Artículos (Microbiología)

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Reporting antimicrobial susceptibility and detection of carbapenemase production in single and double carbapenemase-producing Gram-negative clinical isolates: a nationwide proficiency study
(Frontiers Media, 2025-06-10) Fernández-Cuenca, Felipe; Delgado Valverde, María Mercedes; Guridi-Fernández, Pablo; Gimeno-Cardona, Concepción; Hidalgo-Díaz, Carmen; Pascual Hernández, Álvaro; Microbiología; CTS210: Resistencia a Antimicrobianos
Purpose The objective was to assess the ability of Spanish clinical microbiology laboratories to report reliable carbapenem susceptibility test results and to detect carbapenemase production (CP) and/or carbapenemase genes in double (DCP) and single carbapenemase-producing (SCP) isolates.Methods Twelve isolates (8 SCP and 4 DCP) selected from the Andalusian Reference Laboratory were sent to 83 laboratories with requests for MICs and phenotypic and genotypic tests used for CP.Results Overall, there was lower essential agreement and a higher number of clinical errors in DCP than in SCP isolates. Phenotypic tests showed higher sensitivity for DCP isolates than for SCP isolates: lateral flow immunoassay (99.0% vs. 95.1%), carbapenem inactivation method (100% vs. 93%) and chromogenic media (100% vs. 83.3%); conversely, sensitivities for DCP versus SCP isolates was lower using disk diffusion with inhibitors (83.3% vs. 90.4%) and hydrolysis-based assays (81.3% vs. 86.1%). Molecular methods showed higher sensitivity for DCP isolates than phenotypic methods, and higher sensitivity for DCP isolates than for SCP isolates. In addition, concordance between genes detected and the reference was higher in DCP than in SCP isolates (98.9% vs. 83%). However, blaVIM-1 and blaIMP-8 were not detected in 77.5% and 42.2% of the determinations, respectively, for DCP isolates.Conclusion The main differences between DCP versus SCP isolates were the lower reliability of gradient strips, higher overall sensitivity of phenotypic methods for DCP isolates, but lower sensitivity with disk diffusion inhibitors and hydrolysis-based assays. Molecular assays were generally more sensitive for carbapenemase gene detection in DCP than in SCP isolates, although concordance was lower.
Phosphate solubilization capacity by bacteria in soybean crops
(International Institute of Ecology, 2025-07-04) Vey, R.T.; Jacques, R.J.S.; Pavinato, P.S.; López Baena, Francisco Javier; Spanevello, J.F.; Bronzatto, E.S.; Martín, T.N.; Microbiología; Conselho Nacional de Desenvolvimento Científico e Tecnológico. Brasil; Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior. Brasil; BIO169: Biotecnología de la Interacción de Microorganismos con Leguminosas y Otras Plantas de Interés Agrícola
The availability of phosphorus (P) to plants is reduced by its binding to solid mineral and soil organic particles. However, phosphate-solubilizing microorganisms can increase nutrient availability by secreting extracellular enzymes such as fosfatases. The objective was to evaluate the phosphate solubilization capacity of bacteria coinoculated in soybean crops. Soybean plants were grown in nutrient solution in a combination of treatments of bacteria inoculated into the seeds [Bradyrhizobium japonicum (Brady); Brady + Pseudomonas fluorescens (Pf); Brady + Bacillus megaterium (Bm) + Bacillus subtilis (Bs); and Brady + Bs] with doses of P. In the laboratory, another experiment was conducted to evaluate the phosphate solubilization capacity in the NBRIP solid culture medium by the bacteria Bs, Bs+Bm, Pf and the isolate of Pseudomonas spp. The root dry mass increased by 201.26% with Brady+Bs coinoculation. Considering the phosphorus content in the aerial part of plant content for a dose of 40 kg ha-1 of NH4H2PO4, with B. japonicum + P. fluorescens resulted in an increase of 26.7% in relation to the control. The use of B. japonicum + B. megaterium/B. subtilis increased the phosphorus concentration in the shoot plant by 22.5%. In the laboratory solubilization test, the bacteria B. subtilis showed a medium phosphate solubilization index, making this bacterium an alternative for better use of this nutrient in the soil.
Implications of gene expression heterogeneity in the interplay between acquired resistance and bacterial metabolism
(Nature Research, 2025-07-22) Romero Muñoz, María; Pulido, Marina R.; Recacha, Esther; Díaz Díaz, Sara; Murillo Torres, Marina; Docobo Pérez, Fernando; Rodríguez Martínez, José Manuel; Microbiología; CTS210: Resistencia a Antimicrobianos
Gene expression heterogeneity has an impact on human bacterial pathogens responses, including antimicrobial resistance genes expression. Promoter region variability in resistance genes may include different regulatory boxes involved in metabolic processes essential for bacterial survival. In this study, a molecular tool was developed to characterize promoter region variability and resistance gene expression. For these, 46 bacterial clinical isolates were used. Sequence analysis of resistance genes promoter region showed the existence of different variants for each promoter and identified gene-specific regulatory boxes. Using a fluorescent transcriptional reporter, we analysed the most common promoter variants of the most prevalent acquired resistance genes in clinical isolates (qnrA, qnrB, blaOXA-48, blaKPC-3 and blaVIM-1, aac(6’)-Ib-cr, and fosA). Gene expression fluctuations were found to be dependent on culture medium used. Specific gene promoter variants showed lower expression levels in poor (M9) medium (p < 0.0001) and an induction of expression under antimicrobials presence (tetracycline, quinolones and beta-lactams). qnrB1 genes were regulated by phoB and lexA boxes; blaOXA-48 was regulated by the argR box or fnr and arcA boxes. Differences in regulation of resistance gene promoter variants observed in this study suggest heterogeneity in expression under different bacterial culture conditions and a new link between metabolism and acquired resistance.
Case report: Analysis of phage therapy failure in a patient with a Pseudomonas aeruginosa prosthetic vascular graft infection
(Frontiers Media SA, 2023-05-19) Blasco, Lucía; López-Hernández, Inmaculada; Rodríguez-Fernández, Miguel; Pérez-Florido, Javier; Casimiro-Soriguer, Carlos S.; Djebara, Sarah; Merabishvili, Maya; Pirnay, Jean Paul; Rodríguez-Baño, Jesús; Tomás, María; López-Cortés, Luis E.; Medicina; Microbiología; Instituto de Biomedicina de Sevilla (IBIS)
Clinical case of a patient with a Pseudomonas aeruginosa multidrug-resistant prosthetic vascular graft infection which was treated with a cocktail of phages (PT07, 14/01, and PNM) in combination with ceftazidime-avibactam (CZA). After the application of the phage treatment and in absence of antimicrobial therapy, a new P. aeruginosa bloodstream infection (BSI) with a septic residual limb metastasis occurred, now involving a wild-type strain being susceptible to ß-lactams and quinolones. Clinical strains were analyzed by microbiology and whole genome sequencing techniques. In relation with phage administration, the clinical isolates of P. aeruginosa before phage therapy (HE2011471) and post phage therapy (HE2105886) showed a clonal relationship but with important genomic changes which could be involved in the resistance to this therapy. Finally, phenotypic studies showed a decrease in Minimum Inhibitory Concentration (MIC) to ß-lactams and quinolones as well as an increase of the biofilm production and phage resistant mutants in the clinical isolate of P. aeruginosa post phage therapy.
Fosfomycin in bacteraemic urinary tract infection due to multidrug-resistant Escherichia coli: insights of post hoc DOOR analysis of the FOREST trial
(Taylor & Francis Ltd, 2024-12-09) Sojo-Dorado, Jesús; López-Hernández, Inmaculada; Gutiérrez Gutiérrez, Belén; Rosa-Riestra, Sandra; Docobo Pérez, Fernando; Hernánez-Torres, Alicia; Pascual Hernández, Álvaro; Rodríguez-Baño, Jesús; Medicina; Microbiología; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Instituto de Salud Carlos III; Gobierno de España; BIO210: Microorganismos Eucariotas
Purpose: A post hoc analysis of data from a previously published clinical trial was conducted using the desirability of outcome ranking (DOOR) methodology with the aim provide additional information on the use of fosfomycin for the treatment of bacteraemic urinary tract infection (BUTI) caused by multi-drug-resistant (MDR) E. coli. Methods: Three DOOR systems with five, six and seven categories, respectively were developed. Safety and efficacy were prioritised in all rankings, but step down to oral therapy and exposure to antibiotics with lower ecological impact were also considered in DOOR-6 and DOOR-7. The probability that a patients assigned to fosfomycin was classified into a more desirable outcome category was calculated for the three DOOR definitions. Subgroups analyses and an ordinal logistic regression model were also performed. Results: Data from 143 participants were analysed. The probability of having a more desirable outcome after treatment with fosfomycin versus the comparators was 0.44 (95% CI 0.36 - 0.52) for DOOR-5; 0.50 (95% IC 0.42 - 0.58) using DOOR-6 and 0.61 (95% CI 0.53-0.69) with DOOR-7. In subgroups, the highest probability of having a better DOOR with fosfomycin was seen in the clinically evaluable population and among patients without chronic heart disease or renal insufficiency for the DOOR-7 definition. Conclusions: DOOR analysis could be applied to the FOREST trial data; the results were somehow different for the different DOOR systems used. Overall, fosfomycin was favoured when oral step-down treatment and use of antibiotics with lower ecological impact were included.
Treatment of Infections Caused by Extended-Spectrum-Beta-Lactamase-, AmpC-, and Carbapenemase-Producing Enterobacteriaceae
(American Society Microbiology, 2018-02-14) Rodríguez-Baño, Jesús; Gutiérrez Gutiérrez, Belén; Machuca, Isabel; Pascual Hernández, Álvaro; Medicina; Microbiología; Gobierno de España; Instituto de Salud Carlos III; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); CTS210: Resistencia a Antimicrobianos
Therapy of invasive infections due to multidrug-resistant Enterobacteriaceae (MDR-E) is challenging, and some of the few active drugs are not available in many countries. For extended-spectrum β-lactamase and AmpC producers, carbapenems are the drugs of choice, but alternatives are needed because the rate of carbapenem resistance is rising. Potential active drugs include classic and newer β-lactam–β-lactamase inhibitor combinations, cephamycins, temocillin, aminoglycosides, tigecycline, fosfomycin, and, rarely, fluoroquinolones or trimethoprim-sulfamethoxazole. These drugs might be considered in some specific situations. AmpC producers are resistant to cephamycins, but cefepime is an option. In the case of carbapenemase-producing Enterobacteriaceae (CPE), only some “second-line” drugs, such as polymyxins, tigecycline, aminoglycosides, and fosfomycin, may be active; double carbapenems can also be considered in specific situations. Combination therapy is associated with better outcomes for high-risk patients, such as those in septic shock or with pneumonia. Ceftazidime-avibactam was recently approved and is active against KPC and OXA-48 producers; the available experience is scarce but promising, although development of resistance is a concern. New drugs active against some CPE isolates are in different stages of development, including meropenem-vaborbactam, imipenem-relebactam, plazomicin, cefiderocol, eravacycline, and aztreonam-avibactam. Overall, therapy of MDR-E infection must be individualized according to the susceptibility profile, type, and severity of infection and the features of the patient.
A Predictive Model of Mortality in Patients With Bloodstream Infections due to Carbapenemase-Producing Enterobacteriaceae
(Elsevier, 2016-10) Gutiérrez Gutiérrez, Belén; Salamanca, Elena; Cueto López, Marina de; Hsueh, Po-Ren; Viale, Pierluigi; Paño Pardo, José Ramón; Pascual Hernández, Álvaro; Rodríguez-Baño, Jesús; Medicina; Microbiología; Gobierno de España; Instituto de Salud Carlos III; European Union; Cleveland Department of Veterans Affairs; COMBACTE-CARE project, Innovative Medicines Initiative; European Federation of Pharmaceutical Industries and Associations (EFPIA); Geriatric Research Education and Clinical Center VISN 10; National Institute of Allergy and Infectious Diseases of the National Institutes of Health; CTS210: Resistencia a Antimicrobianos
Objective: To develop a score to predict mortality in patients with bloodstream infections (BSIs) due to carbapenemase-producing Enterobacteriaceae (CPE). Patients and Methods: A multinational retrospective cohort study (INCREMENT project) was performed from January 1, 2004, through December 31, 2013. Patients with clinically relevant monomicrobial BSIs due to CPE were included and randomly assigned to either a derivation cohort (DC) or a validation cohort (VC). The variables were assessed on the day the susceptibility results were available, and the predictive score was developed using hierarchical logistic regression. The main outcome variable was 14-day all-cause mortality. The predictive ability of the model and scores were measured by calculating the area under the receiver operating characteristic curve. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated for different cutoffs of the score. Results: The DC and VC included 314 and 154 patients, respectively. The final logistic regression model of the DC included the following variables: severe sepsis or shock at presentation (5 points); Pitt score of 6 or more (4 points); Charlson comorbidity index of 2 or more (3 points); source of BSI other than urinary or biliary tract (3 points); inappropriate empirical therapy and inappropriate early targeted therapy (2 points). The score exhibited an area under the receiver operating characteristic curve of 0.80 (95% CI, 0.74-0.85) in the DC and 0.80 (95% CI, 0.73-0.88) in the VC. The results for 30-day all-cause mortality were similar. Conclusion: A validated score predictive of early mortality in patients with BSIs due to CPE was developed.
Effectiveness and tolerability of intravenous fosfomycin in treating complicated urinary tract infections caused by Escherichia coli: a prospective cohort study from the FOSFOMIC project
(Elsevier, 2025-05) Moreno Mellado, Elisa; Aslan, Abdullah Tarik; Akova, Murat; León, Eva; Merchante Gutiérrez, Nicolás; Vinuesa, David; Merino Bohórquez, Vicente; Rodríguez-Baño, Jesús; Docobo Pérez, Fernando; Gutiérrez Gutiérrez, Belén; departamento de Medicina; departamento de Farmacología; departamento de Microbiología; CIBERINFEC; European Union (UE); Gobierno de España; Instituto de Salud Carlos III
Objectives: The FOSFOMIC study assessed the clinical and microbiological effectiveness, and safety of intravenous fosfomycin in treating complicated urinary tract infections (cUTIs) caused by Escherichia coli, in comparison with other intravenous antimicrobials. Methods: A prospective, multinational matched cohorts study involving adults with community-acquired cUTIs and receiving targeted therapy with intravenous fosfomycin or other first-line drugs (beta-lactams or fluoroquinolones) was conducted from November 2019 to May 2023 in ten centres from Spain, Italy, and Türkiye. Matching criteria included type of infection acquisition, Charlson and Pitt scores. Endpoints were clinical and microbiological cure, mortality, recurrence, and adverse effects. Analyses used conditional logistic regression and desirability of outcome ranking (DOOR). Results: Overall, 155 matched pairs were included. Clinical and microbiological cure rates were 65.2% (101/155; 95% CI, 57.4–72.2) and 63.2% (98/155; 95% CI, 55.4–70.4) with fosfomycin and comparators, respectively (adjusted OR, 1.09; 95% CI, 0.68–1.73; p 0.73). Mortality rates were 1.9% (3/155; 95% CI, 0.7–5.5) and 5.8% (9/155; 95% CI, 3.1–10.7), respectively (p 0.11). Recurrence rates were 14.2% (22/155; 95% CI, 9.6–20.6) in the fosfomycin group vs. 10.3% (16/155; 95% CI, 6.1–16.1) (p 0.39). Severe adverse effects occurred in 1.9% (3/155; 95% CI, 0.7–5.5) of patients treated with fosfomycin vs. 0.6% (1/155; 95% CI, 0.0–3.3) in the control group (p 0.62). Non-severe adverse effects were more frequent with fosfomycin, affecting 23.3% (36/155; 95% CI, 17.0–30.7) compared with 7.7% (12/155; 95% CI, 4.1–13.1) in the control group (adjusted OR, 5.36; 95% CI, 2.04–14.1; p < 0.001). In DOOR analysis, fosfomycin demonstrated comparable effectiveness in treating pyelonephritis (probability of better DOOR, 54.0%; 95% CI, 48.5–59.6) and in comparison with ceftriaxone (50.3%; 95% CI, 44.7–55.8), without evidence of inferiority in bacteraemic urinary tract infections (DOOR, 47.3%; 95% CI, 41.7–52.8). Discussion: Fosfomycin is a viable option for treating cUTIs caused by E. coli, allowing for diversification in the treatment of these high-incidence infections.
Modified sequential multiplex PCR for determining capsular serotypes of invasive pneumococci recovered from Seville
(Elsevier, 2010-09) Santos Sánchez, Guillermo; Álvarez López, Ana Isabel; Ponce España, Eduardo; Álvarez Ríos, Ana Isabel; Lardone, Patricia Judith; Carrillo Vico, Antonio; Microbiología; Medicina Preventiva y Salud Pública; Instituto de Biomedicina de Sevilla (IBIS); CTS204: Biotecnología Aplicada al Estudio de Enfermedades Infecciosas
The heptavalent pneumococcal vaccine’s introduction resulted in a decline in invasive disease caused by Streptococcus pneumoniae, but was accompanied by an increase in non-vaccine serotypes. We evaluated a modified scheme of the sequential multiplex PCRs adapted to the prevalence of serotypes in Seville (Spain) for determining capsular serotypes of S. pneumoniae invasive clinical isolates. In adults, the modified scheme allowed us to type 73% with the first three reactions, and 92% with two additional PCRs. In paediatric patients, it allowed us to type 73.5% with the first three reactions, and 90% with the two additional PCRs. The multiplex PCR approach was successfully adapted to target the serotypes most prevalent in Seville.
The role of the calmodulin-binding and calmodulin-like domains of the epidermal growth factor receptor in tyrosine kinase activation
(John Wiley & Sons, 2021-07) Abdelli, Faten; Jellali, Karim; Anguita, Estefanía; González-Muñoz, María; Villalobo Polo, Eduardo; Madroñal, Ivan; Alcalde, Juan; Ben Ali, Mamdouh; Elloumi-Mseddi, Jihene; Jemel, Ikram; Tebar, Francesc; Enrich, Carlos; Aifa, Sami; Villalobo, Antonio; Microbiología; Consejo Superior de Investigaciones Científicas (CSIC); Agencia Española de Cooperación Internacional para el Desarrollo (AECID); Secretaría de Estado de Investigación, Desarrollo e Innovación; Comunidad de Madrid
The epidermal growth factor receptor (EGFR) harbors a calmodulin (CaM)-binding domain (CaM-BD) and a CaM-like domain (CaM-LD) upstream and downstream, respectively, of the tyrosine kinase (TK) domain. We demonstrate in this paper that deletion of the positively charged CaM-BD (EGFR/CaM-BD∆) inactivated the TK activity of the receptor. Moreover, deletion of the negatively charged CaM-LD (EGFR/CaM-LD∆), leaving a single negative residue (glutamate), reduced the activity of the receptor. In contrast, substituting the CaM-LD with a histidine/valine-rich peptide (EGFR/InvCaM-LD) caused full inactivation. We also demonstrated using confocal microscopy and flow cytometry that the chimera EGFR-green fluorescent protein (GFP)/CaM-BD∆, the EGFR/CaM-LD∆, and EGFR/InvCaM-LD mutants all bind tetramethylrhodamine-labelled EGF. These EGFR mutants were localized at the plasma membrane as the wild-type receptor does. However, only the EGFR/CaM-LD∆ and EGFR/InvCaM-LD mutants appear to undergo ligand-dependent internalization, while the EGFR-GFP/CaM-BD∆ mutant seems to be deficient in this regard. The obtained results and in silico modelling studies of the asymmetric structure of the EGFR kinase dimer support a role of a CaM-BD/CaM-LD electrostatic interaction in the allosteric activation of the EGFR TK.
Bipolar Biogeographical Distribution of Parafrancisella Bacteria Carried by the Ciliate Euplotes
(Springer Nature, 2023-07-11) Candelori, Annalisa; Di Giuseppe, Graziano; Villalobo Polo, Eduardo; Sjödin, Andreas; Vallesi, Adriana; Microbiología; Italian Ministero dell’Università e della Ricerca (MUR)
Parafrancisella adeliensis, a Francisella-like endosymbiont, was found to reside in the cytoplasm of an Antarctic strain of the bipolar ciliate species, Euplotes petzi. To inquire whether Euplotes cells collected from distant Arctic and peri-Antarctic sites host Parafrancisella bacteria, wild-type strains of the congeneric bipolar species, E. nobilii, were screened for Parafrancisella by in situ hybridization and 16S gene amplification and sequencing. Results indicate that all Euplotes strains analyzed contained endosymbiotic bacteria with 16S nucleotide sequences closely similar to the P. adeliensis 16S gene sequence. This finding suggests that Parafrancisella/Euplotes associations are not endemic to Antarctica, but are common in both the Antarctic and Arctic regions.
Enhancing SARS-CoV-2 surveillance through regular genomic sequencing in Spain: the RELECOV network
(MDPI, 2023-05-10) Vázquez Morón, Sonia; Iglesias Caballero, María; Lepe Jiménez, José Antonio; García, Federico; Melón, Santiago; Marimon, José M.; Casas, Inmaculada; Microbiología
Millions of SARS-CoV-2 whole genome sequences have been generated to date. However, good quality data and adequate surveillance systems are required to contribute to meaningful surveillance in public health. In this context, the network of Spanish laboratories for coronavirus (RELECOV) was created with the main goal of promoting actions to speed up the detection, analyses, and evaluation of SARS-CoV-2 at a national level, partially structured and financed by an ECDC-HERA-Incubator action (ECDC/GRANT/2021/024). A SARS-CoV-2 sequencing quality control assessment (QCA) was developed to evaluate the network’s technical capacity. QCA full panel results showed a lower hit rate for lineage assignment compared to that obtained for variants. Genomic data comprising 48,578 viral genomes were studied and evaluated to monitor SARS-CoV-2. The developed network actions showed a 36% increase in sharing viral sequences. In addition, analysis of lineage/sublineage-defining mutations to track the virus showed characteristic mutation profiles for the Delta and Omicron variants. Further, phylogenetic analyses strongly correlated with different variant clusters, obtaining a robust reference tree. The RELECOV network has made it possible to improve and enhance the genomic surveillance of SARS-CoV-2 in Spain. It has provided and evaluated genomic tools for viral genome monitoring and characterization that make it possible to increase knowledge efficiently and quickly, promoting the genomic surveillance of SARS-CoV-2 in Spain.
An increase in erythromycin resistance in methicillin-susceptible Staphylococcus aureus from blood correlates with the use of macrolide/lincosamide/streptogramin antibiotics. EARS-Net Spain (2004–2020)
(Frontiers Media, 2023-09-26) El Mammery, Achraf; Ramírez de Arellano, Eva; Cañada García, Javier E.; Cercenado, Emilia; Villar Gómara, Laura; Casquero García, Verónica; Lepe Jiménez, José Antonio; Oteo Iglesias, Jesús; Spanish EARS-Net Group; Microbiología; Instituto de Salud Carlos III; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE)
Objectives: To describe and analyse erythromycin resistance trends in blood isolates of Staphylococcus aureus (EARS-Net Spain, 2004–2020) and the association of these trends with the consumption of macrolide, lincosamide, and streptogramin B (MLSB) antibiotics. To assess molecular changes that could be involved in erythromycin resistance trends by whole genome analysis of representative isolates. Materials and methods: We collected antibiotic susceptibility data for all first-blood S. aureus isolates in patients from 47 Spanish hospitals according to EARS-Net criteria. MLSB antibiotic consumption was obtained from the Spanish Agency for Medicines and Medical Devices (2008–2020). We sequenced 137 representative isolates for core genome multilocus sequence typing, resistome and virulome analysis. Results: For the 36,612 invasive S. aureus isolates, methicillin resistance decreased from 26.4% in 2004 to 22.4% in 2020. Erythromycin resistance in methicillin-susceptible S. aureus (MSSA) increased from 13.6% in 2004 to 28.9% in 2020 (p < 0.001); however, it decreased from 68.7 to 61.8% (p < 0.0001) in methicillin-resistant S. aureus (MRSA). Total consumption of MLSB antibiotics increased from 2.72 defined daily doses per 1,000 inhabitants per day (DID) in 2014 to 3.24 DID in 2016. By WGS, the macrolide resistance genes detected were erm (59.8%), msrA (46%), and mphC (45.2%). The erm genes were more prevalent in MSSA (44/57, 77.2%) than in MRSA (38/80, 47.5%). Most of the erm genes identified in MSSA after 2013 differed from the predominant ermC gene (17/22, 77.3%), largely because ermT was significantly associated with MSSA after 2013 (11/29, 37.9%). All 13 ermT isolates in this study, except one, belonged to ST398 and came from 10 hospitals and six Spanish provinces. Conclusion: The significant increase in erythromycin resistance in blood MSSA correlated with the consumption of the MLSB antibiotics in Spain. These preliminary data seem support the hypothesis that the human ST398 MSSA clade with ermT-mediated resistance to erythromycin may be involved in this trend.
Rifampin breakpoint for Acinetobacter baumannii based on pharmacokinetic- pharmacodynamic models with Monte Carlo simulation
(Sociedad Española de Quimioterapia, 2012-06) Lepe Jiménez, José Antonio; García Cabrera, Emilio; Gil Navarro, María Victoria; Aznar Martín, Javier; Microbiología; Medicina Preventiva y Salud Pública; CTS204: Biotecnología Aplicada al Estudio de Enfermedades Infecciosas
Objective: The aim of this study is to develop a pharmacokinetic–pharmacodynamic (PK–PD) rifampin breakpoint for Acinetobacter baumannii based on Monte Carlo simulation and to compare it with the reference value establish by the French Society for Microbiology (SFM). Methods: A 10,000 subject’s Monte Carlo simulation for rifampin with intravenous dose of 10 mg/Kg/day and 20 mg/Kg/day was performed. The distribution of MIC was calculated using unique clinical isolates of A. baumannii. The PK–PD parameter calculated was Cmaxfree/MIC. Results: The isolates rifampin MIC50 and MIC90 were 2 and 32 mg/L respectively, ranging between 0.023-32 mg/L. According to interpretive criteria established by the SFM: 468 (75.8%) isolates were susceptible (MIC ≤ 4 mg/L) and 150 (24.2%) were non susceptible (MIC > 4 mg/L). For 10 mg/Kg/day dose: the probability (%) of attaining Cmax-free/MIC ratio values = 8 by Monte Carlo simulation in the study population was 0.4%, the rifampin MIC cut off value obtained from an optimal treatment (target ≥ 90%), was 0.125 mg/L. The probability of obtaining a Cmaxfree/MIC ratio equal to 10 was 0.2% and the MIC cut off value obtained <0.125 mg/L. At doses of 20 mg/kg/day: the probability of obtaining a Cmax-free/MIC ratio equal to 8 was 0.8%, the rifampin MIC cut off value obtained was 0.25 mg/L. For a Cmaxfree/MIC = 10, it was 0.6% and 0.125 mg/L, respectively. The percentage of susceptible isolates ranging 0% to 1%, depending on the dose and therapeutic target used. Conclusion: the rifampin breakpoints obtained from our PK/PD Monte Carlo simulation differ from those established by SFM, although further clinical studies in patients are needed to confirm our findings and improve the use of this antibiotic.
Role of the 40S beak ribosomal protein eS12 in ribosome biogenesis and function in Saccharomyces cerevisiae
(Taylor & Francis, 2020-06-07) Martín Villanueva, Sara; Fernández Fernández, José; Rodríguez Galán, Olga; Fernández Boraita, Julia; Villalobo Polo, Eduardo; Cruz Díaz, Jesús de la; Microbiología; Genética; Ministerio de Economía y Competitividad (MINECO). España; Junta de Andalucía
In eukaryotes, the beak structure of 40S subunits is formed by the protrusion of the 18S rRNA helix 33 and three ribosomal proteins: eS10, eS12 and eS31. The exact role of these proteins in ribosome biogenesis is not well understood. While eS10 is an essential protein encoded by two paralogous genes in Saccharomyces cerevisiae, eS12 and eS31 are not essential proteins encoded by the single-copy genes RPS12 and UBI3, respectively. Here, we have analysed the contribution of yeast eS12 to ribosome biogenesis and compared it with that of eS31. Polysome analysis reveals that deletion of either RPS12 or UBI3 results in equivalent 40S deficits. Analysis of pre-rRNA processing indicates that eS12, akin to eS31, is required for efficient processing of 20S pre-rRNA to mature 18S rRNA. Moreover, we show that the 20S pre-rRNA accumulates within cytoplasmic pre-40S particles, as deduced from FISH experiments and the lack of nuclear retention of 40S subunit reporter proteins, in rps12∆ and ubi3∆ cells. However, these particles containing 20S pre-rRNA are not efficiently incorporated into polyribosomes. We also provide evidence for a genetic interaction between eS12 or eS31 and the late-acting 40S assembly factors Enp1 and Ltv1, which appears not to be linked to the dynamics of their association with or release from pre-40S particles in the absence of either eS12 or eS31. Finally, we show that eS12- and eS31-deficient ribosomes exhibit increased levels of translational misreading. Altogether, our data highlight distinct important roles of the beak region during ribosome assembly and function.
Overexpression of βTrCP1 elicits cell death in cisplatin-induced senescent cells
(Nature Publishing Group, 2025) Belmonte-Fernández, Alejandro; Herrero-Ruíz, J.; Limón Mortés, María Cristina; Sáez, C.; Japón, MA; Mora Santos, María del Mar; Romero Portillo, Francisco; Microbiología
Identification and validation of clinical phenotypes in Staphylococcus aureus bloodstream infection and their association with mortality (FEN-AUREUS study)
(Elsevier, 2025-05) Gutiérrez Gutiérrez, Belén; Gallego-Mesa, Belén; Kaasch, Achim J.; Riediger, Matthias; Rieg, Siegbert; Trigo, Marta; Salto-Alejandre, Sonsoles; Merchante Gutiérrez, Nicolás; Pascual Hernández, Álvaro; López-Cortés, Luis E.; Rodríguez-Baño, Jesús; Medicina; Microbiología; Instituto de Biomedicina de Sevilla (IBIS); Instituto de Salud Carlos III; Gobierno de España; CTS210: Resistencia a Antimicrobianos
Background Staphylococcus aureus bacteraemia (SAB) is heterogeneous in patients and infection-related features. The aim of the study was to identify clinical phenotypes among patients with SAB, to evaluate their association with mortality, and to derive and validate a simplified probabilistic model for phenotypes assignment. Methods Phenotypes were derived using two-stage cluster analysis of 2128 patients from the ISAC cohort (recruited between 2013 and 2015), analysing 62 variables. Cox regression assessed phenotype–mortality associations. Logistic regression was employed to develop a simplified probabilistic model for sub-phenotype allocation, validated in two external international cohorts: INSTINCT (1217 patients, recruited between 2006 and 2011) and FEN-AUREUS (1185 patients, recruited between January 2021 and October 2024). The association between sub-phenotypes and 30-day mortality in the validation cohorts was also assessed.
Usefulness of sonication in the microbiological diagnosis of cardiovascular implantable electronic device infections: systematic review, meta-analysis and meta-regression
(Biomed Central (BMC), 2024-11-05) Martín-Gutiérrez, Guillermo; Martín Pérez, Carlos; Ortiz de la Rosa, José Manuel; Gutiérrez Carretero, Encarnación; Alarcón, Arístides de; Lepe Jiménez, José Antonio; Cirugía; Microbiología; Instituto de Salud Carlos III; Gobierno de España; CTS1134: Investigación Traslacional en la Fisiopatología Cardiovascular; CTS204: Biotecnología Aplicada al Estudio de Enfermedades Infecciosas
Background Multiple studies have demonstrated the utility of sonication to improve culture yield in patients with cardiovascular implantable electronic device (CIED) infections. Objective To analyze the usefulness of sonication in the microbiological diagnosis of CIED infections in comparison with traditional cultures. Methods Systematic database searches were performed to identify studies that provided enough data concerning both sensitivity and specificity of traditional (non-sonicated) and sonicated cultures from CIED samples. The diagnostic accuracy measures were obtained by three different statistical approaches: (i) The univariate model; (ii) The bivariate random; and (iii) The Bayesian bivariate hierarchical model. Heterogeneity was assessed using meta-regression. Findings Nine studies met the criteria for inclusion in the meta-analysis (1684 cultures). The summary estimates of sensitivity were higher for sonicated cultures (0.756) in comparison with non-sonicated cultures (0.446). On meta-regression, sonication of CIEDs significantly increased the sensitivity (p = 0.001) as well as the rates of false positive results (p = 0.003). The final model also showed that the studies that used a threshold for positivity were associated with lower rates of false positive results (p < 0.001).
Overexpression of βTrCP1 elicits cell death in cisplatin-induced senescent cells
(Springer, 2025-03-25) Belmonte Fernández, Alejandro; Herrero Ruiz, Joaquín; Limón Mortés, María Cristina; Sáez, Carmen; Japón, Miguel Ángel; Mora Santos, María del Mar; Romero Portillo, Francisco; Microbiología; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Union (UE); Universidad de Sevilla
Senescence is a non-proliferative cellular state derived from aging or in response to exogenous insults, such as those that cause DNA damage. As a result of cancer treatments like cisplatin, certain tumor cells may undergo senescence. However, rather than being beneficial for patients, this is detrimental because these cells might proliferate again under specific conditions and, more importantly, because they synthesize and secrete molecules that promote the proliferation of nearby cells. Therefore, to achieve complete tumor remission, it is necessary to develop senolytic compounds to eliminate senescent cells. Here, we studied the role of βTrCP1 in cell proliferation and senescence and found that lentiviral overexpression of βTrCP1 induces the death of senescent cells obtained after cisplatin treatment in both two-dimensional cell cultures and tumorspheres. Mechanistically, we demonstrated that overexpression of βTrCP1 triggers proteasome-dependent degradation of p21 CIP1, allowing damaged cells to progress through the cell cycle and consequently die. Furthermore, we identified nucleophosmin 1 (NPM1) as the intermediary molecule involved in the effect of βTrCP1 on p21 CIP1. We determined that increased amounts of βTrCP1 partially retains NPM1 in the nucleoli, preventing it from associating with p21 CIP1, thus leaving it unprotected from degradation by the proteasome. These results have allowed us to discover a potential new target for senolytic drugs, as retaining NPM1 in the nucleoli under senescent conditions induces cell death.
TtsI: Beyond Type III Secretion System Activation in Rhizobia
(MDPI, 2025-01-05) Jiménez Guerrero, Irene; Acosta Jurado, Sebastián; Navarro Gómez, Pilar; Fuentes Romero, Francisco; Alias Villegas, Cynthia; López Baena, Francisco Javier; Vinardell González, José María; Microbiología; Ministerio de Ciencia e Innovación (MICIN). España
The expression of the rhizobial symbiotic genes is controlled by various transcriptional regulators. After induction with appropriate plant flavonoids, NodD is responsible for the activation of the expression of genes related to Nod factor synthesis and secretion, but also, in most rhizobia harbouring a symbiotic type III secretion system (T3SS), the expression of ttsI. The ttsI gene encodes the positive regulator of the expression of T3SS-related genes, including those coding for structural components and for type III-secreted effector proteins. However, besides this general role among T3SS-harbouring rhizobia, different works have shown additional functions of TtsI in the regulation (positive or negative) of other bacterial traits such as the production of modified lipopolysaccharides or different types of motility (swimming or surface spreading). Interestingly, these additional functions appear to be rather specific than general among rhizobia. Moreover, in Sinorhizobium fredii HH103, TtsI affects the expression of various genes belonging to the nod regulon, including several transcriptional regulators. This review summarizes all the well-known bacterial traits affected by TtsI and describes other rhizobial genes that are regulated by TtsI but whose function remains to be established.

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