Treatment of community-acquired lower respiratory tract infections in adults

Community-acquired lower respiratory tract infection (LRTI) is a common cause of acute illness in adults. The spectrum of disease ranges from a mild mucosal colonisation or infection, acute bronchitis or acute exacerbation of chronic bronchitis/chronic obstructive pulmonary disease (AE-CB/COPD), to an overwhelming parenchymal infection with the patient presenting with severe community-acquired pneumonia (CAP). Although the great majority of LRTIs are self-limiting viral infections, CAP is most often a bacterial disease with a substantial mortality. Thus, antibiotic treatment is rarely indicated for acute bronchitis and is only indicated for the more severe cases of AE-CB/COPD, but it is nearly always indicated for CAP, for which a delay in treatment may increase the risk of a fatal outcome. It may be difficult to differentiate between a viral and a bacterial LRTI, or between bronchitis/AE-CB/COPD and CAP. This may be one reason why antibiotics are prescribed to more than two-thirds of patients with LRTIs in Europe and the USA. Considering the worldwide development of antibiotic resistance, this is not an acceptable situation. Since an empirical approach is nearly always necessary in the management of LRTI, greater emphasis must be placed on the decision of whether or not to prescribe an antibiotic at all. This decision should be based on an assessment of the severity of the disease, including underlying risk factors, and on markers for bacterial/parenchymal/ invasive LRTI. The choice of empirical therapy must be based on the same data together with epidemiological information. The choice of antibiotic must always cover Streptococcus pneumoniae, which remains the main pathogen of morbidity and mortality in CAP. In hospital, attempts should be made to obtain an aetiological diagnosis in order to be able to switch to a specific treatment or to evaluate a failure of empirical therapy. Several guidelines for the management of community-acquired pneumonia have been published during the last 10 yrs. Some reports indicate that the implementation of such guidelines has resulted in lowered costs, length of stay in hospital and mortality. However, the results from these studies are not consistent and the evidence is still weak.