Chlamydia pneumoniae, an etiological agent for respiratory tract infec
tion, was found as a cause of persistent infection in a family group.
During the observation period of 21/2 years, serology and polymerase c
hain reaction for C. pneumoniae demonstrated a failure to eradicate th
e organism, despite several prolonged courses of antibiotics known to
be effective against Chlamydia species.