Diógenes Expedito Maia, Mesquita Felipe Pantoja, da Silva Emerson Lucena, Pereira Vinicius Carvalho, de Souza Paulo Roberto Honório, Dos Santos Pedro Victor Coelho, de Sousa Paulo César Pereira, de Souza Pedro Filho Noronha, Rocha Marcos Fábio Gadelha, Sidrim José Júlio Costa, Cordeiro Rossana de Aguiar, Guedes Gláucia Morgana de Melo, Montenegro Raquel Carvalho, Castelo-Branco Débora de Souza Collares Maia
Department of Pathology and Legal Medicine, Postgraduate Program in Medical Microbiology, Group of Applied Medical Microbiology, Federal University of Ceará, Fortaleza, Ceará, 60430-275, Brazil.
Laboratory of Pharmacogenetics, Drug Research and Development Center (NPDM), Federal University of Ceará, Rua Coronel Nunes de Melo, 1000 - Rodolfo Teófilo, Fortaleza, Brazil.
Microb Pathog. 2025 Sep;206:107701. doi: 10.1016/j.micpath.2025.107701. Epub 2025 May 12.
5-Fluorouracil (5-FU) is a chemotherapeutic agent that disrupts pyrimidine metabolism, which can interact with gut microbiota, potentially causing dysbiosis and promoting antibiotic resistance. This study analyzed its antimicrobial and antibiofilm effects on Escherichia coli and Enterococcus spp. The Minimum Inhibitory Concentrations (MIC) and Minimum Biofilm Eradication Concentrations (MBEC) of 5-FU were determined against 17 clinical isolates, including resistant and susceptible strains. Biofilm formation and viability were assessed using crystal violet staining and resazurin assays, respectively. Growth curves were generated by exposing selected strains to increasing concentrations of 5-FU and monitoring Optical Density (OD) at 630 nm over 24 h. Flow cytometry was used to evaluate membrane integrity, using Propidium Iodide (PI), and Reactive Oxygen Species (ROS) production, with DCFH-DA, while Scanning Electron Microscopy (SEM) was used to show the structural alterations in bacterial cells. 5-FU MIC values ranged from 128 to 512 μM against E. coli and 1-32 μM against Enterococcus spp., with higher MICs observed against resistant strains. MBEC values exceeded planktonic MICs by up to 16-fold for E. coli and 64-fold for Enterococcus spp., ranging from 128 to >2048 μM. At MIC concentrations, membrane damage was increased in both species, while at subinhibitory concentrations, ROS production was exclusively detected in Enterococcus faecalis strains. SEM revealed severe structural alterations, including pore formation, cell shrinkage, cytoplasmic leakage, and cell disintegration highlighting the impact of 5-FU on bacterial morphology. These findings highlight the antibacterial effect of 5-FU, underscoring its potential impact on gut microbial dynamics and the selective pressures it exerts during chemotherapy.
5-氟尿嘧啶（5-FU）是一种干扰嘧啶代谢的化疗药物，它可与肠道微生物群相互作用，可能导致生态失调并促进抗生素耐药性。本研究分析了其对大肠杆菌和肠球菌的抗菌及抗生物膜作用。测定了5-FU对17株临床分离株（包括耐药和敏感菌株）的最低抑菌浓度（MIC）和最低生物膜清除浓度（MBEC）。分别使用结晶紫染色和刃天青试验评估生物膜形成和活力。通过将选定菌株暴露于浓度递增的5-FU中并在24小时内监测630nm处的光密度（OD）来生成生长曲线。使用碘化丙啶（PI）通过流式细胞术评估膜完整性，并使用2',7'-二氯二氢荧光素二乙酸酯（DCFH-DA）评估活性氧（ROS）的产生，同时使用扫描电子显微镜（SEM）显示细菌细胞的结构变化。5-FU对大肠杆菌的MIC值范围为128至512μM，对肠球菌的MIC值为1至32μM，对耐药菌株观察到更高的MIC值。大肠杆菌的MBEC值比浮游菌MIC值高出多达16倍，肠球菌的MBEC值比浮游菌MIC值高出多达64倍，范围为128至>2048μM。在MIC浓度下，两种菌的膜损伤均增加，而在亚抑菌浓度下，仅在粪肠球菌菌株中检测到ROS产生。SEM显示出严重的结构变化，包括孔形成、细胞收缩、细胞质泄漏和细胞解体，突出了5-FU对细菌形态的影响。这些发现突出了5-FU的抗菌作用，强调了其对肠道微生物动态的潜在影响以及化疗期间它所施加的选择压力。
