Development and Clinical Evaluation of a CRISPR-Based Diagnostic for Rapid Group B Streptococcus Screening

Lingxiao Jiang; Weiqi Zeng; Wanting Wu; Yingying Deng; Fusheng He; Wenli Liang; Mingyao Huang; Hong Huang; Yongjun Li; Xiaorui Wang; Hang Su; Shilei Pan; Teng Xu


Emerging Infectious Diseases. 2021;27(9):2379-2388. 

In This Article

Abstract and Introduction


Vertical transmission of group B Streptococcus (GBS) is among the leading causes of neonatal illness and death. Colonization with GBS usually is screened weeks before delivery during pregnancy, on the basis of which preventive measures, such as antibiotic prophylaxis, were taken. However, the accuracy of such an antenatal screening strategy has been questionable because of the intermittent nature of GBS carriage. We developed a simple-to-use, rapid, CRISPR-based assay for GBS detection. We conducted studies in a prospective cohort of 412 pregnant women and a retrospective validation cohort to evaluate its diagnostic performance. We demonstrated that CRISPR-GBS is highly sensitive and offered shorter turnaround times and lower instrument demands than PCR-based assays. This novel GBS test exhibited an overall improved diagnostic performance over culture and PCR-based assays and represents a novel diagnostic for potential rapid, point-of-care GBS screening.


Group B Streptococcus (GBS) is a common commensal bacteria of vaginal flora with reported carriage rates of 4%–40%.[1–3] Vertical transmission of (GBS) through fetal aspiration of infected amniotic fluid or during birth canal passage has been considered one of the most important causes of neonatal illness and death.[3,4] GBS colonization during pregnancy has been a leading cause of severe neonatal infectious diseases, including sepsis, pneumonia, and meningitis.[5,6] Early onset neonatal infections can be prevented in most cases by providing intrapartum antibiotic prophylaxis to the colonized mother.[7] However, GBS carriages are often intermittent, and the rate of GBS colonization varies during pregnancy.[1,8] On the other hand, use of antibiotic prophylaxis solely relying on risk assessment leads to unnecessary treatment in many women. Therefore, determination of colonization at the time of delivery is crucial for the prevention of neonatal infection.[9]

Culture-based methods remain the most commonly used screening practice and the standard for GBS detection; however, because of technical limitations, including turnaround time, pregnant women are usually screened for GBS at 35–37 weeks of gestation.[6] As many studies have pointed out, the predictive value of GBS decreases as the interval time increases between screening and delivery.[10,11] These studies underlie the needs for a more rapid and sensitive diagnostic for intrapartum GBS screening.

CRISPR/Cas has been widely used as a programmable tool for gene editing and other in vivo applications since 2013.[12–14] However, recently, the collateral, promiscuous cleavage activities of a unique group of Cas enzymes were discovered and harnessed for in vitro nucleic acid detection.[15–17]

To address the unmet clinical needs for GBS screening, we developed CRISPR-GBS, a novel CRISPR/Cas13-based in vitro diagnostic assay, and conducted a prospective cohort study and a validation study in >400 clinical cases to evaluate its diagnostic performance among different technology platforms, including culture and PCR-based methods. Our findings demonstrate that CRISPR-GBS is rapid and easy-to-use, having a low instrument requirement and a level of sensitivity that surpasses PCR-based assays.