RELEVANCE OF CHLAMYDIA-PNEUMONIAE MURINE PNEUMONITIS MODEL TO EVALUATION OF ANTIMICROBIAL AGENTS

A mouse model of Chlamydia pneumoniae pneumonitis was established in o utbred MFI mice immunosuppressed with cyclophosphamide. Following intr anasal inoculation with 2.2 x 10(3) inclusion-forming units of C. pneu moniae TW-183 per mouse, chlamydiae were culturable from the lungs for at least 29 days, Progressive subacute pneumonitis with perivascular and peribronchial lymphoid cell hyperplasia was observed, and C. pneum oniae organisms were located in consolidated areas of tissue by immuno cytochemistry. Mice were treated orally, commencing at 8 days after in fection, with clinically achievable concentrations of amoxicillin-clav ulanate or ciprofloxacin (three times daily for 7 days), ofloxacin, do xycycline, or erythromycin (twice daily for 7 days), or azithromycin ( once daily for 4 days), Despite disparate antichlamydial activity in c ell culture and different pharmacokinetic properties in infected anima ls, all treatments reduced the chlamydial load in the lungs (P < 0.05) when the loads were evaluated by culture at 1 and 10 days after the c essation of dosing, and this was reflected in the histopathological an d immunocytochemistry scores, There was no significant difference betw een these treatments, and C. pneumoniae TW-183 was eradicated from the majority but not from all mice. These results confirm the limited cli nical data available to date. In conclusion, a range of oral antimicro bial agents commonly used for the treatment of community-acquired resp iratory infection was found to be efficacious in this experimental mod el of C. pneumoniae pneumonitis, which may therefore be of utility in chemotherapy and follow-up studies.