FIG 6.

Administration of CLR or ERY decreased NE activity in BALF and ameliorated arterial oxygen saturation in a murine model of MRSP pneumonia. BALB/c mice (eight mice in each group) were intratracheally infected with MRSP NU4471 (5 × 10⁸ CFU in 50 μl PBS). Uninfected mice were intratracheally administered 50 μl PBS only. CLR (150 mg/kg), ERY (150 mg/kg), or gum arabic solution (GA sol.; Ctrl) was administered orally to the infected mice every 12 h. (A) Representative hematoxylin and eosin-stained lung tissue sections. Scale bar = 100 μm. (B) Mean linear intercept of alveolar septa. (C) NE activity in the BALF was determined by a method using an NE-specific substrate. (D) The arterial oxygen saturation was monitored. In panels B to D, the data represent the mean ± SEM and were evaluated using one-way analysis of variance with Tukey’s multiple-comparison test. †, Significantly different from the uninfected group at P < 0.05. *, Significant difference between the indicated groups at P < 0.05. BALF, bronchoalveolar lavage fluid; CLR, clarithromycin; Ctrl, control; ERY, erythromycin; GA sol., gum arabic solution; MRSP, macrolide-resistant Streptococcus pneumoniae; NE, neutrophil elastase; rPLY, recombinant pneumolysin; SEM, standard error of the mean.