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Raquel Sá-Leão Lab


In our group we are studying how human interventions, such as the use of vaccines and antibiotics, impact on the nasopharyngeal ecosystem, a rich niche frequently inhabited by potentially pathogenic bacteria such as Streptococcus pneumoniae.

Raquel Sá-Leão
Investigador Principal
PhD in 2002 in Biology, ITQB NOVA

Phone (+351) 214469872


Research Interests

The human microbiota consists of all the microbes that live in and on the human body. To improve our understanding of human health and disease, we need to gain a deeper knowledge on the intra- and interspecies bacterial interactions, and host-bacteria interactions that occur in the human body influencing which species and strains persist in it.

In our group we are focusing on the nasopharyngeal ecosystem, a rich niche frequently inhabited by potentially pathogenic bacteria such as Streptococcus pneumoniae (or pneumococcus), Haemophilus influenzae, and Moraxella catarrhalis. Colonization by these bacteria, which is typically asymptomatic, is particularly frequent among young children. Although disease per se is incidental in the lifestyle of these bacteria, the burden of disease caused by them is substantial worldwide.

In recent years, multivalent pneumococcal conjugate vaccines, targeting a limited subset of the circulating pneumococcal capsular types have been introduced in several countries. We are studying how these vaccines, together with antibiotic use, impact on the pneumococcal population and on the nasopharyngeal ecosystem as a whole. Depending on local vaccine coverage, antibiotic use, circulating strains and relationship between competitors, different outcomes in colonization and disease overall may be observed. Our studies are contributing to estimate the medium and long-term public health impact of the use of vaccines and antibiotics.


Group Members

  • Alexandra Simões, PhD, Project Manager
  • Ana Cristina Paulo, Post Doc
  • Carina Valente, Post Doc
  • João Paulo Machado, PhD, Investigator
  • Sara Handem, PhD student
  • Sofia Félix, PhD student
  • Sónia Almeida, PhD student
  • Catarina Candeias, Research Fellow
  • Tiago Touret, Research Fellow
  • Ana Cruz, Research Fellow/Master Student
  • Bárbara Ferreira, Master Student
  • Bruno Gonçalves, Master Student
  • João Borralho, Master Student
  • João Lança, Master Student
  • Miguel Queirós, Master Student



Selected Publications

  1. Paulo AC., and R. Sá-Leão. 2017. Periodic cycles of pneumococcal serotypes carried by children before and after 7-valent pneumococcal conjugate vaccine. PLOS ONE 12(4): e0176723. doi:10.1371/journal.pone.0176723

  2. Valente, C., S. Dawid, F. R. Pinto, J. Hinds, A. S. Simões, K. Gould, L. A. Mendes, H. de Lencastre, and R. Sá-Leão. 2016. The blp locus of Streptococcus pneumoniae plays a limited role in the selection of which strains can co-colonize the human nasopharynx. Appl. Environ. Microbiol. pii: AEM.01048-16. doi: 10.1128/AEM.01048-16.

  3. Nunes S, Félix S, Valente C, Simões AS, Tavares DA, Almeida ST, Paulo AC, Brito-Avô A, de Lencastre H, Sá-Leão R. 2016. The impact of private use of PCV7 in 2009 and 2010 on serotypes and antimicrobial resistance of Streptococcus pneumoniae carried by young children in Portugal: comparison with data obtained since 1996 generating a 15-year study prior to PCV13 introduction. Vaccine. 34: 1648-56. doi:10.1016/j.vaccine.2016.02.045.  


Laboratory's Webpage

For further information visit the laboratory's website (soon available)


Microbiologia Molecular de Patogéneos Humanos (PT)

A microbiota humana é constituída por todos os microorganismos que vivem no corpo humano. Estes microorganismos interagem entre si e com o hospedeiro contribuindo para o estado de saúde do indivíduo.
O objectivo principal do nosso grupo é o estudo da microbiologia da nasofaringe, um nicho ecológico que é frequentemente colonizado por bactérias potencialmente patogénicas entre as quais se encontram os pneumococos. Em particular, estamos interessados em compreender de que forma intervenções como o uso de vacinas e antibióticos afetam este ecossistema, a saúde do indivíduo e, em última análise, a saúde pública.


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