Management of lower respiratory tract infections in out-patients.

Lower respiratory tract infections (LRTIs) are one of the most frequent medical conditions seen in out-patients. They all cause morbidity, and although most are minor some may be life-threatening, thus appropriate disease management is important. Clinical features are usually used to classify LRTIs, but this approach may be inaccurate. It may therefore be simpler to describe a patient's symptoms without applying a label, such as "bronchitis", since the latter means different things to different people. Classification of LRTIs should aim to aid management. The two main management decisions are: whether to manage the patient at home; and whether to prescribe antibiotics. Investigations are carried out in the hospital environment to aid these decisions, however in the community investigation in only a minority of cases are done as they are costly and impractical. Markers of severity of LRTI have been identified in a number of studies and their value in clinical practice is now being assessed, however most studies suggest that severely ill patients are correctly identified and admitted to hospital. Currently, antibiotics are used liberally for lower respiratory tract infections. However most infections are not bacterial in origin and will not be affected by such therapy. The idea that antibiotics are harmless placebos for such illnesses is no longer tenable since the appearance and rapid spread of antibiotic resistance in bacteria. Only in community-acquired pneumonia and some patients with exacerbations of chronic bronchitis do antibiotics actually alter the course of the illness. In those groups antibiotics should be targetted at the casual pathogens and in other groups such therapy should be avoided. Much current research interest is focused on determining which (if any) is the best antibiotic in these situations.