Streptococcus pneumoniae: Drug Resistance and Optimal Therapeutic Approaches

Streptococcus pneumoniae accounts for millions of infectious deaths annually. It is the most common bacterial cause of community-acquired pneumonia, especially among "at-risk" patients such as those with chronic obstructive pulmonary disease (COPD), diabetes, over 50 years of age, or who have been exposed to a nursing home or daycare facility environment. Antimicrobial resistance among S. pneumoniae has increased globally in the last 30 years, but most significantly in the U.S. over the past 15 years, with multidrug-resistant phenotypes now accounting for over one-quarter of all current community-acquired pneumococcal isolates. This resistance affects empirical prescribing, as only infrequently is therapy targeted based on microbiological findings. As the classical agents such as β-lactams, macrolides and tetracyclines are losing their predictable activity unless significantly higher doses are administered, clinicians are turning to the fluoroquinolones. However, a specific concern is the recent increase in fluoroquinolone use which has led to the emergence of fluoroquinolone-resistant strains, many of which are susceptible only to gemifloxacin. This potent agent continues to maintain its antibacterial activity and proven clinical efficacy against a wide range of fluoroquinolone-resistant phenotypes. Nonetheless, the emergence of fully fluoroquinolone-resistant bacterial strains is virtually certain unless new approaches are adopted in the initial therapy of patients who are at risk of multidrug-resistant S. pneumoniae (MDRSP) and other resistant pathogens. Continued monitoring and vigilance are essential in order to maintain the activity of currently approved and active antimicrobials in the continuing battle against MDRSP and other adaptable bacterial pathogens.