Figure 3. Respiratory activity of B. pseudomallei undergoing nitrosative stress.

Survival of B. pseudomallei after 2.5 h of treatment with 12.5 µg/ml of imipenem (A). Some of the specimens were co-treated with either 500 µM potassium cyanide (KCN) or 100 µM spermine NONOate (sNO). The percent survival was determined as described in figure 1. The data are the mean ± SD from 3 observations collected on 3 separate days. The ability of B. pseudomallei to consume O₂ was monitored polarographically (B). The data shown in panel B are representative from 3 independent experiments. B. pseudomallei were adapted for 5 h in an anaerobic chamber and the % survival scored 2.5 h after the addition of 64 µg/ml ceftazidime (CT) or 25 µg/ml imipenem (IM) (C). The results in C are expressed as % survival over controls that were not exposed to antibiotics. B. pseudomallei controls in the anaerobic chamber neither grew nor lost viability in the time frame tested. p<0.01 compared to sNO- and KCN-treated groups.