Update on community-acquired pneumonia: impact of antibiotic resistance on clinical outcomes

In contrast to the rapid expansion in the number of published studies reporting the increasing rate of antimicrobial drug resistance among common respiratory pathogens, there remain few controlled studies examining the impact of these trends on clinical outcomes. Those studies that are published are hampered by small sample sizes, biases inherent in observational designs, and the relative infrequency of isolates showing high-level resistance, particularly high-level beta-lactam resistance among clinical isolates of Streptococcus pneumoniae. This update summarizes recent published studies addressing the impact of drug resistance on outcomes for lower respiratory tract infections. The majority of these studies are retrospective cohort studies, focusing on the impact of beta-lactam-resistant pneumococcal infections in patients with community-acquired pneumonia. These studies support the conclusion that current levels of pneumococcal drug resistance do not result in clinical treatment failures for patients with community-acquired pneumonia. However, as patterns of drug resistance evolve, future studies will be needed to address the continued appropriateness of current empirical treatment guidelines for these patients.