Usefulness of a Rapid Real-time PCR Assay in Prenatal Screening for Group B Streptococcus Colonization

ABSTRACTLife-threatening infection in neonates due to group BStreptococcus(GBS) is preventable by screening of near-term pregnant women and treatment at delivery. A total of 295 vaginal-rectal swabs were collected from women attending antepartum clinics in Calgary, Alberta, Canada. GBS colonization was detected by the standard culture method (Strep B Carrot Broth subcultured to blood agar with a neomycin disk) and compared to recovery with Strep Group B Broth (Dalynn Biologicals) subcultured to StrepBSelectchromogenic medium (CM; Bio-Rad Laboratories) and the Fast-Track Diagnostics GBS real-time PCR (quantitative PCR [qPCR]) assay (Phoenix Airmid Biomedical Corp.) performed with broth-enriched samples and the Abbottm2000sp/m2000rt system. A total of 62/295 (21%) women were colonized with GBS; 58 (19.7%) cases were detected by standard culture, while CM and qPCR each found 61 (20.7%) cases. The qPCR and CM were similar in performance, with sensitivities, specificities, and positive and negative predictive values of 98.4 and 98.4%, 99.6 and 99.6%, 98.4 and 98.4%, and 99.6 and 99.6%, respectively, compared to routine culture. Both qPCR and CM would allow more rapid reporting of routine GBS screening results than standard culture. Although the cost per test was similar for standard culture and CM, the routine use of qPCR would cost approximately four times as much as culture-based detection. Laboratories worldwide should consider implementing one of the newer methods for primary GBS testing, depending on the cost limitations of different health care jurisdictions.

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Real-time PCR-assay in the delivery suite for determination of group B streptococcal colonization in a setting with risk-based antibiotic prophylaxis

The Journal of Maternal-Fetal & Neonatal Medicine ◽

10.3109/14767058.2013.818128 ◽

2013 ◽

Vol 27 (4) ◽

pp. 328-332 ◽

Cited By ~ 15

Author(s):

Stellan Håkansson ◽

Karin Källén ◽

Maria Bullarbo ◽

Per-Åke Holmgren ◽

Katarina Bremme ◽

...

Keyword(s):

Antibiotic Prophylaxis ◽

Real Time ◽

Real Time Pcr ◽

Pcr Assay ◽

Group B

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Comparison of group B strep IDI-StrepB real-time PCR assay to standard culture

American Journal of Obstetrics and Gynecology ◽

10.1016/j.ajog.2005.10.751 ◽

2005 ◽

Vol 193 (6) ◽

pp. S186

Author(s):

Kristin Atkins (F) ◽

Robyn Atkinson ◽

Anthony Shanks ◽

W. Michael Dunne ◽

Gilad Gross

Keyword(s):

Real Time ◽

Real Time Pcr ◽

Pcr Assay ◽

Standard Culture ◽

Group B

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Evaluation of Culture Method and Real-Time PCR for Detection of Vaginal Group B Streptococcus Colonization in Pregnant at the Last Trimester

Gulhane Medical Journal ◽

10.5455/gulhane.37392 ◽

2014 ◽

Vol 56 (2) ◽

pp. 80

Author(s):

Samer ALWEDYAN ◽

Ramazan GMRAL ◽

mit GOKTOLGA ◽

Fatih SAHINER ◽

Orhan BEDIR ◽

...

Keyword(s):

Real Time ◽

Real Time Pcr ◽

Group B Streptococcus ◽

Culture Method ◽

Group B

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Development of Conventional and Real-Time PCR Assays for the Rapid Detection of Group B Streptococci

Clinical Chemistry ◽

10.1093/clinchem/46.3.324 ◽

2000 ◽

Vol 46 (3) ◽

pp. 324-331 ◽

Cited By ~ 106

Author(s):

Danbing Ke ◽

Christian Ménard ◽

François J Picard ◽

Maurice Boissinot ◽

Marc Ouellette ◽

...

Keyword(s):

Real Time ◽

Real Time Pcr ◽

Rapid Detection ◽

Culture Method ◽

Conventional Pcr ◽

Pcr Assay ◽

Group B Streptococci ◽

Standard Culture ◽

Pcr Assays ◽

Group B

Abstract Background: Group B streptococci (GBS), or Streptococcus agalactiae, are the leading bacterial cause of meningitis and bacterial sepsis in newborns. Currently available rapid methods to detect GBS from clinical specimens are unsuitable for replacement of culture methods, mainly because of their lack of sensitivity. Methods: We have developed a PCR-based assay for the rapid detection of GBS. The cfb gene encoding the Christie-Atkins-Munch-Petersen (CAMP) factor was selected as the genetic target for the assay. The PCR primers were initially tested by a conventional PCR method followed by gel electrophoresis. The assay was then adapted for use with the LightCyclerTM. For this purpose, two fluorogenic adjacent hybridization probes complementary to the GBS-specific amplicon were designed and tested. In addition, a rapid sample-processing protocol was evaluated by colony-forming unit counting and PCR. A total of 15 vaginal samples were tested by both standard culture method and the two PCR assays. Results: The conventional PCR assay was specific because it amplified only GBS DNA among 125 bacterial and fungal species tested, and was able to detect all 162 GBS isolates from various geographical areas. This PCR assay allowed detection of as few as one genome copy of GBS. The real-time PCR assay was comparable to conventional PCR assay in terms of sensitivity and specificity, but it was more rapid, requiring only ∼30 min for amplification and computer-based data analysis. The presence of vaginal specimens had no detrimental effect on the sensitivity of the PCR with the sample preparation protocol used. All four GBS-positive samples identified by the standard culture method were detected by the two PCR assays. Conclusion: These assays provide promising tools for the rapid detection and identification of GBS.

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