title: The pneumococcus: why a commensal misbehaves.
abstract: Several characteristics of Streptococcus pneumoniae (pneumococcus) combine to make it a particularly problematic pathogen. Firstly, the pneumococcus has the capacity to cause disease through the expression of virulence factors such as its polysaccharide capsule and pore-forming toxin. In addition, the pneumococcus is highly adaptable as demonstrated by its ability to acquire and disseminate resistance to multiple antibiotics. Although the pneumococcus is a major cause of disease, the organism is most commonly an "asymptomatic" colonizer of its human host (the carrier state), with transmission occurring exclusively from this reservoir of commensal organisms. Thus, it is unclear how the organism's virulence and adaptability promote its persistence or host to host spread during its carrier state. This review summarizes current understanding of how these characteristics may contribute to the commensal lifestyle of the pneumococcus.
authors.affiliation: Department of Microbiology and Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA, 19104, USA. weiser@mail.med.upenn.edu
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Weiser
mesh_terms: D000818:Animals; D002353:Carrier State / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D011008:Pneumococcal Infections / Q000276:immunology / Q000382:microbiology* / Q000503:physiopathology*; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors