CRISPR/Cas12a-based assay for the rapid and high-sensitivity detection of Streptococcus agalactiae colonization in pregnant women with premature rupture of membrane

BACKGROUND

Streptococcus agalactiae or group B Streptococcus (GBS) is a leading infectious cause of neonatal morbidity and mortality. It is essential to establish a robust method for the rapid and ultra-sensitive detection of GBS in pregnant women with premature rupture of membrane (PROM).

METHODS

This study developed a CRISPR-GBS assay that combined the advantages of the recombinase polymerase amplification (RPA) and CRISPR/Cas12a system for GBS detection. The clinical performance of the CRISPR-GBS assay was assessed using vaginal or cervical swabs that were collected from 179 pregnant women with PROM, compared in parallel to culture-based matrix-assisted laser desorption ionization time-of-flight mass spectrometry (culture-MS) method and real-time quantitative polymerase chain reaction (qPCR) assay.

RESULTS

The CRISPR-GBS assay can be completed within 35 min and the limit of detection was as low as 5 copies μL^-1. Compared with the culture-MS, the CRISPR-GBS assay demonstrated a sensitivity of 96.64% (144/149, 95% confidence interval [CI] 92.39-98.56%) and a specificity of 100% (30/30, 95% CI  88.65-100%). It also had a high concordance rate of 98.88% with the qPCR assay.

CONCLUSIONS

The established CRISPR-GBS platform can detect GBS in a rapid, accurate, easy-to-operate, and cost-efficient manner. It offered a promising tool for the intrapartum screening of GBS colonization.

Evaluation of the Revogene® GBS DS assay performance for the intrapartum screening of group B streptococcus in comparison with intrapartum culture

Prevention of perinatal Group B Streptococcus (GBS) transmission is crucial in our effort to prevent Early-onset GBS disease. Here, we established the performance of the Revogene GBS DS assay for the detection of group B streptococcus on intrapartum vaginal samples in a laboratory environment using a prospective noninterventional study design. Intrapartum vaginal swabs were enriched using a selective culture method which served as study reference method. Overall, 119 patients were enrolled with an antenatal and intrapartum Group B Streptococcus colonization prevalence of 12.9% and 11.8%, respectively. Compared to intrapartum culture, the Revogene GBS DS assay had a sensitivity of 92.9% and a specificity of 99.1%, while the antenatal culture displayed a sensitivity 78.6% of and specificity of 96.2%. The Revogene GBS DS assay displayed an acceptable performance according to the European Group B Streptococcus consensus recommendations. Complementary studies in clinical practice are needed to confirm these findings.

Prevalence of group B streptococcus anogenital colonization and feasibility of an intrapartum screening and antibiotic prophylaxis protocol in Cameroon, Africa

OBJECTIVE

To evaluate group B streptococcus (GBS) colonization prevalence and feasibility of intrapartum GBS screening/antibiotic prophylaxis (IAP) in Cameroon, Africa.

METHODS

Prospective cohort in the Cameroon Baptist Convention Health Services network. Maternity providers collected anogenital swabs from consenting term women in labor for testing by a rapid GBS-polymerase chain reaction (PCR) system. Positive tests (GBS+) resulted in initiation of intravenous ampicillin until delivery. Primary outcomes were GBS prevalence and proportion of GBS+ women receiving ampicillin before delivery and more than 4 hours before delivery.

RESULTS

A total of 219 women were enrolled from January 10 to April 27, 2017. GBS prevalence was 12.3% (95% confidence interval [CI] 7.9-16.7) with GBS+ women more likely to reside in urban areas (19.6% vs 9.7%, P=0.004). Of 27 GBS+ women, 19 (70.4%) received ampicillin before delivery and 14 (51.9%) 4 hours or longer before delivery. A median two doses of ampicillin (interquartile range [IQR] 1-5) were given and started at a median of 105 minutes (IQR 90-155) after swab collection and 20 minutes (IQR 10-45) after GBS result. Of the 8 women who did not receive ampicillin, 7 (87.5%) delivered before test results.

CONCLUSION

A GBS IAP protocol is feasible in Cameroon and should be evaluated for widespread implementation in Cameroon and other low-income countries to decrease GBS-related morbidity.