In contrast to the tremendous number of articles and meetings devoted to elucidating the mechanisms of antibacterial drug resistance and describing the emergence of drug resistance patterns, little research has been completed on the impact of bacterial drug resistance on clinical outcomes. Moreover.among the studies that have been completed, the better-designed studies generally have failed to detect an effect of most current levels of antibacterial drug resistance on clinical outcomes for patients who have CAP. Yet, practice patterns are shifting in response to the perception that current levels of drug resistance necessitate changes in treatment patterns. This is unfortunate because it severely limits one's ability to continue to monitor the effectiveness of available therapies in light of changing patterns of antibacterial drug resistance. If levels of drug resistance continue to rise, it is likely that outcomes from those drug treatments will be affected adversely. In this regard, the recent licensing of a 7-valent pneumococcal conjugate vaccine for infants and young children may have an important effect on future trends in antibacterial drug resistance. The vaccine reduces childhood carriage of vaccine serotypes,which are among the most common serotypes found among drug-resistant isolates, and may reduce transmission of these serotypes to adults [65]. In conclusion, antibacterial drug resistance has not reduced substantially the effectiveness of first-line treatments for CAP. Whether levels of drug resistance will continue to increase or decline is unknown. Therefore,carefully designed outcomes studies likely will continue to be essential to help define optimal therapy for patients who have CAP.