From ‘Legionellosis acquired through a dental unit’ to ‘Was Legionellosis acquired through a dental unit?’

The case reported by Scho¨nning et al.1 refers to a case described online by Lundholm of a 67-year-old male with a diagnosis of leukaemia. On 20 November 2012, the patient was admitted to hospital to undergo high-dose chemotherapy before undergoing bone marrow transplantation. On 22 November, he underwent routine dental examination. Chemotherapy was performed on 28 November. On 3 December, the patient started to show respiratory symptoms. He was admitted to the intensive care unit where he died from Legionnaires’ disease (LD). The analysis of the environmental samples performed in the dental ward is intriguing. Water from the cup filler was positive [2000 colony-forming units (cfu)/L] for the same Legionella pneumophila serogroup 1 specimen detected in the patient’s sputum collected through bronchoscopy. All the remaining 38 water samples resulted negative. According to Lundholm, these samples included the dental unit, which was subjected to water treatment regularly. Despite this treatment, a high level of heterotrophic bacteria (200 cfu/mL) was detected in dental unit water.