Severe bilateral pleuropneumonia caused by Legionella sainthelensi: a case report

Abstract

Background: Legionella spp. are ubiquitous freshwater bacteria responsible for rare but potentially severe cases of Legionnaires' disease (LD). Legionella sainthelensi is a non-pneumophila Legionella species that was first isolated in 1980 from water near Mt. St-Helens (USA). Although rare cases of LD caused by L. sainthelensi have been reported, very little data is available on this pathogen.

Case presentation: We describe the first documented case of severe bilateral pleuropneumonia caused by L. sainthelensi. The patient was a 35-year-old woman with Sharp's syndrome treated with long-term hydroxychloroquine and corticosteroids who was hospitalized for an infectious illness in a university hospital in Reunion Island (France). The patient's clinical presentation was complicated at first (bilateral pneumonia, multiloculated pleural effusion, then bronchopleural fistula) but her clinical condition eventually improved with the reintroduction of macrolides (spiramycin) in intensive care unit. Etiological diagnosis was confirmed by PCR syndromic assay and culture on bronchoalveolar lavage.

Conclusions: To date, only 14 documented cases of L. sainthelensi infection have been described worldwide. This pathogen is difficult to identify because it is not or poorly detected by urinary antigen and molecular methods (like PCR syndromic assays that primarily target L. pneumophila and that have only recently been deployed in microbiology laboratories). Pneumonia caused by L. sainthelensi is likely underdiagnosed as a result. Clinicians should consider the possibility of non-pneumophila Legionella infection in patients with a compatible clinical presentation when microbiological diagnostic tools targeted L. pneumophila tested negative.

Keywords: Case report; Legionella sainthelensi; Legionnaires’ disease; PCR syndromic testing; bilateral pleuropneumonia.

Fig. 1

Injected chest CT scan showing bilateral pleuropneumonia with left bronchopleural fistula (second control CT scan performed on Day 10). a Axial slice of injected thoracic CT scan in parenchymal window. Right upper lobe parenchymal nodular lesion with central necrosis (black arrow). Bilateral axillary lymphadenomegalies (black stars). b Frontal minimal intensity projection image of thoracic CT scan in parenchymal window showing left lower lobe pneumonia (white arrow) with bronchopleural fistula (black arrow) and multiloculated pneumothorax (white stars) with septa (dotted arrow)