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Infect Genet Evol

Title:		Pherotypes of pneumococcal strains co-existing in healthy children
Author(s):		Vestrheim DF; Gaustad P; Aaberge IS; Caugant DA;
Address:		"Department of Bacteriology and Immunology, Norwegian Institute of Public Health, Oslo, Norway. didrik.frimann.vestrheim@fhi.no"
Journal Title:		Infect Genet Evol
Year:		2011
Volume:		20110707
Issue:		7
Page Number:		1703 - 1708
DOI:		10.1016/j.meegid.2011.07.003
ISSN/ISBN:		1567-7257 (Electronic) 1567-1348 (Linking)
Abstract:		"Genetic diversity in the species Streptococcus pneumoniae is mainly driven by horizontal gene transfer. S. pneumoniae is naturally competent for transformation. Competence is induced by a pheromone termed competence stimulating peptide (CSP) by a quorum-sensing mechanism. Two CSP pherotypes predominate amongst clinical isolates of S. pneumoniae, CSP-1 and CSP-2, with ability to trigger competence in bacteria of the homologue pherotype. Opposing theories on the effect of pherotypes on speciation have been proposed, either as a barrier for intra-pherotype gene transfer, or as a mechanism for fratricide resulting in lysis of non-competent bacterial cells. The aim of the present study was to determine pherotype distribution in strains of S. pneumococci isolated from the nasopharynges of healthy children. We sequenced the locus encoding CSP, comC, in sets of strains obtained from children colonised by multiple pneumococcal strains simultaneously. The impact of pherotype on co-colonisation was determined by comparing the observed distribution of pherotypes in co-colonising strains with the estimated pair-wise probability based on the overall pherotype distribution in the sample set. Five distinct comC alleles were identified, encoding CSP belonging to the two dominating pherotypes, CSP-1 (62.7%) and CSP-2 (37.3%). The observed distribution of pherotypes in sets of co-colonising pneumococcal strains did not differ from the probability estimate. Thus, co-colonisation of S. pneumoniae in healthy children is not restricted by pherotype"
Keywords:		"Bacterial Proteins/genetics Base Sequence Child Cross-Sectional Studies DNA Transformation Competence/genetics DNA, Bacterial/genetics Genes, Bacterial Genetic Variation Humans Multilocus Sequence Typing Nasopharynx/microbiology Norway Serotyping Streptoc;"
Notes:		"MedlineVestrheim, Didrik F Gaustad, Peter Aaberge, Ingeborg S Caugant, Dominique A eng Netherlands 2011/07/19 Infect Genet Evol. 2011 Oct; 11(7):1703-8. doi: 10.1016/j.meegid.2011.07.003. Epub 2011 Jul 7"