The continuing challenge of lower respiratory tract infections

Lower respiratory tract infections have been a major cause of morbidity and mortality among humans since the dawn of history. The initial hope that the era of antibiotics would remove this scourge has been replaced by the more realistic view that although antimicrobial agents represent a major therapeutic advance, they have not yet solved all of the problems of lower respiratory tract infections. The pneumococcus, for example, causes mortality in a certain number of patients despite antimicrobial therapy. An even greater challenge is being imposed by the emergence of antimicrobial resistance among important bacterial pathogens, especially Strep-tococcus pneumoniae. Throughout recorded history, pneumonia has been a major cause of morbidity and mortality among hu-mans. Indeed, despite all the advances made by medical science, lower respiratory tract infections are still the most frequent among infectious causes of mortality worldwide. In 1998, the World Health Organization reported 13.7 million deaths due to lower respiratory tract infections [1]. Of all the common causes of huma