Staphylococcus epidermidis bacteriophages: New insights on endolysins and phage-biofilm interactions.
The increasing numbers of healthcare-associated infections are alarming and have resulted in higher morbidity and mortality rates, which ultimately are a burden to the public health systems. Staphylococcus epidermidis is the most predominant species isolated in central line-associated bloodstream infections and central venous catheter-associated bloodstream infections, due to the high tolerance of S. epidermidis biofilms to antibiotics, alternative strategies are required to treat these infections. Currently, the use of bacteriophages (phages) is seen as an important strategy to combat pathogenic organisms.
In this thesis we isolated and characterized the first S. epidermidis broad lytic spectra phage. Indeed, this phage lysed all the strains tested, showing a specific behavior. Genomic characterization exhibited a genome without temperate traces and that does not encode any toxins of bacterial origin, suggesting that could be a good candidate for therapeutical purposes.
Another goal of this thesis was to provide a deeper knowledge about phage (endo)lysins that are phage-encoded peptidoglycan hydrolases, described also as promising antimicrobial agents. For that, a database containing more than 700 lysins derived from around 900 genomes were organized and characterized in silico. New catalytic domains and cell binding domains were predicted and described. Furthermore, a new nomenclature was provided, suggesting standardization on lysins annotation.
Acknowledgments: Funding from FCT (SFRH/BD/66166/2009) and projects FCT Strategic Project PEst-OE/EQB/LA0023/2013 and the Project “BioHealth – Biotechnology and Bioengineering approaches to improve health quality”, Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER. The authors also acknowledge the project “Consolidating Research Expertise and Resources on Cellular and Molecular Biotechnology at CEB/IBB”, Ref. FCOMP-01-0124-FEDER-027462
Melo LDR, Sillankorva S, Ackermann H-W, Kropinski AM, Azeredo J, Cerca N (2014). Isolation and characterization of a new Staphylococcus epidermidis broad-spectrum bacteriophage. J Gen Virol. 2014 Feb;95(Pt 2):506-15. doi: 10.1099/vir.0.060590-0.
Oliveira H*, Melo LDR*, Santos SB, Nóbrega FL, Ferreira EC, Cerca N, Azeredo J, Kluskens LD (2013). Molecular aspects and comparative genomics of bacteriophage endolysins. J Virol. 2013 Apr;87(8):4558-70. doi: 10.1128/JVI.03277-12
PhD Degree: Biomedical Engineering
Year of conclusion: 2014
Institution: CEB-Biological Engineering Centre, University of Minho
Supervisor: Nuno Cerca