ITQB: MMHP - PhD Theses
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- Studies on the regulation of bacterioci loci in Streptococcus mitisPublication . Borralho, João Pedro Mestre; De Tecnologia Química e Biológica António Xavier, Instituto"Horizontal gene transfer (HGT) is a fundamental force of bacterial evolution, driving the spread of antibiotic resistance and virulence, among other traits. It occurs primarily through three mechanisms: conjugation, transduction, and transformation. Transformation holds particular significance both historically and biologically. Streptococcus pneumoniae (or the pneumococcus), a human pathogen, stands out both for its disease burden, but also for its central role in the discovery of transformation. Transformation remains unique among HGT mechanisms, in that it requires a specialized physiological state, competence, during which cells actively take up and integrate extracellular DNA.(...)"
- Exploring cellular communication diversity for the development of novel anti-pneumococcal therapeuticsPublication . Ferreira, Bárbara Miranda; Sá Leão, Raquel"The upper respiratory tract (URT) harbors dynamic microbial communities in which commensal and potentially pathogenic species coexist, interact, and are continuously shaped by host-derived and environmental selective forces. Within this ecosystem, Streptococci of the Mitis group (SMG) are particularly prominent. Streptococcus mitis persists as a long-term commensal and continuous member of the microbiota, while Streptococcus pneumoniae remains a major opportunistic pathogen capable of asymptomatic carriage as well as invasive disease. Despite their divergent lifestyles, these closely related species often occupy overlapping ecological niches and engage in horizontal gene transfer, processes that drive phenotypic diversification of traits such as polysaccharide capsule structure and antimicrobial resistance."
- A targeted approach to control Streptococcus pneumoniae infectionPublication . Candeias, Catarina; Sá-Leão, Raquel"The human upper respiratory tract (URT) hosts diverse bacterial communities, with the Streptococcus genus playing a key role in health and disease. Among these, S. pneumoniae can asymptomatically colonize the URT in biofilms, facilitating its persistence, transmission, and potential progression to diseases like pneumonia, meningitis, sepsis and severe secondary infections after influenza A (IAV). While antibiotics and pneumococcal conjugate vaccines (PCVs) have successfully reduced the disease burden, challenges like antibiotic resistance and limited serotype coverage require alternative approaches. Targeting colonization, leveraging colonization resistance by commensals such as S. mitis and S. oralis, and using antimicrobial peptides like bacteriocins, offer promising strategies to inhibit pathogens and combat pneumococcal disease more effectively.(...)"
- Exploring commensal streptococci to prevent Streptococcus pneumoniae colonizationPublication . Handem, SaraSeveral Streptococcus species colonize various niches of the upper respiratory tract (URT). Among the over 50 distinct streptococcal species, some are considered opportunistic pathogens whereas others are considered commensals. Nevertheless, many co-exist in the same niche, having evolved numerous strategies to compete and survive.
- Pneumococcal adaptation during invasionPublication . Félix, Sofia; Sá-Leão, Raquel; Muñoz-Almagro, Carmen"Streptococcus pneumoniae, or the pneumococcus, frequently colonizes the human nasopharynx, particularly in children. From the nasopharynx, the pneumococcus can transit to other body sites and cause disease such as otitis media, pneumonia, bacteremia and meningitis. Multivalent pneumococcal conjugate vaccines (PCV), targeting pneumococcal capsular types, or serotypes, have been designed and implemented since 2001, to reduce the incidence of pneumococcal disease worldwide. (...)"
- Dynamics of bacterial colonization in the upper respiratory tract of the adult hostPublication . Almeida, Sónia T."Bacterial infections caused by microorganisms such as, Streptococcus pneumoniae and Staphylococcus aureus are a main cause of morbidity and mortality worldwide, particularly among young children, the elderly, and the immunocompromised of all ages. However, disease is incidental, and the natural lifestyle of these bacteria is through asymptomatic colonization of the upper respiratory tract. (...)"
- Studies on non-typeability and molecular identification of the pneumococcusPublication . Tavares, Débora A.Pneumococcus(is(a(major(human(pathogen.(Its(main(virulence(factor(is(the(capsule,( which( is( of( polysaccharide( nature.( The( detection( of( the( capsule( using( specific( antisera( is( used( to( identify( pneumococcus.( Also,( differences( in( structural( and( antigenic(properties(of(the(polysaccharides(composing(the(capsule(have(been(used( to(classify(pneumococcus(into(serotypes.(