Understanding the stress mechanisms induced by vancomycin: Effects of a sublethal vancomycin dose on E. faecalis

ITQB PhD Seminars
 

Title: Understanding the stress mechanisms induced by vancomycin: Effects of a sublethal vancomycin dose on E. faecalis

Speaker: Tânia Ribeiro

Laboratory: Antibiotic Stress and Virulence of Enterococci

Abtract

Enterococci are harmless in healthy individuals but constitute a serious threat to patients with compromised immune system or under prolonged antibiotic treatments. Isolation of enterococci responsible for nosocomial infections has grown in parallel with the use of antibiotics. In fact, this genus has an extraordinary ability to survive to a wide range of environmental stresses, in which category exposure to antibiotics may be included. The use of vancomycin, a glycopeptide antibiotic, to treat multiresistant enterococcal infections is now close to became obsolete due to increasing isolation of vancomycin-resistant enterococci (VRE).
Acquired resistance to this antibiotic is mostly due to two types of gene clusters, designated vanA and vanB, which confer resistance by the same mechanism and encode related enzymes (Reynolds et al., 1994). In previous work we observed that an E. faecalis ΔvanB isogenic mutant has an intermediate vancomycin minimum inhibitory concentration (MIC). Suggests that vancomycin may act directly on other genes, either via a vanRB-dependent pathway or indirectly. In order to identify the genes involved in this response to vancomycin we studied the transcriptional response of E. faecalis to a therapeutic dose of vancomycin using a genome-wide microarray based on the V583 genome sequence.
Results show that E. faecalis respond globally to a therapeutic dose of vancomycin, suggesting that survival/resistance to this antibiotic may involve other cell elements besides the van resistance genes. This work is heuristic but provides valuable information for further study towards a comprehensive understanding of the E. faecalis response mechanisms to a chemical stress.

Short CV

2002 – Graduation in Biochemistry
Faculdade de Ciências da Universidade de Lisboa
2003 to 2005 – Master degree in Clinical Microbiology
Faculdade de Medicina da Universidade de Lisboa
2006 until now - PhD student
Stress by Antibiotic and Virulence in Enterococcus lab, ITQB/IBET
Gilmore´s Lab, Schepens Eye Research Institute, Harvard Medical School
LME, Caen University