Enterococcus faecalis alters antibiotic susceptibility in Pseudomonas aeruginosa mixed-species biofilms

Article Article scientifique Article Enterococcus faecalis alters antibiotic susceptibility in Pseudomonas aeruginosa mixed-species biofilms eng 2026-04-30 2026-05-21 author Anderson Caleb 0000-0003-3395-7805 Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland. 405924 Département de microbiologie et médecine moléculaire (MIMOL) author Mattenberger Yves Benoît 0000-0002-1651-7691 Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland. 502615 Département de microbiologie et médecine moléculaire (MIMOL) author Parga Martinez Ana 0000-0002-7670-6603 Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland.,Department of Microbiology and Parasitology, Aquatic One Health Research Center (ARCUS), Faculty of Biology, Universidade de Santiago de Compostela, Santiago de Compostela, Spain. 408513 Département de microbiologie et médecine moléculaire (MIMOL) author Portalier Heïdi Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland. 419203 author Tan Casandra Ai Zhu 0000-0002-4637-488X Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore. author Esteban Henao Maria Camila Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland. 403070 Département de microbiologie et médecine moléculaire (MIMOL) author Viollier Patrick 0000-0002-5249-9910 Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland. 706923 Département de microbiologie et médecine moléculaire (MIMOL) author Kline Kimberly Ann 0000-0002-5472-3074 Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland.,Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore. 984962 Département de microbiologie et médecine moléculaire (MIMOL) e0054825 10.1128/jb.00548-25 42059591 0021-9193 PMC13192264 https://journals.asm.org/doi/10.1128/jb.00548-25 Bacterial infections often occur in polymicrobial biofilms where nutrient limitation and interspecies interactions can profoundly shape microbial physiology. Enterococcus faecalis can antagonize Pseudomonas aeruginosa growth under conditions of iron limitation, such as those found in the mammalian host. Here, we report that this growth antagonism reveals surviving P. aeruginosa cells capable of surviving antibiotic challenge, including ampicillin, cefepime, and ciprofloxacin, when grown in iron-restricted biofilms with E. faecalis . Transcriptomic profiling of P. aeruginosa revealed a distinctive response characterized by broad downregulation of biosynthetic, metabolic, and virulence pathways, alongside selective induction of membrane remodeling proteins, transport systems, and biofilm-associated genes. Induction of arnT in P. aeruginosa , required for lipid A modification, correlated with enhanced antibiotic survival to ampicillin, cefepime, and ciprofloxacin. Additionally, the diguanylate cyclase SiaD and efflux transporter MfsC in P. aeruginosa were implicated in decreased antibiotic susceptibility to the same antibiotics. This transcriptional response was unique to the dual stress of iron deprivation and microbial competition with E. faecalis , illustrating how interspecies interactions can simultaneously inhibit and protect P. aeruginosa , shedding light on potential persistence mechanisms in iron-limited polymicrobial environments. IMPORTANCE : This study addresses antibiotic susceptibility in Pseudomonas aeruginosa , a major opportunistic ESKAPE pathogen, within polymicrobial biofilms and under host-relevant iron-restricted conditions. Polymicrobial biofilm-associated infections are notoriously difficult to treat due to complex interspecies interactions and increased antibiotic resilience. We demonstrate that Enterococcus faecalis not only antagonizes P. aeruginosa growth under iron limitation but also induces a unique transcriptional profile, enhancing P. aeruginosa survival during antibiotic challenge. This shift involves broad transcriptional reprogramming in P. aeruginosa , characterized by global metabolic downregulation and activation of envelope remodeling pathways, including the arn operon. These findings reveal how interspecies interactions under iron stress can both suppress and protect bacterial pathogens and underscore the importance of considering community context in treatment strategies for persistent infections. Enterococcus faecalis Pseudomonas aeruginosa Antibiotic Antibiotic resistance Biofilm Iron restriction Polymicrobial Dewey 616 National Research Foundation Singapore SCELSE Société Académique de Genève Kline Lab Installation Regional Government of Galicia ED6481B-2023/117 Fondation privé des HUG RC08-20 Swiss National Science Foundation Phenotypic adaptation to hypoxia by Enterococcus faecalis during colonization and infection 219227 CH 54 Département de microbiologie et médecine moléculaire 21B false 554 Régulation du cycle cellulaire dans C.crescentus, une bactérie asymétrique 895 1396 Pathogenesis of biofilm-associated infections 1044 https://www.ncbi.nlm.nih.gov/bioproject/PRJNA1365690/ Journal of bacteriology 208 5 cfb31eb1-6796-4868-860c-a133de8dba4a Article (Published version) Public 2026_Anderson_J_Bact.pdf 1572287 application/pdf CC BY-4.0 3a1f10ab9634eabbcec5950e49b7ea33ed8823e534cfeaeb353dfadd6c346528 d8dc3714-9c98-4458-937d-e632d92c4150 Supplemental data Public jb.00548-25-s0001.tif 14484048 image/tiff 89edb1fe533caf26406723d472f504d94b660ee1375e582c485d8ed2bfc5df82 4d46c1fc-a966-4af8-adf1-6f0aa279b5d1 Supplemental data Public jb.00548-25-s0002.tif 8625364 image/tiff bbe994da73c5779b016ccc69764c4dec0b4530c8e9fa81496f7714bd55431a98 167695aa-90d8-452e-89c1-f120ebc44e61 Supplemental data Public jb.00548-25-s0003.docx 44117 application/vnd.openxmlformats-officedocument.wordprocessingml.document 32cfa20dd7eac0bb228e2c9718cc102fc599687e3f1880631922388a3f42f10f 68cafa19-194c-4a60-96c8-7f75f1a7de8c Supplemental data Public jb.00548-25-s0004.xlsx 1085281 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet 97f190d91f7508d35df5f2bae44628ed72b1f5a41b8707d16d23c3f872c482b0 d5795b3d-3cd6-47d8-8f18-3ab22c1bbe0a Supplemental data Public jb.00548-25-s0005.xlsx 1058039 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet 60a4ba00ae116d28c491d1add9b3a3009cf3c1f1e11243e91ac85cb00367a88f d4f14149-6884-4d5c-91ad-25aa9e804c49 Supplemental data Public jb.00548-25-s0006.xlsx 349946 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet 161d968bf1226d008ea8bb5eafb72d80c7d864a0c72b559c68c84b190f4eecc5 500bed01-f092-4c69-a460-75264e8ea3f8 Supplemental data Public jb.00548-25-s0007.xlsx 46073 application/vnd.openxmlformats-officedocument.spreadsheetml.sheet b582ef5a65fcfc8fcfb822f6563d93a86daf43aaadebf9ec9eceeff454a2d93a openAccess Faculté de médecine / Section de médecine fondamentale / Département de microbiologie et médecine moléculaire

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Enterococcus faecalis alters antibiotic susceptibility in Pseudomonas aeruginosa mixed-species biofilms	Journal of bacteriology			2026	1	0

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