Description

Non-invasive investigations are generally unhelpful in providing an aetiology for pneumonia in HIV infection although
normal blood gases or normal lung function tests make it
unlikely that significant organic disease is present. The polymerase chain reaction (PCR) is both sensitive and specific for
pneumocystis pneumonia but is not in routine use as it is more
expensive than conventional tests. Sputum examination is
unhelpful as firstly sputum is rarely produced and secondly
pneumocystis does not grow in vitro. Some centres used
induced sputum techniques for diagnosis. The patient inhales
hypertonic saline and the material coughed up is then examined for pneumocystis. However, this is less reliable than bronchoscopy with broncho-alveolar lavage which is regarded as the
gold standard for diagnosis. Material obtained using simple
routine stains provides a high diagnostic yield for pneumocystis pneumonia