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Ítem Acceso Abierto Acinetobacter baumannii NCIMB8209: a rare environmental strain displaying extensive insertion sequence-mediated genome remodeling resulting in the loss of exposed cell structures and defensive mechanisms(American Society for Microbiology, 2020-07-29) Repizo, Guillermo Daniel; Espariz, Martín; Seravalle, Joana L.; Díaz Miloslavich, Juan Ignacio; Steimbrüch, Bruno A.; Shuman, Howard A.; Viale, Alejandro M.Ítem Acceso Abierto Acquisition of plasmids conferring carbapenem and aminoglycoside resistance and loss of surface-exposed macromolecule structures as strategies for the adaptation of Acinetobacter baumannii CC104O/CC15P strains to the clinical setting(Microbiology Society, 2020-03-26) Cameranesi, María Marcela; Paganini, Julián; Limansky, Adriana S.; Morán Barrio, Jorgelina ; Salcedo, Suzana P.; Viale, Alejandro M.; Repizo, Guillermo DanielÍtem Acceso Abierto Differential role of the T6SS in Acinetobacter baumannii virulence(Public Library of Science (PLOS), 2015-09-24) Repizo, Guillermo Daniel; Gagné, Stéphanie; Foucault-Grunenwald, Marie-Laure; Borges, Vitor; Charpentier, Xavier; Limansky, Adriana S.; Gomes, João Paulo; Viale, Alejandro M.; Salcedo, Suzana P.Ítem Acceso Abierto Dynamic state of plasmid genomic architectures resulting from XerC/D-mediated site-specific recombination in Acinetobacter baumannii Rep_3 superfamily resistance plasmids carrying blaOXA-58- and TnaphA6-resistance modules(Frontiers Media, 2023-02-09) Giacone, Lucía; Cameranesi, María Marcela; Sánchez, Rocio Inés; Limansky, Adriana S.; Morán Barrio, Jorgelina ; Viale, Alejandro M.The acquisition of blaOXA genes encoding different carbapenem-hydrolyzing class-D β-lactamases (CHDL) represents a main determinant of carbapenem resistance in the nosocomial pathogen Acinetobacter baumannii. The blaOXA-58 gene, in particular, is generally embedded in similar resistance modules (RM) carried by plasmids unique to the Acinetobacter genus lacking self-transferability. The ample variations in the immediate genomic contexts in which blaOXA-58-containing RMs are inserted among these plasmids, and the almost invariable presence at their borders of nonidentical 28-bp sequences potentially recognized by the host XerC and XerD tyrosine recombinases (pXerC/D-like sites), suggested an involvement of these sites in the lateral mobilization of the gene structures they encircle. However, whether and how these pXerC/D sites participate in this process is only beginning to be understood. Here, we used a series of experimental approaches to analyze the contribution of pXerC/D-mediated site-specific recombination to the generation of structural diversity between resistance plasmids carrying pXerC/D-bounded blaOXA-58- and TnaphA6-containing RM harbored by two phylogenetically- and epidemiologicallyclosely related A. baumannii strains of our collection, Ab242 and Ab825, during adaptation to the hospital environment. Our analysis disclosed the existence of different bona fide pairs of recombinationally-active pXerC/D sites in these plasmids, some mediating reversible intramolecular inversions and others reversible plasmid fusions/resolutions. All of the identified recombinationally-active pairs shared identical GGTGTA sequences at the cr spacer separating the XerC- and XerD-binding regions. The fusion of two Ab825 plasmids mediated by a pair of recombinationally-active pXerC/D sites displaying sequence differences at the cr spacer could be inferred on the basis of sequence comparison analysis, but no evidence of reversibility could be obtained in this case. The reversible plasmid genome rearrangements mediated by recombinationally-active pairs of pXerC/D sites reported here probably represents an ancient mechanism of generating structural diversity in the Acinetobacter plasmid pool. This recursive process could facilitate a rapid adaptation of an eventual bacterial host to changing environments, and has certainly contributed to the evolution of Acinetobacter plasmids and the capture and dissemination of blaOXA-58 genes among Acinetobacter and non-Acinetobacter populations co-residing in the hospital niche.Ítem Embargo Light modulates important pathogenic determinants and virulence in ESKAPE pathogens Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus(American Society for Microbiology, 2021-02-08) Tuttobene, Marisel Romina; Pérez, J. F.; Pavesi, Estefanía S.; Pérez Mora, Bárbara; Biancotti, Daiana; Cribb, Pamela; Altilio, Matías; Müller, Gabriela Leticia; Gramajo, Hugo Cesar; Tamagno, G.; Ramírez, María Soledad; Diacovich, Lautaro; Mussi, María Alejandra; https://orcid.org/0000-0002-9904-7890; https://orcid.org/0000-0002-3339-0100; https://orcid.org/0000-0002-4168-3624; Rabinovich, Gabriel: provide HaCaT cells; Voyich, Jovanka: provide the hla and complemented hla mutantLight sensing has been extensively characterized in the human pathogen Acinetobacter baumannii at environmental temperatures. However, the influence of light on the physiology and pathogenicity of human bacterial pathogens at temperatures found in warm-blooded hosts is still poorly understand. In this work, we show that Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa (ESKAPE) priority pathogens, which have been recognized by the WHO and the CDC as critical, can also sense and respond to light at temperatures found in human hosts. Most interestingly, in these pathogens, light modulates important pathogenicity determinants as well as virulence in an epithelial infection model, which could have implications in human infections. In fact, we found that alpha-toxin-dependent hemolysis, motility, and growth under iron-deprived conditions are modulated by light in S. aureus. Light also regulates persistence, metabolism, and the ability to kill competitors in some of these microorganisms. Finally, light exerts a profound effect on the virulence of these pathogens in an epithelial infection model, although the response is not the same in the different species; virulence was enhanced by light in A. baumannii and S. aureus, while in A. nosocomialis and P. aeruginosa it was reduced. Neither the BlsA photoreceptor nor the type VI secretion system (T6SS) is involved in virulence modulation by light in A. baumannii. Overall, this fundamental knowledge highlights the potential use of light to control pathogen virulence, either directly or by manipulating the light regulatory switch toward the lowest virulence/persistence configuration. IMPORTANCE: Pathogenic bacteria are microorganisms capable of producing disease. Dangerous bacterial pathogens, such as Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii, are responsible for serious intrahospital and community infections in humans. Therapeutics is often complicated due to resistance to multiple antibiotics, rendering them ineffective. In this work, we show that these pathogens sense natural light and respond to it by modulating aspects related to their ability to cause disease; in the presence of light, some of them become more aggressive, while others show an opposite response. Overall, we provide new understanding on the behavior of these pathogens, which could contribute to the control of infections caused by them. Since the response is distributed in diverse pathogens, this notion could prove a general concept.Ítem Acceso Abierto Microevolution in the major outer membrane protein OmpA of Acinetobacter baumannii(Microbiology Society, 2020-06-04) Viale, Alejandro M.; Evans, Benjamin A.Ítem Acceso Abierto Prevalence of Acinetobacter baumannii strains expressing the type 6 secretion system in patients with bacteremia(Taylor & Francis, 2017-07-31) Repizo, Guillermo DanielAcinetobacter baumannii (Ab) is an important nosocomial pathogen, of major concern worldwide due to its multi-drug resistance and the recent appearance of hyper-virulent strains in the clinical setting. Ab multi-drug resistant (MDR) strains are frequently associated to different types of infections, such as pneumonia, skin burns, endocarditis, meningitis and septicemia, prevalent in intensive care units. For these reasons, Ab has just been included by the World Health Organization in the list of critical priority pathogens for further studies and development of novel therapeutic approaches. In this respect, advanced knowledge of Ab physiology and mechanisms involved in environmental persistence, host colonization and virulence, all of which could be included in what is known as the physiopathology of the microorganism, is required to reduce the socio-economic impact caused by Ab infections. [...]Ítem Acceso Abierto Site-specific recombination at XerC/D sites mediates the formation and resolution of plasmid co-integrates carrying a blaOXA-58- and TnaphA6-resistance module in Acinetobacter baumannii(Frontiers Media, 2018-01-26) Cameranesi, María Marcela ; Morán Barrio, Jorgelina; Limansky, Adriana S.; Repizo, Guillermo Daniel; Viale, Alejandro M.Ítem Acceso Abierto Staring at the cold sun: blue light regulation is distributed within the genus acinetobacter(Public Library of Science (PLOS), 2013-01-24) Golic, Adrián Ezequiel; Vaneechoutte, Mario; Nemec, Alexandr; Viale, Alejandro M.; Actis, Luis A.; Mussi, María AlejandraWe previously showed that the opportunistic nosocomial pathogen Acinetobacter baumannii is able to sense and respond to light via BlsA, a BLUF (Blue-Light-sensing Using FAD)-domain photoreceptor protein. Here, we extend our previous studies showing that light regulation is not restricted to A. baumannii, but rather widespread within the genus Acinetobacter. First, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the Acinetobacter calcoaceticus-A. baumannii complex. In many of these species blue light acts as a key factor guiding the decision between motility or sessility at 24°C, whereas in A. baumannii, light inhibits both motility and biofilm formation. We also show that light regulation of motility occurred not only at 24°C but also at 37°C in non-A. baumannii species, contrasting the situation of A. baumannii which only shows photoregulation at 24°C. Second, we show that Acinetobacter baylyi (strain ADP1) BLUF-photoreceptors can functionally replace in vivo the A. baumannii 17978 BlsA protein and that the pathways leading to biofilm formation are inversely regulated at 24°C between these two microorganisms. Finally, we found the presence of predicted genes coding BLUF-containing proteins in all Acinetobacter sequenced genomes, even though the copy number is variable among them. Phylogenetic analysis suggests a common origin for all BLUF domains present in members of this genus, and could distinguish well-differentiated clusters that group together BLUF homologs from different species, a situation particularly clear for members of the ACB complex. Despite a role played by these BLUF domain-containing proteins in the photoregulation observed in the members of the genus Acinetobacter is a likely scenario given our findings in A. baumannii and A. baylyi, further research will contribute to confirm this possibility.Ítem Acceso Abierto Virulence role of the outer membrane protein CarO in carbapenem-resistant Acinetobacter baumannii(Taylor & Francis, 2020-12-10) Labrador-Herrera, Gema; Pérez-Pulido, Antonio J.; Álvarez-Marína, Rocío; Casimiro-Soriguer, Carlos S.; Cebrero-Cangueiro, Tania; Morán Barrio, Jorgelina ; Pachón, Jerónimo; Viale, Alejandro M.; Pachón-Ibáñez, María Eugenia