Physician

GBS PNA FISH from Lim Broth

For in vitro diagnostic use.

GBS PNA FISH® (Cat. No. KT010) is a qualitative nucleic acid hybridization assay intended for the detection of Streptococcus agalactiae (aka Group B Strep - GBS) from turbid Lim broth cultures obtained from vaginal and rectal swabs of pregnant women between 35 and 37 weeks gestation.

GBS PNA FISH provides rapid identification of S. agalactiae on smears made from Lim broth cultures obtained from vaginal and rectal swabs incubated overnight at 35-37°C. The 1.5 hours fluorescence in situ hybridization (FISH) assay uses fluorescently labeled peptide nucleic acid (PNA) probes that target the species-specific ribosomal RNA (rRNA) of S. agalactiae. Results are visualized using fluorescence microscopy. S. agalactiae is identified as multiple bright green fluorescent cocci in multiple fields of view. The absence of fluorescence indicates a negative result.

Features and Benefits

Results Reporting - Rapid Identification of GBS in Lim Broth

Once a turbid Lim broth culture is obtained, the GBS PNA FISH test is performed and within 90 minutes, results are available and can be reported to the patient’s physician.

According to the US Centers for Disease Control and Prevention (CDC), Group B Strep is the most common cause of neonatal morbidity and mortality. Approximately 1 in 4 pregnant women are colonized with Group B Strep and can transmit the bacterium to the newborn during delivery. To prevent the transmission and subsequent infection, women are routinely screened for colonization between 35 and 37 weeks gestation, and if positive, receive antibiotics at the start of labor to eradicate the bacteria. Accurate detection of Group B Strep colonization is therefore crucial to prevent as many infections as possible. (2)

During the routine laboratory testing process, vaginal and rectal swabs from pregnant women are inoculated into selective enrichment broth, e.g. Lim Broth, and incubate overnight to stimulate the growth of Group B Strep bacteria. A sample is subsequently taken for further culture workup and identification using conventional, phenotypic methods. This process can take anywhere from 3 to 4 days, and while Lim Broth is highly sensitive and selective for Group B Strep, the subsequent workup and phenotypic identification can be time consuming and may miss some true positives due to non-β-hemolytic strains and overgrowth of normal flora that can hide S. agalactiae colonies. (3)

GBS PNA FISH combines the high sensitivity of Lim Broth with the speed, accuracy and ease-of-use of the PNA FISH molecular diagnostic platform to provide accurate Group B Strep detection fit for the routine laboratory workflow. In a recent clinical study, GBS PNA FISH was shown to detect up to 42% more Group B Strep positives than conventional culture methods, as it enables the detection of positives that may be non-β hemolytic or overgrown by normal flora. The authors of the study also found that the test produced results 2 to 3 days faster and concluded that use of the PNA FISH assay for the detection of GBS from Lim broth culture showed an increased sensitivity, required decreased specimen handling, and had a shorter turnaround time than culture. (4) 

As the latest addition to the line of rapid, molecular diagnostic tests from AdvanDx, GBS PNA FISH provides accurate, reliable detection in less than 24 hours and further enables physicians to select appropriate therapy for their patients. 

1. GBS PNA FISH Kit package insert
2. US Centers for Disease Control and Prevention.  Preventing Group B Strep - Link
3. Davies HD, Miller MA, Faro S, Gregson D, Kehl SC, Jordan JA.  Multicenter study of a rapid molecular-based assay for the diagnosis of group B Streptococcus colonization in pregnant women - Link 
4. Montague NS, Cleary TJ, Martinez OV, Procop GW.  Detection of group B streptococci in Lim broth by use of group B streptococcus peptide nucleic acid fluorescent in situ hybridization and selective and nonselective agars – Link

   PN1625A