Differential Adherence Capacities of Clinical Isolates of Streptococcus pneumoniae at Different Growth States to Human Respiratory Epithelial Cells ( in vitro )

摘要

This study was conducted to evaluate the adherence and invasion capacity of four clinically important pneumococcal serotypes at early-, mid- and late-log phases at 1 and 3 h incubation times to A549 cells-a human respiratory epithelial cell. We observed that adherence capacity varied among the different isolates at all growth phases (p 0.05). Bacterial adherence also increased after a longer exposure to the host cells but significant differences were mostly observed at only early- and late-log phases at both incubation times. No bacterial invasion was however observed at 1 h post incubation but that at 3 h, a few bacteria penetrated the host cells but the bacterial cfu numbers were statistically insufficient for analysis. More studies are required to further confirm these observations.