FIG 2.

In vitro drug susceptibility test against actively growing M. tuberculosis H37Rv and nongrowing SS18b. (A) M. tuberculosis H37Rv culture was split into several samples and incubated with different drugs, as indicated. Serial dilutions were made and plated 7 days after the addition of drugs. (B) An SS18b culture was divided into several samples and processed as described for the experiment shown in panel A. Bars represent the means ± standard deviations of two experiments. Statistically significant differences relative to the untreated control (No Drug) were calculated using a Student t test. *, P < 0.05; **, P < 0.005; ***, P < 0.0005; ns, no significant difference. Drug concentrations were as follows: INH, 0.25 μg/ml; RIF, 0.5 μg/ml; LZD, 2.5 μg/ml; PNU, 2.5 μg/ml; AZD, 2.5 μg/ml.