There have been a number of discoveries, notably the role of Chlamydia pneumoniae in both community-acquired pneumonia (CAP) and acute exacerbations of chronic bronchitis (AECB), as well as recognition of the predominance of pathogens, such as Haemophilus influenzae in AECB and an appreciation of the role of polymicrobial infection. However, the most important factor has been the widespread emergence and dissemination of resistance in pathogens causing RTIs. This predominantly applies to penicillin and macrolide resistance among Streptococcus pneumoniae but also to amoxicillin-resistance in 30-45% of H. influenzae in many countries and > 90% of Moraxella catarrhalis in most of them.

A consensus group recently formulated principles, which should govern the decision to use antibiotic(s) in RTI as outlined in this slide (1).