Occurrence of macrolides resistance in Legionella pneumophila ST188: results of the Belgian epidemiology and resistome investigation of clinical isolates

Michel, Charlotte, Echahidi, Fedoua, De Muylder, Geraldine, Sewell, Max, Boostrom, Ian, Denis, Olivier, Spiller, Owen B. ORCID: https://orcid.org/0000-0002-9117-6911 and Pierard, Denis 2025. Occurrence of macrolides resistance in Legionella pneumophila ST188: results of the Belgian epidemiology and resistome investigation of clinical isolates. International Journal of Infectious Diseases 153 , 107786. 10.1016/j.ijid.2025.107786

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Abstract

Objectives The incidence of Legionnaires’ disease steadily increases worldwide. Although Legionella pneumophila is known as pathogenic, systematic investigations into antibiotic resistance are scarce, and reports of resistance in isolates are recently emerging. Methods Clinical cases and metadata reported to the Belgian National Reference Centre between 2011 and 2022 were retrospectively analyzed. A total of 283 clinical isolates were typed by core genome multi-locus sequence typing (cgMLST). Acquired genes or mutations triggering resistance were extracted from all of them. Results The number of Legionnaires’ disease cases has increased in Belgium. Urinary antigen testing remains the main used test, but polymerase chain reaction and serology allow the diagnostic in 14.8% and 2.4% of cases, respectively. cgMLST showed a good discrimination between sequence typing (ST) and minimal variation for ST47 isolates, whereas ST1s were more diverse. Genotypic screening identified a 23S ribosomal RNA mutation linked to a high-level macrolide resistance in one isolate of ST188, which is genetically closed to resistant isolates from France. Conclusion The increase in incidence is of concern and likely an under-estimate due to the reliance on urine antigen testing. Routine typing by cgMLST allows good discrimination and the first clinical isolate reported as resistant for macrolides was cultured, underscoring the need to define resistance breakpoints and incorporate antimicrobial susceptibility testing as routine clinical investigation practice.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine
Publisher:	Elsevier
ISSN:	1201-9712
Date of First Compliant Deposit:	30 January 2025
Date of Acceptance:	14 January 2025
Last Modified:	12 Feb 2025 10:46
URI:	https://orca.cardiff.ac.uk/id/eprint/175750

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