Polymerase Chain Reaction (PCR) Assays in Amniotic Fluid offer advantages versus culture alone for diagnosis of IAI

Historically microbial culture of AF has been recognized as the “gold standard” for the detection of intraamniotic infection. However, the disadvantage of using a culture-based approach for bacterial identification is it depends on growth conditions favorable to a select group of known microorganisms. Consequently, uncultivated or difficult-to-cultivate bacteria will not be detected by culture alone.¹²

In addition, antibiotic use prior to obtaining amniotic fluid for laboratory testing can result in the inability of culture to detect pathogenic organisms.

Molecular microbiology techniques such as Quantitative Polymerase Chain Reaction (qPCR) and Pyrosequencing can detect microbes independent of culture. These techniques amplify highly conserved gene sequences that allow detection and broad taxonomic identification of pathogenic microorganisms in biological fluids.

Ribosomal RNA is the most conserved and least variable gene in all cells including bacteria. For this reason, genes that encode ribosomal RNA have been used extensively to identify medically important microorganisms such as bacteria and fungi. The 16S and 23S rRNA gene sequences are typically used to identify bacteria species while the corresponding 18S rRNA gene sequences are used to identify fungi.

Numerous investigators have shown that 16S rDNA PCR testing is 30%-50% more sensitive than culture alone in clinical studies using laboratory testing of amniotic fluid to detect intraamniotic infection.¹³

“By using PCR to examine for evidence of microbes, we have confirmed a higher rate of detection of infection associated with spontaneous preterm delivery than detected by standard culture techniques.”

Miralles R, Hodge et al. “Relationship between Antenatal Inflammation and Antenatal Infection Identified by Detection of Microbial Genes by Polymerase Chain Reaction”, Pediatric Research, 2005;57(4):570-577.

“A broad-spectrum bacterial PCR assay may prove to be a useful alternative to culture for the diagnosis of amniotic fluid infection in women in preterm labor.”

Hitti J, et al. “Broad-Spectrum Bacterial Rdna Polymerase Chain Reaction Assay for Detecting Amniotic Fluid Infection Among Women in Premature Labor”, Clinical Infectious Disease, 1997;24(6):1228-1232.

ProteoGenix through the ProteoGenix Clinical Laboratory is the first and only company to offer a commercially available 16S rDNA polymerase chain reaction (PCR) test in amniotic fluid for the detection of bacteria, Mycoplasma and Ureaplasma species DNA to aid in the clinical diagnosis of IAI.

ProteoGenix Offers The First Commercially Available AF PCR Test For Detection Of IAI

The ProteoGenix AF Bacteria/Mycoplasma/Ureaplasma End Point PCR Test uses broad-spectrum PCR assay based on 16S ribosomal DNA to provide a qualitative and sensitive tool for detecting the presence of bacterial/Mycoplasma and Ureaplasma species DNA in amniotic fluid. The ProteoGenix AF End Point PCR test offers the following benefits:

• The ProteoGenix PCR analysis is completed on amniotic fluid, which is not commonly available through the majority of hospital and reference laboratories. This provides an additional option to aid physicians in the detection of IAI.

• ProteoGenix has developed a proprietary specimen collection, transport and preparation system that specifically optimizes the performance of the PCR test in amniotic fluid. This proprietary process improves the accuracy and reproducibility of patient results.
  
  Extraction is a critical step in isolating bacterial DNA. Most extraction techniques utilize “off the shelf” reagents designed for extraction of various types of specimens. ProteoGenix has developed a proprietary extraction process that utilizes specialized reagents to maximize extraction efficiency of the bacterial DNA from amniotic fluid. ProteoGenix has also improved analytical sensitivity and reduced false positive results by optimizing their methods to reduce trace amounts of bacterial DNA found in commercial PCR reagents.

• Demonstrated sensitivity of 100% and specificity of 96% versus bacterial/Mycoplasma and Ureaplasma species in AF culture.

• The ability to detect the most common causative pathogens of IAI; including Mycoplasma and Ureaplasma species that have been shown to be present in 30% to 50% of IAI cases. Tests to detect these pathogens are not commonly available in most laboratories.

• In a clinical study of the diagnosis of IAI in preterm labor patients with intact fetal membranes; the ProteoGenix AF Endpoint PCR test detected microbial pathogens in ~25% more cases than amniotic fluid bacterial and Mycoplasma culture alone.

• The ProteoGenix Amniotic Fluid 16S rDNA by Endpoint PCR for detection of Bacterial/Mycoplasma and Ureaplasma species is available via the CLIA certified ProteoGenix Clinical Laboratory. Please contact (888) 429-7935 for more information.