Diagnosis of legionnaires' disease by urinary antigen and DNA detection: a case report

A 38-year-old male patient who was admitted to a private hospital in Kuala Lumpur presented with fever, symptoms of respiratory infection and diarrhoea. On admission, he was febrile, toxic looking, dehydrated with hypotension and tachycardia. No clinical signs of respiratory infection were detected on admission. Initially he was treated as a case of septicaemia with fluid therapy and intravenous antibiotic (Perfloxacin). Subsequently, he was noticed to have pneumonia in the right lower zone of the lung. His sputum, stool and blood were sent for culture and the results were negative. Sputum culture for Legionella and serological tests for Mycoplasma and Legionella were also reported negative. Sandwich ELISA performed on his urine sample detected Legionella pneumophila antigen. L. pneumophila mip gene was also detected in his urine by polymerase chain reaction. The patient was commenced on Erythromycin and he responded favourably to the treatment. The present case shows that L. pneumophila should not be overlooked as one of the causative agents of pneumonia and rapid techniques of urinary antigen and DNA detection should be utilized to make an early diagnosis of the infection.