Dr. Maria Soledad Ramirez, BiologICAL SCIENCE


Ph.D. Microbiology, University of Buenos Aires, Argentina (UBA)
Postdoctoral fellowship, CONICET, University of Buenos Aires, Argentina (UBA) Fulbright-CONICET Research Fellowship, Fulbright-CONICET
Member of the CONICET Research career, Argentina
Faculty, School of medicine, UBA, Argentina

Research Areas

Dr. Ramírez current research program focuses on the study and identification of mechanisms of antibiotic resistance, their dissemination and evolution, as well as their impact on the morbidity and mortality of bacterial infections.

Antibiotic-resistant bacteria pose a serious threat to human health, and the increase in infections caused by such pathogens is a growing concern worldwide. In fact, in 2013, the Centers for Disease Control and Prevention (CDC) estimated that in the United States around 2 million people were infected with multidrug- resistant bacteria every year. This is the reason why different research lines related to antimicrobial resistance (AMR) are going on in Dr. Ramirez’ lab.

In the last years we have been exploring in detail different aspects of an important nosocomial pathogen- Acinetobacter baumannii- that has a particular ability to acquire antimicrobial resistance traits and survive in the hospital environment.

One of the aspects of this bacterium that we have been exploring is its ability to acquire exogenous DNA. We aim to identify environmental conditions and signals that trigger competence and the genes coding for structural and regulatory functions involved in the transformation process in A. baumannii. Moreover, we are exploring the specific role of albumin and other proteins found in human body fluids in competence development. This understanding could ultimately facilitate the exploration of novel approaches to treat severe A. baumannii human infections, particularly those caused by emerging multi-drug resistant isolates. We are working to shed light on this poorly understand process- competence for transformation- in this important pathogen.

Moreover, and as part of a fruitful collaboration establish with Dr Mussi, we have recently recognized a new aspect of A. baumanniipathophysiology valuable in the above context: its ability to perceive and respond to light modulating motility and biofilm formation, virulence against eukaryotic hosts and even susceptibility to certain antibiotics clinically relevant such as minocycline and tigecycline. In this sense, the goal of this research line is to evaluate whether the environmental signal light could be used to optimize the utilization of clinical relevant antibiotics, such as minocycline and tigecycline, to control infections caused by multidrug resistant pathogens. We are also studying other important pathogens in addition to A. baumannii, such as Staphylococcus aureus and Pseudomonas aeruginosa, microorganisms that also showed modulation by light of antibiotic susceptibility. We plan also to provide insights into the mechanisms of light signal transduction in A. baumannii to better understand this process and broaden the knowledge of the physiology and pathogenicity of this bacterium.

Since the establishment of her research group, Dr. Ramirez has mentored many students who have successful transitioned to Masters and PhD programs as well as careers in the private sector. Her students present their work at international, regional and local conferences with her support and also are co-author of papers.


  1. Ramirez MS, Don M, Merkier AK, Bistué AJ, Zorreguieta A, Centrón D, Tolmasky ME. Naturally competent Acinetobacter baumanniiclinical isolate as a convenient model for genetic studies. J Clin Microbiol. 2010 Apr;48(4):1488-90. PubMed PMID: 20181905; PubMed Central PMCID: PMC2849597.
  2. Traglia GM, Chua K, Centrón D, Tolmasky ME, Ramírez MS. Whole-genome sequence analysis of the naturally competentAcinetobacter baumannii clinical isolate A118. Genome Biol Evol. 2014 Aug 26;6(9):2235-9. PubMed PMID: 25164683; PubMed Central PMCID: PMC4202317.
  3. Ramírez MS, Traglia GM, Pérez JF, Müller GL, Martínez F, Golic AE, Mussi MA. White and blue light induce reduction in susceptibility to minocycline and tigecycline in Acinetobacter sp. and other bacteria of clinical importance. J Med Microbiol. 2015 Mar 3;PubMed PMID: 25737436.
  4. Ramírez M.S., Müller G., Pérez J., Golic A., Mussi M.A. (2015). More than just light: Clinical relevance of light perception in the nosocomial pathogen Acinetobacter baumannii and other members of the genus Acinetobacter. Photochem. Photobiol., in press. PUBMED PMID: 26303173.
  5. Vilacoba E, Almuzara M, Gulone L, Traglia GM, Figueroa SA, Sly G, Fernández A, Centrón D, Ramírez MS. Emergence and spread of plasmid-borne tet(B)::ISCR2 in minocycline-resistant Acinetobacter baumannii isolates. Antimicrob Agents Chemother. 2013 Jan;57(1):651-4. PubMed PMID: 23147737; PubMed Central PMCID: PMC3535920.
  6. Vilacoba E, Almuzara M, Gulone L, Rodriguez R, Pallone E, Bakai R, Centrón D, Ramírez MS. Outbreak of extensively drug-resistantAcinetobacter baumannii indigo-pigmented strains. J Clin Microbiol. 2013 Nov;51(11):3726-30. PubMed PMID: 23985923; PubMed Central PMCID: PMC3889758.
  7. Almuzara M, Traglia GM, Krizova L, Barberis C, Montaña S, Bakai R, Tuduri A, Vay C, Nemec A, Ramírez MS. A taxonomically unique Acinetobacter strain with proteolytic and hemolytic activities recovered from a patient with a soft tissue injury. J Clin Microbiol. 2015 Jan;53(1):349-51. PubMed PMID: 25392359; PubMed Central PMCID: PMC4290954.
  8. Ramirez MS, Nikolaidis N, Tolmasky ME. Rise and dissemination of aminoglycoside resistance: the aac(6')-Ib paradigm. Front Microbiol. 2013;4:121. PubMed PMID: 23730301; PubMed Central PMCID: PMC3656343.
  9. Stietz MS, Ramírez MS, Vilacoba E, Merkier AK, Limansky AS, Centrón D, Catalano M. Acinetobacter baumannii extensively drug resistant lineages in Buenos Aires hospitals differ from the international clones I-III. Infect Genet Evol. 2013 Mar;14:294-301. PubMed PMID: 23313831.
  10. Montaña S, Vilacoba E, Traglia GM, Almuzara M, Pennini M, Fernández A, Sucari A, Centrón D, Ramírez MS. Genetic Variability of AdeRS Two-Component System Associated with Tigecycline Resistance in XDR-Acinetobacter baumannii Isolates. Curr Microbiol. 2015 Jul;71(1):76-82. ubMed PMID: 25941024.

Grants & Special Projects

  • 2012     IANAS (InterAmerican Network of Academies of Sciences) Fellowship Award, IANAS
  • 2012     ICAAC Young Investigator Award for 2012, American Society for Microbiology (ASM)
  • 2013     Young Scientist Travel Grant, FEMS and ESCMID