Assay of antibiotic susceptibility of Chlamydia pneumoniae.

It is well known that treatment of Chlamydia pneumoniae infections is difficult. High doses and prolonged treatment is often needed to achieve clinical cure despite good in vitro effect of the drugs used. We here discuss different methodological problems in the determination of MIC and MBC values of C. pneumoniae. The length of the preincubation time and the lack of fluctuation of the antibiotic concentrations may affect the outcome of the currently used assay.