Figure 7.

Applications of HNO₂-mediated killing of mucoid P. aeruginosa to clinical specimens. (A) Killing of FRD1 by NO₂^– in sterile ultrasupernatants of CF airway secretions derived from explanted CF lungs. Bacteria were incubated anaerobically for 24 hours, and 15 mM NO₂^– was added. CFUs were determined (n = 3) and plotted as the X ± SEM versus time. *P < 0.01 versus CFU decrease before adding NO₂^–. (B) NO generation in CF ASL by 15 mM NO₂^–. Except for the media and pH, experimental conditions were identical to those used in Figure 4B. (C) Effects of NO₂^– on killing of FRD1 and FRD1/pmucA in mouse lungs. CD1 mice were infected with FRD1 or FRD1/pmucA as described in Methods. Infected mice were treated with buffer (black bars) and buffered NO₂^– (white bars) daily, and viable bacteria from the lung homogenates were enumerated. n = 8 per group. *P < 0.01 versus buffer alone. (D) Effects of long-term NO₂^– treatment on killing of FRD1 in mouse lungs. Another group of FRD1-infected mice were treated daily with buffer (–, 50 mM sodium phosphate, pH 6.5) or buffer with 15 mM NO₂^– (+) for 16 days (n = 8 per group). Organisms surviving treatment with buffer and NO₂^– were shown in logarithmic scale. *P < 0.01 versus buffer alone. (E) CI experiments with 10⁶ FRD1 and FRD1/pmucA intratracheally instilled into CD1 mouse airways and incubated for 6 days prior to harvesting of mouse lungs and enumeration of CFUs after homogenization.