JUAN ALFONSO Ayala Serrano

Scopus Publications

Novel Resistance Regions Carrying TnaphA6, blaVIM-2, and blaPER-1, Embedded in an ISPa40-Derived Transposon from Two Multi-Resistant Pseudomonas aeruginosa Clinical Isolates
Romina Papa-Ezdra, Nicolás F. Cordeiro, Matilde Outeda, Virginia Garcia-Fulgueiras, Lucía Araújo, Verónica Seija, Juan A. Ayala, Inés Bado, Rafael Vignoli
Antibiotics, 2023
Antibiotic resistance is an alarming problem throughout the world and carbapenem-resistant Pseudomonas aeruginosa has been cataloged as critical in the World Health Organization list of microorganisms in urgent need for the development of new antimicrobials. In this work, we describe two novel resistance regions responsible for conferring a multidrug resistance phenotype to two clinical isolates of P. aeruginosa (Pa873 and Pa6415) obtained from patients hospitalized in the ICU of University Hospital of Uruguay. Bacterial identification and antibiotic susceptibility tests were performed using MALDI-TOF and the Vitek 2 system, respectively. WGS was performed for both isolates using Oxford Nanopore Technologies and Illumina and processed by means of hybrid assembly. Both isolates were resistant to ceftazidime, cefepime, piperacillin–tazobactam, aztreonam, and imipenem. Strain Pa6415 also showed resistance to ciprofloxacin. Both strains displayed MICs below the susceptibility breakpoint for CAZ-AVI plus 4 mg/L of aztreonam as well as cefiderocol. Both resistance regions are flanked by the left and right inverted repeats of ISPa40 in two small regions spanning 39.3 and 35.6 kb, for Pa6415 and Pa873, respectively. The resistance region of Pa6415 includes TnaphA6, and the new Tn7516 consists of IRi, In899, qacEΔ1-sul1-ISCR1, qnrVC6-ISCR1-blaPER-1-qacEΔ1-sul1, araJ-like, IS481-like tnpA, ISPa17, and IRR. On the other hand, the resistance region of Pa873 includes Tnaph6 and the new Tn7517 (IRi, In899, qacEΔ1-sul1, ISCR1–blaPER-1–qacEΔ1-sul1, araJ-like, IS481-like tnpA, ISPa17, and IRR). It is necessary to monitor the emergence of genetic structures that threaten to invalidate the available therapeutic resources.
Peptidoglycan editing in non-proliferating intracellular Salmonella as source of interference with immune signaling
Sara B. Hernández, Sónia Castanheira, M. Graciela Pucciarelli, Juan J. Cestero, Gadea Rico-Pérez, Alberto Paradela, Juan A. Ayala, Sonsoles Velázquez, Ana San-Félix, Felipe Cava, Francisco García-del Portillo
Plos Pathogens, 2022
Salmonella enterica causes intracellular infections that can be limited to the intestine or spread to deeper tissues. In most cases, intracellular bacteria show moderate growth. How these bacteria face host defenses that recognize peptidoglycan, is poorly understood. Here, we report a high-resolution structural analysis of the minute amounts of peptidoglycan purified from S. enterica serovar Typhimurium (S. Typhimurium) infecting fibroblasts, a cell type in which this pathogen undergoes moderate growth and persists for days intracellularly. The peptidoglycan of these non-proliferating bacteria contains atypical crosslinked muropeptides with stem peptides trimmed at the L-alanine-D-glutamic acid-(γ) or D-glutamic acid-(γ)-meso-diaminopimelic acid motifs, both sensed by intracellular immune receptors. This peptidoglycan has a reduced glycan chain average length and ~30% increase in the L,D-crosslink, a type of bridge shared by all the atypical crosslinked muropeptides identified. The L,D-transpeptidases LdtD (YcbB) and LdtE (YnhG) are responsible for the formation of these L,D-bridges in the peptidoglycan of intracellular bacteria. We also identified in a fraction of muropeptides an unprecedented modification in the peptidoglycan of intracellular S. Typhimurium consisting of the amino alcohol alaninol replacing the terminal (fourth) D-alanine. Alaninol was still detectable in the peptidoglycan of a double mutant lacking LdtD and LdtE, thereby ruling out the contribution of these enzymes to this chemical modification. Remarkably, all multiple mutants tested lacking candidate enzymes that either trim stem peptides or form the L,D-bridges retain the capacity to modify the terminal D-alanine to alaninol and all attenuate NF-κB nuclear translocation. These data inferred a potential role of alaninol-containing muropeptides in attenuating pro-inflammatory signaling, which was confirmed with a synthetic tetrapeptide bearing such amino alcohol. We suggest that the modification of D-alanine to alaninol in the peptidoglycan of non-proliferating intracellular S. Typhimurium is an editing process exploited by this pathogen to evade immune recognition inside host cells.
The Spanish Society for Microbiology and Latin American microbiologists: seventy-five years of joint scientific ventures
J. Ayala, R. Kolter
International Microbiology, 2021
As part of this Special Issue of International Microbiology celebrating the 75th anniversary of the founding of the Spanish Society for Microbiology (SEM), Guest Editor Rafael Giraldo invited us to contribute an opinion article on the topic of 75 years of joint scientific ventures between Latin American microbiologists and Spanish microbiologists. Since the creation of SEM in 1945 (Pérez Prieto, NoticiaSEM 98:1, 2016) Latin American microbiologists have been participants, both as individuals and as members of the national associations that are currently integrated into the Latin American Association for Microbiology (ALAM). Thus, the histories of Spanish and Latin American microbiology (Chica and Skinner, Int Microbiol 13:159–164, 2010; Chica, Int Microbiol 11:221–225, 2008) have been closely linked over the last 75 years. In order to provide our perspective on the topic, we decided to provide answers to three questions: What are key aspects of the history of Spanish and Latin American Microbiology interactions? What have been some of our personal experiences in which these interactions shaped our careers? What is our outlook for the future of such interactions?
A Secreted NlpC/P60 Endopeptidase from Photobacterium damselae subsp. piscicida Cleaves the Peptidoglycan of Potentially Competing Bacteria
Johnny Lisboa, Cassilda Pereira, Aline Rifflet, Juan Ayala, Mateus S. Terceti, Alba V. Barca, Inês Rodrigues, Pedro José Barbosa Pereira, Carlos R. Osorio, Francisco García-del Portillo, Ivo Gomperts Boneca, Ana do Vale, Nuno M. S. dos Santos
Msphere, 2021
Peptidoglycan (PG) is a major component of the bacterial cell wall formed by long chains of two alternating sugars interconnected by short peptides, generating a mesh-like structure that enwraps the bacterial cell. Although PG provides structural integrity and support for anchoring other components of the cell envelope, it is constantly being remodeled through the action of specific enzymes that cleave or join its components.
Thermostability enhancement of the Pseudomonas fluorescens esterase I by in vivo folding selection in Thermus thermophilus
Diana M. Mate, Noé R. Rivera, Esther Sanchez‐Freire, Juan A. Ayala, José Berenguer, Aurelio Hidalgo
Biotechnology and Bioengineering, 2020
Prolonged stability is a desired property for the biotechnological application of enzymes since it allows its reutilization, contributing to making biocatalytic processes more economically competitive with respect to chemical synthesis. In this study, we have applied selection by folding interference at high temperature in Thermus thermophilus to obtain thermostable variants of the esterase I from Pseudomonas fluorescens (PFEI). The most thermostable variant (Q11L/A191S) showed a melting temperature (Tm) of 77.3 ± 0.1°C (4.6°C higher than the wild‐type) and a half‐life of over 13 hr at 65°C (7.9‐fold better than the wild‐type), with unchanged kinetic parameters. Stabilizing mutations Q11L and A191S were incorporated into PFEI variant L30P, previously described to be enantioselective in the hydrolysis of the (−)‐enantiomer of the Vince lactam. The final variant Q11L/L30P/A191S showed a significant improvement in thermal stability (Tm of 80.8 ± 0.1°C and a half‐life of 65 min at 75°C), while retaining enantioselectivity (E > 100). Structural studies revealed that A191S establishes a hydrogen bond network between a V‐shaped hairpin and the α/β hydrolase domain that leads to higher rigidity and thus would contribute to explaining the increase in stability.
Protein determinants of dissemination and host specificity of metallo-β-lactamases
Carolina López, Juan A. Ayala, Robert A. Bonomo, Lisandro J. González, Alejandro J. Vila
Nature Communications, 2019
The worldwide dissemination of metallo-β-lactamases (MBLs), mediating resistance to carbapenem antibiotics, is a major public health problem. The extent of dissemination of MBLs such as VIM-2, SPM-1 and NDM among Gram-negative pathogens cannot be explained solely based on the associated mobile genetic elements or the resistance phenotype. Here, we report that MBL host range is determined by the impact of MBL expression on bacterial fitness. The signal peptide sequence of MBLs dictates their adaptability to each host. In uncommon hosts, inefficient processing of MBLs leads to accumulation of toxic intermediates that compromises bacterial growth. This fitness cost explains the exclusion of VIM-2 and SPM-1 from Escherichia coli and Acinetobacter baumannii, and their confinement to Pseudomonas aeruginosa. By contrast, NDMs are expressed without any apparent fitness cost in different bacteria, and are secreted into outer membrane vesicles. We propose that the successful dissemination and adaptation of MBLs to different bacterial hosts depend on protein determinants that enable host adaptability and carbapenem resistance. Metallo-β-lactamases (MBLs) confer resistance to carbapenem antibiotics. Here, López et al. show that the host range of MBLs depends on the efficiency of MBL signal peptide processing and secretion into outer membrane vesicles, which affects bacterial fitness.
Regulation of AmpC-Driven β-Lactam Resistance in Pseudomonas aeruginosa: Different pathways, different signaling
Gabriel Torrens, Sara Belén Hernández, Juan Alfonso Ayala, Bartolome Moya, Carlos Juan, Felipe Cava, Antonio Oliver
Msystems, 2019
The hyperproduction of the chromosomal AmpC β-lactamase is the main mechanism driving β-lactam resistance inPseudomonas aeruginosa, one of the leading opportunistic pathogens causing nosocomial acute and chronic infections in patients with underlying respiratory diseases. In the current scenario of the shortage of effective antipseudomonal drugs, understanding the molecular mechanisms mediating AmpC hyperproduction in order to develop new therapeutics against this fearsome pathogen is of great importance. It has been accepted for decades that certain cell wall-derived soluble fragments (muropeptides) modulate AmpC production by complexing with the transcriptional regulator AmpR and acquiring different conformations that activate/repressampCexpression. However, these peptidoglycan-derived signals have never been characterized in the highly prevalentP. aeruginosastable AmpC hyperproducer mutants. Here, we demonstrate that the previously described fragments enabling the transientampChyperexpression during cefoxitin induction (1,6-anhydro-N-acetylmuramyl-pentapeptides) also underlie thedacB(penicillin binding protein 4 [PBP4]) mutation-driven stable hyperproduction but differ from the 1,6-anhydro-N-acetylmuramyl-tripeptides notably overaccumulated in theampDknockout mutant. In addition, a simultaneous greater accumulation of both activators appears linked to higher levels of AmpC hyperproduction, although our results suggest a much stronger AmpC-activating potency for the 1,6-anhydro-N-acetylmuramyl-pentapeptide. Collectively, our results propose a model of AmpC control where the activator fragments, with qualitative and quantitative particularities depending on the pathways and levels of β-lactamase production, dominate over the repressor (UDP-N-acetylmuramyl-pentapeptide). This study represents a major step in understanding the foundations of AmpC-dependent β-lactam resistance inP. aeruginosa, potentially useful to open new therapeutic conceptions intended to interfere with the abovementioned cell wall-derived signaling.IMPORTANCEThe extensive use of β-lactam antibiotics and the bacterial adaptive capacity have led to the apparently unstoppable increase of antimicrobial resistance, one of the current major global health challenges. In the leading nosocomial pathogenPseudomonas aeruginosa, the mutation-driven AmpC β-lactamase hyperproduction stands out as the main resistance mechanism, but the molecular cues enabling this system have remained elusive until now. Here, we provide for the first time direct and quantitative information about the soluble cell wall-derived fragments accounting for the different levels and pathways of AmpC hyperproduction. Based on these results, we propose a hierarchical model of signals which ultimately governampChyperexpression and resistance.
Remote induction of cellular immune response in mice by anti-meningococcal nanocochleates - nanoproteoliposomes
Beatriz Tamargo Santos, Catherine Fleitas Pérez, Juan F. Infante Bourzac, Yanet Márquez Nápoles, Wendy Ramírez González, Virgilio Bourg, Damaris Torralba, Viviana Pérez, Antonio Mouriño, Juan Ayala, Alexis Labrada Rosado, Lotfi Aleya, Simona Bungau, V. Gustavo Sierra González
Science of the Total Environment, 2019
New adjuvant formulations, based on proteoliposomes <40 nm and cochleates <100 nm, without Al(OH)3 adjuvant, were evaluated regarding their ability to generate Th1 immune response through a Delayed -Type Hypersensitivity Test, at the mouse model, by using a Neisseria meningitidis B protein complex as antigen. The formulations were administered by intramuscular (IM) (2 inoculations - at baseline and after 14 days) and intranasal (IN) (3 inoculations at 7 days) immunization pathways. All IM immunized groups were able to induce similar response to these formulations as well as to VA-MENGOC-BC® vaccine - containing Al(OH)3 adjuvant (used as positive control of the trial). In all groups, the induced inflammation (IP) rate was statistically higher than in the negative control group (CN) (p < 0.05). Immunogenicity, measured by HSR and CD4+ lymphocyte increase was equivalent to the control vaccine and most important, granuloma reactogenicity at the site of injection was eliminated, fact demonstrated by histological study. All groups of animals immunized by IN route showed HSR reactions and statistically significant differences with respect to the CN group. However, IP values were lower, with statistical differences (p < 0.05) for the same adjuvant formulation IM administered, except the AIF2-nCh formulation that generated statistically similar induction (p > 0.05) by both immunization pathways, suggesting it to be the best candidate for the next IN trial. Proteoliposome and cochleate formulations tested were able to mount potent Th-1 immune response, equivalent to the original vaccine formulation, with the advantage of less reactogenicity in the site of the injection, caused by the toxicity of Al(OH)3 adjuvant gel.
Pathogenesis of Salmonella typhimurium mutants in two experimental models in vivo
Vaccimonitor, 2019
The peptidoglycan and biofilm matrix of Staphylococcus epidermidis undergo structural changes when exposed to human platelets
Maria Loza-Correa, Juan A. Ayala, Iris Perelman, Keith Hubbard, Miloslav Kalab, Qi-Long Yi, Mariam Taha, Miguel A. de Pedro, Sandra Ramirez-Arcos
Plos One, 2019
Staphylococcus epidermidis is a bacterium frequently isolated from contaminated platelet concentrates (PCs), a blood product used to treat bleeding disorders in transfusion patients. PCs offer an accidental niche for colonization of S. epidermidis by forming biofilms and thus avoiding clearance by immune factors present in this milieu. Using biochemical and microscopy techniques, we investigated the structural changes of the peptidoglycan (PG) and the biofilm matrix of S. epidermidis biofilms formed in whole-blood derived PCs compared to biofilms grown in glucose-supplemented trypticase soy broth (TSBg). Both, the PG and the biofilm matrix are primary mechanisms of defense against environmental stress. Here we show that in PCs, the S. epidermidis biofilm matrix is mainly of a proteinaceous nature with extracellular DNA, in contrast to the predominant polysaccharide nature of the biofilm matrix formed in TSBg cultures. PG profile studies demonstrated that the PG of biofilm cells remodels during PC storage displaying fewer muropeptides variants than those observed in TSBg. The PG muropeptides contain two chemical modifications (amidation and O-acetylation) previously associated with resistance to antimicrobial agents by other staphylococci. Our study highlights two key structural features of S. epidermidis that are remodeled when exposed to human platelets and could be used as targets to reduce septic transfusions events.
A specialized peptidoglycan synthase promotes salmonella cell division inside host cells
Sónia Castanheira, Juan J. Cestero, Gadea Rico-Pérez, Pablo García, Felipe Cava, Juan A. Ayala, M. Graciela Pucciarelli, Francisco García-del Portillo
Mbio, 2017
Targeting the permeability barrier and peptidoglycan recycling pathways to disarm Pseudomonas aeruginosa against the innate immune system
Gabriel Torrens, Marcelo Pérez-Gallego, Bartolomé Moya, Marta Munar-Bestard, Laura Zamorano, Gabriel Cabot, Jesús Blázquez, Juan A. Ayala, Antonio Oliver, Carlos Juan
Plos One, 2017
In vivo functional and molecular characterization of the Penicillin-Binding Protein 4 (DacB) of Pseudomonas aeruginosa
Cristian Gustavo Aguilera Rossi, Paulino Gómez-Puertas, Juan Alfonso Ayala Serrano
BMC Microbiology, 2016
Genetic dissection of the type VI secretion system in Acinetobacter and identification of a novel peptidoglycan hydrolase, TagX, required for its biogenesis
Brent S. Weber, Seth W. Hennon, Meredith S. Wright, Nichollas E. Scott, Véronique de Berardinis, Leonard J. Foster, Juan A. Ayala, Mark D. Adams, Mario F. Feldman
Mbio, 2016
The Absence of a Mature Cell Wall Sacculus in Stable Listeria monocytogenes L-Form Cells Is Independent of Peptidoglycan Synthesis
Patrick Studer, Marina Borisova, Alexander Schneider, Juan A. Ayala, Christoph Mayer, Markus Schuppler, Martin J. Loessner, Yves Briers
Plos One, 2016
Role of Pseudomonas aeruginosa low-molecular-mass penicillin-binding proteins in AmpC expression, β-lactam resistance, and peptidoglycan structure
Alaa Ropy, Gabriel Cabot, Irina Sánchez-Diener, Cristian Aguilera, Bartolome Moya, Juan A. Ayala, Antonio Oliver
Antimicrobial Agents and Chemotherapy, 2015
Metabolite profiling and peptidoglycan analysis of transient cell wall-deficient bacteria in a new Escherichia coli model system
Alexander Cambré, Michael Zimmermann, Uwe Sauer, Bram Vivijs, William Cenens, Chris W. Michiels, Abram Aertsen, Martin J. Loessner, Jean-Paul Noben, Juan A. Ayala, Rob Lavigne, Yves Briers
Environmental Microbiology, 2015
The Cpx envelope stress response modifies peptidoglycan cross-linking via the L,D-transpeptidase LdtD and the novel protein YgaU
Margarita Bernal-Cabas, Juan Alfonso Ayala, Tracy L. Raivio
Journal of Bacteriology, 2015
β-lactamases produced by amoxicillin-clavulanate-resistant enterobacteria isolated in Buenos Aires, Argentina: A new blaTEM gene
José A. Di Conza, Alejandra Badaracco, Juan Ayala, Cynthia Rodriguez, Ángela Famiglietti, Gabriel O. Gutkind
Revista Argentina De Microbiologia, 2014
Rapid identification and discrimination of bacterial strains by laser induced breakdown spectroscopy and neural networks
S. Manzoor, S. Moncayo, F. Navarro-Villoslada, J.A. Ayala, R. Izquierdo-Hornillos, F.J. Manuel de Villena, J.O. Caceres
Talanta, 2014
Identification of the first blaCMY-2 gene in Salmonella enterica serovar Typhimurium isolates obtained from cases of paediatric diarrhoea illness detected in South America
Nicolás F. Cordeiro, Lucía Yim, Laura Betancor, Daniela Cejas, Virginia García-Fulgueiras, María Inés Mota, Gustavo Varela, Leonardo Anzalone, Gabriela Algorta, Gabriel Gutkind, Juan A. Ayala, José A. Chabalgoity, Rafael Vignoli
Journal of Global Antimicrobial Resistance, 2013
Increased bile resistance in Salmonella enterica mutants lacking Prc periplasmic protease
Sara B Hernández, J. Ayala, Gadea Rico-Pérez, F. García-del Portillo, J. Casadesús
International Microbiology, 2013
Two multidrug-resistant salmonella infantis isolates behave like hypo-invasive strains but have high intracellular proliferation
Revista Argentina De Microbiologia, 2012
Induced protection by nanocochleates derived from proteoliposomes from Leptospira interrogans serovar canicola
Vaccimonitor, 2012
Antimicrobial resistance determinants among anaerobic bacteria isolated from footrot
María Lorenzo, Nuria García, Juan Alfonso Ayala, Santiago Vadillo, Segundo Píriz, Alberto Quesada
Veterinary Microbiology, 2012
Expression of OXA-type and SFO-1 β-lactamases induces changes in peptidoglycan composition and affects bacterial fitness
Ana Fernández, Astrid Pérez, Juan A. Ayala, Susana Mallo, Soraya Rumbo-Feal, Maria Tomás, Margarita Poza, Germán Bou
Antimicrobial Agents and Chemotherapy, 2012
First human isolate of Salmonella enterica serotype enteritidis harboring bla CTX-M-14in South America
Inés Bado, Virginia García-Fulgueiras, Nicolás F. Cordeiro, Laura Betancor, Leticia Caiata, Verónica Seija, Luciana Robino, Gabriela Algorta, José A. Chabalgoity, Juan A. Ayala, Gabriel O. Gutkind, Rafael Vignoli
Antimicrobial Agents and Chemotherapy, 2012
The identification and characterization of IbpA, a novel α-crystallin-type heat shock protein from mycoplasma
Innokentii E. Vishnyakov, Sergei A. Levitskii, Valentin A. Manuvera, Vassili N. Lazarev, Juan A. Ayala, Vadim A. Ivanov, Ekaterina S. Snigirevskaya, Yan Yu. Komissarchik, Sergei N. Borchsenius
Cell Stress and Chaperones, 2012
Amph, a bifunctional DD-endopeptidase and DD-carboxypeptidase of Escherichia coli
S. M. Gonzalez-Leiza, M. A. de Pedro, J. A. Ayala
Journal of Bacteriology, 2011
Analysis of genes encoding penicillin-binding proteins in clinical isolates of Acinetobacter baumannii
Rodrigo Cayô, María-Cruz Rodríguez, Paula Espinal, Felipe Fernández-Cuenca, Alain A. Ocampo-Sosa, Álvaro Pascual, Juan A. Ayala, Jordi Vila, Luis Martínez-Martínez
Antimicrobial Agents and Chemotherapy, 2011
Molecular analysis of the effector mechanisms of cefoxitin resistance among bacteroides strains
J. Soki, S. M. Gonzalez, E. Urban, E. Nagy, J. A. Ayala
Journal of Antimicrobial Chemotherapy, 2011
Lysinibacillus sphaericus S-layer protein toxicity against Culex quinquefasciatus
Lucía C. Lozano, Juan A. Ayala, Jenny Dussán
Biotechnology Letters, 2011
Extended-spectrum β-lactamases and plasmid-mediated quinolone resistance in enterobacterial clinical isolates in the paediatric hospital of Uruguay
V. Garcia-Fulgueiras, I. Bado, M. I. Mota, L. Robino, N. F. Cordeiro, A. Varela, G. Algorta, G. Gutkind, J. A. Ayala, R. Vignoli
Journal of Antimicrobial Chemotherapy, 2011
Identification and discrimination of bacterial strains by laser induced breakdown spectroscopy and neural networks
D. Marcos-Martinez, J.A. Ayala, R.C. Izquierdo-Hornillos, F.J. Manuel de Villena, J.O. Caceres
Talanta, 2011
Oligomeric forms, functions and cellular localization of α-Crystallin type protein from Acholeplasma laidlawii
Tsitologiya, 2010
Identification of the full set of Listeria monocytogenes penicillin-binding proteins and characterization of PBPD2 (Lmo2812)
Dorota Korsak, Zdzislaw Markiewicz, Gabriel O Gutkind, Juan A Ayala
BMC Microbiology, 2010
Induction of β-lactamase production in Aeromonas hydrophila is responsive to β-lactam-mediated changes in peptidoglycan composition
A. E. Tayler, J. A. Ayala, P. Niumsup, K. Westphal, J. A. Baker, L. Zhang, T. R. Walsh, B. Wiedemann, P. M. Bennett, M. B. Avison
Microbiology, 2010
A novel OXA-10-like β-lactamase is present in different Enterobacteriaceae
Ayelén Porto, Juan Ayala, Gabriel Gutkind, José Di Conza
Diagnostic Microbiology and Infectious Disease, 2010
BlaCTX-M-2 and blaCTX-M-28 extended-spectrum β-lactamase genes and class 1 integrons in clinical isolates of Klebsiella pneumoniae from Brazil
Ana Catarina S Lopes, Dyana Leal Veras, Alexsandra Mariá S Lima, Rita de Cássia Andrade Melo, Juan Ayala
Memorias do Instituto Oswaldo Cruz, 2010
Detection of class 1 and 2 integrons, extended-spectrum β-lactamases and qnr alleles in enterobacterial isolates from the digestive tract of Intensive Care Unit inpatients
Inés Bado, Nicolás F. Cordeiro, Luciana Robino, Virginia García-Fulgueiras, Verónica Seija, Cristina Bazet, Gabriel Gutkind, Juan A. Ayala, Rafael Vignoli
International Journal of Antimicrobial Agents, 2010
Surveillance of antibiotic resistance evolution and detection of class 1 and 2 integrons in human isolates of multi-resistant Salmonella Typhimurium obtained in Uruguay between 1976 and 2000
Marina Macedo-Viñas, Nicolás F. Cordeiro, Inés Bado, Silvia Herrera-Leon, Magdalena Vola, Luciana Robino, Ruben Gonzalez-Sanz, Soledad Mateos, Felipe Schelotto, Gabriela Algorta, Juan A. Ayala, Aurora Echeita, Rafael Vignoli
International Journal of Infectious Diseases, 2009
The penicillin-binding proteins: Structure and role in peptidoglycan biosynthesis (FEMS Microbiology Reviews (2008) 32, (234-258))
Eric Sauvage, Frédéric Kerff, Mohammed Terrak, Juan A. Ayala, Paulette Charlier
FEMS Microbiology Reviews, 2008
Morphogenesis of rod-shaped sacculi
Tanneke Den Blaauwen, Miguel A. de Pedro, Martine Nguyen-Distèche, Juan A. Ayala
FEMS Microbiology Reviews, 2008
The penicillin-binding proteins: Structure and role in peptidoglycan biosynthesis
Eric Sauvage, Frédéric Kerff, Mohammed Terrak, Juan A. Ayala, Paulette Charlier
FEMS Microbiology Reviews, 2008
Ciprofloxacin-resistant enterobacteria harboring the aac(6′)-Ib-cr variant isolated from feces of inpatients in an intensive care unit in Uruguay [7]
Nicolás F. Cordeiro, Luciana Robino, Julio Medina, Verónica Seija, Inés Bado, Virginia García, Maximiliano Berro, Julio Pontet, Lucía López, Cristina Bazet, Gloria Rieppi, Gabriel Gutkind, Juan A. Ayala, Rafael Vignoli
Antimicrobial Agents and Chemotherapy, 2008
Unstable Escherichia coli L forms revisited: Growth requires peptidoglycan synthesis
Danièle Joseleau-Petit, Jean-Claude Liébart, Juan A. Ayala, Richard D'Ari
Journal of Bacteriology, 2007
Experimental validation of Haldane's hypothesis on the role of infection as an evolutionary force for Metazoans
Alfonso Navas, Guillermo Cobas, Miguel Talavera, Juan A. Ayala, Juan A. López, José L. Martínez
Proceedings of the National Academy of Sciences of the United States of America, 2007
Biochemical characterization of PER-2 and genetic environment of bla PER-2
Pablo Power, José Di Conza, María Margarita Rodríguez, Bárbara Ghiglione, Juan A. Ayala, José María Casellas, Marcela Radice, Gabriel Gutkind
Antimicrobial Agents and Chemotherapy, 2007
Characterisation of KLUA-9, a β-lactamase from extended-spectrum cephalosporin-susceptible Kluyvera ascorbata, and genetic organisation of blaKLUA-9
María Margarita Rodríguez, Pablo Power, Cédric Bauvois, José Di Conza, Juan A. Ayala, Moreno Galleni, Gabriel Gutkind
International Journal of Antimicrobial Agents, 2007
CTX-M: Changing the face of ESBLs in Europe
D. M. Livermore, R. Canton, M. Gniadkowski, P. Nordmann, G. M. Rossolini, G. Arlet, J. Ayala, T. M. Coque, I. Kern-Zdanowicz, F. Luzzaro, L. Poirel, N. Woodford
Journal of Antimicrobial Chemotherapy, 2007
Characterization of HMW-PBPs from the rod-shaped actinomycete Corynebacterium glutamicum: Peptidoglycan synthesis in cells lacking actin-like cytoskeletal structures
Noelia Valbuena, Michal Letek, Efrén Ordóñez, Juan Ayala, Richard A. Daniel, José A. Gil, Luis M. Mateos
Molecular Microbiology, 2007
Genetic environment of CTX-M-2 in Klebsiella pneumoniae isolates from hospitalized patients in Uruguay
Revista Argentina De Microbiologia, 2006
The DD-carboxypeptidase activity encoded by pbp4B is not essential for the cell growth of Escherichia coli
Daniel Vega, Juan A. Ayala
Archives of Microbiology, 2006
Biochemical and molecular characterization of three new variants of AmpC β-lactamases from Morganella morganii
Pablo Power, Moreno Galleni, Juan A. Ayala, Gabriel Gutkind
Antimicrobial Agents and Chemotherapy, 2006
New TEM-derived extended-spectrum β-lactamase and its genomic context in plasmids from Salmonella enterica serovar derby isolates from Uruguay
Rafael Vignoli, Nicolas F. Cordeiro, Virginia García, María Inés Mota, Laura Betancor, Pablo Power, José A. Chabalgoity, Felipe Schelotto, Gabriel Gutkind, Juan A. Ayala
Antimicrobial Agents and Chemotherapy, 2006
Morphological changes and proteome response of Corynebacterium glutamicum to a partial depletion of Ftsl
Noelia Valbuena, Michal Letek, Angelina Ramos, Juan Ayala, Diana Nakunst, Joern Kalinowski, Luis M. Mateos, José A. Gil
Microbiology, 2006
Penicillin-binding proteins of Bacteroides fragilis and their role in the resistance to imipenem of clinical isolates
Juan Ayala, Alberto Quesada, Santiago Vadillo, Jerónimo Criado, Segundo Píriz
Journal of Medical Microbiology, 2005
Peptidoglycan precursor pools associated with MraY and FtsW deficiencies or antibiotic treatments
Beatriz Lara, Dominique Mengin-Lecreulx, Juan A. Ayala, Jean Heijenoort
FEMS Microbiology Letters, 2005
Transcriptional analysis of the blaCTX-M-2 gene in Salmonella enterica serovar infantis
José A. Di Conza, Gabriel O. Gutkind, Marta E. Mollerach, Juan A. Ayala
Antimicrobial Agents and Chemotherapy, 2005
Enteropathogenic Escherichia coli strains carrying genes encoding the PER-2 and TEM-116 extended-spectrum β-lactamases isolated from children with diarrhea in Uruguay
Rafael Vignoli, Gustavo Varela, María Inés Mota, Nicolas F. Cordeiro, Pablo Power, Elizabet Ingold, Pilar Gadea, Alfredo Sirok, Felipe Schelotto, Juan A. Ayala, Gabriel Gutkind
Journal of Clinical Microbiology, 2005
Description of In116, the first blaCTX-M-2-containing complex class 1 integron found in Morganella morganii isolates from Buenos Aires, Argentina
Pablo Power, Moreno Galleni, José Di Conza, Juan A. Ayala, Gabriel Gutkind
Journal of Antimicrobial Chemotherapy, 2005
Molecular characterization of InJR06, a class 1 integron located in a conjugative plasmid of Salmonella enterica ser. Typhimurium
International Microbiology, 2005
Chromosome-encoded CTX-M-3 from Kluyvera ascorbata: A possible origin of plasmid-borne CTX-M-1-derived cefotaximases
María Margarita Rodríguez, Pablo Power, Marcela Radice, Carlos Vay, Angela Famiglietti, Moreno Galleni, Juan A. Ayala, Gabriel Gutkind
Antimicrobial Agents and Chemotherapy, 2004
Characterization and chromosomal organization of the murD-murC-ftsQ region of Corynebacterium glutamicum ATCC 13869
Angelina Ramos, Maria P. Honrubia, Daniel Vega, Juan A. Ayala, Ahmed Bouhss, Dominique Mengin-Lecreulx, José A. Gil
Research in Microbiology, 2004
Relationship between penicillin-binding protein patterns and β-lactamases in clinical isolates of Bacteroides fragilis with different susceptibility to β-lactam antibiotics
Segundo Píriz, Santiago Vadillo, Alberto Quesada, Jerónimo Criado, Rosario Cerrato, Juan Ayala
Journal of Medical Microbiology, 2004
First Class A Carbapenemase Isolated from Enterobacteriaceae in Argentina [3]
Marcela Radice, Pablo Power, Gabriel Gutkind, Karina Fernández, Carlos Vay, Angela Famiglietti, Nora Ricover, Juan A. Ayala
Antimicrobial Agents and Chemotherapy, 2004
CTX-M-12 β-Lactamase in a Klebsiella pneumoniae Clinical Isolate in Colombia
Maria Virginia Villegas, Adriana Correa, Federico Perez, Tania Zuluaga, Marcela Radice, Gabriel Gutkind, José María Casellas, Juan Ayala, Karen Lolans, John P. Quinn, the Colombian Nosocomial Resistance Study Group
Antimicrobial Agents and Chemotherapy, 2004
Cloning and expression of the Mycoplasma hominis ftsZ gene for a cell division protein
Genetika, 2003
Studies on the interaction of the antibiotic moenomycin A with the enzyme penicillin-binding protein 1b
Thomas Rühl, Mohammed Daghish, Andrij Buchynskyy, Karen Barche, Daniela Volke, Katherina Stembera, Uwe Kempin, Dietmar Knoll, Lothar Hennig, Matthias Findeisen, Ramona Oehme, Sabine Giesa, Juan Ayala, Peter Welzel
Bioorganic and Medicinal Chemistry, 2003
Relationship between β-lactamase production, outer membrane protein and penicillin-binding protein profiles on the activity of carbapenems against clinical isolates of Acinetobacter baumannii
F. Fernandez-Cuenca
Journal of Antimicrobial Chemotherapy, 2003
Cloning and expression of the Mycoplasma hominis ftsZ gene for a cell division protein
K. T. Momynaliev, O. V. Smirnova, V. N. Lazarev, T. A. Akopian, V. V. Chelysheva, V. M. Govorun, J. A. Ayala, A. N. Simankova, S. N. Borchsenius
Russian Journal of Genetics, 2003
Topological characterization of the essential Escherichia coli cell division protein FtsW
B Lara
FEMS Microbiology Letters, 2002
Moenomycin-mediated affinity purification of penicillin-binding protein 1b
Katherina Stembera, Andrij Buchynskyy, Stefan Vogel, Dietmar Knoll, Awad A. Osman, Juan A. Ayala, Peter Welzel
Chembiochem, 2002
Novel class 1 integron (InS21) carrying blaCTX-M-2 in Salmonella enterica serovar infantis
José Di Conza, Juan A. Ayala, Pablo Power, Marta Mollerach, Gabriel Gutkind
Antimicrobial Agents and Chemotherapy, 2002
A surface plasmon resonance analysis of the interaction between the antibiotic moenomycin a and penicillin-binding protein 1b
Chembiochem, 2002
Characterization of the Mycoplasma hominis ftsZ gene and its sequence variability in mycoplasma clinical isolates
K.T Momynaliev, O.V Smirnova, V.N Lazyrev, T.A Akopian, V.V Chelysheva, J.A Ayala, A.N Simankova, S.N Borchsenius, V.M Govorun
Biochemical and Biophysical Research Communications, 2002
Analysis of the O-antigen chain length distribution during extracellular and intracellular growth of Shigella flexneri
Gustavo Varela, Felipe Schelotto, José di Conza, Juan A Ayala
Microbial Pathogenesis, 2001
Biological cost of AmpC production for Salmonella enterica serotype typhimurium
M. I. Morosini, J. A. Ayala, F. Baquero, J. L. Martínez, J. Blázquez
Antimicrobial Agents and Chemotherapy, 2000
The catalytic, glycosyl transferase and acyl transferase modules of the cell wall peptidoglycan-polymerizing penicillin-binding protein 1b of Escherichia coli
Mohammed Terrak, Tushar K. Ghosh, Jean Van Heijenoort, Jozef Van Beeumen, Maxime Lampilas, Jozsef Aszodi, Juan A. Ayala, Jean‐Marie Ghuysen, Martine Nguyen‐Distèche
Molecular Microbiology, 1999
Characterization of Acholeplasma laidlawii ftsZ gene and its gene product
A.V Kukekova, A.Yu Malinin, J.A Ayala, S.N Borchsenius
Biochemical and Biophysical Research Communications, 1999
mraW, an essential gene at the dcw cluster of Escherichia coli codes for a cytoplasmic protein with methyltransferase activity
Maite Carrión, Manuel J. Gómez, Rafael Merchante-Schubert, Silvina Dongarrá, Juan A. Ayala
Biochimie, 1999
Regulation of transcription of cell division genes in the Eschericia coli dcw cluster
M. Vicente, M. J. Gomez, J. A. Ayala
Cellular and Molecular Life Sciences, 1998
Cell division inhibition in Salmonella typhimurium histidine- constitutive strains: An ftsI-like defect in the presence of wild-type penicillin-binding protein 3 levels
David A. Cano, Chakib Mouslim, Juan A. Ayala, Francisco García-del Portillo, Josep Casadesús
Journal of Bacteriology, 1998
Contribution of the P(mra) promoter to expression of genes in the Escherichia coli mra cluster of cell envelope biosynthesis and cell division genes
Dominique Mengin-Lecreulx, Juan Ayala, Ahmed Bouhss, Jean van Heijenoort, Claudine Parquet, Hiroshi Hara
Journal of Bacteriology, 1998
dacD, an Escherichia coli gene encoding a novel penicillin-binding protein (PBP6b) with DD-carboxypeptidase activity
M R Baquero, M Bouzon, J C Quintela, J A Ayala, F Moreno
Journal of Bacteriology, 1996
The non-penicillin-binding module of the tripartite penicillin-binding protein 3 of Escherichia coli is required for folding and/or stability of the penicillin-binding module and the membrane-anchoring module confers cell septation activity on the folded structure
C Goffin, C Fraipont, J Ayala, M Terrak, M Nguyen-Distèche, J M Ghuysen
Journal of Bacteriology, 1996
Site-directed mutagenesis of penicillin-binding protein 3 of Escherichia coli: Role of Val-545
Juan Ayala, Colette Goffin, Martine Nguyen-DistÃ¨che, Jean-Marie Ghuysen
FEMS Microbiology Letters, 1994
Cell cycle control: Prokaryotic solutions to eukaryotic problems?
V. Norris, J.A. Ayala, K. Begg, J.-P. Bouché, P. Bouloc, E. Boye, J. Canvin, S. Casaregola, A.J. Cozzone, E. Crooke, R. D'Ari, M.A. de Pedro, W.D. Donachie, R.J. Doyle, G.R. Drapeau, R. Fontana, S. Foster, J.A. Fralick, P. Freestone, R.C. Gayda, M. Goldberg, S. Grant, E. Guzman, J.H. Hageman, C.F. Higgins, M. Hofnung, I.B. Holland, J.-V. Holtje, P. Hughes, M. Inouye, S. Inouye, A. Jaffé, A. Jimenez-Sanchez, D. Joseleau-Petit, W. Keck, F. Kepes, A. Kornberg, P. Kuempel, H. Labischinski, A. Lobner-Olesen, J. Lutkenhaus, P.E. March, M. Matsuhashi, G. McGurk, W. Messer, J. Meury, Y. Milner, K. Modha, K. Nagai, T. Nagata, Y. Nishimura, S. Normark, E. Orr, A. Ottolenghi, L. Paolozzi, P. Poulsen, J.E. Rebollo, E.Z. Ron, J. Rouviere-Yaniv, K. Rudd, G.P.C. Salmond, G. Satta, U. Schwarz, S. Seror, A.J. Simon, B.G. Spratt, K. Sreekumar, S. Sweeney, I. Toth, R. Utsumi, D. Vinella, M. Wachi, B.M. Wilkins, P.H. Williams, C. Yanofsky
Journal of Theoretical Biology, 1994
Molecular biology of bacterial septation
Juan A. Ayala, Teresa Garrido, Miguel A. De Pedro, Miguel Vicente
New Comprehensive Biochemistry, 1994
Gene sequence and biochemical characterization of FOX-1 from Klebsiella pneumoniae, a new AmpC-type plasmid-mediated β-lactamase with two molecular variants
M Gonzalez Leiza, J C Perez-Diaz, J Ayala, J M Casellas, J Martinez-Beltran, K Bush, F Baquero
Antimicrobial Agents and Chemotherapy, 1994
Engineering and overexpression of periplasmic forms of the penicillin-binding protein 3 of Escherichia coli
C Fraipont, M Adam, M Nguyen-Distèche, W Keck, J Van Beeumen, J A Ayala, B Granier, H Hara, J M Ghuysen
Biochemical Journal, 1994
Site-directed mutagenesis of dicarboxylic acid residues of the penicillin-binding module of the Escherichia coli penicillin-binding protein 3
Colette Goffin, Juan A. Ayala, Martine Nguyen-DistÃ¨che, Jean-Marie Ghuysen
FEMS Microbiology Letters, 1993
Site‐directed mutagenesis of dicarboxylic acid residues of the penicillin‐binding module of the Escherichia coli penicillin‐binding protein 3
Colette Goffin, Juan A. Ayala, Martine Nguyen-DistÃ¨che, Jean-Marie Ghuysen
FEMS Microbiology Letters, 1993
Membrane intermediates in the peptidoglycan metabolism of Escherichia coli: Possible roles of PBP 1b and PBP 3
Y van Heijenoort, M Gómez, M Derrien, J Ayala, J van Heijenoort
Journal of Bacteriology, 1992
Erratum: Membrane intermediates in the peptidoglycan metabolism of escherichia coli: Possible roles of PBP 1b and PBP 3 (Journal of Bacteriology 174:11 (3555))
Journal of Bacteriology, 1992
Identification of a new mutation in Escherichia coli that suppresses a pbpB (Ts) phenotype in the presence of penicillin-binding protein 1B
Francisco GarcÃa Portillo, Miguel A. Pedro, Juan A. Ayala
FEMS Microbiology Letters, 1991
Induction of a class I β-lactamase from Citrobacter freundii in Escherichia coli requires active ftsZ but not ftsA or ftsQ products
A C Ottolenghi, J A Ayala
Antimicrobial Agents and Chemotherapy, 1991
Nucleotide sequence of the regulatory region of the gene pbpB of Escherichia coli
M.J. Górnez, B. Fluoret, J. van Heijenoort, J.A. Ayala
Nucleic Acids Research, 1990
Cloning and expression of the ponB gene, encoding penicillin-binding protein 1B of Escherichia coli, in heterologous systems
J Plá, F Rojo, M A de Pedro, J A Ayala
Journal of Bacteriology, 1990
A new β-lactam-binding protein derived from penicillin-binding protein 3 of Escherichia coli
R Prats, M Gomez, J Pla, B Blasco, J A Ayala
Journal of Bacteriology, 1989
Organization of the murE-murG region of Escherichia coli: Identification of the murD gene encoding the D-glutamic-acid-adding enzyme
D Mengin-Lecreulx, C Parquet, L R Desviat, J Plá, B Flouret, J A Ayala, J van Heijenoort
Journal of Bacteriology, 1989
A lacZ-pbpB gene fusion coding for an inducible hybrid protein that recognizes localized sites in the inner membrane of Escherichia coli
J A Ayala, J Plá, L R Desviat, M A de Pedro
Journal of Bacteriology, 1988
Variability in the posttranslational processing of penicillin-binding protein 1b among different strains of Escherichia coli
Fernando Rojo, José Berenguer, Juan A. Ayala, Miguel A. De Pedro
Biochemistry and Cell Biology, 1987
Interaction of FtsA and PBP3 proteins in the Escherichia coli septum
A Tormo, J A Ayala, M A de Pedro, M Aldea, M Vicente
Journal of Bacteriology, 1986
Changes in protein synthesis and in RNA poly A+ population after treatment of Dictyostelium amoebae by 5‐bromo‐2′‐deoxyuridine
M. Scrive‐Menahem, J. Ayala, M. Jacquet, B. Felenbok
Biology of the Cell, 1985
Partial crypticity of penicillin-binding protein 1b in purified cell envelopes of Escherichia coli
Fernando Rojo, Juan A. Ayala, Miguel A. de Pedro, David Vázquez
Current Microbiology, 1984
Application of a charge/size two-dimensional gel electrophoresis system to the analysis of the penicillin-binding proteins of Escherichia coli
Juan A. Ayala, M.A. de Pedro, D. Vázquez
FEBS Letters, 1984
Characterization and regulation of the expression of a cloned sequence derived from a post-aggregation regulated mRNA of Dictyostelium discoideum
Biology of the Cell, 1984
Analysis of the different molecular forms of penicillin‐binding protein 1B in Escherichia coli ponB mutants lysogenized with specialized transducing λ(ponB+) bacteriophages
Fernando ROJO, Juan A. AYALA, Miguel A. PEDRO, David VAZQUEZ
European Journal of Biochemistry, 1984
Binding Of 125I-Labeled β-lactam antibiotics to the penicillin binding proteins of escherichia coli
FERNANDO ROJO, JUAN A. AYALA, ENRIQUE J. DE LA ROSA, MIGUEL A. DE PEDRO, VICENTE ARÁN, JOSÉ BERENGUER, DAVID VÁZQUEZ
Journal of Antibiotics, 1984
Polyadenylated RNA population present in dormant spores of Dictyostelium discoideum
Jacques Camonis, Jacqueline Julien, Juan Ayala, Michel Jacquet
Cell Differentiation, 1982
OXIDATION OF FUEL OIL #6 STUDIED BY DIFFERENTIAL SCANNING CALORIMETRY.
Preprints of Papers American Chemical Society Division of Fuel Chemistry, 1981
Thermal denaturation of Micrococcus lysodeikticus adenosine triphosphatase. Influence of temperature on the circular dichroism, fluorescence and enzymic activity of the protein
J A Ayala, M Nieto
Biochemical Journal, 1978
Activation parameters and molecular changes induced by substrate hydrolysis of the adenosine triphosphatase of Micrococcus lysodeikticus. A comparison of three different soluble forms of the enzyme
Juan Ayala, José Carreira, Manuel Nieto, Emilio Muñoz
Molecular and Cellular Biochemistry, 1977
Optical properties and denaturation by guanidinium chloride and urea of the adenosine triphosphatase of Micrococcus lysodeikticus. A comparison of four molecular forms of the enzyme
M Nieto, J A Ayala
Biochemical Journal, 1977
Activation Parameters of the Adenosine Triphosphatase of Micrococcus lysodeikticus A Comparison of the Soluble and Membrane‐Bound Forms of the Enzyme
Juan AYALA, Manuel NIETO, Josè CARREIRA, Emilio MUÑOZ
European Journal of Biochemistry, 1976

JUAN ALFONSO Ayala Serrano

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