Artículos (Microbiología)

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Sustainable bacterial cellulose-chitosan composite: A novel approach for the treatment of osteochondral defects
(Elsevier, 2026-12) Castillejo, Ana; Martínez Muñoz, Guillermo; Delgado Pujol, Ernesto J.; Casado Jurado, David; Rodríguez Lucena, David; Vázquez Cabello, Juan; Pérez Bernal, Juan Luis; Beltrán, Ana M.; Villalobo Polo, Eduardo; Begines Ruiz, Belén; Torres Hernández, Yadir; Alcudia Cruz, Ana; Química Orgánica y Farmacéutica; Ingeniería y Ciencia de los Materiales y del Transporte; Citología e Histología Normal y Patológica; Química Orgánica; Química Analítica; Microbiología; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España
The treatment of osteochondral defects remains one of the most significant challenges in regenerative medicine due to the limited self-repair capacity of articular cartilage. This study proposes a multidisciplinary approach through the design and fabrication of an innovative biphasic scaffold (BS) that integrates a porous commercially pure titanium (c.p. Ti) substrate with a sustainable chitosan-bacterial cellulose (CS-BC) biocomposite. The metallic phase, produced via the space-holder technique with 60 vol% porosity, was engineered to replace damaged subchondral bone, while the biopolymeric phase was optimized to replicate the viscoelastic and biological performance of cartilage. To prevent post-operative infections that may lead to implant rejection, the scaffolds were functionalized with silver nanoparticles (AgNPs) through a dual incorporation approach involving both bulk loading and surface adsorption. Experimental results identified composite 11 (3% w/v CS, 10% w/w BC) as the most promising candidate, achieving a 99% crosslinking degree and a swelling capacity of approximately 400%. Mechanical characterization revealed that the inclusion of 10% w/w bacterial cellulose enhanced the elastic strain capacity to 9.7%, significantly improving the material's resilience compared to pure chitosan counterparts. Microbiological assays demonstrated sustained antibacterial efficacy against E. coli for up to 21 days and against S. aureus for at least 5 days. Furthermore, SEM analysis confirmed the successful infiltration of the biocomposite into the titanium pores, resulting in a unified hybrid platform that mimics the biomechanical and biofunctional requirements of native joint tissue. This synergistic system offers a promising solution for the long-term functional regeneration of complex osteochondral lesions.
Followers' Choice: The Trends Transforming PrecisionMedicine, Synthetic Biology, and Sustainable Microbiology
(2026-05-05) Bernal Guzmán, Patricia; Palacios Ferrer, Rocío; Ramos, Juan L.; Microbiología
Strict Aerobic Lifestyle and Anaerobic Survival of Bacteria:Inseparable Twins?
(Wiley, 2026-06-01) Neumann-Schaal, Meina; Borrero de Acuña, José Manuel; Jahn, Dieter; Microbiología
For many decades the existence of strict aerobic bacteria was part of every textbook. However, considering habitats like soilsor surfaces, many of these microorganisms are exposed to drastic changes in oxygen tension. A simple rain shower can changeoxygen diffusion rates by a factor of 10.000. Thus, for many of the so-called strict aerobic bacteria, anaerobic growth and survivalstrategies were discovered, mainly relying on the use of alternative electron acceptors to oxygen, redox-active metabolites, orfermentation processes generating ATP at the substrate level. Survival without growth was recognized as an important lifestyleof bacteria. With the increasing availability of genome data, many highly diverse growth and survival strategies have becomeapparent in bacteria. But the overall picture is far from complete. Only recently, a novel puzzle piece of the anaerobic survivalstrategy of the opportunistic pathogen and model bacterium Pseudomonas aeruginosa in the absence of alternative electron ac-ceptors was elucidated. It relies on the re-wiring of carbon flux away from the Entner-Doudoroff pathway towards the pentose–phosphate pathway and use of a phosphoketolase to allow for metabolic flux while preventing nonproductive NADH formationunder these fermentation conditions and for ATP generation via acetate kinase.
Evaluation of a novel lateral flow immunochromatographic assay, Certest ResisCheck® Carbapenemases, for the rapid detection and differentiation of carbapenemase in Gram-negative bacteria from bacterial culture
(Oxford University Press, 2026-05-16) Monge Olivares, Laura; López Hernández, Inmaculada; Fernández Cuenca, Felipe Manuel; Pascual Hernández, Álvaro; López Cerero, Lorena; Microbiología; European Union (UE); European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); CTS210: Resistencia a Antimicrobianos
Objectives: Carbapenemase-producing Gram-negative bacteria represent a major clinical challenge. Rapid detection and characterization of carbapenemase group is essential for guiding therapy and for infection control. We evaluated the performance of Certest ResisCheck® Carbapenemases, a novel lateral flow immunoassay (LFIA), for detecting the main carbapenemase groups from bacterial culture. Materials and methods: A multicentre collection of 351 well-characterized clinical Gram-negative isolates, studied by whole-genome sequencing, was tested using this assay. 57 KPC, 53 NDM, 63 VIM, 68 OXA-48-like, 64 IMP and 100 carbapenem resistant non-carbapenemase producers were included. Results: The LFIA showed an overall sensitivity of 96.4% and specificity of 100%. The positive predictive value (PPV) was 100%, and the negative predictive value (NPV) was 91.7%. No false-positives or cross-reactions with extended-spectrum β-lactamases (ESBLs) or cephalosporinases were observed either with isolates harbouring multiple carbapenemases. Detection rates for IMP and NDM variants reached 100%. Sensitivity for KPC, OXA-like and VIM was slightly lower (93.0%, 95.6% and 96.8%, respectively). Nine false-negative results were observed: KPC-31 (n = 4), VIM-63 (n = 2) and OXA-1054-producing (n = 3) isolates. Increasing the bacterial inoculum managed to obtain a positive result for KPC-31 and VIM-63, but OXA-1054 remained undetected. Conclusions: Certest ResisCheck® Carbapenemases is a rapid, accurate, and reliable tool for detecting carbapenemases in clinical settings. While some rare variants may escape detection, its strong performance across diverse bacterial species supports its use as part of routine diagnostics to guide timely antimicrobial therapy and control the spread of resistance.
Molecular epidemiology of OXA-1054, a novel carbapenem-hydrolysing Class D β-lactamase, in Enterobacteriaceae isolated from wastewaters
(Springer Nature, 2026-05-04) Monge Olivares, Laura; González Pinto, Lucía; Pulido, Marina R.; Bulnes Ramos, Ángel; Arca Suárez, Jorge; Pascual Hernández, Álvaro; López Cerero, Lorena; Microbiología; Instituto de Biomedicina de Sevilla (IBIS); Fundacin Francisco Soria Melguizo; Junta de Andalucía; Agencia Estatal de Investigación. España; CTS210: Resistencia a Antimicrobianos
Class D carbapenemase-producing Enterobacteriaceae have spread globally in recent decades. The increasing detection of novel variants, often differing by amino acid substitutions or deletions in the β5-β6 loop of OXA-48 or OXA-372 lineages, indicated ongoing dissemination. In this work we describe the molecular epidemiology of a novel OXA-372-like carbapenemase gene, blaOXA-1054, that was identified in Citrobacter, Enterobacter and Raoultella isolates collected from hospital discharges, river water and raw wastewater in Seville, Spain. Cloning of the blaOXA-1054 gene in Escherichia coli confirmed its contribution to carbapenem resistance within the Enterobacterales background. The genetic context of blaOXA-1054 was highly variable, but a conserved backbone, characterized by the IS21 family transposition genes, istA and istB, was consistently present upstream. Frequent co-localization with an ampC gene and heavy metal resistance operons (arsenic and mercury) suggests potential for co-selection under multiple selective pressures. Our study shows that blaOXA-1054 is embedded within a mobile genetic module with strong potential for horizontal transfer, which underscores the importance of monitoring emerging OXA variants in both clinical and environmental settings.
Activity of imipenem-relebactam, ceftolozane-tazobactam and comparators against clinical isolates of Enterobacterales and Pseudomonas aeruginosa causing severe infections in hematological and oncological patients: A prospective multicenter study
(Elsevier, 2025-09) Cercenado, Emilia; Alcalá, Luis; Irigoyen-von-Sierakowski, Álvaro; Rodríguez-Sánchez, Belén; Marín, Mercedes; GEIRAS-SEIMC Study Group; Lepe Jiménez, José Antonio; Pascual Hernández, Álvaro; Microbiología; MSD Investigator Sponsored Programme (MISP)
Objectives Studies regarding the activity of antimicrobials against isolates causing severe infections in oncological and hematological patients are scarce. Ceftolozane-tazobactam (TOL/TAZ) and imipenem-relebactam (IMP/REL) are among the new antimicrobials active against multiresistant gramnegative microorganisms. We evaluate the in vitro activity of these antimicrobials and comparators against recent clinical isolates from hematology and oncology patients in Spain. Methods A total of 55 centers participated in a nationwide study. The isolates were prospectively recovered from patients with bacteremia, lower respiratory tract infections (LRTIs), complicated urinary infections (cUTI), and complicated intra-abdominal infections (cIAIs). The activities of TOL/TAZ, IMP/REL, imipenem (IMP), meropenem (MER), ceftazidime (CAZ), cefepime (FEP), piperacillin-tazobactam (PIP/TAZ), levofloxacin (LEV), and amikacin (AK) were studied following the EUCAST guidelines. Resistance mechanisms were detected by standard methods. Results A total of 997 isolates (563 Enterobacterales (EB) and 434 Pseudomonas aeruginosa (PA)) were collected. The source of EB/PA were: bacteremia (n = 347/182), LRT (n = 51/139), urine (n = 95/64), and intraabdominal samples (n = 70/49). Among EB, 93.6%, 98.9%, 98.6%, 87.4%, 82.2%, 93.6%, 98.6%, 73.7%, and 97.3% were susceptible to TOL/TAZ, IMP/REL, MER, FEP, CAZ, PIP/TAZ, IMP, LEV, and AK, respectively. The corresponding values for PA were 92.2%, 90.1%, 87.8%, 81.9%, 81.7%, 75.7%, 75.2%, 63.3%, and 96.1%, respectively. A total of 14/17 isolates (EB/PA) were carbapenenase-producers, and 82 EB isolates were ESBL-producers. IMP/REL restored the activity of IMP in 14,7% of IMP-resistant PA. Conclusions TOL/TAZ and IMP/REL were the most active of the beta-lactams against PA. IMP/REL was the most active agent against EB; 30% of the isolates were resistant to levofloxacin.
An international observational study to assess the impact of the Omicron variant emergence on the clinical epidemiology of COVID-19 in hospitalised patients
(eLife Sciences Publications, Ltd, 2022-10-05) Goncalves, Bronner P.; Hall, Matthew; Jassat, Waasila; Balan, Valeria; Murthy, Srinivas; Kartsonaki, Christiana; Semple, Malcolm G.; Rojek, Amanda; Baruch, Joaquin; Reyes, Luis Felipe; ISARIC Clinical Characterisation Group; Lepe Jiménez, José Antonio; Microbiología; UK Foreign, Commonwealth and Development Office (FCDO); Bill & Melinda Gates Foundation; European Union (UE); Liverpool Experimental Cancer Medicine Centre
Background: Whilst timely clinical characterisation of infections caused by novel SARS-CoV-2 variants is necessary for evidence-based policy response, individual-level data on infecting variants are typically only available for a minority of patients and settings. Methods: Here, we propose an innovative approach to study changes in COVID-19 hospital presentation and outcomes after the Omicron variant emergence using publicly available population-level data on variant relative frequency to infer SARS-CoV-2 variants likely responsible for clinical cases. We apply this method to data collected by a large international clinical consortium before and after the emergence of the Omicron variant in different countries. Results: Our analysis, that includes more than 100,000 patients from 28 countries, suggests that in many settings patients hospitalised with Omicron variant infection less often presented with commonly reported symptoms compared to patients infected with pre-Omicron variants. Patients with COVID-19 admitted to hospital after Omicron variant emergence had lower mortality compared to patients admitted during the period when Omicron variant was responsible for only a minority of infections (odds ratio in a mixed-effects logistic regression adjusted for likely confounders, 0.67 [95% confidence interval 0.61–0.75]). Qualitatively similar findings were observed in sensitivity analyses with different assumptions on population-level Omicron variant relative frequencies, and in analyses using available individual-level data on infecting variant for a subset of the study population. Conclusions: Although clinical studies with matching viral genomic information should remain a priority, our approach combining publicly available data on variant frequency and a multi-country clinical characterisation dataset with more than 100,000 records allowed analysis of data from a wide range of settings and novel insights on real-world heterogeneity of COVID-19 presentation and clinical outcome.
Pseudomonas aeruginosa antibiotic susceptibility profiles, genomic epidemiology and resistance mechanisms: a nation-wide five-year time lapse analysis
(Elsevier, 2023-11) Sastre-Femenia, Miquel Àngel; Fernández-Muñoz, Almudena; Gomis-Font, María Antonia; Taltavull, Biel; López-Causapé, Carla; Arca-Suárez, Jorge; Martínez-Martínez, Luis; Cantón, Rafael; Larrosa, Nieves; Oteo-Iglesias, Jesús; Zamorano, Laura; Oliver, Antonio; GEMARA-SEIMC/CIBERINFEC Pseudomonas Study Group; Lepe Jiménez, José Antonio; Microbiología; Instituto de Salud Carlos III; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE)
Background Pseudomonas aeruginosa healthcare-associated infections are one of the top antimicrobial resistance threats world-wide. In order to analyze the current trends, we performed a Spanish nation-wide high-resolution analysis of the susceptibility profiles, the genomic epidemiology and the resistome of P. aeruginosa over a five-year time lapse. Methods A total of 3.180 nonduplicated P. aeruginosa clinical isolates from two Spanish nation-wide surveys performed in October 2017 and 2022 were analyzed. MICs of 13 antipseudomonals were determined by ISO-EUCAST. Multidrug resistance (MDR)/extensively drug resistance (XDR)/difficult to treat resistance (DTR)/pandrug resistance (PDR) profiles were defined following established criteria. All XDR/DTR isolates were subjected to whole genome sequencing (WGS). Findings A decrease in resistance to all tested antibiotics, including older and newer antimicrobials, was observed in 2022 vs 2017. Likewise, a major reduction of XDR (15.2% vs 5.9%) and DTR (4.2 vs 2.1%) profiles was evidenced, and even more patent among ICU isolates [XDR (26.0% vs 6.0%) and DTR (8.9% vs 2.6%)] (p < 0.001). The prevalence of Extended-spectrum β-lactamase/carbapenemase production was slightly lower in 2022 (2.1%. vs 3.1%, p = 0.064). However, there was a significant increase in the proportion of carbapenemase production among carbapenem-resistant strains (29.4% vs 18.1%, p = 0.0246). While ST175 was still the most frequent clone among XDR, a slight reduction in its prevalence was noted (35.9% vs 45.5%, p = 0.106) as opposed to ST235 which increased significantly (24.3% vs 12.3%, p = 0.0062). Interpretation While the generalized decrease in P. aeruginosa resistance, linked to a major reduction in the prevalence of XDR strains, is encouraging, the negative counterpart is the increase in the proportion of XDR strains producing carbapenemases, associated to the significant advance of the concerning world-wide disseminated hypervirulent high-risk clone ST235. Continued high-resolution surveillance, integrating phenotypic and genomic data, is necessary for understanding resistance trends and analyzing the impact of national plans on antimicrobial resistance.
Recommendations of the Spanish Antibiogram Committee (COESANT) for in vitro susceptibility testing of antimicrobial agents by disk diffusion
(Elsevier, 2023-11) Rivera, Alba; Viñado, Belén; Benito, Natividad; Docobo Pérez, Fernando; Fernández-Cuenca, Felipe; Fernández-Domínguez, Javier; Guinea, Jesús; Navarro, Ferrán; Microbiología
Disk diffusion is a well standardized method that provides reliable categorical results to guide antimicrobial therapy in numerous types of infections. Based on the guidelines of the European Committee on Antimicrobial Susceptibility Testing (EUCAST), which are widely implemented in Spain, the Spanish Antibiogram Committee (COESANT) has drawn up recommendations for antimicrobial selection by the disk diffusion technique, including selective reporting and its use for the detection of resistance mechanisms. Factors affecting disk diffusion results, along with advantages and shortcomings of the method, are also discussed.
Recomendaciones del Comité Español del Antibiograma (COESANT) para la realización de los Informes de Sensibilidad Antibiótica Acumulada
(Elsevier, 2023-08) Larrosa, María Nieves; Canut-Blasco, Andrés; Benito, Natividad; Cantón, Rafael; Cercenado, Emilia; Docobo Pérez, Fernando; Fernández-Cuenca, Felipe; Fernández-Domínguez, Javier; Guinea, Jesús; Oliver, Antonio; Microbiología
El Comité Español del Antibiograma (COESANT) presenta en este documento una serie de recomendaciones cuya finalidad es unificar la forma en la que los Servicios y Unidades de Microbiología Clínica españoles realizan los informes de sensibilidad acumulada de las bacterias, aisladas en muestras clínicas, frente a los antimicrobianos. Las recomendaciones se fundamentan en las recogidas en el Procedimiento de Microbiología Clínica n° 51, «Preparación de informes acumulados de sensibilidad a los antimicrobianos» de la Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica (SEIMC), publicado en 2014, y recoge las modificaciones en las definiciones de las interpretaciones de las categorías clínicas publicadas en el año 2019 por el European Committee on Antimicrobial Susceptibility Testing (EUCAST). Su objetivo final es establecer una forma homogénea de elaborar estos resúmenes para poder comparar resultados de diferentes centros o sumar su información y así realizar una adecuada vigilancia local o incluso nacional de la evolución de la sensibilidad a los antimicrobianos.
Antibiotic potentiation and inhibition of cross-resistance in pathogens associated with cystic fibrosis
(eLife Sciences Publications, 2026) Kaderábková, Nikol; Furniss, R. Christopher D.; Maslova, Evgenia; Potter, Kathryn E.; Eisaiankhongi, Lara; Bernal Guzmán, Patricia; Filloux, Alain; Landeta, Cristina; González, Diego; AI Mavridou, Despoina; Microbiología; Ministerio de Ciencia e Innovación (MICIN). España
Critical Gram-negative pathogens, like Pseudomonas, Stenotrophomonas, and Burkholderia, are now resistant to most antibiotics. Complex resistance profiles, together with synergistic interactions between these organisms, increase the likelihood of treatment failure in distinct infection settings, for example in the lungs of cystic fibrosis (CF) patients. Here, we discover that cell envelope protein homeostasis pathways underpin both antibiotic resistance and cross-protection in CF-associated bacteria. We find that inhibition of oxidative protein folding inactivates multiple species-specific resistance proteins. Using this strategy, we sensitize multidrug-resistant Pseudomonas aeruginosa to β-lactam antibiotics and demonstrate promise of new treatment avenues for the recalcitrant emerging pathogen Stenotrophomonas maltophilia. The same approach also inhibits crossprotection between resistant S. maltophilia and susceptible P. aeruginosa, allowing eradication of both commonly co-occurring CF-associated organisms. Our results provide the basis for the development of next-generation strategies that target antibiotic resistance, while also impairing specific interbacterial interactions that enhance the severity of polymicrobial infections.
Outcomes of a paediatric antimicrobial stewardship program in the Emergency Department observation unit of a hospital in Spain
(Taylor and Francis, 2025-06-03) Suárez Casillas, Paloma; Peñalva, Germán; Guisado-Gil, Ana Belén; González de Boado, Blanca; Hurtado-Mingo, Ángela; Molina, José; Mejías Trueba, Marta; Lepe Jiménez, José Antonio; Cisneros, José Miguel; Sánchez-Álvarez, María; Microbiología; Medicina
common, even though most infections are caused by viruses, resulting in misuse of antimicrobials. We aimed to assess the impact of a comprehensive antimicrobial stewardship program (ASP) on the optimisation of antimicrobial prescribing and clinical outcomes in a paediatric Emergency Department Observation Unit (EDOU). Methods: A quasi-experimental before-and-after longitudinal study was conducted at the EDOU of a paediatric hospital, over 24 quarters from January 2017 to December 2023, excluding 2020 due to the pandemic and the phase-in period. The ASP intervention included the development and implementation of clinical guidelines, rapid diagnostic tests (RDTs), and staff stabilisation. Data on antimicrobial use and clinical outcomes, such as revisits within 72 h and hospital admissions, were collected and analysed using Bayesian structural time series models. Results: The study included 33,799 patients transferred to the EDOU. Mean antimicrobial consumption significantly decreased from 46.5 ± 12.9 pre-intervention defined daily doses (DDDs) per 100 patients transferred to the Observation Unit (TOs) to 20.1 ± 3.0 DDDs per 100 TOs in the intervention period (p<0.0001). Significant reductions were observed for amoxicillin-clavulanic acid, amoxicillin, and azithromycin. The percentage of revisits and hospital admissions remained stable for the whole period. Conclusion: The implementation of ASP measures improved antimicrobial prescribing in the paediatric EDOU. These findings support the need for continued efforts in ASP, emphasising the development and implementation of guidelines, RDTs, and staff stabilisation.
Development of a Comprehensive Program for the Early Diagnosis and Treatment of Severe Infections in a Tertiary Hospital in Spain
(Oxford University Press, 2025-09-01) Martín-Gutiérrez, Guillermo; Molina, José; Martín Pérez, Carlos; Aguilar Guisado, Manuela; Solla, María; Ramos-Morán, Belén; Aldabó, Teresa; Amaya-Villar, Rosario; Lepe Jiménez, José Antonio; Cisneros, José Miguel; Microbiología; Medicina; Instituto de Salud Carlos III; European Union (UE)
linical outcomes in patients with severe infections. Method. We conducted a pre–post quasi-experimental study evaluating patients with severe pneumonia or sepsis before (October 2019–February 2020) and after (March 2022–March 2023) rDTSI implementation. The program integrated rapid molecular diagnostics, a 24/7 laboratory workflow, and multidisciplinary training. Primary outcomes included time from clinical diagnosis to pathogen-directed therapy and targeted therapy within 48 h. Secondary outcomes assessed antimicrobial appropriateness (DOOR-MAT), length of stay, and mortality. Results. The rDTSI program significantly reduced the median time to pathogen-directed therapy in pneumonia (48.8 vs 23.6 h, P < .001) and increased targeted therapy within 48 h (36.17% to 58.14%, P = .049). Hospital stays decreased (38.9 to 22.2 days, P < .001). In sepsis, diagnostic times (19.4 vs 18.1 h, P = .028) and DOOR-MAT scores (80.4 vs 88.0, P = .024) improved, while other clinical outcomes remained unchanged. Conclusions. The rDTSI program accelerated microbiological diagnosis, optimized antimicrobial therapy, and improved hospital efficiency in severe infections. These findings support integrating rapid diagnostics into antimicrobial stewardship programs to enhance severe infection management.
Burden of bacterial antimicrobial resistance among hospitalised patients in Spain: findings from three nationwide prospective studies
(Elsevier, 2025-01-30) Peñalva, Germán; Cantón, Rafael; Pérez-Rodríguez, María Teresa; González-López, Juan José; Rodríguez-Baño, Jesús; Lepe Jiménez, José Antonio; Cisneros, José Miguel; Paño-Pardo, José Ramón; Toro López, María Dolores del; BMR-SEIMC Study Group; Microbiología; Medicina
and to set its priority. We aimed to estimate the burden of disease caused by multidrug-resistant microorganisms (MDRO) in hospitalised patients in Spain. Methods Three prospective nationwide studies were conducted in 2018, 2019 and 2023. All patients with a new diagnosis of infection with any of 10 selected MDROs plus Clostridioides difficile during the study period (one week in 2018 and 2019 and two weeks in 2023) were included. Patient demographic, and clinical outcomes were analysed, including incidence, crude all-cause 30-day mortality and years of life lost (YLL). These results were used to calculate weighted and seasonally adjusted annual estimates for the whole country. Findings In total, 82, 133 and 130 centres participated in the study in 2018, 2019 and 2023, respectively, recording a total of 907, 1392 and 2351 MDRO infections, representing a weighted incidence density of 3.54 (95% CI 2.92–4.17), 5.01 (3.95–6.07), and 4.41 (3.55–5.27) cases/1000 stays, respectively. A total of 161, 198 and 352 patients died with an MDRO infection, representing a weighted incidence density of 0.46 (0.16–0.76), 0.43 (0.17–0.69), and 0.62 (0.52–0.72) deaths/1000 stays, respectively. Based on these data, a nationwide occurrence of 155,294 MDRO infections (95% CI 127,928–182,569) with 20,065 deaths (6938–32,958) was estimated for 2018, 210,451 MDRO infections (165,963–254,975) with 17,982 deaths (7071–28,700) for 2019, and 173,653 MDRO infections (139,814–207258) with 24,582 deaths (20,461–28,796) for 2023. Interpretation The burden of disease caused by MDRO infections among hospitalised patients in Spain is very high and remains stable over the study period. National actions to combat bacterial resistance need to be intensified.
Tke5 is a Pseudomonas putida toxin that kills plant pathogens by depolarising membranes
(Nature Research, 2026-03-14) Velázquez, Carmen; Arce Rodríguez, Alejandro; Altuna-Álvarez, Jon; Rojas Palomino, Jessica; Flores-Ceron, Andony; Cando-Narváez, Citlaly; Ruiz Camas, Adrián; Peña Noya, Javier de la; Civantos Jiménez, Cristina; Bernal Guzmán, Patricia; Microbiología; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Union (UE); Gobierno Vasco; Generalitat Valenciana; Universitat Jaume I
The soil bacterium Pseudomonas putida injects toxic proteins into neighbouring competitors, including resilient phytopathogens, using the Type VI secretion system(T6SS). The secretion of toxins endows P. putida with a significant fitness advantage, allowing this biocontrol agent to thrive in plantrelated polymicrobial environments and prevent phytopathogen infections. Despite its agricultural significance, the toxin repertoire of P. putida, particularly those secreted via the K2- and K3-T6SSs, remains poorly understood. We present a comprehensive molecular study of Tke5, a potent toxin encoded within the K3-T6SS, which represents the initial biophysical and functional analysis of the BTH_I2691 family. Our data demonstrate that Tke5 is a pore-forming toxin that disrupts bacterial membranes through selective ion transport, inducingmembrane depolarisation and cell death. Tke5 is neutralised by Tki5 in the inner membrane of Gram-negative bacteria. Unlike detergent-like poreforming toxins, Tke5 preserves overall membrane integrity, avoiding large, non-specific disruptions. This mechanism offers apowerful approach to targeting resilient phytopathogens. This study reveals a previously undescribed mode of action within a widespread yet understudied toxin family. Our findings highlight the potential of P. putida as a biocontrol agent, offering alternatives to chemical pesticides by exploiting novel toxin mechanisms, crucial for developing effective strategies to combat plant pathogens.
Bacterial Extracellular Vesicles in Biomedical Research and Clinical Translation
(Wiley, 2026-04-12) Arce Rodríguez, Alejandro; De la Peña Noya, Javier; Borrero de Acuña, José Manuel; Microbiología; Ministerio de Hacienda. España; European Union (UE); Junta de Andalucía; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
Bacterial Extracellular Vesicles (bEVs) are lipid (single- or double-bilayer) nanostructures secreted by virtually all bacteria that play fundamental roles in intercellular communication and have emerged as powerful, multifunctional tools in biomedicine. Their intrinsic ability to encapsulate and protect diverse biomolecules (including proteins, nucleic acids, lipids, metabolites and immunomodulatory factors) makes them highly attractive for therapeutic and diagnostic applications. Recent advances in molecular and synthetic biology have further expanded the biomedical potential of bEVs through targeted bioengineering strategies such as genetic manipulation, surface functionalisation, glycoengineering and modular display technologies, enabling the scalable production of customised bEVs with enhanced safety, stability, targeting precision and functional versatility. These innovations have unlocked a broad range of applications, including licenced and experimental vaccines, immune modulation strategies, drug delivery systems, diagnostic tools and regenerative medicine approaches. Despite this progress, key translational challenges remain, particularly regarding scalability, safety, standardisation and regulatory frameworks and addressing these issues will be critical for the successful integration of bEV-based technologies into novel therapeutic and diagnostic platforms
Genomic Surveillance and Antigenic Characterization of Respiratory Syncytial Virus (RSV) in Spain During the 2023-2024 Season of Nirsevimab Administration
(Oxford University Press (OUP), 2025) Iglesias-Caballero, María; Mas, Vicente; Campoy, Albert; Calvo, Cristina; García, María Luz; Alcolea, Sonia; Moreno-Parrado, Laura; Reina, Jordi; Lepe Jiménez, José Antonio; Casas, Inmaculada; Microbiología; Instituto de Salud Carlos III; European Union (UE)
Respiratory Syncytial Virus (RSV) is a leading cause of respiratory infections in infants and older adults. In Spain, surveillance is supported by the SiVIRA system and the RELECOV genomic sequencing network. The 2023–2024 season marked the first nationwide administration of nirsevimab, a monoclonal antibody for preventing severe RSV in infants. This study analyzes the genomic evolution of RSV during this period, focusing on potential escape mutations in the F protein. RSV-A showed high genetic diversity with eleven circulating lineages, while RSV-B was dominated by lineage B.D.E.1. Phylogenetic analysis revealed three distinct B.D.4.1.1 groups, one sharing mutations with B.D.E.1 in the nirsevimab binding site. Despite these changes, neutralization assays confirmed that nirsevimab and other monoclonal antibodies remained effective. No significant antigenic drift compromising immunoprophylaxis was observed. These findings support the continued efficacy of nirsevimab and highlight the importance of genomic surveillance for tracking RSV evolution and informing future immunization strategies.
Structure of the O-antigen of the lipopolysaccharide isolated from Pantoea ananatis AEP17, a rhizobacterium associated with rice
(Elsevier, 2013-03-22) Contreras Sánchez-Matamoros, Rocío; Gil Serrano, Antonio Miguel; Tejero Mateo, María Pilar; Ollero Márquez, Francisco Javier; Megías Saavedra, Esaú; Rodríguez Carvajal, Miguel Ángel; Química Orgánica; Microbiología; Ministerio de Educación y Ciencia (MEC). España
The lipopolysaccharide of a Gram-negative bacterium having a putative plant-growth promoting activity (Pantoea ananatis AEP17) has been isolated and subjected to partial hydrolysis. The O-antigen has been studied by mass spectrometry and NMR experiments. On the basis of these experiments it is concluded that the following repeating unit is present in the polysaccharide: →3)-β-d-GlcpNAc-(1→3)[α-d-GalpAN-(1→2)]-α-l-Rhap-(1→2)-α-l-Rhap-(1→3)-α-l-Rhap-(1→2)-α-l-Rhap-(1→ The occurrence of d-galacturonamide (GalAN) is unusual in bacterial O-polysaccharides. It has only been reported in Escherichia coli O65 [Perry, M. B.; MacLean, L. L. Carbohydr. Res. 1999, 322, 57–66].
T6SS-Effector Hunters Uncover PIX: A Novel Delivery/Marker Domain
(Cell Press, 2024-07) Bernal Guzmán, Patricia; Microbiología; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE); Junta de Andalucía
Gram-negative bacteria use the T6SS to eject effectors into prey cells, aided by delivery domains. Recently uncovered by Carobbi et al., a new delivery domain, PIX, allowed the identification of hundreds of new effectors. They are order- and function-specific and exclusively orphan effectors, raising novel questions in the field.
Structure of surface polysaccharides from Aeromonas sp AMG272, a plant-growth promoting rhizobacterium isolated from rice rhizosphere
(Elsevier, 2018-06-15) Contreras Sánchez-Matamoros, Rocío; Gil Serrano, Antonio Miguel; Espuny Gómez, María del Rosario; Ollero Márquez, Francisco Javier; Megías, Manuel; Rodríguez Carvajal, Miguel Ángel; Microbiología; Química Orgánica
Aeromonas sp. AMG272 is a Gram-negative bacterium that has been isolated from agricultural soil and studied for its plant growth-promoting activities. Structures of the O-specific polysaccharide chain of the AMG272 lipopolysaccharide and its capsular polysaccharide were elucidated using GLC-MS and NMR spectroscopy. The structure of the O-specific polysaccharide, →4)-α-L-Rhap-(1→3)-β-D-GlcpNAc-(1→, has been found in other Aeromonas strains and related bacteria, whereas the structure of the capsular polysaccharide has not been reported before: →6)[β-D-Fucp3NAc4Ac-(1→3)]-α-D-GlcpNAc-(1→4)-α-D-Galp-(1→3)-α-D-GalpNAc-(1→4)-α-D-Galp-(1→.

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