Figure 5. Effect of imipenem and nitrosative stress on H₂O₂ synthesis.

The production of H₂O₂ by B. pseudomallei diluted to OD₆₀₀ of 0.5 was measured polarographically (A). Some of the specimens were treated with 12.5 µg/ml imipenem (IM), and where indicated the bacterial cells were treated with 100 µM spermine NONOate (sNO) or 500 µM KCN. Untreated cells are shown as controls. The H₂O₂ probe was washed with fresh LB broth between individual specimens. The data are representative of 3 observations collected on 3 separate days. The killing of anaerobic B. pseudomallei by 50 µg/ml IM was tested in LBG broth in the presence or absence of 50 mM NO₃ ⁻ (B). p<0.01 compared to the KCN-treated group. Nitrate reductase activity was monitored by measuring the accumulation of NO₂ ⁻ by the Griess reaction (C).