(194 days)
The Immunocard STAT! STEC O157 is a rapid test for the detection of antigens from shiga toxin producing E. coli O157 as an aid in the diagnosis of E. coli O157:H7 infection. The test can be used to directly test stool specimens, or confirmatory stool cultures grown in MacConkey broth or sorbitol MacConkey (SMAC) plates.
Stool or culture material are prepared / diluted and added to the sample port of the device. The sample mobilizes gold particles, coated with monoclonal antibody specific for the O157 lipopolysacchride, and migrates along the membrane through the Test and Control zones. The test zone contains immobilized monoclodal antibody specific for an epitope common to shiga toxin producing E. coli. After ten minutes the Test and Control zones are observed for the presence of red/purple lines across the membrane surface. If a shiga toxin producing E. coli O157 is present in the sample, a complex is formed between the capture antibody, the shiga toxin producing E. coli O157, and the monoclonal antibody-gold conjugate which can be seen visually as a red/purple line in the Test zone. No red/purple line in the Test zone indicates a negative result. The Control line serves as a procedural control, to assure that the sample has migrated the appropriate distance along the membrane.
This document describes the ImmunoCard STAT! STEC O157 device, a rapid test for detecting E. coli O157 antigens.
Here's an analysis of its acceptance criteria and the study performance:
1. Table of Acceptance Criteria and Reported Device Performance:
The document doesn't explicitly state "acceptance criteria" for the ImmunoCard STAT! STEC O157. However, it presents the performance of the device in comparison to a predicate device (E. coli O157 Elisa Stool Assay), which implies these performance metrics are considered acceptable for market clearance. The key performance metrics are Sensitivity and Specificity for stool samples.
| Metric | Acceptance Criteria (Implied) | Reported Device Performance (ImmunoCard STAT! STEC O157) |
|---|---|---|
| Sensitivity | Not explicitly stated but expected to be comparable to predicate or acceptable for diagnostic aid | 82% (for Stool specimens) |
| Specificity | Not explicitly stated but expected to be comparable to predicate or acceptable for diagnostic aid | 99% (for Stool specimens) |
Note: The document also lists performance for the predicate device across various sample types including formalinized stool, MacConkey broth, and SMAC plates (100% Sensitivity, 99-100% Specificity), but these are for the predicate and not the ImmunoCard explicitly across all those sample types in the summary table.
2. Sample Size Used for the Test Set and Data Provenance:
- Sample Size: The document does not explicitly state the sample size used for the clinical test set evaluating the ImmunoCard STAT! STEC O157.
- Data Provenance: The document does not specify the country of origin of the data or whether the study was retrospective or prospective. It only mentions "patient stool" in the intended use and comparison tables.
3. Number of Experts Used to Establish Ground Truth and Qualifications:
The document does not provide information on the number of experts used or their qualifications for establishing the ground truth of the test set.
4. Adjudication Method for the Test Set:
The document does not describe any adjudication method (e.g., 2+1, 3+1, none) used for the test set.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This device is a manual, visually read lateral flow immunoassay. Its interpretation is straightforward (presence or absence of a line). Therefore, a study focusing on inter-reader variability or the improvement of human readers with AI assistance would not be applicable.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study:
Yes, the study primarily describes the standalone performance of the device. The ImmunoCard STAT! STEC O157 is a rapid test that provides a visual reading (red/purple line) after ten minutes, interpreted by a laboratory technician without any algorithmic or AI involvement. The reported sensitivity and specificity are for this standalone operation.
7. Type of Ground Truth Used:
The document doesn't explicitly state the exact "ground truth" method used for the clinical study. However, given that it's a diagnostic test for E. coli O157 and the comparison to "culture" is mentioned (in the statement "The safety and effectiveness of both assays are both substantially equivalent when compared to culture"), it is highly probable that bacteriological culture was used as the gold standard for confirming the presence or absence of E. coli O157 in patient stool samples.
8. Sample Size for the Training Set:
The document does not provide information on a "training set" sample size. This type of device (lateral flow immunoassay) typically does not involve machine learning algorithms that require a distinct training set. Its development involves optimizing chemical and biological components, not training a model on data in the conventional sense.
9. How the Ground Truth for the Training Set Was Established:
As there is no mention of a training set for a machine learning model, there is no information on how its ground truth was established. The development of such a diagnostic test relies on fundamental microbiology, immunology, and chemistry principles, not data-driven model training.
§ 866.3255
Escherichia coli serological reagents.(a)
Identification. Escherichia coli serological reagents are devices that consist of antigens and antisera used in serological tests to identifyEscherichia coli from cultured isolates derived from clinical specimens. Additionally, some of these reagents consist ofEscherichia coli antisera conjugated with a fluorescent dye used to identifyEscherichia coli directly from clinical specimens or cultured isolates derived from clinical specimens. The identification aids in the diagnosis of diseases caused by this bacterium belonging to the genusEscherichia, and provides epidemiological information on diseases caused by this microorganism. AlthoughEscherichia coli constitutes the greater part of the microorganisms found in the intestinal tract in humans and is usually nonpathogenic, those strains which are pathogenic may cause urinary tract infections or epidemic diarrheal disease, especially in children.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 866.9.