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

Disclosures

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

In This Article

Discussion

We developed and demonstrated a CRISPR-based assay that offered short turn-around time and great sensitivity, which makes it a potential rapid, point-of-care assay for intrapartum GBS diagnosis, even in low-resource settings. Debates have occurred over approaches of preventing neonatal diseases caused by GBS infection.[25] However, both of the 2 commonly used conventional strategies (i.e., risk-based screening or late antenatal microbiologic testing) have their own limitations.[3,26] A point-of-care, rapid intrapartum GBS diagnosis at the onset of labor or membrane rupture is highly desired clinically because it would enable more accurate antibiotic prophylaxis and better antimicrobial stewardship.[5] Successful development of such a diagnostic has been hindered by its requirement for a combination of short turn-around time, high diagnostic performance, low technical complexity, and low instrument requirement. In our study, we took advantage of the programmable CRISPR/Cas system for GBS detection. The CRISPR-GBS assay as established and demonstrated in our study takes <1.5 hours to complete, has a sensitivity comparable to enriched culture, and does not require any sophisticated instruments. These features illustrate its great potential to be an onsite, rapid diagnostic for intrapartum GBS screening. Given the low complexity of the CRISPR-GBS assay established in our study, integration of the entire testing into a compact desktop instrument for an automated sample-in-report-out assay is highly feasible.

In our prospective study, we found the prevalence of GBS in our cohort to be slightly higher than 20% by CRIPSR. Although studies have shown differential prevalence between rectal and vaginal screening, the question of whether this could be caused by a lack of assay sensitivity for detecting borderline bacterial level remains controversial.[1,24,27] In current clinical practice, vaginal–rectal swab specimens are commonly collected for optimized GBS detection, despite reported discomfort or even pain associated with rectal swabs.[28,29] Determining whether patients could be spared the discomfort of rectal specimens without compromising the results with a more sensitive assay would be worthwhile. With this sensitive and rapid CRISPR assay, further studies are also warranted to evaluate its diagnostic and clinical value as an intrapartum assay by comparing it to antepartum culture.[30]

Apart from GBS diagnosis, obtaining the information on drug susceptibility is also of great clinical value. For instance, recent reports have showed a trend of increased erythromycin and clindamycin resistance internationally.[31–33] Genotypic analysis has been proven to have great predictive value for drug resistance. Given the highly sensitive nature of this CRISPR diagnostic technology, it holds the potential to simultaneously detect genes related to drug susceptibility.[34] An expanded CRISPR-GBS assay would be able to not only diagnose GBS colonization but also provide genetic insight into drug susceptibility for first-line antibiotics. On the basis of the proof-of-principle demonstrated in our study for direct-from-swab testing, rapid CRISPR detection of both pathogen and drug sensitivities would permit the precise approach to identification of GBS colonization and prevention of related neonatal diseases.

Because GBS is an important infection agent for multiple invasive infectious diseases such as meningitis, CRISPR-GBS could also be a promising tool for potentially much wider applications. A future multicenter study with a larger cohort would provide a more thorough evaluation of its diagnostic value, including its performance under different clinical settings.

In summary, the CRISPR-based rapid GBS assay we established in this study exhibits great diagnostic performance for GBS colonization under analytical and clinical settings. This novel test offers improved diagnostic performance over culture- and PCR-based assays and represents a novel option for potential rapid, point-of-care GBS screening.

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