Diagnostic and epidemiological landscape of anaerobic bacteria in Europe, 2020–2023 (ANAEuROBE)
Matteo Boattini, Gabriele Bianco, Paulo Bastos, Viktoria Eirini Mavromanolaki, Sofia Maraki, Anastasia Spiliopoulou, Vasileios Kakouris, Yordan Kalchev, Ana Budimir, Branka Bedenić, Žana Rubić, Monica Licker, Corina Muşuroi, Emese Juhász, Katalin Kristóf, Mateja Pirš, Ivana Velimirović, Michael Berktold, Adriana Liptáková, Adriana Krajčíková, Pavel Dřevı́nek, Anezka Gryndlerova, Monika Brzychczy‐Włoch, Aldona Olechowska‐Jarząb, Filip Bielec, Małgorzata Brauncajs, Edyta Podsiadły, Grażyna Nurzyńska, Patrycja Zalas‐Więcek, Kristian Riesbeck, Helena Andersson, Tone Tønjum, Johan Christian Berild, Truls Michael Leegaard, Asger Nellemann Rasmussen, Kristian Schønning, Stefan Glöckner, Jürgen Rödel, Mohamed Tarek Badr, Georg Häcker, Dan Stark, Axel Hamprecht, Anna Dudakova, Jonathan Jantsch, Stefano Mancini, Chantal Quiblier, Damien Jacot, Gilbert Greub, Tiziano Ferniani, Simone Ambretti, Maddalena Calvo, Stefania Stefani, Rogier P. Schade, Erlangga Yusuf, Stefanie van Kleef–van Koeveringe, Sarah Vandamme, Alexia Verroken, Hector Rodriguez‐Villalobos, François Duigou, Stéphane Corvec, Pauline Floch, Clémence Massip, Delphine Chainier, Olivier Barraud, M Louissaint, Assaf Mizrahi, Saied Ali, Maeve Doyle, Clarice Egan, Sinéad McNicholas, Javier Colomina-Rodríguez, Ignacio Torres, Raúl Gilarranz Luengo, Nieves Larrosa, Maria Belen Viñado Perez, Ana Verónica Halperín, Sergio Fuente García, Rafael Cantón, Miguel Seruca, Vasco Santos Mendes, Dinah Carvalho, Rossana Cavallo, José Melo‐Cristino, Cristina Costa
Abstract
• The use of MALDI-TOF mass spectrometry for anaerobes identification is now systematised in Europe. • Gradient diffusion strip and disk diffusion were the preferred methods for antibiotic susceptibility testing, while no centre used the agar dilution reference method. • Fusobacterium nucleatum and Parvimonas micra were among the most frequently isolated anaerobes, but do not currently have species-specific EUCAST breakpoints. • The most alarming resistance profiles were detected in some species belonging to the Bacteroides fragilis group. • Benzylpenicillin maintained high activity against Clostridium perfringens and Fusobacterium necrophorum but not against Fusobacterium nucleatum . Despite being implicated in a wide spectrum of community- and healthcare-acquired infections, anaerobes have not yet been incorporated into systematic surveillance programs in Europe. We conducted a multicentre retrospective observational study analysing all anaerobic strains isolated from blood cultures in 44 European Hospital Centres over a 4-y period (2020–2023). Diagnostic approach, epidemiology, and antimicrobial susceptibility according to EUCAST v. 15.0 were investigated. Our study included 14,527 anaerobes, most of which were Gram-positive (45%) or Gram-negative (40%) bacilli. MALDI-TOF coupled to mass spectrometry was the most widely used tool for species identification (98%). Antimicrobial susceptibility testing was performed in the vast majority of centres, using mostly gradient diffusion strip (77%) and disk diffusion (45%) methods according to EUCAST guidelines. The most prevalent species were Cutibacterium acnes (18.7%), Bacteroides fragilis (16.3%), Clostridium perfringens (5.3%), Bacteroides thetaiotaomicron (4.2%), Fusobacterium nucleatum (3.5%), and Parvimonas micra (3.4%). C. acnes showed high resistance to benzylpenicillin (18%), clindamycin (39%), and imipenem (19% and 13% by MIC methods and disk diffusion, respectively). B. fragilis showed high resistance to amoxicillin/clavulanate (24%), piperacillin/tazobactam (22% and 14% by MIC methods and disk diffusion, respectively), clindamycin (22% by both MIC methods and disk diffusion), meropenem (13%), and metronidazole (10%, only by disk diffusion). A similar resistance pattern was observed in B. thetaiotaomicron, Bacteroides ovatus , and Parabacteroides distasonis. C. perfringens showed high resistance to clindamycin (69% and 45% by MIC methods and disk diffusion, respectively), while benzylpenicillin and metronidazole maintained over 90% activity. F. nucleatum showed high resistance to benzylpenicillin (11%), while Fusobacterium necrophorum showed alarming rates of resistance to clindamycin (12%), meropenem (16%) and metronidazole (11%). This study presented an up-to-date analysis of the diagnostics and epidemiology of anaerobic bacteria in Europe, providing insights for future comparative analyses and the development of antimicrobial diagnostic and management strategies, as well as the optimization of current antibiotic treatments.