Results show excellent clinical performance, sensitivity, specificity, reproducibility, and ease of use
A new publication released in the Journal of Clinical Microbiology reports results of a multisite analysis of the ARIES® GBS Assay. Lead author Diana R. Hernandez from Geisinger, senior author Arundhati Rao from Baylor Scott and White Health, and collaborators issued their findings in the paper entitled “Multicenter Diagnostic Accuracy Evaluation of the Luminex® ARIES® Real-Time PCR Assay for Group B Streptococcus detection in Lim-Enriched samples.”
Nucleic Acid Amplification Tests (NAATs)
As the authors note, mother-to-child transmission of Group B Streptococcus (GBS) and subsequent sepsis is a leading cause of neonatal mortality. Conventional testing with enriched culture is recommended for expectant mothers at 35 to 37 weeks of gestation, but there are challenges to this approach. “The entire protocol has several limitations, including the timing of enrichment to the subjective identification of colonies on [sheep’s blood agar] and the relatively low sensitivity of culture, which ranges from 54 to 90%,” the scientists note.
Nucleic acid amplification tests (NAATs) offer an attractive alternative to culture-based testing, but this approach has not yet overtaken conventional methods even though performance is promising. “It is estimated that using NAAT after enrichment results in 218 fewer cases of early-onset GBS disease per million births, as well as 6 fewer deaths or cases of disability in infants per million births,” the authors write.
Clinical Performance
In this study, the team evaluated the clinical performance of the PCR-based ARIES® GBS Assay, a NAAT that “targets a genomic region downstream from the S. agalactiae cfb gene,” they explain. The analysis involved hundreds of prospective samples collected and tested at TriCore Reference Laboratories in New Mexico, Scott and White Hospital in Texas, and Geisinger Medical Center in Pennsylvania. Results were compared to culture-based testing as well as to other NAATs.
In total, the ARIES® GBS Assay was used to analyze 688 clinical specimens, of which 98% generated valid results on the first try. Of the 14 specimens that did not, 13 generated valid results when re-tested. Agreement between the ARIES® GBS Assay and culture tests “was 92.3% with a sensitivity and specificity of 96.1% and 91.4%, respectively,” the authors report. For the 53 samples with discordant results, bidirectional sequencing determined that 47 were consistent with the ARIES® result, not the culture result. Additionally, the authors found that the ARIES® GBS Assay performance was comparable to other NAATs. Finally, the assay had excellent specificity, showing no cross-reactivity to more than 100 microbes tested or to contaminants often found in GBS samples.
Scientists also performed a reproducibility study, which demonstrated “that the ARIES® GBS assay has excellent inter- and intra-laboratory reproducibility regardless of instrument, module or technician processing the samples,” they report. Setup for the assay takes less than five minutes, with results generated in two hours.
“The ARIES® GBS Assay is a sensitive, specific, and precise NAAT for GBS screening in pre-term women,” the authors conclude. “Its ease of use, short tech and turnaround-time, and scalability make it a suitable option for use in either small community hospitals or large healthcare systems.”
Related Content
- White Paper: Diagnostic and Treatment Challenges for Mycoplasma genitalium — [White Paper]
- Emerging pathogens and antibiotic resistance make STIs an urgent challenge — [MLO Online]
- Testing Gaps Remain in Addressing GBS Infections Among Infants — [MLO Online]
- Help Save a Baby by Spreading the Word About GBS — [Blog]
- ARIES® GBS Assay Product Information — [Web Page]
