A man with culture sterile cavitating lung lesions: molecular techniques can provide the key to diagnosis.

A 20-year-old male presented to the Emergency Department with pyrexia, dyspnoea, chest pain and haemoptysis. Cavitating lung lesions were noted on chest X-ray and the patient was admitted to the intensive care unit where he was intubated and ventilated. Routine investigations including serial cultures did not provide an aetiological diagnosis. As such, a CT-guided lung biopsy was carried out and 16S rDNA PCR was undertaken on the sample. This identified Fusobacterium necrophorum as the causative organism. The patient was treated for Lemierre's syndrome and successfully discharged from hospital. This case highlights how DNA tissue typing on a lung biopsy sample can be the key to successful diagnosis in an atypical pneumonia and raises the question as to whether this infrequently used approach should be added to forthcoming community acquired pneumonia guidelines.