(141 days)
REMEL's Xpect™ Cryptosporidium kit is an in vitro qualitative immunoassay for the detection of Cryptosporidium antigens in preserved and unpreserved fecal specimens. This test is intended as an aid in the laboratory diagnosis of suspected Cryptosporidium infections.
The Xpect™ Cryptosporidium Lateral Flow Assay is a chromatographic immunoassay that detects the presence of Cryptosporidium antigen. The test utilizes sample wicking to capture Cryptosporidium antigen on a test line containing antigen-specific antibody. A specimen is added to a dilution tube containing a buffered solution. A conjugate containing colored micro-particles linked to murine monoclonal antibody specific for Cryptosporidium is added. The mixture is dispensed into the sample well of the device and wicks along a membrane containing capture antibody stripes. The Cryptosporidium immune complex, if present, reacts with anti-Cryptosporidium antibody at the test line. Conjugate not bound at the test line is later captured at the control line containing anti-mouse antibody. A red line of any intensity will appear at the Cryptosporidium test position if Cryptosporidium antigen is present. A line in the Control position indicates that the test is working properly.
Here's a summary of the acceptance criteria and study details for the Xpect™ Cryptosporidium Lateral Flow Assay, based on the provided 510(k) notification:
Acceptance Criteria and Device Performance
| Acceptance Criteria Category | Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Sensitivity | Not explicitly stated (implied to be high enough for clinical utility relative to microscopy) | 96.4% (95% CI: 91.2-98.6%) |
| Specificity | Not explicitly stated (implied to be high enough for clinical utility relative to microscopy) | 98.3% (95% CI: 96.6-99.1%) |
| Cross-Reactivity | No cross-reactivity with common intestinal parasites and bacteria. | No cross-reactivity observed with 24 specified organisms, including Ascaris lumbricoides, Blastocystis hominis, Campylobacter coli, Giardia lamblia, and others. |
| Interfering Substances | No interference with common substances (blood, mucin, fecal fat) and anti-diarrheal products. | No interference observed with blood, mucin, fecal fat, Pepto-Bismol®, and Kaopectate®. Interference observed with Imodium® A-D at 20% (v/v) for low levels of Cryptosporidium antigen. |
| Reproducibility | Consistent results across different sites and days. | 100% agreement with expected results for 630 samples tested across seven sites (including one in-house site) over three days. |
| Percent Agreement vs. Microscopy (for comparison with predicate) | Not explicitly stated, but typically a high percentage agreement is expected. | 94.5% for Xpect™ Cryptosporidium (vs. microscopy), 84.9% for Predicate Device (vs. microscopy) |
Study Details
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Sample sizes used for the test set and data provenance:
- Sensitivity/Specificity Study:
- Total Samples: 578 (112 positive for Cryptosporidium by microscopy, 466 negative by microscopy).
- Provenance: Not explicitly stated regarding country of origin; the study was conducted at "six geographically diverse laboratories" (implying multiple sites within a country or potentially internationally), and data was retrospective (compared to microscopy, which would have been performed on collected samples).
- Percent Agreement Study (Comparison with Predicate):
- Total Samples: 146 (30 positive for Cryptosporidium by microscopy, 116 negative by microscopy).
- Provenance: Not explicitly stated regarding country of origin or retrospective/prospective nature.
- Sensitivity/Specificity Study:
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Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- The ground truth for the test set was established by microscopy. The document does not specify the number of experts (e.g., microscopists) involved in reading these slides or their qualifications. It's common in diagnostic studies for the comparator method (like microscopy) to be performed by qualified laboratory personnel, but this detail is not provided.
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Adjudication method for the test set:
- The document does not specify any formal adjudication method for the microscopy results that served as the ground truth. It simply states the comparison was "to microscopy."
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If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- No, an MRMC comparative effectiveness study was not done. This device is a standalone in vitro diagnostic (IVD) lateral flow assay, not an AI or imaging device designed to assist human readers.
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If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes, this was a standalone performance study. The Xpect™ Cryptosporidium Lateral Flow Assay is an "algorithm-only" in the sense that it provides a direct qualitative result (presence/absence of a line) without human interpretation beyond reading the line. The presented sensitivity and specificity values represent the performance of the device itself.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- The primary ground truth used was microscopy (specifically, for detection of Cryptosporidium).
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The sample size for the training set:
- The document does not provide information regarding a separate training set for algorithm development. As this is a lateral flow immunoassay, not an AI or machine learning model, a distinct "training set" in the context of data-driven algorithm development is typically not applicable. The assay's performance characteristics are inherent to its design and manufacturing.
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How the ground truth for the training set was established:
- As there's no explicit mention of a training set in the context of algorithm development, this information is not applicable to this device. Early development and optimization of the assay would involve various characterized positive and negative samples, but these are not typically referred to as a "training set" in the same way as for AI.
§ 866.3220
Entamoeba histolytica serological reagents.(a)
Identification. Entamoeba histolytica serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies toEntamoeba histolytica in serum. Additionally, some of these reagents consist of antisera conjugated with a fluorescent dye (immunofluorescent reagents) used to identifyEntamoeba histolytica directly from clinical specimens. The identification aids in the diagnosis of amebiasis caused by the microscopic protozoan parasiteEntamoeba histolytica and provides epidemiological information on diseases caused by this parasite. The parasite may invade the skin, liver, intestines, lungs, and diaphragm, causing disease conditions such as indolent ulcers, an amebic hepatitis, amebic dysentery, and pulmonary lesions.(b)
Classification. Class II (special controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to § 866.9.