International Microbiology最新文献

{"title":"High-yield gamma-aminobutyric acid synthesis by wild-type Levilactobacillus brevis strains isolated from traditional Iranian Kashk.","authors":"Tooba Sadat Ahmadi, Mohammad Rabbani Khorasgani, Abolghasem Esmaeili","doi":"10.1007/s10123-026-00839-8","DOIUrl":"10.1007/s10123-026-00839-8","url":null,"abstract":"<p><strong>Aims: </strong>Gamma-aminobutyric acid (GABA) is a principal inhibitory neurotransmitter involved in neuronal excitability, relaxation, anxiety modulation, and gut-brain axis regulation. Lactic acid bacteria (LAB), as prolific microbial producers of GABA, are prime candidates for developing psychobiotic and functional foods due to their generally recognized as safe (GRAS) status and health-promoting properties. This study aimed to isolate and identify novel wild-type, high GABA-producing LAB from the traditional Iranian fermented dairy product Kashk.</p><p><strong>Methods and results: </strong>A total of 33 Kashk samples, comprising 28 indigenous/artisanal and 5 commercial samples, were collected from Isfahan province. From the 28 indigenous/artisanal samples, 33 Gram-positive, catalase-negative LAB isolates were recovered. GABA production was quantified in a medium containing 5% monosodium glutamate using paper chromatography coupled with spectrophotometry. Eight isolates exhibiting GABA yields above 10 g/L (11.2-26.6 g/L) were selected for further study. 16 S rRNA gene sequencing identified all eight isolates (K-Isf 2, 8, 11, 12, 16, 25, 27, and 28) as Levilactobacillus brevis, exhibiting notable intraspecies variation in GABA biosynthesis. Phylogenetic analysis placed most isolates within a cohesive Levilactobacillus brevis cluster, whereas isolate 28 represented a divergent lineage. All high-performing isolates originated from cow's milk Kashk.</p><p><strong>Conclusions: </strong>The identified thermotolerant Levilactobacillus brevis strains exhibit high intrinsic GABA biosynthetic capacity and significant intraspecies variability, making them valuable candidates for biotechnological exploitation.</p><p><strong>Impact statement: </strong>These novel Levilactobacillus brevis strains from traditional Kashk underline the potential of native Iranian fermented foods as reservoirs of psychobiotic microorganisms. Their strong GABA-producing performance positions them as promising functional starter cultures for developing antihypertensive and anti-stress fermented products.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":"1137-1148"},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653850/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147874188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the Mechanism of Berberine Reversing MRSA Resistance to β-Lactam Antibiotics by Inhibiting blaZ Expression.","authors":"Fangfang Zhou, Xuemei Gu, Ming Lin, Yue Dai, Yanan Li, Mingming Jiang, Bianba Yangzong, Ying Wang, Xiaochun Sun, Lei Wang","doi":"10.1007/s10123-026-00838-9","DOIUrl":"10.1007/s10123-026-00838-9","url":null,"abstract":"<p><p>This study elucidates a novel mechanism by which the natural product berberine (BBR) reverses methicillin-resistant Staphylococcus aureus (MRSA) resistance to β-lactam antibiotics. It was established that BBR interferes with the BlaR1/BlaI regulatory pathway by means of downregulating the signal sensor gene blaR1 and the repressor gene blaI, thereby significantly suppressing the expression of the β-lactamase-encoding gene blaZ at the transcriptional level. The combination susceptibility testing demonstrated that BBR and Oxacillin exhibited synergistic or additive effects in 76.92% of the bacterial strains that were tested. This enhanced efficacy was closely associated with the presence of the blaZ gene. Molecular docking and dynamics simulations further confirmed that BBR stably binds to the active site of the BlaZ protein. These findings systematically clarify the multi-target mechanism of BBR as an antibiotic synergist and provide an important theoretical basis for developing combination therapeutic strategies against MRSA.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":"1177-1188"},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653821/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147987483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of Acantamoeba isolated from water resources located in the northwest of Iran by using the high-resolution melting analysis assay.","authors":"Elham Hajialilo, Soodabeh Shabani, Babak Rahmani, Mehrzad Saraei, Mohammad Ali Hosseini, Marjan Ghalandari, Atefeh Elekaei, Peyman Heydarian","doi":"10.1007/s10123-026-00857-6","DOIUrl":"10.1007/s10123-026-00857-6","url":null,"abstract":"<p><strong>Background: </strong>Free-living amoebae (FLA), such as Acanthamoeba, are protozoan parasites that take advantage of opportunities with a widespread distribution in various environmental sources, such as a wide range of water sources. The amoeba can accidentally infect individuals and cause a variety of diseases, including amoebic encephalitis and keratitis, in both immunocompetent and immune-deficient individuals. The amoeba can act as reservoirs and carriers for pathogenic microorganisms, increasing the risk of pathogenicity in humans. The objective of this research was to identify the genotypes, besides in addition to the species of the FLA, in water sources in Qazvin province using high-resolution melting analysis (HRM).</p><p><strong>Methods: </strong>A total of 44 DNA isolates from FLA, including samples from swimming pools irrigation canals, and drinking water, were analyzed for the 18SrDNA gene using HRM. The data was evaluated using Chi-square test and Fisher's exact tests.</p><p><strong>Results: </strong>The Molecular analysis revealed that 79.5% of the isolates were of the T3 genotype, 6.9% were of the T4 genotype of Acanthamoeba, and 13.6% were identified as Protoacantamoeba bohemica species. The statistical analysis exhibited a significant difference among the contamination and water source.</p><p><strong>Conclusion: </strong>As water sources directly related to the public health, this study recommends paying close attention to treating water sources and utilizing new and accurate molecular methods to identify the potential pathogenic amoeba.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":"1443-1449"},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653825/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148360739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Docosahexaenoic acid alleviates DSS-induced colitis by regulating the gut microbiota and restoring the gut barrier.","authors":"Sumin Wang, Shiping Hu, Yan Yan, Lingyi Wu, Li Tang, Yiyang Hu, Wanneng Wang","doi":"10.1007/s10123-026-00859-4","DOIUrl":"10.1007/s10123-026-00859-4","url":null,"abstract":"<p><p>Docosahexaenoic acid (DHA), a long-chain omega-3 polyunsaturated fatty acid, has well-recognized anti-inflammatory activity; however, the mechanisms underlying its protective effects in inflammatory bowel disease (IBD) remain incompletely understood. In this study, we investigated the effects of DHA in a dextran sulfate sodium (DSS)-induced mouse model of colitis and examined whether these effects were mediated by the gut microbiota. DHA administration markedly alleviated DSS-induced colitis, as indicated by reduced body weight loss, disease activity, mortality, colon shortening, histological injury, intestinal barrier disruption, and colonic inflammatory responses. 16 S rRNA gene sequencing showed that DHA reshaped the gut microbial community and increased the abundance of beneficial taxa, including Bifidobacterium. Antibiotic cocktail (ABX)-mediated microbiota depletion largely abolished the protective effects of DHA, whereas fecal microbiota transplantation (FMT) from DHA-treated donors transferred resistance to DSS-induced colitis to recipient mice. DHA also restored tight junction protein expression and increased the frequency of colonic regulatory T cells in a microbiota-dependent manner. These findings indicate that DHA alleviates experimental colitis by modulating the gut microbiota, restoring intestinal barrier integrity, and regulating mucosal immune homeostasis. DHA may therefore represent a promising dietary strategy for the prevention or adjunctive treatment of ulcerative colitis (UC).</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":"1451-1463"},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653849/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148375689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing the antifungal and antioxidant activity of Agaricus bisporus extract using gamma radiation: implications for shelf-life extension of fresh-cut apples.","authors":"Mohamed S Abd El-Al, Doaa A Emam, Eman Araby, Abeer A Khattab","doi":"10.1007/s10123-026-00806-3","DOIUrl":"10.1007/s10123-026-00806-3","url":null,"abstract":"<p><p>Fresh-cut fruits are highly perishable due to enzymatic browning and microbial spoilage following tissue disruption. This study investigated whether γ-irradiation of the edible mushroom Agaricus bisporus enhances its antioxidant and antifungal properties and whether the treated extract can be applied as a natural preservative for fresh-cut apples. Ethanolic extracts of A. bisporus were irradiated at 0-8.0 kGy and evaluated against six apple-spoiling fungi (Penicillium expansum, P. chrysogenum, Botrytis cinerea, Fusarium oxysporum, Aspergillus flavus, and A. niger). Among the tested solvents, ethanol yielded the most potent extract, showing a 14-mm inhibition zone against P. chrysogenum. Irradiation at 6.0 kGy significantly increased total phenolic content (3.25 mg GAE g⁻¹) and DPPH scavenging activity (46.3% at 100 µg mL⁻¹) (p < 0.05). The 6.0 kGy extract inhibited fungal enzymes-protease (40%), cellulase (35%), and lipase (45%)-and caused hyphal deformation, as observed by SEM. Sorbitol protection assays indicated cell-wall targeting. GC-MS profiling revealed irradiation-induced modifications in the fatty acid and sterol compositions. When applied at 10% (w/v) to fresh-cut apples stored at 4 °C for 10 days, the irradiated extract reduced browning, retained firmness, and decreased fungal and bacterial counts by 1.3 and 1.6 log CFU g⁻¹, respectively. Overall, mild γ-irradiation (6.0 kGy) enhanced the bioactivity and preservative potential of A. bisporus extract, supporting its application as a natural, clean-label agent for fresh-cut produce preservation.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":"1107-1120"},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653835/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147815328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transcutaneous electrical nerve stimulation changed the relative abundance of intestinal microbiota in rats with knee osteoarthritis: a potential treatment for KOA.","authors":"Yang Zhang, Tong Ma, Ran Chen, Hong-Bin Zhao, Yan Sun","doi":"10.1007/s10123-026-00854-9","DOIUrl":"10.1007/s10123-026-00854-9","url":null,"abstract":"<p><strong>Background: </strong>Knee osteoarthritis (KOA) is a common degenerative bone disease, and transcutaneous electrical nerve stimulation (TENS) is an alternative and complementary therapy (ACM). This study revealed the role of TENS in regulating the intestinal microbiota in KOA rats.</p><p><strong>Methods: </strong>This study concentrated on the intestinal microbiota of KOA rats which were treated with TENS for 1, 2, and 3 weeks. Three intensities of TENS were used to treat KOA rats, and the expressions of IL6/8, PI3K-AKT were measured. The intestinal microbiota was analyzed by 16 S rDNA sequencing.</p><p><strong>Results: </strong>Compared with the Model Control group, TENS could improve symptoms of KOA rats and inhibit the expressions of IL6/8 by down-regulating the PI3K-AKT expression. After 3 weeks of treatment with TENS, compared with the Model Control group, the abundances of Bacteroidetes, Bacteroidetes, and Thermodesulfobacteria increased in the TENS groups; the abundances of Ficmicutes, Campylobacter, and Verruca decreased in the TENS groups.</p><p><strong>Conclusion: </strong>TENS could improve the histomorphology of knee and inhibit inflammation in KOA rats. After treatment with TENS, the intestinal microbiota gradually changed from 1,2,3 weeks and the abundance of them was different with three intensities of TENS. Further study will elucidate the underlying mechanisms of TENS in altering gut microbiota and the potential therapeutic applications of these intestinal microbiota for KOA.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":"1357-1366"},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653860/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148301767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rosemary essential oil nanoparticles enhance antimicrobial activity and induce bacterial DNA disruption.","authors":"Habiba A Ahmed, Hala El-Adawi, Asmaa Abdel-Fattah, Abeer E Abd El-Wahab","doi":"10.1007/s10123-026-00815-2","DOIUrl":"10.1007/s10123-026-00815-2","url":null,"abstract":"<p><p>The current work aimed to formulate Rosemary essential oil nanoparticles (Ros-ES-NPs) and evaluate their antimicrobial effect in comparison with free oil (Ros- ES). Physicochemical characterization was performed using Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering, zeta potential analysis, transmission electron microscop y (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The cytotoxic activity of Ros-ES-NPs on human lung fibroblast cell line (Wi-38) was examined in comparison with Ros- ES using MTT assay. Ros-ES exhibited dose-dependent cytotoxicity, with an IC₅₀ of approximately 6.06 mg/ml on Wi-38. In contrast, the Ros-ES-NPs not only showed no toxicity but actually appeared to increase cell viability (up to ≈ 136%) possibly due to high metabolic actvity.The antimicrobial activity of Ros-ES and Ros-ES-NPs was evaluated against three isolates of Multidrug-Resistant Bacteria, comprising two Gram-negative isolates (Shigella flexneri and Klebsiella pneumoniae) and one Gram-positive isolate (Streptococcus pneumoniae), alongside Candida albicans as the fungal pathogen. Ros-ES-NPs showed a significant antimicrobial efficacy against all isolates under study where, at 25 mg/ml, Ros-ES inhibited K. pneumoniae and Shigella flexneri by 55.16 ± 0.09% and 76.47 ± 1.16%, respectively, whereas Ros-ES-NPs showed inhibition rates of 95.66 ± 9.74% and 87.13 ± 2.63%, respectively. Against Streptococcus pneumoniae, at 25 mg/ml, Ros-ES inhibited by 68.75 ± 0.60%, while Ros-ES-NPs exhibited a higher inhibition rate of 80.73 ± 5.6%. In case of C. albicans, Ros-Es showed a higher inhibition (81.85 ± 0.54) than Ros-Es-NPs (60.39 ± 5.69). Rosemary essential oil nano-formulation significantly enhances antibacterial efficacy while improving biocompatibility and inducing pronounced microbial DNA damage.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":"1149-1159"},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653882/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147929564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrated transcriptomic and metabolomic analysis reveals the regulatory networks in response to heat stress in Pleurotus pulmonarius.","authors":"Na Lu, Guanping Chen, Hailong Wei, Jiayao Lin, Weike Wang","doi":"10.1007/s10123-026-00852-x","DOIUrl":"10.1007/s10123-026-00852-x","url":null,"abstract":"<p><p>An integrated transcriptomic and metabolomic analysis was conducted to elucidate the molecular mechanisms underlying heat stress response in Pleurotus pulmonarius, a commercially important edible mushroom sensitive to elevated temperatures. Through comparative RNA-seq and UPLC-MS based metabolomics, we identified 4,388 differentially expressed genes (DEGs) and 1,282 differentially accumulated metabolites (DAMs) in mycelia exposed to 42 °C for 6 h compared with control conditions. Integrated pathway analysis revealed that pyrimidine metabolism, tryptophan metabolism, and cysteine/methionine metabolism were coordinately reprogrammed at both transcriptional and metabolic levels, forming a synergistic regulatory network. These pathways collectively provide essential precursors for nucleic acid synthesis, modulate auxin (IAA)-mediated stress signaling, and sustain antioxidant capacity, respectively. Our findings establish a systems-level framework for understanding heat adaptation in P. pulmonarius and highlight key metabolic nodes that may serve as targets for molecular breeding of thermotolerant cultivars.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":"1345-1356"},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653963/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148301740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel Aureobasidium pullulans isolate for the biological control of Penicillium commune in potato decay and its optimization for enhanced antifungal activity using the Taguchi method.","authors":"Noushin Shafiee, Keivan Beheshti-Maal, Hamid Reza Akkafi, Hashem Nayeri","doi":"10.1007/s10123-026-00863-8","DOIUrl":"10.1007/s10123-026-00863-8","url":null,"abstract":"<p><p>Penicillium commune is a significant postharvest fungal pathogen responsible for blue mold rot in stored potatoes, resulting in substantial economic losses worldwide. In this study, we isolated and characterized a novel epiphytic strain of Aureobasidium pullulans SBAN-IAUF-1 from potato foliage and evaluated its antagonistic activity against Penicillium commune SBAN-IAUF-12. The new isolate exhibited strong inhibitory effects, reducing pathogen growth by 60% in vitro and 69.41% in vivo, outperforming values reported for most previously studied A. pullulans strains. Extracellular antifungal metabolites produced by Aureobasidium pullulans SBAN-IAUF-1 also showed substantial antifungal activity, indicating that extracellular antifungal metabolites play a key role in antagonism. To further enhance extracellular antifungal metabolites activity, we applied a Taguchi L9 orthogonal design, which identified optimal culture conditions and significantly increased the extracellular antifungal metabolites activity. The optimal conditions suggested by L9 analysis for maximizing extracellular antifungal metabolites production were 20 °C, 7 days of incubation, pH 5, and 1% (wv^- 1) YMB concentration. This study provides the first report of a potato-derived A. pullulans isolate optimized through Taguchi methodology for controlling Penicillium commune. The strong biocontrol activity of Aureobasidium pullulans SBAN-IAUF-1 highlights its potential as an environmentally safe and effective candidate for postharvest management of blue mold disease in potatoes.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":"1509-1520"},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653843/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148470461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synergistic and antibiofilm activity of colistin combined with cinnamaldehyde and eugenol against colistin-resistant Acinetobacter baumannii clinical isolates.","authors":"Abdulhamit Çalı, Rukiye Aslan, Kübra Fırtına Topcu, Cem Çelik","doi":"10.1007/s10123-026-00848-7","DOIUrl":"10.1007/s10123-026-00848-7","url":null,"abstract":"<p><strong>Objective: </strong>This study aimed to evaluate the effectiveness of combinations of colistin (COL) with cinnamaldehyde (CIN) or eugenol (EUG) against planktonic and biofilm forms of colistin-resistant clinical Acinetobacter baumannii isolates.</p><p><strong>Methods: </strong>Minimum inhibitory concentration (MIC) values of COL and essential oil components in 10 colistin-resistant clinical isolates were evaluated by the broth microdilution method. Interactions were classified by the fractional inhibitory concentration index (ΣFICI) using the checkerboard method. Biofilm formation was detected using the crystal violet method and the inhibitory effects of selected combination ratios on biofilm formation were evaluated in isolates showing synergy. In addition, the time-dependent effects of synergy combinations on 48-h pre-formed biofilm biomass were examined.</p><p><strong>Results: </strong>Median MIC values of COL, CIN, and EUG were 8 (4-32), 128 (128-128), and 512 (256-1024) µg/mL, respectively. In combination, the MIC of COL decreased to 1 (0.5-16) µg/mL with CIN and to 2 (0.5-8) µg/mL with EUG (p = 0.002). Synergy was observed in half of the isolates in both combinations (median ΣFICI: 0.532 and 0.469). Three isolates formed strong biofilms and seven formed moderate biofilms. Biofilm inhibition ranged from 1.1% to 50.5% for COL-CIN combination and from 11.7% to 80.0% for the COL-EUG combination. In 48-h pre-formed biofilms, the residual biomass at 24 h was significantly lower than that at 1 h for both combinations (p < 0.05).</p><p><strong>Conclusions: </strong>COL-CIN and COL-EUG combinations reduced MICs in colistin-resistant A. baumannii and decreased both biofilm formation and 48-h pre-formed biofilm biomass. These findings are promising for combination-based antibiofilm strategies.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":"1319-1328"},"PeriodicalIF":2.9,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13653846/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148217705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}