TABLE 2.

Effect of rifampin and spectinomycin on chlamydial plaque formation

AntibioticDrug concn (ng/ml [Rif] or μg/ml [Spc])C. psittaci 6BCC. trachomatis L2
Input PFUaNo. of plaquesbInput PFUaNo. of plaquesb
Rif2NTNA2.4 × 103Too many to count
5NTNA2.4 × 1050
104.8 × 10402.2 × 1050
254.8 × 10502.2 × 1060
502.1 × 107422.8 × 1072
100108502.2 × 1071
200108236.4 × 1072*
Spc201.1 × 10502.4 × 103Too many to count
402.9 × 10502.4 × 1050
1002.0 × 10601.9 × 1060
2002.1 × 107132.3 × 1070
300108814.6 × 1070*
  • a The largest inoculum size tested that was not cytotoxic.

  • b The average number of plaques (minimum of three independent experiments). NT, not tested; NA, not applicable; *, cell monolayer was unhealthy due to the large concentration of infectious particles.