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J Clin Microbiol. 2019 Mar 28;57(4). pii: e02040-18. doi: 10.1128/JCM.02040-18. Print 2019 Apr.

Streptococcus agalactiae Strains with Chromosomal Deletions Evade Detection with Molecular Methods.

Author information

1
Cepheid, Sunnyvale, California, USA Isabella.tickler@cepheid.com.
2
Cepheid, Sunnyvale, California, USA.
3
Stanford University Medical Center, Palo Alto, California, USA.
4
Department of Medical Microbiology and Immunology, Creighton University School of Medicine, Omaha, Nebraska, USA.
5
Woman's Hospital, Baton Rouge, Louisiana, USA.
6
Willis-Knighton Health System, Shreveport, Louisiana, USA.
7
University of Wisconsin-Madison, Madison, Wisconsin, USA.
8
Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA.

Abstract

Surveillance of circulating microbial populations is critical for monitoring the performance of a molecular diagnostic test. In this study, we characterized 31 isolates of Streptococcus agalactiae (group B Streptococcus [GBS]) from several geographic locations in the United States and Ireland that contain deletions in or adjacent to the region of the chromosome that encodes the hemolysin gene cfb, the region targeted by the Xpert GBS and GBS LB assays. PCR-negative, culture-positive isolates were recognized during verification studies of the Xpert GBS assay in 12 laboratories between 2012 and 2018. Whole-genome sequencing of 15 GBS isolates from 11 laboratories revealed four unique deletions of chromosomal DNA ranging from 181 bp to 49 kb. Prospective surveillance studies demonstrated that the prevalence of GBS isolates containing deletions in the convenience sample was <1% in three geographic locations but 7% in a fourth location. Among the 15 isolates with chromosomal deletions, multiple pulsed-field gel electrophoresis types were identified, one of which appears to be broadly dispersed across the United States.

KEYWORDS:

Streptococcus agalactiae ; group B streptococcus; whole-genome sequencing

PMID:
30760532
PMCID:
PMC6440789
[Available on 2019-09-28]
DOI:
10.1128/JCM.02040-18

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