Macrolide-resistant Streptococcus pneumoniae in community-acquired pneumonia:: Clinical and microbiological outcomes for patients treated with levofloxacin

The rapid emergence and increasing prevalence of antimicrobial resistance in Streptococcus pneumoniae have greatly complicated the choice of empirical treatment for community-acquired pneumonia (CAP). The newer macrolides, azithromycin and clarithromycin, have been popular choices for empirical therapy because of their activity against the common pathogens responsible for CAP and their improved tolerability, compared with that of erythromycin. Unfortunately, rates of resistance of S. pneumoniae to the macrolide class of antimicrobials have increased steadily during the past decade and have reached 40% in certain areas of the United States. Although the clinical relevance of macrolide-resistant strains of S. pneumoniae has been questioned, breakthrough bacteremias and clinical failures have been reported among patients receiving macrolide therapy. We reviewed the levofloxacin clinical database to determine the clinical and microbiological outcomes for patients with CAP infected with macrolide-resistant S. pneumoniae. Levofloxacin, including the 750-mg shortcourse regimen currently under investigation, produced a successful clinical response in 96.9% of patients with CAP due to macrolide-resistant S. pneumoniae, compared with 95.1% of all patients.