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Molecular Characterization of Nonhemolytic and Nonpigmented Group B Streptococci Responsible for Human Invasive Infections.
- Source :
-
Journal of clinical microbiology [J Clin Microbiol] 2016 Jan; Vol. 54 (1), pp. 75-82. Date of Electronic Publication: 2015 Oct 21. - Publication Year :
- 2016
-
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.<br /> (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)
- Subjects :
- Adult
Bacteriological Techniques
Culture Media chemistry
France epidemiology
Gene Deletion
Genetic Association Studies
Genetic Complementation Test
Genome, Bacterial
Humans
Infant, Newborn
Sequence Analysis, DNA
Streptococcal Infections epidemiology
Streptococcus agalactiae classification
Hemolysin Proteins analysis
Pigments, Biological analysis
Streptococcal Infections microbiology
Streptococcus agalactiae genetics
Streptococcus agalactiae isolation & purification
Subjects
Details
- Language :
- English
- ISSN :
- 1098-660X
- Volume :
- 54
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Journal of clinical microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 26491182
- Full Text :
- https://doi.org/10.1128/JCM.02177-15