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Gastrointestinal Pathogen Panel (GPP) PCR (10 results)

Test Code: 67008

Cpt Code:

87506 (x1)

Clinical Utility

The xTAG® Gastrointestinal Pathogen Panel (GPP) is a multiplexed nucleic acid test intended for the simultaneous qualitative detection and identification of multiple viral, parasitic, and bacterial nucleic acids in human stool specimens from individuals with signs and symptoms of infectious colitis or gastroenteritis. The detection and identification of 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, laboratory findings, and epidemiological information. A gastrointestinal microorganism multiplex nucleic acid-based assay also aids in the detection and identification of acute gastroenteritis in the context of outbreaks.

Procedure

Nucleic acid is extracted from the specimen, which undergoes reverse transcription to generate complementary DNA (cDNA). The target cDNA is amplified using polymerase chain reaction (PCR), then analyzed with Luminex® xTag® technology to detect the presence or absence of each pathogen in the panel. This test has not been cleared or approved for diagnostic use by the U.S. Food and Drug Administration.

Specificity

Detects 10 Gastrointestinal Pathogen targets: Campylobacter (C. jejuni, C. coli and C. lari only), Cryptosporidium (C. parvum and C. hominis only), Escherichia coli O157, Enterotoxigenic Escherichia coli (ETEC) LT/ST, Giardia (G. lamblia only, also known as G. intestinalis and G. duodenalis), Norovirus GI/GII, Rotavirus A, Salmonella, Shiga Toxin-producing Escherichia coli (STEC) stx1/stx2, and Shigella (S. boydii, S. sonnei, S. flexneri and S. dysenteriae).

Assay Range

Qualitative (Positive, Not Detected) for: Campylobacter, Cryptosporidium, Escherichia coli O157, Enterotoxigenic Escherichia coli (ETEC), Giardia lamblia (also known as G. intestinalis and G. duodenalis), Norovirus GI/GII, Rotavirus A, Salmonella, Shiga Toxin-producing Escherichia coli (STEC), and Shigella.

Assay Limitations

1. Positive results obtained using the xTAG GPP assay are presumptive and must be confirmed with an FDA cleared or approved test or other acceptable reference method. All results should be used and interpreted in the context of a full clinical evaluation as an aid in the diagnosis of gastrointestinal infection.

a. There is a risk of false positive values resulting from cross-contamination by target organisms, their nucleic acids or amplified product.

b. There is a risk of false positive values resulting from non-specific signals in the assay.

2. Analyte targets (virus, bacteria or parasite nucleic acid sequences) may persist in vivo, independent of virus, bacteria or parasite viability. Detection of analyte target(s) does not guarantee that the corresponding live organism(s) is present, or that the corresponding organism(s) is the causative agent for clinical symptoms.

3. As with any hybridization-based assay, underlying polymorphisms in primer-binding regions can affect the targets being detected and subsequently the calls made.

4. Campylobacter: the xTAG GPP assay was designed to detect C. jejuni, C. coli and C. lari; however, some strains of Campylobacter fetus subsp. fetus may be detected, (Campylobacter fetus subsp. fetus (NCTC 10842, type strain [ATCC 27374]) at a concentration of 6 x108 cfu/mL resulted in a positive call for Campylobacter).

5. Escherichia coli (Migula) Castellani and Chalmers strain CDC EDL 1284 [929-78] (serotype O124:NM [ATCC 43893]) (enteroinvasive) resulted in a positive call for Shigella.

6. Cryptosporidium: the xTAG GPP assay detects C. parvum and C. hominis only.

7. Giardia: xTAG GPP assay detects G. lamblia only (also known as G. intestinalis and G. duodenalis).

8. Primers for Shigella are expected to cross-react with enteroinvasive E. coli (EIEC) and Salmonella subterranean (at a concentration of 6 x 108 cfu/mL). Enteroinvasive E. coli (strain CDC EDL 1284 [929-78], serotype O124:NM) cross-reacting with Shigella in the xTAG GPP kit is expected as EIEC is genetically, biochemically and physiologically closely related to Shigella. EIEC strains possess some of the biochemical characteristics of E. coli, but some strains can cause dysentery using the same method of invasion used by Shigella. Both Shigella and EIEC can be separated from other E. coli by PCR targeting the invasion plasmid antigen H (ipaH) gene. However, PCR alone cannot distinguish between Shigella from EIEC. Additional physiological and biochemical typing, and serological typing must be used in combination with the ipaH gene PCR to distinguish between Shigella and EIEC. EIEC also causes diarrhea predominantly in tropical countries with occasional cases reported in the US.

9. There is a risk of false negative values due to the presence of strain/species sequence variability in the targets of the assay, procedural errors, amplification inhibitors in specimens, or inadequate numbers of organisms for amplification.

10. A target call of STEC stx1/stx2 may be from either Shigella dysenteriae or from STEC.

11. The performance of this test has not been established for monitoring treatment of infection with any of the panel organisms.

12. Positive and negative predictive values are highly dependent on prevalence. False negative test results are more likely prevalent when disease is high. False positive test results are more likely during periods when prevalence is low.

13. This test is a qualitative test and does not provide the quantitative value of detected organism present.

 

Causes For Rejection

Specimens beyond their acceptable length of time from collection as listed in the specimen handling, or specimen types other than those listed.

Turnaround Time

Same day (within 12 to 18 hours of receiving specimen), Monday through Saturday.

Shipping

Ship Monday through Friday. Friday shipments must be labeled for Saturday delivery. All specimens must be labeled with patient's name and collection date. A Viracor-IBT test requisition form must accompany each specimen. Multiple tests can be run on one specimen. Ship specimens FedEx Priority Overnight® to: Viracor-IBT Laboratories, 1001 NW Technology Dr, Lee's Summit, MO 64086.

Specimen Information

fecal

NY approved. Collect small amount of fecal material (size of pea, or 2 mL liquid stool) and place into screw top tube for shipment. Store frozen and ship on dry ice for overnight delivery to Viracor-IBT.

Disclaimer

Specimens are approved for testing in New York only when indicated in the Specimen Information field above. The CPT codes provided are based on Viracor-IBT's interpretation of the American Medical Association's Current Procedural Terminology (CPT) codes and are provided for informational purposes only. CPT coding is the sole responsibility of the billing party. Questions regarding coding should be addressed to your local Medicare carrier. Viracor-IBT assumes no responsibility for billing errors due to reliance on the CPT codes illustrated in this material.

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