Rapid Molecular Assay Detects Bacteria in Antenatal Samples

A diagnostic test rapidly reveals DNA of Group B Streptococcus bacteria (GBS) in enrichment media far quicker than traditional culture methods.

A fully automated in vitro diagnostic method (IVD) detects the gram-positive GBS in selective enrichment broth by the polymerase chain reaction (PCR) and takes just over an hour. GBS is also known as Streptococcus agalactiae.

The assay is designed for use with vaginal or rectal swabs specimens from antepartum pregnant women. The assay, called the BD MAX GBS is performed on the BD MAX system that fully-automates cell lysis, nucleic acid extraction, PCR set-up, amplification, and detection. Screening of vaginal/rectal swabs late in gestation can detect women who are likely to be colonized with GBS at the time of delivery. Clinical data support prevention of early onset GBS disease with antibiotics administered during labor and delivery to mothers who are colonized with GBS.

BD Diagnostics, (La Jolla, CA, USA) manufacture the assay and the system. The assay represents a "significant advance” in neonatal healthcare by streamlining the GBS screening process and addressing the limitations of culture methods, according to a statement issued by the company. The current standard for preventing GBS infection is to screen women at 35 to 37 weeks gestation using culture methods, which can be limited by sensitivity, turnaround time, and the need for highly trained technologists to interpret the results.

In contrast, the BD MAX GBS assay identifies GBS in just over an hour from Lim broth. There is a built-in process control for each sample with a two minutes hands-on time per sample. In addition, by automating sample lysis through PCR detection, the BD MAX System offers walkaway convenience for up to 24 samples in approximately two-and-a-half hours. The U.S. Food and Drug Administration (FDA; Rockville, MD, USA), has cleared the BD MAX GBS assay for marketing.

GBS remains one of the leading infectious causes of morbidity and mortality among newborns. Maternal colonization with GBS is a major risk factor for early-onset of the disease in infants. GBS colonized women are more than 25 times more likely to deliver infants with early-onset GBS disease. GBS causes severe, invasive disease in young infants, including sepsis, meningitis, and pneumonia. The mortality rate of babies that are infected with GBS is as high as 20%.

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