococcus milleri were studied clinically, and a comparative study was made of the backgrounds and factors influencing the development of infectious diseases caused by Streptococcus milleri and Streptococcus pneumoniae. The patients (six males and two females) with infectious diseases caused by Streptococcus milleri ranged in age from 21 to 81 years old with an average age of 62.0 years. The infectious diseases encountered among the patients were pyothorax in three patients, and in one patient each pyothorax and lung abscess, pleurisy, a secondary infection of pulmonary emphysema, skin infection related to a tracheostomy, a subdural abscess and a brain abscess, respectively. Six out of the eight cases had infections which formed pus. An underlying disease existed in seven cases, and, in five of these seven cases, it influenced the general condition of these patients. Six serum antibody titers for the S. milleri groups were examined in the First Department of Internal Medicine, University of the Ryukyus. Three cases for S. anginosus, two cases for S. intermedius, and one case for S. constellatus showed high titers of X1024 or X2048. Therefore, the examination of the serum antibody titer seems useful for the diagnosis of infections caused by the S. milleri group. We also carried out a comparative investigation of the backgrounds and factors of infectious diseases caused by S. milleri and S. pneumoniae. There are more underlying diseases in infections caused by S. milleri than in those caused by S. pneumoniae. There were more smokers among the patients with infections caused by S. milleri than among those with S. pneumonia infections.(ABSTRACT TRUNCATED AT 250 WORDS)