Principles of antibiotic treatment of community-acquired pneumonia in the outpatient setting.

Community-acquired pneumonia (CAP) is a common illness with high rates of morbidity and mortality. Nearly 80% of the treatment for this condition is provided in the outpatient setting. Among the etiologic agents associated with bacterial CAP, the predominant pathogen is Streptococcus pneumoniae. Treatment of CAP for the most part is empirical; therefore, any antibiotic treatment should cover both typical and atypical pathogens. The beta-lactams have historically been considered standard therapy for the treatment of CAP. However, the impact of rising resistance rates is now a primary concern facing physicians. For patients with comorbidities or recent antibiotic therapy, current guidelines recommend either combination therapy with a beta-lactam and a macrolide or an antipneumococcal fluoroquinolone alone. Fluoroquinolones are broad-spectrum antibiotics that exhibit high levels of penetration into the lungs and low levels of resistance. Evidence from clinical trials indicates clinical success rates of > 90% for moxifloxacin, gatifloxacin, and levofloxacin in the treatment of CAP due to S pneumoniae. Data from comparative clinical trials suggest fluoroquinolone monotherapy is as efficacious as beta-lactam-macrolide combination therapy in the treatment of CAP patients. The respiratory fluoroquinolone levofloxacin has also been shown to be effective in CAP patients for the treatment of macrolide-resistant S pneumoniae. The use of azithromycin, telithromycin, and fluoroquinolones in short-course regimens has been shown to be efficacious, safe, and tolerable in patients with CAP. Based on clinical evidence, high-dose, short-course therapies may represent a significant advance in the management of CAP.