Co-infection with Legionella and SARS-CoV-2, France, March 2020

Abstract

We describe a March 2020 co-occurrence of Legionnaires' disease (LD) and coronavirus disease in France. Severe acute respiratory syndrome coronavirus 2 co-infections were identified in 7 of 49 patients from LD case notifications. Most were elderly men with underlying conditions who had contracted severe pneumonia, illustrating the relevance of co-infection screening.

Keywords: COVID-19; Legionella; Legionnaires’ disease; SARS-CoV-2; coronavirus disease; pneumonia; respiratory infections; severe acute respiratory syndrome coronavirus 2; viruses; zoonoses.

Figure 1

Timeline of first Legionnaires’ disease symptoms among 7 Legionnaires’ disease/COVID-19 co-infected patients, France, March 2020. COVID-19, coronavirus disease; D, day; ECMO, extracorporeal membrane oxygenation; UAT, urinary antigen test.

Figure 2

Timeline of detection of SARS-CoV-2 and Legionella in patient 1, a 71-year-old man receiving chemotherapy for multiple myeloma, France, March 2020. A) Serum Legionella DNA load estimated by qPCR C_t and SARS-CoV-2 RNA load expressed as the number of log₁₀ RNA copies/mL serum. B) Pulmonary Legionella DNA load estimated by qPCR C_t, targeting the 16sRNA gene (R-DiaLeg, Diagenode, https://www.diagenode.com) and SARS-CoV-2 RNA load (Institut Pasteur, Paris protocol). Arrows indicate dates of computed tomography scans, green triangles indicates dates of positive Legionella cultures, and orange circle indicates date of lung microbiome testing. Values are normalized according to cellular quantification using the CELL Control r-gene kit (bioMérieux, https://www.biomerieux.com) and expressed as the number of log₁₀ RNA copies/100 cells from pulmonary TA and BAL. BAL, broncho-alveolar lavage; C_t, cycle threshold; D, days after onset of symptoms; qPCR, quantitative PCR; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; TA, tracheal aspirations.