Brazilian Journal of Microbiology最新文献

{"title":"Arbovirus co-circulation and epidemiological convergence in a changing climate: challenges for surveillance, diagnosis and public health preparedness.","authors":"Gian Marco Ludovici, Alba Iannotti, Colomba Russo, Francesco Gargallo di Castel Lentini, Manousos E Kambouris, Mostafa Mohammed Atiyah, Sijo Asokan, Andrea Malizia, Marta Giovanetti","doi":"10.1007/s42770-026-02083-8","DOIUrl":"10.1007/s42770-026-02083-8","url":null,"abstract":"<p><p>Arboviral diseases are undergoing substantial epidemiological changes driven by climate change, urbanization, global mobility, vector expansion, and evolving ecological conditions. These processes increasingly favor the geographic overlap and co-circulation of multiple arboviruses, including in regions previously considered at limited risk. In this review, we describe this broader process as epidemiological convergence, referring to the progressive overlap of arboviral transmission systems across shared geographic, ecological, vector, host, and public health contexts. Such convergence creates interconnected challenges for clinical recognition, laboratory diagnosis, surveillance, and outbreak response. Diagnostic uncertainty is further amplified by overlapping clinical presentations, serological cross-reactivity, previous arboviral exposure, and co-infections or sequential infections. At the same time, pathogen-specific surveillance systems may inadequately capture increasingly complex transmission patterns, highlighting the need for integrated and interoperable approaches. One Health provides an essential framework for integrating human, animal, vector, and environmental dimensions of arboviral transmission. Complementarily, selected principles derived from Chemical, Biological, Radiological, Nuclear, and Explosive (CBRNE) preparedness may strengthen operational coordination, contingency planning, biosafety, risk communication, and response capacity during complex arboviral scenarios. However, their added value in arboviral settings requires further empirical evaluation. Addressing epidemiological convergence will ultimately require adaptable systems linking epidemiological understanding, diagnostic capacity, integrated surveillance, and operational preparedness.</p>","PeriodicalId":9090,"journal":{"name":"Brazilian Journal of Microbiology","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13558541/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148917762","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":"Encapsulation of probiotic Lactiplantibacillus plantarum S18 in sodium alginate: process optimization using Box-Behnken design for poultry feed application.","authors":"Wissam Hafir, Samia Hamma-Faradji, Zahra Azzouz, Abdellah Zikiou, Imen Trabelsi, Naourez Ktari, Riadh Ben Salah, Farida Bendali","doi":"10.1007/s42770-026-02059-8","DOIUrl":"10.1007/s42770-026-02059-8","url":null,"abstract":"<p><p>This study aimed to develop an effective method for encapsulating lactic acid bacteria (LAB) to improve their low survival rate under harsh environmental conditions. The strains were submitted to a battery of standard tests and criteria commonly used for determining their probiotic properties and attributes. A total of 22 LAB strains were isolated; the isolates were mostly resistant to ciprofloxacin, vancomycin and sulphamethoxazole/trimethoprim (clear zones = 0 mm), whereas S18 and S21 were sensitive and S19, S20 and S22 showed intermediate susceptibility (clear zones between 16 and 20 mm). They also demonstrated high tolerance to simulated gastro-intestinal tract conditions, maintaining viability in Man, Rogosa, and Sharpe (MRS) broth at gastric pH 2.5 and in the presence of 0.3% bile salts. In biofilm formation essays, 12 isolates showed strong adhesion to polystyrene microplates, and all selected strains exhibited significant inhibitory activity against tested pathogens. The strain displaying the best promising probiotic characteristics was identified through 16 S rRNA sequencing as Lactiplantibacillus plantarum S18. Encapsulation of this strain in sodium alginate was optimized using a box-benken design. The highest encapsulation efficiency (99.99%) was achieved using a bacterial cell concentration of 10⁸ CFU/ml, calcium chloride concentration of 1.540 M, a solidification time of 12 min, and a sodium alginate concentration of 2.15%. Overall, the findings demonstrate that sodium alginate-based encapsulation effectively preserves the stability and viability of Lactiplantibacillus plantarum S18, supporting its potential use as a probiotic additive in poultry feed.</p>","PeriodicalId":9090,"journal":{"name":"Brazilian Journal of Microbiology","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13558532/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148917943","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":"Biotechnological valorization of rice waste from Trichoderma production through the development of a streptomyces-based biological soil conditioner.","authors":"Natacha Melo, Mateus Torres Nazari, Vera Analise Schommer, Valdecir Ferrari, Carlos Alberto Mendes Moraes, Regina Célia Espinosa Modolo, Fernando Joel Scariot, Ana Paula Longaray Delamare, Feliciane Andrade Brehm","doi":"10.1007/s42770-026-02039-y","DOIUrl":"10.1007/s42770-026-02039-y","url":null,"abstract":"<p><p>Sustainable soil management is vital for maintaining agricultural productivity while mitigating the environmental impacts of intensive pesticide use. This study evaluated the use of rice waste generated during Trichoderma asperelloides production as a substrate for the cultivation of Streptomyces sp. BEI-18 A through solid-state fermentation to obtain a biological soil conditioner. The rice waste from Trichoderma production (RWTP) underwent solid-state fermentation (SSF) for seven days, and the product was characterized according to the Brazilian Normative Instruction No. 35/2006 for soil conditioners and amendments. Biological analyses included colony-forming unit (CFU) counts, enzymatic activity (β-glucosidase and arylsulfatase), and respirometry. The conditioner was also applied to soil at different rates in maize (Zea mays L.) pot experiments to assess its effects on soil biological parameters. The application of the biological soil conditioner increased microbial abundance, enzymatic activity, and CO₂ release compared to the control, increasing β-glucosidase classification from moderate to adequate. Although physicochemical parameters did not meet the criteria for physical or chemical classification, the material met the requirements for classification as a biological soil conditioner. The results indicate that rice waste from T. asperelloides production can be reused as a substrate for producing bioinputs capable of enhancing soil biological activity.</p>","PeriodicalId":9090,"journal":{"name":"Brazilian Journal of Microbiology","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13558514/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148917792","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":"Global expression profile of enterohemorrhagic Escherichia coli O157:H7 in phagosome of murine macrophages.","authors":"Nahuel Agustín Riviere, Lin Jiang, Xiuju Wu, Pablo Farace, Lu Guo, Libia Yael Smith, Wanderson Marques Da Silva, Ángel Adrián Cataldi, Ke Xing, Jinlong Bei, Mariano Larzábal","doi":"10.1007/s42770-026-02048-x","DOIUrl":"10.1007/s42770-026-02048-x","url":null,"abstract":"<p><p>Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes foodborne outbreaks leading to hemolytic uremic syndrome (HUS) via Shiga toxin (Stx). During HUS pathogenesis, EHEC O157:H7 is phagocytized by intestinal macrophages, although only a small proportion of internalized bacteria survive within the phagosome. To investigate this persistence, we performed global RNA-seq analysis of intracellular EHEC O157:H7 within murine macrophage phagosomes, complemented by in vitro assays simulating key phagosomal stressors. Our results reveal that EHEC employs a sophisticated survival strategy characterized by metabolic reprogramming and stress resistance. Inside macrophages, EHEC activates the SOS pathway, synthesizes membrane lipids, and engages NO detoxification mechanisms while repressing energetically costly virulence systems -motility, Type 3 Secretion System (T3SS), and Type 6 Secretion System (T6SS)-to prioritize survival. Notably, Shiga toxin gene regulation proved highly context-dependent: phagocytosis selectively upregulated the stx2a A subunit via the SOS response, whereas stx1a remained uninduced, likely restrained by NO-mediated repression. In contrast, under in vitro multi-stress conditions (pH 4.5) engaged the AR2-AR5 acid resistance systems and triggered robust expression of both stx1a subunits (A and B). These findings highlight the dynamic, stress-specific regulatory networks EHEC relies on to persist within the host.</p>","PeriodicalId":9090,"journal":{"name":"Brazilian Journal of Microbiology","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13553990/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148910559","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":"Turnover of microbial specialists and generalists shapes deterministic assembly and network stability along a salinity-alkalinity gradient in inland wetland soils.","authors":"Jie Wei, Fan Chang, Haomin Yang, Yan Sun, Zhi Li, Jun Li, Nannan Liu, Zhuan Hao","doi":"10.1007/s42770-026-02073-w","DOIUrl":"10.1007/s42770-026-02073-w","url":null,"abstract":"<p><p>Salinity-alkalinity gradients impose strong environmental filtering on soil microbial communities, yet the respective roles of generalist and specialist taxa in community assembly and stability remain insufficiently understood in wetland ecosystems. Here, bacterial and fungal communities were investigated across low, moderate, and high saline-alkaline zones in the Luyang Lake wetland, China. Amplicon sequencing was integrated with niche breadth analysis, community assembly inference, co-occurrence network analysis, cohesion metrics, and partial least squares path modeling to assess how generalists and specialists responded to environmental variation and contributed to microbial stability. Bacteria contained a larger generalist pool, whereas fungi were relatively enriched in specialists. Generalists were positively associated with nutrient availability and negatively associated with saline-alkaline stress, while bacterial specialists showed the opposite trend. Niche breadth decreased with increasing salinity-alkalinity, especially in bacteria, and this narrowing was accompanied by stronger deterministic assembly, mainly homogeneous selection. Network analysis further suggested that generalists contributed more to overall community connectivity, whereas specialists became more important for network organization under stronger saline-alkaline stress. Path modeling indicated that bacterial and fungal community stability was associated with distinct response pathways. Overall, salinity-alkalinity reorganized microbial communities by reducing niche breadth, strengthening deterministic assembly, and shifting the relative contributions of generalists and specialists to community stability. These findings improve our understanding of how niche strategy mediates microbial assembly and stability in saline-alkaline wetland soils.</p>","PeriodicalId":9090,"journal":{"name":"Brazilian Journal of Microbiology","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13550284/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148905148","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":"Optimization of fermentation parameters and mutagenesis of Glarea lozoyensis ATCC 20868 towards pneumocandin B₀ production.","authors":"Anshu Baldia, Manish Kumar, Deepanshi Rajput, Kashyap Kumar Dubey","doi":"10.1007/s42770-026-02079-4","DOIUrl":"10.1007/s42770-026-02079-4","url":null,"abstract":"<p><p>Pneumocandin B₀ is a secondary metabolite that acts as a precursor for caspofungin acetate, an antifungal drug. This study focuses on the development of an upstream process for pneumocandin B₀ production through fermentation condition optimization and mutagenesis. A response surface methodology (RSM)-based central composite design (CCD) was employed to increase the production of pneumocandin B₀ in Glarea lozoyensis ATCC 20868. The four independent variables (mannitol, fructose, soybean meal, and pH) were chosen at three different levels to obtain the optimum conditions for pneumocandin B₀ production. The optimized process conditions using RSM-CCD resulted in 29.4 mg/L pneumocandin (11.76-fold increase compared with that of wild-type). To improve pneumocandin B₀ production, mutagenesis (physical/chemical) was also performed using gamma-irradiation and methyl methane sulfonate (MMS). The best-performing MMS-induced mutant strain in optimized medium resulted in increased pneumocandin B_0, i.e., 74.17 mg/L (29-fold increase compared with that of wild-type), at the 2-L shake flask level. Additionally, morphological analysis using scanning electron microscopy revealed significant structural changes in the mutant strains, including altered hyphal and mycelial morphology. These findings suggest that mutagenesis not only enhances production but also modifies cellular physiology. In conclusion, this study presents an integrated strategy that combines media optimization and mutagenesis to significantly increase pneumocandin B₀ production.</p>","PeriodicalId":9090,"journal":{"name":"Brazilian Journal of Microbiology","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13550391/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148905051","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":"Occurrence and antimicrobial resistance profile of Listeria monocytogenes isolated from chilled processed meat products in the Metropolitan Region of Recife, Brazil.","authors":"Anízia Maria Vieira de Souza Lapenda, Eduarda Faria Raymundo, Pedro Marinho de Carvalho Neto, Rinaldo Aparecido Mota, José Wilton Pinheiro Junior, Andrea Paiva Botelho Lapenda de Moura","doi":"10.1007/s42770-026-02070-z","DOIUrl":"10.1007/s42770-026-02070-z","url":null,"abstract":"<p><p>The presence of Listeria monocytogenes in food represents a major challenge to food safety, especially in ready-to-eat products stored under refrigeration. This risk is associated with the ability of the pathogen to survive and multiply during prolonged refrigerated storage, making these foods potential sources of infection and a relevant public health concern. In this context, the aim of this study was to investigate the presence of Listeria monocytogenes in chilled processed meat products sold in bulk in the Metropolitan Region of Recife, PE, Brazil, as well as to evaluate the antimicrobial susceptibility profile of the isolates. A total of 48 samples of sausages and ham from different brands were analyzed, obtained from public markets and supermarkets in the region. Detection of Listeria spp. was performed using conventional methods recommended by the Ministry of Agriculture and Livestock, and antimicrobial susceptibility was assessed by the disk diffusion method. Of the analyzed products, 27/48 (56.25%) samples were positive for Listeria spp. by bacterial isolation. Among these, 15/48 (31.25%) were confirmed as L. monocytogenes. In the disk diffusion assay, one L. monocytogenes isolate showed a multidrug-resistant profile to vancomycin, amoxicillin, ampicillin, and ciprofloxacin. Additionally, among the Listeria spp. isolates, 6/27 (22.22%) showed resistance to at least one of the tested antimicrobials, with emphasis on ciprofloxacin (11.1%). These results demonstrate the presence of Listeria spp. and L. monocytogenes in commercially available chilled processed meat products, highlighting the importance of microbiological monitoring of these foods and surveillance of antimicrobial resistance profiles.</p>","PeriodicalId":9090,"journal":{"name":"Brazilian Journal of Microbiology","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13545191/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148891064","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":"One Health in hospital settings: the role of water as an invisible reservoir of opportunistic pathogens.","authors":"Emilly Brito Ferreira, Jean Lopes da Silva, Monica de Souza Ferreira de Mattos, Hilton Vizi Martinez, Eduardo Jorge Pilau, Maria Cristina Bronharo Tognim, Fabrícia Gimenes, Miguel Machinski Junior, Benício Alves de Abreu Filho","doi":"10.1007/s42770-026-02078-5","DOIUrl":"10.1007/s42770-026-02078-5","url":null,"abstract":"<p><strong>Objectives: </strong>To evaluate the microbiological quality of a hospital's treated water distribution system, characterize opportunistic bacterial isolates and their antimicrobial susceptibility profiles, investigate the genetic relatedness between environmental and clinical isolates from a One Health perspective.</p><p><strong>Study design: </strong>Prospective observational study.</p><p><strong>Methods: </strong>A total of 352 water samples were collected over six months from strategic locations within a public teaching hospital. Samples were analyzed for total coliforms, Escherichia coli, heterotrophic bacteria (HB), bacterial isolation and identification, antimicrobial susceptibility testing, and ERIC-PCR genotyping was applied to Pseudomonas aeruginosa isolates to analyse their similarity with clinical isolates. Statistical analysis used the chi-square test of independence (χ²).</p><p><strong>Results: </strong>Despite legal compliance for coliforms, elevated HB counts were found in 17% of water tank samples and 12% of ICU samples. Pathogens such as Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Enterobacter spp. were isolated. Enterobacter spp. isolates exhibited resistance to multiple β-lactams. Genotypic analysis did not reveal a direct clonal relationship between P. aeruginosa isolates from water and NDM-producing P. aeruginosa isolates recovered from hospitalized patients.</p><p><strong>Conclusions: </strong>Although the hospital water distribution system complied with current microbiological potability standards, opportunistic bacteria were detected in localized areas of the network. The absence of clonal relatedness between environmental and clinical P. aeruginosa isolates suggests that the water system was not an active source of dissemination during the study period. These findings support the value of routine environmental surveillance as part of infection prevention strategies within a One Health framework.</p>","PeriodicalId":9090,"journal":{"name":"Brazilian Journal of Microbiology","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13545182/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148891134","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":"Correction: An experimental multiplex PCR/RT-PCR for detection of the main viruses associated with equine neurological disease.","authors":"S O Scherer, J V J Silva Júnior, N H Pedroso, I F Dionisio, R Weiblen, E F Flores","doi":"10.1007/s42770-026-02082-9","DOIUrl":"10.1007/s42770-026-02082-9","url":null,"abstract":"","PeriodicalId":9090,"journal":{"name":"Brazilian Journal of Microbiology","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13542003/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148886356","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":"Phenotypic and molecular detection of efflux pump and expression profiling genes in Klebsiella pneumoniae exposed to ciprofloxacin and amoxicillin/clavulanic acid.","authors":"Fatima Amer Abd Algabar, Athmar Adnan Hakman, Mudhar A Al-Obaidi","doi":"10.1007/s42770-026-02075-8","DOIUrl":"10.1007/s42770-026-02075-8","url":null,"abstract":"<p><strong>Background: </strong>One of the main strategies Gram-negative bacteria employ to lower internal antibiotic concentrations is efflux. By identifying and eliminating a variety of harmful substances, including antibiotics, these active transport systems help bacteria become less susceptible to drugs and develop new resistance mechanisms. Efflux pumps are involved in bacterial stress response, pathogenicity, biofilm formation, and host physiology alteration in addition to offering an escape from antibacterial chemicals.</p><p><strong>Objective: </strong>This research is designed to study the prevalence of efflux pump genes and the measure expression of )AcrAB, MarA, MdtK OmpK35 and OmpK36 genes before and after treatment with combination of Ciprofloxacin (CIP) and Amikacin (AMC) antibiotic CIP of Klebsiella pneumoniae isolated from hospitalized patients in Iraq hospitals.</p><p><strong>Materials and methods: </strong>During a six-month cross-sectional survey (January-June 2025), twenty K. pneumoniae strains were collected from patients admitted to several teaching hospitals. Their antimicrobial sensitivity was determined by applying the agar-based disk diffusion assay. The ethidium bromide (EtBr) agar cartwheel method can be used to phenotypically detect the activity of efflux pumps in K. pneumoniae isolates. The PCR method was used to determine the frequency of genes encoding AcrAB, marA, mdtK, ompK35, and ompK36 in K. pneumoniae, and the Real-time PCR method was used to determine the expression of the efflux pump gene exposed to ciprofloxacin and amoxicillin.</p><p><strong>Results: </strong>The findings indicate that 90% of K. pneumoniae phenotypically displayed resistance to tetracycline, 90% amoxicillin/clavulanic acid, 90% piperacillin, 90% ciprofloxacin, and 89%. All the Klebsiella isolates show fluorescence under UV light at varying concentrations of ethidium bromide, indicating efflux pump activity. The higher prevalence of AcrAB and MarA genes100%. A multidrug efflux pump-associated gene is identified among the isolates. Moreover, the porin genes OmpK35 and OmpK36 are observed in 66.66% of the samples. In contrast, only 50% of the K. pneumoniae strains harbored the MdtK efflux pump gene. However, the analysis show that 50% of the isolates carry the MarkD gene, which play crucial roles in biofilm formation. The expression of AcrAB, MarA, MdtK ompK35 and OmpK36 genes is higher and exposed to ciprofloxacin and amoxicillin.</p><p><strong>Conclusions: </strong>The efficacy of synergistic antibiotic and efflux pump inhibitor combinations in eradicating MDR bacterial resistance is an encouraging discovery.</p>","PeriodicalId":9090,"journal":{"name":"Brazilian Journal of Microbiology","volume":"57 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13538341/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148879163","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}