ITQB: BEME - PhD Theses
URI permanente para esta coleção:
Navegar
Entradas recentes
- Exploring the factors underlying Staphylococcus epidermidis’ pathogenicityPublication . Espadinha de Oliveira e Costa, Diana"Staphylococcus epidermidis is the major colonizer of the human skin and also an important opportunistic pathogen, having been increasingly recognized over the last decades as a major cause of nosocomial infections associated to medical indwelling devices, including central line associated bloodstream infections and surgical-site infections. The success of S. epidermidis in the hospital environment has been frequently associated to their remarkable capacity to accumulate resistance to several antimicrobial classes and also to the ability of forming biofilms on the surface of the medical devices. Additionally, the carriage of genetic markers such as mecA, IS256 and icaA has also been frequently associated to nosocomial S. epidermidis."
- Evolutionary genomics of Staphylococcus saprophyticus: origin and disease signatures of pathogenic clonesPublication . Lawal, Opeyemi U."Staphylococcus saprophyticus is the second only to Escherichia coli as the leading cause of uncomplicated urinary tract infection (UTI), and it is associated with 10-20% of this type of infection in young women. Besides being a uropathogen, S. saprophyticus is also known to be a common coloniser of the gut, vagina, perineum, and the rectum of humans. Moreover, it colonises food producing animals such as pigs, and is a frequent contaminant of meat and fermented food products. Although the source(s) of S. saprophyticus causing UTI in humans are considered to be endogenous, increased contact with animal production settings and consumption of contaminated meat products have been hypothesised to increase the risk of human colonisation and infection with this bacterium.(...)"
- Origin and evolution of the β-lactam resistance determinant in staphylococciPublication . Mateus, Joana Rita Gonçalves Araújo RoloIn staphylococci, resistance to methicillin and to all β-lactam antibiotics is provided by the mecA gene, which encodes a penicillin-binding protein with low affinity to β-lactams (PBP2a). The mecA is carried by a mobile genetic element, the staphylococcal cassette chromosome mec (SCCmec), one of the most widely studied bacterial pathogenicity islands. SCCmec carries mecA and its regulators (the mec complex), as well as cassette chromosome recombinases encoded by ccr genes that form the ccr complex. These recombinases assure the mobility of the cassette. In addition, SCCmec cassettes carry joining regions (J regions) that link the orfX to the mec complex (J3); the mec complex to the ccr complex (J2) and the ccr complex to the end of the cassette (J1). The J regions can carry additional antibiotic resistance determinants, transposons, insertion sequences and plasmids. The SCCmec element always inserts at the same site in the bacterial chromosome, downstream orfX (which encodes a RNA methyltransferase), located 500 kb downstream the origin of replication. SCCmec is a very diverse element; so far eleven different types have been identified in Staphylococcus aureus and many more are probably carried by coagulase-negative staphylococcal species. SCCmec is transferred horizontally among strains and species of Staphylococcus, through an unknown molecular mechanism.