Artículos (Microbiología)

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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.
Quorum sensing network in clinical strains of A. baumannii: AidA is a new quorum quenching enzyme
(Public Library of Science, 2017-03-22) López, María; Mayer, Celia; Fernández García, Laura; Blasco, Lucía; Muras, Andrea; Martín Ruiz, Federico; Bou, German; Otero, Ana; Tomás, María; Pachón Díaz, Jerónimo; Pascual Hernández, Álvaro; Rodríguez-Baño, Jesús; Cisneros, José Miguel; Universidad de Sevilla. Departamento de Microbiología; Universidad de Sevilla. Departamento de Medicina; Instituto de Salud Carlos III; Consejo Superior de Investigaciones Científicas (CSIC); Gobierno de España; Xunta de Galicia
Acinetobacter baumannii is an important pathogen that causes nosocomial infections generally associated with high mortality and morbidity in Intensive Care Units (ICUs). Currently, little is known about the Quorum Sensing (QS)/Quorum Quenching (QQ) systems of this pathogen. We analyzed these mechanisms in seven clinical isolates of A. baumannii. Microarray analysis of one of these clinical isolates, Ab1 (A. baumannii ST-2_clon_2010), previously cultured in the presence of 3-oxo-C12-HSL (a QS signalling molecule) revealed a putative QQ enzyme (α/ß hydrolase gene, AidA). This QQ enzyme was present in all non-motile clinical isolates (67% of which were isolated from the respiratory tract) cultured in nutrient depleted LB medium. Interestingly, this gene was not located in the genome of the only motile clinical strain growing in this medium (A. baumannii strain Ab421_GEIH-2010 [Ab7], isolated from a blood sample). The AidA protein expressed in E. coli showed QQ activity. Finally, we observed downregulation of the AidA protein (QQ system attenuation) in the presence of H2O2 (ROS stress). In conclusion, most of the A. baumannii clinical strains were not surface motile (84%) and were of respiratory origin (67%). Only the pilT gene was involved in surface motility and related to the QS system. Finally, a new QQ enzyme (α/ß hydrolase gene, AidA protein) was detected in these strains.
Response to Bile Salts in Clinical Strains of Acinetobacter baumannii Lacking the AdeABC Efflux Pump: Virulence Associated with Quorum Sensing
(Frontiers Media, 2017-05-09) López, María; Blasco, Lucía; Gato, Eva; Pérez, Astrid; Fernández García, Laura; Martínez Martínez, Luis; Rodríguez-Baño, Jesús; Pascual Hernández, Álvaro; Garnacho Montero, José; Pachón Díaz, Jerónimo; Cisneros, José Miguel; Universidad de Sevilla. Departamento de Microbiología; Universidad de Sevilla. Departamento de Medicina
Introduction: Acinetobacter baumannii is an opportunistic nosocomial pathogen associated with multiple infections. This pathogen usually colonizes (first stage of microbial infection) host tissues that are in contact with the external environment. As one of the sites of entry in human hosts is the gastrointestinal tract, the pathogen must be capable of tolerating bile salts. However, studies analyzing the molecular characteristics involved in the response to bile salts in clinical strains of A. baumannii are scarce. Material and Methods: Microbiological and transcriptional studies (arrays and RT-PCR) in the response to bile salts were carried out in isogenic (A. baumanni ΔadeB ATCC 17978 and A. baumannii ΔadeL ATCC 17978) and clinical strains from clone ST79/PFGE-HUI-1 which is characterized by lacking the AdeABC efflux pump and by overexpression the AdeFGH efflux pump. Results and Discussion: In presence of bile salts, in addition to the glutamate/aspartate transporter were found overexpressed in A. baumannii ΔadeB ATCC 17978, the virulence factors (surface motility, biofilm, and Type VI Secretion System) which are associated with activation of the Quorum Sensing system. Overexpression of these factors was confirmed in clinical strains of clone ST79/PFGE-HUI-1. Conclusions: This the first study about the adaptive response to bile salts investigating the molecular and microbiological characteristics in response to bile salts of an isogenic model of A. baumannii ATCC 17978 and clinical isolates of A. baumannii (clinical strains of ST79/PFGE-HUI-1) lacking the main RND efflux pump (AdeABC). Clinical isolates of A. baumannii lacking the AdeABC efflux pump (clone ST79/PFGE-HUI-1) displayed a new clinical profile (increased invasiveness) possibly associated with the response to stress conditions (such as the presence of bile salts).
Genome Sequence of Airborne Acinetobacter sp. Strain 5-2Ac02 in the Hospital Environment, Close to the Species of Acinetobacter towneri
(American Society for Microbiology, 2016-12-08) Barbosa, Beathriz; Fernández García, Laura; Gato, Eva; López, María; Blasco, Lucía; Leão, Robson Souza; Pascual Hernández, Álvaro; Tomás, María; Universidad de Sevilla. Departamento de Microbiología; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Xunta de Galicia; Instituto de Salud Carlos III; Gobierno de España
Acinetobacter spp. are found in 53% of air colonization samples from the hospital environment. In this work, we sequenced all the genome of airborne Acinetobacter sp. strain 5-2Ac02. We found important features at the genomic level in regards to the rhizome. By phylogenetic analysis, A. towneri was the species most closely related to Acinetobacter sp. 5-2Ac02.
Methicillin-resistant Staphylococcus aureus (MRSA) catheter-related bacteraemia in haemodialysis patients
(BioMed Central, 2015-10-30) Cuervo, Guillermo; Camoez, Mariana; Shaw, Evelyn; Domínguez, María Ángeles; Gasch, Oriol; Padilla, Belén; Rodríguez-Baño, Jesús; Lepe Jiménez, José Antonio; Pascual Hernández, Álvaro; Universidad de Sevilla. Departamento de Medicina; Universidad de Sevilla. Departamento de Microbiología; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Instituto de Salud Carlos III
Background The aim of the study was to determine clinical and microbiological differences between patients with methicillin-resistant Staphylococcus aureus (MRSA) catheter-related bacteraemia (CRB) undergoing or not undergoing haemodialysis, and to compare outcomes. Methods Prospective multicentre study conducted at 21 Spanish hospitals of patients with MRSA bacteraemia diagnosed between June 2008 and December 2009. Patients with MRSA-CRB were selected. Data of patients on haemodialysis (HD-CRB) and those not on haemodialysis (non-HD-CRB) were compared. Results Among 579 episodes of MRSA bacteraemia, 218 (37.7 %) were CRB. Thirty-four (15.6 %) were HD-CRB and 184 (84.4 %) non-HD-CRB. All HD-CRB patients acquired the infection at dialysis centres, while in 85.3 % of the non-HD-CRB group the infection was nosocomial (p < .001). There were no differences in age, gender or severity of bacteraemia (Pitt score); comorbidities (Charlson score ≥ 4) were higher in the HD-CRB group than in the non-HD-CRB group (73.5 % vs. 46.2 %, p = .003). Although there were no differences in VAN-MIC ≥1.5 mg/L according to microdilution, using the E-test a higher rate of VAN-MIC ≥1.5 mg/L was observed in HD-CRB than in non-HD-CRB patients (63.3 % vs. 44.1 %, p = .051). Vancomycin was more frequently administered in the HD-CRB group than in the non-HD-CRB group (82.3 % vs. 42.4 %, p = <.001) and therefore the appropriate empirical therapy was significantly higher in HD-CRB group (91.2 % vs. 73.9 %, p = .029). There were no differences with regard to catheter removal (79.4 % vs. 84.2 %, p = .555, respectively). No significant differences in mortality rate were observed between both groups (Overall mortality: 11.8 % vs. 27.2 %, p = .081, respectively), but there was a trend towards a higher recurrence rate in HD-CRB group (8.8 % vs. 2.2 %, p = .076). Conclusions In our multicentre study, ambulatory patients in chronic haemodialysis represented a significant proportion of cases of MRSA catheter-related bacteraemia. Although haemodialysis patients with MRSA catheter-related bacteraemia had significantly more comorbidities and higher proportion of strains with reduced vancomycin susceptibility than non-haemodialysis patients, overall mortality between both groups was similar.
Sensibilidad de microorganismos gramnegativos de infecciones intraabdominales y evolución de los aislados con β-lactamasas de espectro extendido en el estudio smart en españa (2002-2010)
(Sociedad Española de Quimioterapia, 2011) Cantón, Rafael; Loza, Elena; Aznar Martín, Javier; Calvo, Jorge; Cercenado, Emilia; Cisterna, Ramón; González Romo, Fernando; López Hontangas, José Luis; Rubio Calvo, Carmen; Suárez Barrenechea, Ana Isabel; Tubau, Fe; Weber, Irene; Yuste, Patricia; Cavanillas, Rafael; Pascual Hernández, Álvaro; Universidad de Sevilla. Departamento de Microbiología; Universidad de Sevilla. CTS210: Resistencia a Antimicrobianos
Introducción. El estudio SMART (Study for Monitoring Antimicrobial Resistance Trends) tiene como objetivo monitorizar la sensibilidad a los antimicrobianos de los microorganismos gramnegativos aislados en la infección intraabdominal, con especial seguimiento de los que producen β-lactamasas de espectro extendido (BLEE). Material y métodos. Se han analizado por microdulución los datos de sensibilidad de 8.869 aislados recogidos en el estudio SMART en España entre 2002 y 2010 en el que han participado 16 centros. Resultados. Escherichia coli fue el patógeno más frecuente (60,9% en la infección intraabdominal adquirida en la comunidad y 49,9% en la nosocomial) seguido de Klebsiella pneumoniae (8,9% vs 9,2%). Pseudomonas aeruginosa fue más habitual en la infección nosocomial (5,6% comunitaria y 8,6% nosocomial). La frecuencia de aislados con BLEE fue: E. coli 8,7%, K. pneumoniae 8,4%, Klebsiella oxytoca 1,4% y Proteus mirabilis 1,6%. En los pacientes de mayor edad aumentó la proporción global de aislados con BLEE (6,8% en pacientes >60 años). Ertapenem y meropenem fueron los antimicrobianos más activos en el conjunto de las enterobacterias (rango de sensibilidad con criterios EUCAST, 89-100%) y también entre los aislados con BLEE (95,5-100%). La actividad de amoxicilina/ácido clavulánico y piperacilina/tazobactam fue considerablemente inferior, en particular en los aislados con BLEE. Ertapenem mantuvo una buena actividad (sensibilidad >95%) en los productores de BLEE resistentes a amoxicilina/ácido clavulánico, piperacilina/tazobactam o fluoroquinolonas. Conclusiones. Los datos de sensibilidad del estudio SMART en España avalan las guías terapéuticas actuales de infección intraabdominal que sitúan al ertapenem como tratamiento empírico de elección, teniendo en cuenta sobre todo la elevada frecuencia de aislados con BLEE en nuestro medio.
Evaluación del medio chromID ESBL para la detección de portadores de enterobacterias productoras de betalactamasas de espectro extendido
(Elsevier, 2011-07) Del Castillo, María Carmen; López Cerero, Lorena; Casal, Mar; Pascual Hernández, Álvaro; Universidad de Sevilla. Departamento de Microbiología; Universidad de Sevilla. CTS210: Resistencia a Antimicrobianos
El aumento de la prevalencia de infecciones causadas por enterobacterias productoras de betalactamasas de espectro extendido (BLEE), tanto en la comunidad como en el ámbito hospitalario, plantea la necesidad, en determinadas investigaciones epidemiológicas de brotes nosocomiales, de disponer de métodos rápidos para la detección de portadores de estos microorganismos.
Epidemiologia de las blees en la comunidad: un problema emergente
(Elsevier, 2007-10) López Cerero, Lorena; Pascual Hernández, Álvaro; Universidad de Sevilla. Departamento de Microbiología; Instituto de Biomedicina de Sevilla (IBIS); Universidad de Sevilla. CTS210: Resistencia a Antimicrobianos
La emergencia de infecciones comunitarias por Escherichia coli productora de betalactamasas de espectro extendido (BLEE) es un fenómeno nuevo y generalizado, coincidente con la irrupción de enzimas CTX-M, que en nuestro país comienza a partir del año 2000. Las enzimas que se observan con más frecuencia pertenecen a la familia CTX-M y en segundo lugar encontramos SHV-12. Estos aislados están implicados principalmente en infecciones urinarias y se asocian a factores de riesgo como el uso de sonda urinaria y de antibióticos previamente. Su epidemiología es compleja ya que se han descrito clones epidémicos que afectaban a pacientes extra e intrahospitalarios, así como la detección de aislados no agrupados clonalmente y la diseminación horizontal de un grupo determinado de enzimas mediante elementos móviles. Existen portadores fecales en la comunidad, pero se desconoce actualmente el reservorio y las formas de transmisión, lo que supone una limitación para establecer medidas de control eficaces.
Extended-spectrum and CMY-type b-lactamase-producing Escherichia coli in clinical samples and retail meat from Pittsburgh, USA and Seville, Spain
(Elsevier, 2010-01) Doi, Yusuke; Paterson, David L.; Pascual Hernández, Álvaro; López Cerero, Lorena; Navarro, M. D.; Adams-Haduch, J. M.; Qureshi, Z. A.; Rodríguez-Baño, Jesús; Universidad de Sevilla. Departamento de Microbiología; Universidad de Sevilla. Departamento de Medicina; Instituto de Biomedicina de Sevilla (IBIS); Junta de Andalucía; Ministerio de Sanidad y Consumo. España; National Foundation of Infectious Diseases and the Infectious Diseases Society of America; National Institute of Allergy and Infectious Diseases; National Institutes of Health. United States; Universidad de Sevilla. CTS210: Resistencia a Antimicrobianos
Infections due to Escherichia coli producing extended-spectrum β-lactamase (ESBL) or CMY-type β-lactamase (CMY) are increasingly observed in non-hospitalized patients. The origin of these organisms is uncertain, but retail meat contaminated with E. coli may be a source. In the present study, clinical information and strains collected from patients infected or colonized with ESBL-producing and CMY-producing E. coli at hospitals in Pittsburgh, USA and Seville, Spain were investigated. Retail meat purchased in these cities was also studied for the presence of these organisms. Twenty-five and 79 clinical cases with ESBL-producing E. coli and 22 cases and one case with CMY-producing E. coli were identified in Pittsburgh and Seville, respectively. Among them all, community-acquired and healthcareassociated cases together constituted 60% of the cases in Pittsburgh and 73% in Seville. Community-acquired cases were more common in Seville than in Pittsburgh (49% vs. 13%; p <0.001). ESBL-producing and CMY-producing E. coli isolates were commonly recovered from the local retail meat. In particular, 67% (8/12) of retail chickens in Seville and 85% (17/20) of those in Pittsburgh contained ESBLproducing and CMY-producing E. coli isolates, respectively. Among the ESBL-producing isolates, CTX-M and SHV were the most common ESBL types in both clinical and meat isolates. Approximately half of the ESBL-producing and CMY-producing E. coli isolates from meat belonged to phylogenetic groups associated with virulent extra-intestinal infections in humans. Community and healthcare environments are now significant reservoirs of ESBL-producing and CMY-producing E. coli. Retail meat is a potential source of these organisms.
Comparative assessment of inoculum effects on the antimicrobial activity of amoxycillin-clavulanate and piperacillin-tazobactam with extended-spectrum beta-lactamase-producing and extended-spectrum beta-lactamase-non-producing Escherichia coli isolates
(Elsevier, 2010-02) López Cerero, Lorena; Picón, Eduardo; Morillo, E.; Hernández, J. R.; Docobo Pérez, Fernando; Pachón Díaz, Jerónimo; Rodríguez-Baño, Jesús; Pascual Hernández, Álvaro; Universidad de Sevilla. Departamento de Microbiología; Universidad de Sevilla. Departamento de Medicina; Instituto de Biomedicina de Sevilla (IBIS); Instituto de Salud Carlos III; Junta de Andalucía; Ministerio de Sanidad y Consumo. España; Universidad de Sevilla. CTS210: Resistencia a Antimicrobianos
A significant inoculum-size effect has been observed with piperacillin-tazobactam, and has been associated with β-lactamase production in extended-spectrum β-lactamase (ESBL) producers. This association has not been previously studied in the case of amoxycillin-clavulanate. Piperacillin-tazobactam and amoxycillin-clavulanate were compared, using high inocula of susceptible strains either harbouring ESBLs or not. Two non-ESBL-producing and 15 amoxycillin-clavulanate-susceptible and piperacillin-tazobactam-susceptible ESBL-producing Escherichia coli isolates, and their respective transconjugants, were tested in dilution susceptibility tests using standard and 100-fold higher inocula. Three ESBL-producing strains and E. coli ATCC 25922 were selected for time-kill studies using standard and high initial inocula. At high inocula, MICs of piperacillin increased >eight-fold for non-ESBL-producing strains, and MICs of piperacillin-tazobactam (8 : 1 ratio or with tazobactam fixed at 4 mg/L) increased>eight-fold for all ESBL-producing strains. However, amoxycillin MICs were not affected by a high inoculum with non-ESBL-producing strains, whereas the MICs of amoxycillin-clavulanate (2 : 1 and 4 : 1) increased ≤four-fold for ESBL producers, using the broth and agar dilution methods. In kinetic studies at a high inoculum, amoxycillin and amoxycillin-clavulanate were bactericidal against E. coli ATCC 25922, whereas piperacillin and piperacillin-tazobactam yielded decreases of <1 log10 CFU/mL. Similarly, at a high inoculum, only amoxycillin-clavulanate was able to maintain bactericidal rates of killing over 24 h against the ESBL-positive E. coli isolates. The stability of amoxycillin-clavulanate and the contrasting results obtained with piperacillin-tazobactam against high inocula of ESBL-non-producing and ESBL-producing E. coli strains appear to be related to aspects other than the amount of β-lactamase production.
Similarities between the genetic environments of blaCTX-M-15 in Escherichia coli from clinical and food samples from Spain and overseas travellers
(Oxford Academic, 2011-09) López Cerero, Lorena; Egea, P.; Rodríguez-Baño, Jesús; Pascual Hernández, Álvaro; Universidad de Sevilla. Departamento de Microbiología; Universidad de Sevilla. Departamento de Medicina; Instituto de Biomedicina de Sevilla (IBIS); Universidad de Sevilla. CTS210: Resistencia a Antimicrobianos
The spread of E. coli producing CTX-M-15 is complex and diverse. The emergence of different pulsotypes of highly virulent B23 ST131 producing CTX-M-15 has contributed to international spread 5 co-transferred with blaOXA-1, blaTEM , tet(A), catB3 and aac(6′)-Ib, but, additionally, dissemination within group A strains with low virulence could also occur.

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