Drug-resistant Streptococcus pneumoniae in Community-acquired Pneumonia.

The emergence of Streptococcus pneumoniae isolates resistant to not only penicillin, but to other antipneumococcal agents as well, has major public health implications. Drug-resistant S. pneumoniae are distributed worldwide, and resistance has become increasingly prevalent in the United States within the past decade. The relevance of resistance, particularly to the beta-lactams, to treatment outcome has been subject to debate. Pneumonia due to intermediate-level-resistant penicillin-resistant isolates of S. pneumoniae appears to be adequately treated by beta-lactam agents. Interpretation of resistance reports, which may be based on achievable cerebrospinal fluid levels of drug, may depend on the clinical setting, and efforts are underway to adjust breakpoints so that reports are more easily applicable to clinical practice. Infectious Diseases Society of America and American Thoracic Society guidelines, as well as others, for community-acquired pneumonia have addressed the impact of drug-resistant S. pneumoniae on antimicrobial selection.