This article forms part of a series of occasional articles which provide an update on the best use of key diagnostic tests in the initial investigation of common or important clinical presentations. The current article focuses on investigation of “non-responding” presumed lower respiratory tract infection (LRTI) in primary care. The article begins with a case of a patient presenting to their GP for the second time with a cough and a discussion then follows on what investigations should be carried out next. The authors note that most LRTIs in primary care are self limiting, and laboratory and other investigations should be reserved for patients with specific risk factors. The main learning points from the article are provided below (direct from source):

• Among patients prescribed an antibiotic for LRTI in primary care, 20-25% will present again within four weeks

• Symptoms of lower respiratory tract infection usually resolve without specific treatment or investigation in a median of three weeks from first consultation

• In most patients laboratory and other investigations are unlikely to be helpful and should be guided by specific risk factors

• Microbiology testing is of little value in most patients. Sputum culture is recommended for patients with chronic lung disease with sputum production and for patients with suspected pneumonia who are not responding to initial therapy

• Chest radiography is most useful if an alternative diagnosis (such as malignancy) is being considered