Detection of group B Streptococcus during antenatal screening in Western Australia: a comparison of culture and molecular methods

Research output: Contribution to journalArticle

Abstract

Aim: Global screening strategies for Group B Streptococcus (GBS) include risk- or culture-based methods to guide intrapartum prophylaxis. In Western Australia (WA), antenatal culture-based screening is routine; however, numerous culture methods exist, in addition to molecular methods. We aimed to assess the comparability of research and diagnostic screening approaches. Methods and Results: Vaginal and rectal swabs were self-collected by pregnant women (n = 531) from King Edward Memorial Hospital, WA, in parallel to routine screening (35–37 weeks of gestation). Research methods involved culture (Strep B Carrot Broth™ and StrepB CHROMagar™) and molecular methods (real-time PCR) and were compared to routine diagnostic screening (Lim Broth and Granada agar). Overall, GBS detection was comparable between research and diagnostic approaches (3–5% discrepancy, kappa = 0·76). Specificity/sensitivity of Carrot Broth was 100%/89%, while that of CHROMagar was 73%/100%, respectively. Direct PCR was unable to detect GBS in ~18% of specimens which were culture positive; however, it exhibited 100% specificity. Conclusions: This clinical evaluation of GBS screening methods provides support for current practice. Significance and Impact of the Study: Although CHROM was highly sensitive, further testing is recommended due to a high false-positive rate. Molecular assays are useful for rapid detection; however, low-titre samples may require additional enrichment prior to molecular analysis to improve sensitivity.

Original languageEnglish
Pages (from-to)598-604
Number of pages7
JournalJournal of Applied Microbiology
Volume127
Issue number2
DOIs
Publication statusPublished - 1 Aug 2019

Fingerprint

Western Australia
Streptococcus agalactiae
Prenatal Diagnosis
Daucus carota
Research
Agar
Real-Time Polymerase Chain Reaction
Pregnant Women
Sensitivity and Specificity
Pregnancy
Polymerase Chain Reaction

Cite this

@article{31327a3b24fb46648a643798079e7405,
title = "Detection of group B Streptococcus during antenatal screening in Western Australia: a comparison of culture and molecular methods",
abstract = "Aim: Global screening strategies for Group B Streptococcus (GBS) include risk- or culture-based methods to guide intrapartum prophylaxis. In Western Australia (WA), antenatal culture-based screening is routine; however, numerous culture methods exist, in addition to molecular methods. We aimed to assess the comparability of research and diagnostic screening approaches. Methods and Results: Vaginal and rectal swabs were self-collected by pregnant women (n = 531) from King Edward Memorial Hospital, WA, in parallel to routine screening (35–37 weeks of gestation). Research methods involved culture (Strep B Carrot Broth™ and StrepB CHROMagar™) and molecular methods (real-time PCR) and were compared to routine diagnostic screening (Lim Broth and Granada agar). Overall, GBS detection was comparable between research and diagnostic approaches (3–5{\%} discrepancy, kappa = 0·76). Specificity/sensitivity of Carrot Broth™ was 100{\%}/89{\%}, while that of CHROMagar™ was 73{\%}/100{\%}, respectively. Direct PCR was unable to detect GBS in ~18{\%} of specimens which were culture positive; however, it exhibited 100{\%} specificity. Conclusions: This clinical evaluation of GBS screening methods provides support for current practice. Significance and Impact of the Study: Although CHROM was highly sensitive, further testing is recommended due to a high false-positive rate. Molecular assays are useful for rapid detection; however, low-titre samples may require additional enrichment prior to molecular analysis to improve sensitivity.",
keywords = "antenatal, culture, GBS, group B Streptococcus, molecular, pregnant, screening, Streptococcus agalactiae",
author = "Furfaro, {L. L.} and Chang, {B. J.} and Payne, {M. S.}",
year = "2019",
month = "8",
day = "1",
doi = "10.1111/jam.14331",
language = "English",
volume = "127",
pages = "598--604",
journal = "Journal of Applied Microbiology",
issn = "1364-5072",
publisher = "John Wiley & Sons",
number = "2",

}

TY - JOUR

T1 - Detection of group B Streptococcus during antenatal screening in Western Australia

T2 - a comparison of culture and molecular methods

AU - Furfaro, L. L.

AU - Chang, B. J.

AU - Payne, M. S.

PY - 2019/8/1

Y1 - 2019/8/1

N2 - Aim: Global screening strategies for Group B Streptococcus (GBS) include risk- or culture-based methods to guide intrapartum prophylaxis. In Western Australia (WA), antenatal culture-based screening is routine; however, numerous culture methods exist, in addition to molecular methods. We aimed to assess the comparability of research and diagnostic screening approaches. Methods and Results: Vaginal and rectal swabs were self-collected by pregnant women (n = 531) from King Edward Memorial Hospital, WA, in parallel to routine screening (35–37 weeks of gestation). Research methods involved culture (Strep B Carrot Broth™ and StrepB CHROMagar™) and molecular methods (real-time PCR) and were compared to routine diagnostic screening (Lim Broth and Granada agar). Overall, GBS detection was comparable between research and diagnostic approaches (3–5% discrepancy, kappa = 0·76). Specificity/sensitivity of Carrot Broth™ was 100%/89%, while that of CHROMagar™ was 73%/100%, respectively. Direct PCR was unable to detect GBS in ~18% of specimens which were culture positive; however, it exhibited 100% specificity. Conclusions: This clinical evaluation of GBS screening methods provides support for current practice. Significance and Impact of the Study: Although CHROM was highly sensitive, further testing is recommended due to a high false-positive rate. Molecular assays are useful for rapid detection; however, low-titre samples may require additional enrichment prior to molecular analysis to improve sensitivity.

AB - Aim: Global screening strategies for Group B Streptococcus (GBS) include risk- or culture-based methods to guide intrapartum prophylaxis. In Western Australia (WA), antenatal culture-based screening is routine; however, numerous culture methods exist, in addition to molecular methods. We aimed to assess the comparability of research and diagnostic screening approaches. Methods and Results: Vaginal and rectal swabs were self-collected by pregnant women (n = 531) from King Edward Memorial Hospital, WA, in parallel to routine screening (35–37 weeks of gestation). Research methods involved culture (Strep B Carrot Broth™ and StrepB CHROMagar™) and molecular methods (real-time PCR) and were compared to routine diagnostic screening (Lim Broth and Granada agar). Overall, GBS detection was comparable between research and diagnostic approaches (3–5% discrepancy, kappa = 0·76). Specificity/sensitivity of Carrot Broth™ was 100%/89%, while that of CHROMagar™ was 73%/100%, respectively. Direct PCR was unable to detect GBS in ~18% of specimens which were culture positive; however, it exhibited 100% specificity. Conclusions: This clinical evaluation of GBS screening methods provides support for current practice. Significance and Impact of the Study: Although CHROM was highly sensitive, further testing is recommended due to a high false-positive rate. Molecular assays are useful for rapid detection; however, low-titre samples may require additional enrichment prior to molecular analysis to improve sensitivity.

KW - antenatal

KW - culture

KW - GBS

KW - group B Streptococcus

KW - molecular

KW - pregnant

KW - screening

KW - Streptococcus agalactiae

UR - http://www.scopus.com/inward/record.url?scp=85067365683&partnerID=8YFLogxK

U2 - 10.1111/jam.14331

DO - 10.1111/jam.14331

M3 - Article

VL - 127

SP - 598

EP - 604

JO - Journal of Applied Microbiology

JF - Journal of Applied Microbiology

SN - 1364-5072

IS - 2

ER -