The ability of adherence and penetration to A549 cells in clinically isolated Streptococcus Pneumoniae *
Streptococcus pneumoniae (S. pneumoniae) is the most common pathogen of community-acquired pneumonia, acute otitis media, meningitis, and bacteremia. In the last two decades, there has been a worldwide increase in the incidence rate of penicillin-resistant S. pneumoniae (PRSP). The difference of pathogenicity between penicillin-susceptible S. pneumoniae (PSSP) and PRSP, however, is not well known. In the present study, the ability of adherence and penetration to A 549 cells, a human lung alveolar carcinoma (type 2 pneumocyte) cell in the 4 strains of S. pneumoniae clinically isolated from blood were examined in vitro. The ability of adherence depended on the contact time and inoculum size in all strains. Results showed that two of the four strains (one is susceptible and the other is intermediately resistant to penicillin) were found to penetrate into A 549 cells, but were not dependent on inoculum size. The ability of adherence and penetration in the 4 strains was not related to their susceptibility to penicillin. The serotypes of invasive strains were 3 and 6 , and were frequently isolated from blood in Japan. These results confirm previous clinical Study. (Accepted on October 21, 2000) Kawasaki Igakkaishi 27 (1): 23-30, 2001
