Examinando por Autor "Tuttobene, Marisel Romina"
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Ítem Acceso Abierto Acinetobacter baumannii response to cefiderocol challenge in human urine(Springer Nature, 2022-05-24) Nishimura, Brent; Escalante, Jenny; Tuttobene, Marisel Romina; Subils, Tomás; Mezcord, Vyanka; Pimentel, Camila; Georgeos, Nardin; Pasteran, Fernando; Rodríguez, Cecilia; Sieira, Rodrigo; Actis, Luis A.; Tolmasky,, Marcelo E.; Bonomo, Robert A.; Ramírez, María SoledadCefiderocol (CFDC) is a novel chlorocatechol-substituted siderophore antibiotic approved to treat complicated urinary tract infections (cUTI) and hospital-acquired and ventilator-acquired pneumonia (HAP/VAP). Previous work determined that albumin-rich human fluids increase the minimum inhibitory concentration (MICs) of Acinetobacter baumannii against CFDC and reduce the expression of genes related to iron uptake systems. This latter effect may contribute to the need for higher concentrations of CFDC to inhibit growth. The presence of human urine (HU), which contains low albumin concentrations, did not modify MIC values of two carbapenem-resistant A. baumannii. Levels of resistance to CFDC were not modified by HU in strain AMA40 but were reduced in strain AB5075. Expanding the studies to other carbapenem-resistant A. baumannii isolates showed that the presence of HU resulted in unmodified or reduced MIC of CDFC values. The expression of piuA, pirA, bauA, and bfnH determined by qRT-PCR was enhanced in A. baumannii AMA40 and AB5075 by the presence of HU in the culture medium. All four tested genes code for functions related to recognition and transport of ferric-siderophore complexes. The effect of HU on expression of pbp1, pbp3, blaOXA-51-like, blaADC, and blaNDM-1, genes associated with resistance to β-lactams, as well as genes coding for efflux pumps and porins was variable, showing dependence with the strain analyzed. We conclude that the lack of significant concentrations of albumin and free iron in HU makes this fluid behave differently from others we tested. Unlike other albumin rich fluids, the presence of HU does not impact the antibacterial activity of CFDC when tested against A. baumannii.Ítem Acceso Abierto Histone-like nucleoid-structuring protein (H-NS) regulatory role in antibiotic resistance in Acinetobacter baumannii(Nature Research, 2021) Rodgers, Deja; Le, Casin; Pimentel, Camila; Tuttobene, Marisel Romina; Subils, Tomás; Escalante, Jenny; Nishimura, Brent; García Véscovi, Eleonora; Sieira, Rodrigo; Bonomo, Robert A.; Tolmasky, Marcelo E.; Ramírez, María SoledadÍtem Acceso Abierto Human serum albumin (HSA) regulates the expression of histone-like nucleoid structure protein (H-NS) in Acinetobacter baumannii(Nature Research, 2022-08-27) Escalante, Jenny; Nishimura, Brent; Tuttobene, Marisel Romina; Subils, Tomás; Pimentel, Camila; Georgeos, Nardin; Sieira, Rodrigo; Bonomo, Robert A.; Tolmasky, Marcelo E.; Ramírez, María SoledadÍtem Acceso Abierto Human Serum Proteins and Susceptibility of Acinetobacter baumannii to Cefiderocol: Role of Iron Transport(MDPI, 2022-03-03) Le, Casin; Pimentel, Camila; Pasteran, Fernando; Tuttobene, Marisel Romina; Subils, Tomás; Escalante, Jenny; Nishimura, Brent; Arriaga, Susana; Carranza, Aimee; Mezcord, Vyanka; Vila, Alejandro J.; Corso, Alejandra; Actis, Luis A.; Tolmasky, Marcelo E.; Bonomo, Robert A.; Ramírez, María SoledadÍtem Acceso Abierto Induced Heteroresistance in Carbapenem-Resistant Acinetobacter baumannii (CRAB) via Exposure to Human Pleural Fluid (HPF) and Its Impact on Cefiderocol Susceptibility(MDPI, 2023-07-21) Mezcord, Vyanka; Escalante, Jenny; Nishimura, Brent; Traglia, German M.; Sharma, Rajnikant; Vallé, Quentin; Tuttobene, Marisel Romina; Subils, Tomás; Marin, Ingrid; Pasteran, Fernando; Actis, Luis A.; Tolmasky, Marcelo E.; Bonomo, Robert A.; Rao, Gauri; Ramírez, María Soledad; https://orcid.org/0000-0003-1896-8450; https://orcid.org/0000-0002-4780-5311; https://orcid.org/0000-0001-5840-5869; https://orcid.org/0000-0001-9644-9088; https://orcid.org/0000-0002-6298-7811; https://orcid.org/0000-0002-9904-7890Infections caused by Carbapenem-resistant Acinetobacter baumannii (CRAB) isolates, such as hospital-acquired pneumonia (HAP), bacteremia, and skin and soft tissue infections, among others, are particularly challenging to treat. Cefiderocol, a chlorocatechol-substituted siderophore antibiotic, was approved by the U.S. Food and Drug Administration (FDA) in 2019 and prescribed for the treatment of CRAB infections. Despite the initial positive treatment outcomes with this antimicrobial, recent studies reported a higher-than-average all-cause mortality rate in patients treated with cefiderocol compared to the best available therapy. The cause(s) behind these outcomes remains unconfirmed. A plausible hypothesis is heteroresistance, a phenotype characterized by the survival of a small proportion of cells in a population that is seemingly isogenic. Recent results have demonstrated that the addition of human fluids to CRAB cultures leads to cefiderocol heteroresistance. Here, we describe the molecular and phenotypic analyses of CRAB heteroresistant bacterial subpopulations to better understand the nature of the less-than-expected successful outcomes after cefiderocol treatment. Isolation of heteroresistant variants of the CRAB strain AMA40 was carried out in cultures supplemented with cefiderocol and human pleural fluid (HPF). Two AMA40 variants, AMA40 IHC1 and IHC2, were resistant to cefiderocol. To identify mutations and gene expression changes associated with cefiderocol heteroresistance, we subjected these variants to whole genome sequencing and global transcriptional analysis. We then assessed the impact of these mutations on the pharmacodynamic activity of cefiderocol via susceptibility testing, EDTA and boronic acid inhibition analysis, biofilm formation, and static time-kill assays. Heteroresistant variants AMA40 IHC1 and AMA40 IHC2 have 53 chromosomal mutations, of which 40 are common to both strains. None of the mutations occurred in genes associated with high affinity iron-uptake systems or β-lactam resistance. However, transcriptional analyses demonstrated significant modifications in levels of expression of genes associated with iron-uptake systems or β-lactam resistance. The blaNDM-1 and blaADC-2, as well as various iron-uptake system genes, were expressed at higher levels than the parental strain. On the other hand, the carO and ompA genes’ expression was reduced. One of the mutations common to both heteroresistant strains was mapped within ppiA, a gene associated with iron homeostasis in other species. Static time-kill assays demonstrated that supplementing cation-adjusted Mueller–Hinton broth with human serum albumin (HAS), the main protein component of HPF, considerably reduced cefiderocol killing activity for all three strains tested. Notably, collateral resistance to amikacin was observed in both variants. We conclude that exposing CRAB to fluids with high HSA concentrations facilitates the rise of heteroresistance associated with point mutations and transcriptional upregulation of genes coding for β-lactamases and biofilm formation. The findings from this study hold significant implications for understanding the emergence of CRAB resistance mechanisms against cefiderocol treatment. This understanding is vital for the development of treatment guidelines that can effectively address the challenges posed by CRAB infections.Ítem Acceso Abierto Interaction of Acinetobacter baumannii with Human Serum Albumin: Does the host hetermine the outcome?(MDPI, 2021-07-08) Pimentel, Camila; Le, Casin; Tuttobene, Marisel Romina; Subils, Tomás; Bonomo, Robert A.; Tolmasky, Marcelo E.; Ramírez, María SoledadÍtem Acceso Abierto Involvement of the histone-like nucleoid structuring protein (H-NS) in Acinetobacter baumannii’s natural transformation(MDPI, 2021-08-26) Le, Casin; Pimentel, Camila; Tuttobene, Marisel Romina; Subils, Tomás; Escalante, Jenny; Nishimura, Brent; Arriaga, Susana; Rodgers, Deja; Bonomo, Robert A.; Sieira, Rodrigo; Tolmasky, Marcelo E.; Ramírez, María Soledad; https://orcid.org/0000-0003-0234-4643; https://orcid.org/0000-0002-4495-563X; https://orcid.org/0000-0002-6298-7811; https://orcid.org/0000-0002-9904-7890Most Acinetobacter baumannii strains are naturally competent. Although some information is available about factors that enhance or reduce the frequency of the transformation of this bacterium, the regulatory elements and mechanisms are barely understood. In this article, we describe studies on the role of the histone-like nucleoid structuring protein, H-NS, in the regulation of the expression of genes related to natural competency and the ability to uptake foreign DNA. The expression levels of the natural transformation-related genes pilA, pilT, pilQ, comEA, comEC, comF, and drpA significantly increased in a ∆hns derivative of A. baumannii A118. The complementation of the mutant with a recombinant plasmid harboring hns restored the expression levels of six of these genes (pilT remained expressed at high levels) to those of the wild-type strain. The transformation frequency of the A. baumannii A118 ∆hns strain was significantly higher than that of the wild-type. Similar, albeit not identical, there were consequences when hns was deleted from the hypervirulent A. baumannii AB5075 strain. In the AB5075 complemented strain, the reduction in gene expression in a few cases was not so pronounced that it reached wild-type levels, and the expression of comEA was enhanced further. In conclusion, the expression of all seven transformation-related genes was enhanced after deleting hns in A. baumannii A118 and AB5075, and these modifications were accompanied by an increase in the cells’ transformability. The results highlight a role of H-NS in A. baumannii’s natural competence.Ítem Embargo Modulación por luz en Acinetobacter baumannii y en otros patógenos bacterianos causantes de infecciones hospitalarias(2020) Tuttobene, Marisel Romina; Mussi, María Alejandra; Ramírez, María SoledadLa luz solar es un estímulo ambiental ubicuo para la gran mayoría de los organismos vivos en la Tierra; por lo tanto, es lógico esperar el desarrollo de "mecanismos de sensado de luz" que los lleven a adaptarse con éxito a nichos ecológicos particulares. Aunque estos mecanismos fueron inicialmente reconocidos en los organismos fotosintéticos, en la actualidad sabemos que la percepción de la luz en los organismos quimiotróficos también ocurre. En esta tesis se estudiaron los mecanismos de detección de luz azul en diferentes patógenos bacterianos relevantes para la clínica. Hemos caracterizado extensivamente la regulación por luz a temperaturas moderadas (23/24ºC) en Acinetobacter baumannii, mostrando que la luz ejerce un efecto global en su fisiología. Específicamente demostramos que la luz modula la captación de hierro, los niveles de catalasa, la formación de biofilms, el catabolismo del ácido fenilacético y acetoína, el quórum sensing, la expresión del sistema de secreción tipo VI, entre otros importantes procesos fisiológicos, muchos de los cuales están relacionados con la capacidad de este patógeno oportunista de persistir en entornos intrahospitalarios adversos. Pudimos dilucidar el mecanismo de transducción de la señal mostrando que muchos de estos procesos dependen del fotorreceptor de tipo BLUF, BlsA, el cual es un regulador global capaz de unirse y antagonizar el funcionamiento de diversos reguladores transcripcionales como Fur, el regulador global del metabolismo del hierro, y de AcoN, el represor del catabolismo de acetoína, de manera luz-dependiente. Así, por ejemplo, BlsA se une al represor Fur únicamente en oscuridad a temperaturas moderadas, posiblemente secuentrándolo e impidiendo así su unión al sitio blanco en el operador. De esta manera, se induce la expresión de los genes que codifican para el sideróforo acinetobactina y se ve estimulado el crecimiento sólo en esta condición de oscuridad, en ambos procesos de manera dependiente de BlsA. Por su parte, BlsA interacciona con AcoN sólo en presencia de luz, impidiendo posiblemente de esta manera su unión al operador del cluster de genes que codifican para enzimas del catabolismo de acetoína . Esto es consistente con la inducción de la expresión génica y el crecimiento en acetoína como única fuente de carbono solamente en esta condición de iluminación. En oscuridad, BlsA no interacciona con AcoN y la expresión génica se mantiene en estado basal. La regulación por luz ocurre así a nivel transcripcional, modulando numerosas vías y clusters génicos. De esta forma, se observa un comportamiento dual de BlsA pudiendo interaccionar en ambas condiciones, además de tratarse de un regulador global. Asimismo, mostramos que en otros patógenos como Staphylococcus aureus y Pseudomonas aeruginosa, que han sido reconocidos por la Organización Mundial de la Salud (OMS) y el Centro para el Control y la Prevención de Enfermedades de los Estados Unidos (CDC), junto a A. baumannii, como críticos, detectan y responden a la luz a temperaturas compatibles con los hosedadores de sangre caliente. Encontramos que en estos patógenos la luz modula importantes determinantes de patogenicidad, así como la virulencia frente a un modelo de infección epitelial, lo que podría tener implicaciones en las infecciones humanas. Tambien encontramos que la hemólisis dependiente de α toxina es modulada por la luz en S. aureus. A su vez, la luz modula el crecimiento en condiciones limitantes de hierro y el metabolismo en estos patógenos ESKAPE. La motilidad y la competición frente a C. albicans, son otras de las características que encontramos moduladas por luz a 37°C. Además de los avances en el conocimiento fundamental que plantean estos nuevos hallazgos, destacan el uso potencial de la luz para controlar la virulencia de estos patógenos, ya sea directamente o manipulando los reguladores del sensado de luz hacia el estado de menor virulencia / persistencia posible.Ítem Acceso Abierto Quorum and light signals modulate acetoin/butanediol catabolism in Acinetobacter spp(Frontiers Media, 2019-06-20) Tuttobene, Marisel Romina; Fernández-García, Laura; Blasco, Lucía; Cribb, Pamela; Ambroa, Anton; Müller, Gabriela Leticia; Fernández-Cuenca, Felipe; Bleriot, Inés; Rodríguez, Ramiro Esteban; Barbosa, Beatriz G. V.; Lopez-Rojas, Rafael; Trastoy, Rocío; López, María; Bou, Germán; Tomás, María; Mussi, María AlejandraÍtem Acceso Abierto The iron content of human serum albumin nodulates the susceptibility of Acinetobacter baumannii to Cefiderocol(MDPI, 2023-02-20) Escalante, Jenny; Nishimura, Brent; Tuttobene, Marisel Romina; Subils, Tomás; Mezcord, Vyanka; Actis, Luis A.; Tolmasky, Marcelo E.; Bonomo, Robert A.; Ramírez, María Soledad