Corticosteroid therapy combined with antibiotics for severe Streptococcus pneumoniae pneumonia in ventilated piglets

Introduction:Streptococcus pneumoniae is the leading cause of community-acquired pneumonia (CAP). β-lactams combined with corticosteroids and macrolides may reduce the treatment failure rate and the mortality of CAP. Objective: We aimed to compare the efficacy of different antibiotic combinations and the adjunct therapy with corticosteroids, in a swine pneumococcal pneumonia model. Methods: Thirty pigs (32±3kg) were mechanically ventilated for 76h. At diagnosis of pneumonia after intrabronchial inoculation of S. pneumoniae 19A, animals were randomized to receive: saline(control); 150mg/kg ceftriaxone (CTX) + 10mg/kg levofloxacin (LVX) q24h; 150mg/kg CTX+ 45mg/kg azithromycin (AZT) q24h;150mg/kg CTX + 10mg/kg LVX q24h + 0.5mg/kg methylprednisolone (MP) q12h; or 150mg/kg CTX + 45mg/kg AZT q24h + 0.5mg/kg MP q12h. Gas exchange and pulmonary mechanics were evaluated every 24h. Upon autopsy, lung biopsies were obtained to quantify bacterial burden. Results: Figure 1 displays main respiratory parameters. Upon autopsy, S. pneumoniae lung tissue burden was 3.7±1.6, 0.5±0.6, 0.1±0.2, 0.1±0.2 logCFU/g, in control, CTX+AZT, CTX+LVX, CTX+LVX+MP groups, respectively (p Conclusions: In this pneumococcal pneumonia model, corticosteroids combined with macrolides showed higher antimicrobial efficacy, while fluoroquinolones may improve respiratory parameters.