(89 days)
The Prodesse® ProGastro SSCS Assav is a multiplex real time PCR in vitro diagnostic test for the qualitative detection and differentiation of Salmonella, Shigella, and Campylobacter (C. jejimi and C. coli only, undifferentiated) nucleic acids and Shiga Toxin 1 (stxl) and Shiga Toxin 2 (stx2) genes. Shiga toxin producing E. coli (STEC) typically harbor one or both genes that encode for Shiga Toxins I and 2. Nucleic acids are isolated and purified from preserved stool specimens obtained from symptomatic patients exhibiting signs and symptoms of gastroenteritis. This test is intended for use, in conjunction with clinical presentation and epidemiological risk factors, as an aid in the differential diagnosis of Salmonella, Shigella, Campylobacter jejuni/Campylobacter coli, and STEC infections in humans.
The results of this test should not be used as the sole basis for diagnosis, treatment, or other patient management decisions. Positive results do not rule out co-infection with other organisms that are are not detected by this test, and may not be the sole or definitive cause of patient illness. Negative ProGastro SSCS Assay results in the setting of clinical illness compatible with gastroenteritis may be due to infection by pathogens that are not detected by this test or non-infectious causes such as ulcerative colitis, irritable bowel syndrome, or Crohn's disease.
The ProGastro SSCS Assay enables detection and differentiation of Salmonella, Shigella, Campylobacter (C. jejuni and C. coli only, undifferentiated) and an Internal Control in the SSC Mix and Shiga Toxin Producing E. coli (STEC, stx1 and stx2 differentiated) and an Internal Control in the STEC Mix.
An overview of the procedure is as follows:
-
- Collect raw stool specimens from symptomatic patients and place into Cary Blair Transport Medium or ParaPak C&S (C&S) Transport Medium .
-
- Add the Gastro RNA/DNA Internal Control (GIC) to every sample to monitor for inhibitors present in the specimens.
-
- Perform isolation and purification of nucleic acids using a NucliSENS easyMAG System and the Automated Magnetic Extraction Reagents (bioMérieux).
-
- Add purified nucleic acids to the SSC Mix included in the ProGastro SSCS Assay Kit. The SSC Mix contains target-specific oligonucleotide primers and probes for detection of Salmonella, Shigella, and Campylobacter (C. jejuni and C. coli only). The primers and probes are complementary to highly conserved regions of genetic sequences for these organisms. The probes are dual-labeled with a reporter dye and a quencher (see table below).
-
- Add purified nucleic acids to the STEC Mix included in the ProGastro SSCS Assay Kit. The STEC Mix contains target-specific oligonucleotide primers and probes for detection of Shiga Toxin 1 and 2 genes (stxl and stx2). The primers and probes are complementary to highly conserved regions of these genes. The probes are dual-labeled with a reporter dye and a quencher (see table below).
-
- Perform amplification of DNA in a Cepheid SmartCycler II instrument. In this process, the probe anneals specifically to the template followed by primer extension and amplification. The ProGastro SSCS Assay is based on Tagman reagent chemistry, which utilizes the 5' - 3' exonuclease activity of Taq polymerase to cleave the probe thus separating the reporter dye from the quencher. This generates an increase in fluorescent signal upon excitation from a light source. With each cycle, additional reporter dye molecules are cleaved from their respective probes, further increasing fluorescent signal. The amount of fluorescence at any given cycle is dependent on the amount of amplification products present at that time. Fluorescent intensity is monitored during each PCR cycle by the real-time instrument.
Here's a breakdown of the acceptance criteria and study information for the ProGastro SSCS Assay:
The document provided details the clinical performance and analytical performance (reproducibility and precision) of the ProGastro SSCS Assay. The primary acceptance criteria for clinical performance are presented as Sensitivity, Specificity, Positive Percent Agreement (PPA), and Negative Percent Agreement (NPA). For analytical performance, it focuses on the agreement with expected results and the Coefficient of Variation (CV) for Ct values.
1. Table of Acceptance Criteria and Reported Device Performance
Clinical Performance (Prospective Study):
| Target | Acceptance Criteria (Implicit from Context) | Reported Device Performance (95% CI) |
|---|---|---|
| Campylobacter | High Sensitivity & Specificity | Sensitivity 100.0% (83.9% - 100.0%) |
| (C. jejuni / C. coli) | Specificity 98.8% (98.0% - 99.3%) | |
| Salmonella | High Sensitivity & Specificity | Sensitivity 95.2% (77.3% - 99.2%) |
| Specificity 99.1% (98.4% - 99.5%) | ||
| Shigella | High Sensitivity & Specificity | Sensitivity 100.0% (79.6% - 100.0%) |
| Specificity 99.5% (98.8% - 99.8%) | ||
| STEC | High Sensitivity & Specificity | Sensitivity 100.0% (70.1% - 100.0%) |
| Specificity 99.2% (98.5% - 99.6%) | ||
| stx1 (Shiga Toxin 1) | High PPA & NPA | PPA 100.0% (67.6% - 100.0%) |
| NPA 40.0% (16.8% - 68.7%) | ||
| stx2 (Shiga Toxin 2) | High PPA & NPA | PPA 100.0% (43.9% - 100.0%) |
| NPA 80.0% (54.8% - 93.0%) |
Clinical Performance (Retrospective Study):
| Target | Acceptance Criteria (Implicit from Context) | Reported Device Performance (95% CI) |
|---|---|---|
| Campylobacter | High PPA & NPA | PPA 96.4% (82.3% - 99.4%) |
| NPA 93.5% (85.7% - 97.2%) | ||
| Salmonella | High PPA & NPA | PPA 100.0% (43.4% - 100.0%) |
| NPA 100.0% (96.4% - 100.0%) | ||
| Shigella | High PPA & NPA | PPA 100.0% (51.0% - 100.0%) |
| NPA 100.0% (96.3% - 100.0%) | ||
| STEC | High PPA & NPA | PPA 100.0% (83.2% - 100.0%) |
| (Overall) | NPA 100.0% (95.7% - 100.0%) | |
| stx1 | High PPA & NPA | PPA 100.0% (78.5% - 100.0%) |
| NPA 100.0% (56.6% - 100.0%) | ||
| stx2 | High PPA & NPA | PPA 100.0% (78.5% - 100.0%) |
| NPA 100.0% (56.6% - 100.0%) |
Reproducibility (Across 3 Sites, 2 Operators/Site, 5 Days - Total 90 runs per condition):
| Target Condition | Acceptance Criteria (Implicit: High agreement, Low CV) | Reported Device Performance (Overall Agreement) | Overall Mean Ct Value | Overall % CV |
|---|---|---|---|---|
| C. jejuni Low Positive | Agreement > 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV 95%, CV |
§ 866.3990 Gastrointestinal microorganism multiplex nucleic acid-based assay.
(a)
Identification. A gastrointestinal microorganism multiplex nucleic acid-based assay is a qualitativein vitro diagnostic device intended to simultaneously detect and identify multiple gastrointestinal microbial nucleic acids extracted from human stool specimens. The device detects specific nucleic acid sequences for organism identification as well as for determining the presence of toxin genes. The detection and identification of a specific gastrointestinal microbial nucleic acid from individuals exhibiting signs and symptoms of gastrointestinal infection aids in the diagnosis of gastrointestinal infection when used in conjunction with clinical evaluation and other laboratory findings. A gastrointestinal microorganism multiplex nucleic acid-based assay also aids in the detection and identification of acute gastroenteritis in the context of outbreaks.(b)
Classification. Class II (special controls). The special controls are set forth in FDA's guideline document entitled: “Class II Special Controls Guideline: Gastrointestinal Microorganism Multiplex Nucleic Acid-Based Assays for Detection and Identification of Microorganisms and Toxin Genes from Human Stool Specimens.” For availability of the guideline document, see § 866.1(e).