Reactivation of Chlamydia pneumoniae lung infection in mice by cortisone

Abstract

To study persistent infection, reactivation of Chlamydia pneumoniae lung infection in mice was attempted by immunosuppression with cortisone treatment. Four-week-old Swiss-Webster mice were treated with cortisone acetate (125 mg/kg) every other day for a total of six doses, starting on day 28 after intranasal inoculation of C. pneumoniae AR-39. C. pneumoniae was recovered from the lungs in 6 of 13 animals after six doses of cortisone, while control animals given saline remained negative. C. pneumoniae DNA was detected by polymerase chain reaction in the 6 culture-positive mice and 2 of 10 controls. The presence of pathogen DNA in this animal model suggested viable organisms in a culture-negative state.