Molecular Characterization of Nonhemolytic and Nonpigmented Group B Streptococci Responsible for Human Invasive Infections - Institut Pasteur Access content directly
Journal Articles Journal of Clinical Microbiology Year : 2016

Molecular Characterization of Nonhemolytic and Nonpigmented Group B Streptococci Responsible for Human Invasive Infections

Abstract

Group B Streptococcus (GBS) is a common commensal bacterium in adults, but is also the leading cause of invasive bacterial infections in neonates in developed countries. The β-hemolysin/cytolysin (β-h/c), which is always associated with the production of an orange-to-red pigment, is a major virulence factor that is also used for GBS diagnosis. A collection of 1,776 independent clinical GBS strains isolated in France between 2006 and 2013 was evaluated on specific medium for β-h/c activity and pigment production. The genomic sequences of nonhemolytic and nonpigmented (NH/NP) strains were analyzed to identify the molecular basis of this phenotype. Gene deletions or complementations were carried out to confirm the genotype-phenotype association. Sixty-three GBS strains (3.5%) were NH/NP, and 47 of these (74.6%) originated from invasive infections, including bacteremia and meningitis, in neonates or adults. The mutations are localized predominantly in the cyl operon, encoding the β-h/c pigment biosynthetic pathway and, in the abx1 gene, encoding a CovSR regulator partner. In conclusion, although usually associated with GBS virulence, β-h/c pigment production is not absolutely required to cause human invasive infections. Caution should therefore be taken in the use of hemolysis and pigmentation as criteria for GBS diagnosis in routine clinical laboratory settings.

Dates and versions

pasteur-01288318 , version 1 (14-03-2016)

Identifiers

Cite

Anne Six, Arnaud Firon, Céline Plainvert, Camille Caplain, Gérald Touak, et al.. Molecular Characterization of Nonhemolytic and Nonpigmented Group B Streptococci Responsible for Human Invasive Infections. Journal of Clinical Microbiology, 2016, 54 (1), pp.75-82. ⟨10.1128/JCM.02177-15⟩. ⟨pasteur-01288318⟩
181 View
0 Download

Altmetric

Share

Gmail Facebook X LinkedIn More