Legionellaantibiotic susceptibility testing: is it time for international standardization and evidence-based guidance?
Authors: Portal Edward , Descours Ghislaine , Ginevra Christophe , Mentasti Massimo , Afshar Baharak , Chand Meera , Day Jessica , Echahidi Fedoua , Franzin Laura , Gaia Valeria , Lück Christian , Meghraoui Alaeddine , Moran-Gilad Jacob , Ricci Maria Luisa , Lina Gerard , Uldum Søren , Winchell Jonas , Howe Robin , Bernard Kathryn , Spiller Owen B , Chalker Victoria J , Jarraud Sophie ,   the ESCMID Study Group for Legionella Infections (ESGLI), Ahlen Catherine , Hashmi Ibrahim Al , Allestam Görel , Amemura-Maekawa Junko , Andersson Sabina , Bangsborg Jette Marie , Bararossa Sheila , Beraud Laetitia , Bernard Kathryn , Borella Paola , Brandsema Petra , Bruin Jacob P , Buzzigoli Andrea , Cano Rosa , Casini Beatrice , Celenza Giuseppe , Chalker Vicki , Collins Samuel , Rotger Sebastian Crespi , Cristina Maria Luisa , Cristino Sandra , David Sophia , Jong Birgitta de , Boer Jeroen den , Echahidi Fedoua , Elverdal Pernille Landsbo , Erdogan Haluk , Euser Sjoerd , Franzin Laura , Fry Norman K , Gaia Valeria , Garcia-Nuñez Marian , Ginevra Christophe , Pasmal de Ameida Concalves Elsa Filipa , Gonçalves Paula , Fernandez Tiscar Graells , Grottola Antonella , Gysin Nicole , Harrison Timothy G , Höfle Manfred , Jarraud Sophie , Jorgensen Charlotte Svaerke , Joseph Carol , Slott Kanto Björn , Kese Darja , Kindingstad Louise , Klingenberg Daniela Emilia , Kösekul Mehmet , Kozak-Muiznieks Natalia , Kura Fumiaki , Kusnetsov Jaana , Lai Sandra , Lee Susanne , Lee John Vincent , Lindsay Diane , Lück Christian , Leuscher Marcel , der Lugt Wilco van , Marques Maria Teresa , Meacci Marisa , Meghraoui Alaeddine , Mentasti Massimo , Mentula Silja , Mikrut Antonija , Modol Josep , Moore Ginny , Moran-Gilad Jacob , Morin Matilda , Otgun Selin Nar , Nataas Olav Bjarte , Abadi Neda Nezam , Pancer Katarzyna , Pecorari Monica , Pedro-Botet Maria Luisa , Pelaz Carmen , Petzold Markus , Pissarides Nicholas , Portal Edward A R , Ramliden Miriam , Raphael Brian , Reddington Kate , Ricci Maria Luisa , Robesyn Emmanuel , Roisin Sandrine , Rumpianesi Fabio , Saenz Henri , Scaturro Maria , Schalk Johanna , Simone Graf , Bjerregaard Stine Skotte , Spagnolo Anna Maria , Spiller Owen B , Aspelund Anna Stjarne , Svarrer Christina Wild , Tartakovshiy Igor , Templeton Kate , Uldum Soren , Veschetti Enrico , Walker James , Wallet France , Wewalka Guenther , Whapham Catherine , Wunderlich Anika , Wybo Ingrid 
Published: January 2021

Legionella pneumophila, a Gram-negative bacillus, is the causative agent of Legionnaire’s disease, a form of severe community-acquired pneumonia. Infection can have high morbidity, with a high proportion of patients requiring ICU admission, and up to 10% mortality, which is exacerbated by the lack of efficacy of typical empirical antibiotic therapy against Legionella spp. The fastidious nature of the entire Legionellaceae family historically required inclusion of activated charcoal in the solid medium to remove growth inhibitors, which inherently interferes with accurate antimicrobial susceptibility determination, an acknowledged methodological shortfall, now rectified by a new solid medium that gives results comparable to those of microbroth dilution. Here, as an international Legionella community (with authors representing various international reference laboratories, countries and clinical stakeholders for diagnosis and treatment of legionellosis), we set out recommendations for the standardization of antimicrobial susceptibility testing methods, guidelines and reference strains to facilitate an improved era of antibiotic resistance determination.