Table 1

Effect of transcription and translation inhibitors on C. trachomatis cytotoxicity

Treatment*Cytotoxicity of C. trachomatis serovar
MoPnDL2Uninfected
No antibiotic3+2+
Rifampicin3+2+
Doxycycline3+2+
Rifampicin + doxycycline3+2+
  • * HeLa cells were grown to confluency in the presence of either 10 μg/ml of rifampicin, 5 μg/ml of doxycycline, or both antibiotics. Antibiotic containing media was removed prior to infection. 

  • Monolayers were infected at an MOI of 100, rocked for 2 h at 37°C, washed three times, fed with MEM + 10% fetal bovine serum, and incubated at 37°C. Cytotoxicity was evaluated at 4 h PI. Cytotoxicity was scored from negative (−) to positive (1+–3+), on the basis of evaluation of cell-rounding, detachment, and lysis compared to cell controls. (A score of 3+ indicated 100% of cells affected; 2+, 75% affected; 1+, 25% affected; −, same as cell control). Antibiotic treatment completely inhibited growth of chlamydiae, as determined by lack of inclusion development at 24 and 48 h PI (data not shown).