Enhanced detection of Legionnaires' disease by PCR testing of induced sputum and throat swabs.

Legionnaires’ disease, particularly that caused by non-pneumophila species, is notoriously underdiagnosed [1, 2]. We recently found a four-fold increase in case detection of Legionnaires’ disease through a laboratory-initiated strategy of systematic PCR testing for Legionella species of all lower respiratory specimens from patients with pneumonia or immune compromised status [3]. This strategy relies on the availability of lower respiratory specimens and the recording of relevant clinical information on laboratory requisition forms by clinicians. We recognised that this strategy will miss testing patients who could not expectorate sputum and when inadequate clinical information is written on laboratory requisition forms. To address this diagnostic gap we enhanced case detection by actively identifying patients with communityacquired pneumonia (CAP) and by collecting induced sputum from those unable to expectorate voluntarily. In addition, we evaluated throat swabs as an alternative specimen for PCR testing.