Artículos (Microbiología)

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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; Universidad de Sevilla. Departamento de 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; Universidad de Sevilla. Departamento de 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; Universidad de Sevilla. Departamento de 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; Universidad de Sevilla. Departamento de 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; Universidad de Sevilla. Departamento de Microbiología; Universidad de Sevilla. Departamento de Medicina Preventiva y Salud Pública; Universidad de Sevilla. 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; Universidad de Sevilla. Departamento de Microbiología; Universidad de Sevilla. Departamento de 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; Universidad de Sevilla. Departamento de 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; Universidad de Sevilla. Departamento de Medicina; Universidad de Sevilla. Departamento de Microbiología; Instituto de Biomedicina de Sevilla (IBIS); Instituto de Salud Carlos III; Gobierno de España; Universidad de Sevilla. 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; Universidad de Sevilla. Departamento de Cirugía; Universidad de Sevilla. Departamento de Microbiología; Instituto de Salud Carlos III; Gobierno de España; Universidad de Sevilla. CTS1134: Investigación Traslacional en la Fisiopatología Cardiovascular; Universidad de Sevilla. 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; Universidad de Sevilla. Departamento de 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; Universidad de Sevilla. Departamento de 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.
A microbiological and genomic perspective of globally collected Escherichia coli from adults hospitalized with invasive E. coli disease
(Oxford University Press, 2025-07-13) Arconada Nuin, Enya; Vilken, Tuba; Britto Xavier, Basil; Doua, Joachim; Morrow, Brian; Geurtsen, Jeroen; Pascual Hernández, Álvaro; Dagher, Michael; Universidad de Sevilla. Departamento de Microbiología; European Community (EC)
Objectives Escherichia coli can cause infections in the urinary tract and in normally sterile body sites leading to invasive E. coli disease (IED), including bacteraemia and sepsis, with older populations at increased risk. We aimed to estimate the theoretical coverage rate by the ExPEC4V and 9V vaccine candidates. In addition, we aimed at better understanding the diversity of E. coli isolates, including their genetic and phenotypic antimicrobial resistance (AMR), sequence types (STs), O-serotypes and the bacterial population structure. Methods Blood and urine culture E. coli isolates (n = 304) were collected from hospitalized patients ≥60 years (n = 238) with IED during a multicentric, observational study across three continents. All isolates were tested for antimicrobial susceptibility, O-serotyped, whole-genome sequenced and bioinformatically analysed. Results A large diversity of STs and of O-serotypes were identified across all centres, with O25b-ST131, O6-ST73 and O1-ST95 being the most prevalent types. A total of 45.4% and 64.7% of all isolates were found to have an O-serotype covered by the ExPEC4V and ExPEC9V vaccine candidates, respectively. The overall frequency of MDR was 37.4% and ST131 was predominant among MDR isolates. Low in-patient genetic variability was observed in cases where multiple isolates were collected from the same patient. Conclusions Our results highlight the predominance of MDR O25b-ST131 E. coli isolates across diverse geographic areas. These findings provide further baseline data on the theoretical coverage of novel vaccines targeting E. coli associated with IED in older adults and their associated AMR levels.
Regional distribution of carbapenemase‑producing Acinetobacter baumannii isolates in southern Spain (Andalusia)
(Springer, 2025) Fernández-Cuenca, Felipe; Rodríguez-Pallares, Salud; López Cerero, Lorena; Gutiérrez-Fernández, José; Bautista, María Fe; Sánchez Gómez, Juan Antonio; Delgado Valverde, María Mercedes; Pascual Hernández, Álvaro; Universidad de Sevilla. Departamento de Microbiología
Objectives This is the first study conducted in southern Spain to determine i) the population structure (PS) of carbapenemresistant (CR) Acinetobacter baumannii isolates by multilocus sequencing typing (MLST) and core genome MLST (cgMLST) and ii) the association between the sequence type ST and the blaOXA-51 variant, capsule polysaccharide locus (KL) and lipooligosaccharide outer core locus (OCL) types. Methods Of 336 isolates submitted to the Andalusian reference laboratory (PIRASOA; December 2017–2020), 73 were subjected to WGS (MiSeq). The following analyses were performed: bacterial identification (ribosomal MLST), carbapenemase gene detection (Resfinder 4.0), PS delineation (MLST by MLSTfinder 2.0 and cgMLST by Ridom SeqSphere+), and KL types and OCL types (Kaptive tool). Results The carbapenemases detected were blaOXA-23 (n = 41), blaOXA-58 (n = 26), blaOXA-24 (n = 5), blaOXA-72 (n = 1) and blaNDM-1 (n = 2). The PS revealed one major ST2 clone (n = 54) and seven minor ST clones by MLST, and 41 lineages by cgMLST. Thirty-five lineages were detected only in a single hospital whereas five lineages were observed in several hospitals and provinces. blaOXA-66 was the most frequent blaOXA-51 variant and was mainly associated with the ST2 clone. Eleven KL types and 3 OCL types were assigned, with KL2 (n = 27), KL7 (n = 16) and OCL1 being the most frequent. Conclusions The PS of CR A. baumannii in Andalusia is characterized by a dominant ST2/blaOXA-23 clone and several lineages, showing local spread of lineages in most hospitals, and intercenter or interregional spread of a few lineages. Singlelocus blaOXA-51-like typing and KL typing may be useful as complementary preliminary typing tool.
Transfer of plasmids harbouring blaOXA-48-like carbapenemase genes in biofilm-growing Klebsiella pneumoniae: Effect of biocide exposure
(Elsevier, 2021-10-22) Pérez Palacios, Patricia; Gual de Torrella, Ana; Delgado Valverde, María Mercedes; Oteo Iglesias, Jesús; Hidalgo Díaz, Carmen; Pascual Hernández, Álvaro; Fernández Cuenca, Felipe Manuel; Universidad de Sevilla. Departamento de Microbiología; Gobierno de España; Instituto de Salud Carlos III; European Regional Development Fund (ERDF)
The spread of OXA-48-encoding plasmids from Klebsiella pneumoniae (OXA-48-Kpn), especially successful high-risk (HR) clones, is a growing concern. Biofilm formation can contribute to the dissemination of OXA-48-Kpn. It is not known whether biocides can affect the transfer of OXA-48-Kpn in biofilm. The aim of this study was to evaluate the effect of biocides on the conjugation frequency (CF) of OXA-48-Kpn in both biofilm and planktonic cultures. For that, seven OXA-48-Kpn isolates (4 belonging to HR clones and 3 to non-HR clones) were selected as donors. Each isolate was mixed (1:1) with Escherichia coli J53 (recipient) and grown on polystyrene microplates without biocides (control) and with 0.25x MIC of triclosan (TRI), chlorhexidine digluconate (CHX), povidone-iodine (POV), sodium hypochlorite (SOD) or ethanol (ETH). The CF was calculated as the number of transconjugants/number of E. coli J53. The results showed that for isolates growing in the absence of biocide, the mean fold change in the CF in biofilm with respect to that determined in planktonic cells (CF-BF/CF-PK) was 0.2 in non-HR isolates and ranged from 2.0 to 14.7 in HR isolates. In HR isolates grown in the presence of biocide, especially CHX, TRI, and ETH, the fold changes in CF-BF/CF-PK decreased, whereas in non-HR isolates the fold changes were similar or increased slightly with CHX, ETH, SOD and POV. In conclusion, the fold changes in the CF-BF/CF-PK are higher in HR isolates comparing to non-HR isolates in abscence of biocides. The fold changes in CF-BF/CF-PK of the HR isolates in the presence of biocides varied with the type of biocides, whereas in non-HR isolates, biocides have no significant effect, or produce only a slight increase in the fold change of CF-BF/CF-PK.
Monitoring the antimicrobial susceptibility of gram-negative organisms involved in intraabdominal and urinary tract infections recovered during the smart study (Spain, 2016 and 2017)
(Sociedad Española de Quimioterapia, 2019) Cantón, Rafael; Loza, Elena; Aznar Martín, Javier; Castillo, Francisco Javier; Cercenado, Emilia; Fraile Ribot, Pablo Arturo; Pascual Hernández, Álvaro; Universidad de Sevilla. Departamento de Microbiología
Introduction. Continuous antimicrobial resistance surveillance is recommended by Public Health authorities. We updated data from the SMART (Study for Monitoring Antimicrobial Resistance Trends) surveillance study in Spain. Material and methods. The antimicrobial susceptibility data and extended-spectrum beta-lactamase (ESBL) production in isolates recovered from intra-abdominal (IAI) (n=1,429) and urinary tract (UTI) (n=937) infections during the 2016- 2017 SMART study in 10 Spanish hospitals were analysed. Results. Escherichia coli was the most frequently microorganism isolated (48.3% and 53.7%) followed by Klebsiella spp. (11.5% and 21.9%) in IAIs and UTIs, respectively. Figures for Pseudomonas aeruginosa were 9.0% and 6.1%, being more frequently recovered from patients with nosocomial infections. Overall, 9.9% (IAI) and 14.0% (UTI) of E. coli, Klebsiella spp. and Proteus mirabilis isolates were ESBL-producers, being Klebsiella pneumoniae (34.5%) from UTI of nosocomial origin the most frequent. ESBL-producers were higher in patients >60 years in both IAIs and UTIs. As in previous years, amikacin (96.3%-100% susceptibility), ertapenem (84.2%-100%) and imipenem (70.3%- 100%) were the most active antimicrobials tested among Enterobacterales species. The activity of amoxicillin-clavulanic, piperacillin-tazobactam, and ciprofloxacin susceptibility was lower, particularly among ESBL-producers. Ertapenem susceptibility (88.9%-100%) was retained in ESBL-E. coli isolates that were resistant to these antimicrobials but decreased (28.6%-100%) in similar isolates of K. pneumoniae. Conclusions. Continuous antimicrobial resistance surveillance from the SMART study reveals overall maintenance of ESBL-producers in Spain, although with higher presence in isolates from UTIs than from IAIs. Moreover, ertapenem activity was high in E. coli irrespective of ESBL production but decreased in K. pneumoniae, particularly among ESBL-producers
Combined Use of the Ab105-2φΔCI Lytic Mutant Phage and Different Antibiotics in Clinical Isolates of Multi-Resistant Acinetobacter baumannii
(MDPI, 2019-11-12) Blasco, Lucía; Ambroa, Antón; López, María; Fernández García, Laura; Bleriot, Inés; Trastoy, Rocío; Rodríguez-Baño, Jesús; Pascual Hernández, Álvaro; Cisneros, José Miguel; Pachón Díaz, Jerónimo; Tomás, María; Universidad de Sevilla. Departamento de Microbiología; Universidad de Sevilla. Departamento de Medicina; Deputación Provincial da Coruña; Xunta de Galicia; Instituto de Salud Carlos III; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica; Gobierno de España
Phage therapy is an abandoned antimicrobial therapy that has been resumed in recent years. In this study, we mutated a lysogenic phage from Acinetobacter baumannii into a lytic phage (Ab105-2phiΔCI) that displayed antimicrobial activity against A. baumannii clinical strain Ab177_GEIH-2000 (isolated in the GEIH-REIPI Spanish Multicenter A. baumannii Study II 2000/2010, Umbrella Genbank Bioproject PRJNA422585, and for which meropenem and imipenem MICs of respectively, 32 µg/mL, and 16 µg/mL were obtained). We observed an in vitro synergistic antimicrobial effect (reduction of 4 log–7 log CFU/mL) between meropenem and the lytic phage in all combinations analyzed (Ab105-2phiΔCI mutant at 0.1, 1 and 10 MOI and meropenem at 1/4 and 1/8 MIC). Moreover, bacterial growth was reduced by 8 log CFU/mL for the combination of imipenem at 1/4 MIC plus lytic phage (Ab105-2phiΔCI mutant) and by 4 log CFU/mL for the combination of imipenem at 1/8 MIC plus lytic phage (Ab105-2phiΔCI mutant) at both MOI 1 and 10. These results were confirmed in an in vivo model (G. mellonella), and the combination of imipenem and mutant Ab105-2phiΔCI was most effective (p < 0.05). This approach could help to reduce the emergence of phage resistant bacteria and restore sensitivity to antibiotics used to combat multi-resistant strains of Acinetobacter baumannii.
Microbes Saving Lives and Reducing Suffering
(Wiley, 2025) Timmis, Kenneth; Karahan, Zeynep Ceren; Ramos, Juan Luis; Koren, Omry; Perez-Cobas, Ana Elena; Steward, Karen; Borrero de Acuña, José Manuel; Haggblom, Max; Universidad de Sevilla. Departamento de Microbiología
Antimicrobial susceptibility trends and evolution of isolates with extended spectrum β-lactamases among Gram-negative organisms recovered during the SMART study in Spain (2011-2015)
(Sociedad Española de Quimioterapia, 2018) Cantón, Rafael; Loza, Elena; Aznar Martín, Javier; Barrón Adúriz, Rubén; Calvo, Jorge; Castillo, F. Javier; Pascual Hernández, Álvaro; Universidad de Sevilla. Departamento de Microbiología
Introduction. The SMART (Study for Monitoring Antimicrobial Resistance Trends) surveillance study monitors antimicrobial susceptibility and extended spectrum β-lactamases (ESBLs) in Gram-negative bacilli recovered from intra-abdominal infections (IAI). Material and methods. Antimicrobial susceptibility of 5,343 isolates from IAI recovered in 11 centres during the 2011-2015 SMART-Spain program was analysed by standard microdilution (EUCAST criteria) and compared with that from 2002-2010. ESBLs were phenotypically detected. Results. Escherichia coli, the most common isolate, significantly decreased in community acquired IAI (60.9% 2002-2010 vs. 56.1% 2011-2015, P=0.0003). It was followed in prevalence by Klebsiella pneumoniae that increased both in the community (8.9% vs. 10.8%, P=0.016) and nosocomial (9.2% vs. 10.8%, P=0.029) IAI and P. aeruginosa, which significantly increased in community acquired IAI (5.6% vs. 8.0%, P=0.0003). ESBLs were more prevalent in K. pneumoniae (16.3%) than in E. coli (9.5%) of nosocomial origin and were more frequently isolated from elderly patients (>60 years). Considering all Enterobacteriaceae, ertapenem (92.3-100%) and amikacin (95.5%-100%) were the most active antimicrobials. Ertapenem activity, unlike amoxicillinclavulanate or piperacillin-tazobactam, remained virtually unchanged in ESBL (100%) and non-ESBL (98.8%) E. coli producers. Its activity decreased in ESBL-K. pneumoniae (74.7%) but was higher than that of amoxicillin-clavulanate (14.0%) and piperacillin-tazobactam (24.0%). Interestingly, ertapenem susceptibility was maintained in >60% of ESBL isolates that were resistant to amoxicillin-clavulanate, piperacillin-tazobactam or fluoroquinolones. Conclusions. SMART-Spain results support current guidelines which include ertapenem as empiric treatment in mild-moderate community-acquired IAI, particularly with ESBL producers. These recommendations will need to be updated with the recently introduction of new antimicrobials.
Evolution of the Quorum network and the mobilome (plasmids and bacteriophages) in clinical strains of Acinetobacter baumannii during a decade
(Nature Research, 2018-02-06) López, M.; Rueda, A.; Florido, J.P.; Blasco, L.; Fernández-García, L.; Trastoy, R.; Pascual Hernández, Álvaro; Tomas, M.; Universidad de Sevilla. Departamento de Microbiología; Instituto de Salud Carlos III; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Gobierno de España; Xunta de Galicia
In this study, we compared eighteen clinical strains of A. baumannii belonging to the ST-2 clone and isolated from patients in the same intensive care unit (ICU) in 2000 (9 strains referred to collectively as Ab_GEIH-2000) and 2010 (9 strains referred to collectively as Ab_GEIH-2010), during the GEIH-REIPI project (Umbrella BioProject PRJNA422585). We observed two main molecular differences between the Ab_GEIH-2010 and the Ab_GEIH-2000 collections, acquired over the course of the decade long sampling interval and involving the mobilome: i) a plasmid harbouring genes for blaOXA 24/40 ß-lactamase and abKA/abkB proteins of a toxin-antitoxin system; and ii) two temperate bacteriophages, Ab105-1ϕ (63 proteins) and Ab105-2ϕ (93 proteins), containing important viral defence proteins. Moreover, all Ab_GEIH-2010 strains contained a Quorum functional network of Quorum Sensing (QS) and Quorum Quenching (QQ) mechanisms, including a new QQ enzyme, AidA, which acts as a bacterial defence mechanism against the exogenous 3-oxo-C12-HSL. Interestingly, the infective capacity of the bacteriophages isolated in this study (Ab105-1ϕ and Ab105-2ϕ) was higher in the Ab_GEIH-2010 strains (carrying a functional Quorum network) than in the Ab_GEIH-2000 strains (carrying a deficient Quorum network), in which the bacteriophages showed little or no infectivity. This is the first study about the evolution of the Quorum network and the mobilome in clinical strains of Acinetobacter baumannii during a decade.
Relationship between Tolerance and Persistence Mechanisms in Acinetobacter baumannii Strains with AbkAB Toxin-Antitoxin System
(American Society for Microbiology, 2018-04-26) Fernández García, Laura; Fernández Cuenca, Felipe Manuel; Blasco, Lucía; López Rojas, Rafael; Ambroa, Antón; López, María; Pascual Hernández, Álvaro; Bou, Germán; Tomás, María; Universidad de Sevilla. Departamento de Microbiología; Instituto de Salud Carlos III; Consejo Superior de Investigaciones Científicas (CSIC); Grupo de Estudio sobre Mecanismos de Acción y Resistencia a los Antimicrobianos, GEMARA (SEIMC); Xunta de Galicia
The molecular mechanisms of tolerance and persistence associated with several compounds in Acinetobacter baumannii clinical isolates are unknown. Using transcriptomic and phenotypic studies, we found a link between mechanisms of bacterial tolerance to chlorhexidine and the development of persistence in the presence of imipenem in an A. baumannii strain belonging to clinical clone ST-2 (OXA-24 β-lactamase and AbkAB toxin-antitoxin [TA] system carried in a plasmid). Interestingly, the strain A. baumannii ATCC 17978 (AbkAB TA system from plasmid) showed persistence in the presence of imipenem and chlorhexidine.

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