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The TECHLAB® E. HISTOLYTICA QUIK CHEK™ test is a rapid membrane enzyme immunoassay for the qualitative detection of adhesin from Entamoeba histolytica in a single use cassette. It is intended for use with human fecal specimens from patients with diarrhea or dysentery as an aid in the diagnosis of E. histolytica gastrointestinal infection. Test results should be considered in conjunction with patient history. FOR IN VITRO DIAGNOSTIC USE

The E. HISTOLYTICA QUIK CHEK™ test uses antibodies to adhesin. The device contains a Reaction Window with two vertical lines of immobilized antibodies. The test line ("T") contains monoclonal antibodies specific for E. histolytica adhesin. The control line ("C") contains antibodies to horseradish peroxidase (HRP). The Conjugate consists of polyclonal antibodies to E. histolytica adhesin coupled to horseradish peroxidase. To perform the test, the sample is added to a tube containing a mixture of Diluent and Conjugate. The diluted sample-conjugate mixture is added to the Sample Well and the device is allowed to incubate at room temperature for 15 minutes. During the incubation, E. histolytica adhesin in the samples bind to the antibodyperoxidase conjugate. The antigen-antibody complexes migrate through a filter pad to a membrane where they are captured by the immobilized antibodies in the Reaction Window is subsequently washed with Wash Buffer, and the test is developed with the addition of Substrate. After a 10 minute incubation period, the "T" reaction is examined visually for the appearance of a vertical blue line on the "T" side of the Reaction Window. A blue line indicates a positive test. A positive "C" reaction, indicated by a vertical blue line on the "C" side of the Reaction Window, monitors/confirms that the sample and reagents were added correctly, the reagents were active at the time of performing the assay, and that the sample migrated properly through the Membrane Device. It also confirms the reactivity of the other reagents associated with the assay.

Here's a breakdown of the acceptance criteria and the study that proves the device meets them, based on the provided text:

E. HISTOLYTICA QUIK CHEK™ Performance Study Summary

The E. HISTOLYTICA QUIK CHEK™ test is a rapid membrane enzyme immunoassay for the qualitative detection of adhesin from Entamoeba histolytica in human fecal specimens.

1. Acceptance Criteria and Reported Device Performance

The study compares the E. HISTOLYTICA QUIK CHEK™ test to a Composite Reference Method (CRM). While explicit "acceptance criteria" are not listed in terms of specific sensitivity/specificity thresholds, the overall performance against the CRM demonstrates the device's efficacy. The reported performance for prospective samples, while showing lower sensitivity, is accompanied by 100% specificity and PPV, indicating no false positives in this dataset. The retrospective data shows 100% sensitivity and specificity.

Table 1: Acceptance Criteria (Implied) and Reported Device Performance

Note: The three false-negative results in the prospective study were PCR positive but antigen negative, suggesting a limitation in antigen detection for those specific samples, rather than a lack of E. histolytica presence.

2. Sample Size Used for the Test Set and Data Provenance

• Total Sample Size: 851 fecal samples
  • Prospective Samples: 755
    • Provenance: Not explicitly stated, but collected from "3 independent sites," implying diverse geographical locations likely within the US given the FDA submission. The context suggests these were real-world clinical samples collected over time.
  • Retrospective Samples: 96
    • Provenance: Not explicitly stated, but referred to as "frozen (retrospective) specimens." Likely from archived clinical samples.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications

Not explicitly stated. The ground truth (Composite Reference Method) involves a combination of tests, not directly requiring individual expert interpretation per se, beyond the expertise required to perform and interpret the individual tests (Microscopy, FDA cleared multiplex NAAT test, Alternate PCR with sequencing).

4. Adjudication Method for the Test Set

The adjudication method for the ground truth (Composite Reference Method - CRM) is clearly defined by an algorithm:

For cases where Microscopy and multiplex NAAT were both negative, no further PCR testing was performed, and the CRM result was deemed negative. This is a rule-based adjudication.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not explicitly mentioned as part of this submission. The study focuses on the standalone performance of the device against a Composite Reference Method.

6. Standalone Performance Study

Yes, a standalone performance study was conducted. The E. HISTOLYTICA QUIK CHEK™ test was evaluated as an "algorithm only (without human-in-the-loop performance)" device, as it is an in vitro diagnostic which provides a visual qualitative result that is then interpreted by a user. The performance metrics (sensitivity, specificity, PPV, NPV) presented in Tables 1 and 2 directly reflect this standalone capability, comparing its results directly to the CRM. The "visual" interpretation by a human is part of the intended use, but the analytical performance is solely dependent on the device's output.

7. Type of Ground Truth Used

The primary ground truth used was a Composite Reference Method (CRM). This CRM combined:

1. Microscopy
2. An FDA cleared multiplex NAAT test
3. Alternate PCR with sequencing

This approach aims to establish a more robust and accurate determination of the true E. histolytica infection status than any single method alone.

8. Sample Size for the Training Set

The document does not explicitly state a separate "training set" sample size or a description of model training, as this device is a rapid membrane enzyme immunoassay (a chemical/biological test), not an AI/machine learning algorithm that requires training data in the traditional sense. The document describes analytical and clinical validation, which ensures the device's inherent functional performance.

9. How the Ground Truth for the Training Set Was Established

As noted above, this device is not an AI/ML algorithm requiring a training set in the conventional sense. Therefore, the concept of establishing ground truth for a training set does not apply here. The device's underlying principles are based on antibody-antigen reactions. Its design and development would have involved internal validation and optimization, but not "training" on a dataset in the way an AI model would.

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The E. histolytica II is an enzyme immunoassay for the rapid detection of the adhesin of E. histolytica in human fecal specimens. It is indicated for use with fecal specimens from patients with diarrhea or dysentery to determine the presence of E. histolytica gastrointestinal infection. The test can be used for fecal specimens submitted for routine clinical testing from adults or children. Conventional microscopy is not a routine prerequisite for use of the test. FOR IN VITRO DIAGNOSTIC USE.

The E. histolytica II can be used to detect adhesin (also referred to as galactose-inhibitable lectin) produced by strains of E. histolytica. It does not cross-react with the adhesin from E. dispar (formerly known as nonpathogenic E. histolytica). The test can be used to detect the adhesin in fecal specimens from persons suspected of having amebiasis. The kit, which includes ready-to-use reagents, contains microtiter wells coated with polyclonal antibody, positive control reagent, monoclonal-antibody conjugate, diluent, one component substrate, wash solution, and stop solution. The microtiter wells coated with polyclonal antibody "capture" the adhesin and the monoclonal antibody conjugate serves as the "detecting" antibody. The polyclonal antibody used to coat the wells is prepared from hyperimmune antiserum developed in goats. The monoclonal antibody used to prepare the conjugate is prepared from mouse ascites fluid. The E. histolytica II is to be used in an ELISA format.

Here's an analysis of the acceptance criteria and the study proving the device's performance, based on the provided text:

Device Name: E. histolytica II

1. Table of Acceptance Criteria and Reported Device Performance:

The document explicitly states that "No performance standards have been developed for this device under §514 of the Food, Drug, and Cosmetic Act." Therefore, formal acceptance criteria in terms of specific sensitivity, specificity, or accuracy thresholds are not listed. Instead, the study's goal was to demonstrate substantial equivalence and improved sensitivity compared to a predicate device and a "gold standard."

The reported performance focuses on correlation with the gold standard and improved sensitivity compared to a previous test.

2. Sample Size Used for the Test Set and Data Provenance:

• Sample Size for Test Set: The exact number of stool specimens analyzed in the clinical evaluations is not specified in the provided text. It only states that the E. histolytica II was used to analyze "stool specimens in areas where amebiasis is endemic."
• Data Provenance:
  • Country of Origin: Not explicitly stated, but the phrase "areas where amebiasis is endemic" suggests diverse geographical locations where the disease is prevalent.
  • Retrospective or Prospective: Not explicitly stated. The description "the E. histolytica II was used to analyze stool specimens...and the results were compared with zymodeme analysis...and with the E. histolytica TEST" could imply either retrospective analysis of archived samples or prospective collection. Without further detail, it cannot be definitively determined.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts:

• Number of Experts: Not specified.
• Qualifications of Experts: Not specified. The "zymodeme analysis" is described as being performed in "a select number of clinical laboratories around the world" that are "capable of performing this type of analysis." This implies highly specialized personnel, but specific qualifications are not detailed.

4. Adjudication Method for the Test Set:

• The text does not describe an explicit adjudication method between multiple readers or experts for the test set. The ground truth ("gold standard") was established by "zymodeme analysis." The E. histolytica II results were then compared to this established ground truth, rather than adjudicated by experts confirming the E. histolytica II results.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study was done:

• No, an MRMC comparative effectiveness study involving human readers and AI assistance was not performed. This device is an in-vitro diagnostic (IVD) ELISA kit, not an AI or imaging-based device that would typically involve human readers interpreting results with or without AI assistance. The comparisons are between different diagnostic tests (ELISA kit vs. culture/zymodeme vs. predicate ELISA kit).

6. If a Standalone Study (i.e., algorithm only without human-in-the-loop performance) was done:

• Yes, in spirit, a standalone study was performed. The E. histolytica II kit itself is a standalone diagnostic tool. Its performance (detecting adhesin) was evaluated and compared directly against a "gold standard" (zymodeme analysis) and a predicate device (E. histolytica TEST) without human interpretation steps that would fundamentally alter the E. histolytica II's core measurement. The kit provides a direct result (e.g., color change indicating presence of adhesin).

7. The Type of Ground Truth Used:

• Expert Consensus / Gold Standard: The ground truth used was zymodeme analysis. The document explicitly states, "For the purpose of our studies, zymodeme analysis represents the 'gold standard'." Zymodeme analysis determines if an isolated Entamoeba strain is pathogenic, which is the specific target of the E. histolytica II.

8. The Sample Size for the Training Set:

• Not applicable / Not specified. As this is a traditional ELISA kit rather than a machine learning model, there isn't a "training set" in the conventional AI sense. The development of the antibodies and optimization of the assay would have involved various experimental samples, but these are not referred to as a "training set" in the context of AI.

9. How the Ground Truth for the Training Set was Established:

• Not applicable / Not specified. For an ELISA kit, the "ground truth" for developing the kit involves standard laboratory practices for antigen/antibody characterization, cross-reactivity testing, and determining optimal assay conditions. This would involve known positive and negative samples, purified antigens, and characterized strains, but it's not described as a "training set" with established ground truth in the same way as an AI model. The document mainly describes the components of the kit and its mechanism of action.

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The E. histolytica Test can be used to detect adhesin (also referred to as galactose-inhibitable lectin) produced by strains of E. histolytica. It does not cross-react with the adhesin from E. dispar (formerly known as nonpathogenic E. histolytica). The test can be used to detect the adhesin in fecal specimens from persons suspected of having amebiasis.

The kit, which includes ready-to-use reagents, contains microtiter wells coated with polyclonal antibody, positive control reagent, monoclonal-antibody conjugate, diluent, two component substrate, wash solution, and intensifier. The microtiter wells coated with polyclonal antibody "capture" the adhesin and the monoclonal antibodyconjugate serves as the "detecting" antibody. The polyclonal antibody used to coat the wells is prepared from hyperimmune antiserum developed in rabbits. The monoclonal antibody used to prepare the conjugate is prepared from mouse ascites fluid. The E. histolytica Test is to be used in an ELISA format.

Here's an analysis of the provided text to extract the requested information about device acceptance criteria and the study that proves the device meets those criteria:

Acceptance Criteria and Device Performance

Study Details

1. Sample size used for the test set and the data provenance: The document does not explicitly state the exact sample size. It mentions "stool specimens in areas where amebiasis is endemic," implying a prospective or at least recently collected retrospective set from endemic regions globally.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts: The text does not specify the number of experts or their qualifications. The ground truth method (zymodeme analysis) is described as "available only in a select number of clinical laboratories around the world," suggesting specialized expertise is involved in performing this analysis, but not in a consensus reading of results.

3. Adjudication method for the test set: Not applicable, as the ground truth (zymodeme analysis) is presented as a definitive biochemical method, not requiring expert adjudication in the traditional sense of image or clinical interpretation.

4. 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: Not applicable. This device is an ELISA diagnostic test, not an AI-assisted diagnostic tool or an imaging modality that would involve human readers.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done: Yes, the device's performance stands alone, comparing its ELISA results directly against zymodeme analysis. It is an in vitro diagnostic test, not requiring human interpretation of complex outputs.

6. The type of ground truth used: Zymodeme analysis of Entamoeba isolates cultured from stool specimens. This is described as the "gold standard" for distinguishing between pathogenic E. histolytica and non-pathogenic E. dispar.

7. The sample size for the training set: Not explicitly stated. The document describes the "clinical evaluations" and comparison with zymodeme analysis, implying a single evaluation set rather than a distinct training set. For an ELISA kit, "training" would typically refer to assay development and optimization, rather than machine learning training.

8. How the ground truth for the training set was established: Not applicable in the context of an ELISA kit with machine learning "training" as described above. The ground truth for the performance evaluation (test set) was established by zymodeme analysis.

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The intended use of the device is for the qualitative and/ or quantitative determination of serum IgG antibodies to Entamoeba histolytica using an Enzyme-Linked Immunosorbent Assay (ELISA) technique.

The device is an Enzyme Linked Immunosorbent Assay (ELISA). The antigen capture takes place in microwells. During the first incubation, antibodies in the patient's serum binds to antigen attached to the test wells. After washing the excess antibodies away, an enzyme complex binds to the antigen-antibody complex. After washings that remove unbound enzyme, a substrate is added which develops a blue color in the presence of the enzyme complex and peroxide. The stop solution ends the reaction and turns the The blue color to yellow. results read may be be spectrophotometrically with a microplate reader or visually.

Here's an analysis of the provided text, focusing on the acceptance criteria and the study details:

Acceptance Criteria and Device Performance

Study Details

1. Sample size used for the test set and the data provenance:

   • Test set size: The text provides conflicting numbers within the table structure.
     • For the "Original 510(k) Test Kit ASK Abstract C 38 Data", it states "Pos. (64) Neg. (104) 168". This implies a total of 168 samples.
     • For the "Modified Test Kit Comparison Data for Bench Study", it shows "Pos. (8) Neg. (49) 57". This implies a total of 57 samples.
     • It is unclear if the "Modified Test Kit" used a subset of the "Original 510(k)" samples or an entirely different set. The wording "Comparison Data for Bench Study" suggests a new, smaller set was used to validate the modified kit against the original.
   • Data provenance: Not explicitly stated. Given the context of a 510(k) submission for a diagnostic test for Entamoeba histolytica, it is likely that the samples were collected from individuals in regions where the disease is prevalent, which would include "endemic third world countries" and "immigration centers in industrialized countries" as mentioned in the "Intended Use". The data is retrospective, as it refers to "samples confirmed as positive or negative".

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • This information is not provided in the text. The ground truth is stated as "Serum samples confirmed as positive or negative for antibodies to E. histolytica", but the method of confirmation (e.g., through culture, PCR, or expert serological evaluation) and the number/qualifications of individuals who made these confirmations are not detailed.

3. Adjudication method for the test set:

   • None described. The text simply states that samples were "confirmed as positive or negative." There is no mention of a process involving multiple experts or an adjudication decision rule.

4. 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 study was not done. This device is an ELISA test system, a laboratory diagnostic kit, not an AI-assisted diagnostic tool. Therefore, the concept of "human readers improve with AI vs without AI assistance" does not apply.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:

   • Yes, a standalone study was done. The performance data (Sensitivity/Specificity) for the "Modified Test Kit" reflects the performance of the assay itself, independent of human interpretation beyond potential visual reading (which was assessed separately as "visual interpretation" and found to be substantially equivalent). The ELISA kit is the "algorithm" here, and its output (color change leading to a positive/negative result) is what was evaluated.

6. The type of ground truth used:

   • The ground truth was based on "Serum samples confirmed as positive or negative for antibodies to E. histolytica". This implies a reference standard based on confirmation of the presence or absence of E. histolytica antibodies, likely through a combination of other established diagnostic methods (e.g., culture, PCR, or a consensus of multiple serological tests or clinical presentations), but the specific method is not detailed. It is not pathology or direct outcomes data in the sense of patient recovery, but rather an established diagnostic classification for the samples.

7. The sample size for the training set:

   • Not applicable / not provided. As an ELISA test kit modification, this submission focuses on validating the performance of the modified kit against a predicate device. There is no mention of a "training set" in the context of machine learning, as the device is not based on AI/machine learning. The "testing" referred to is for validation against known samples.

8. How the ground truth for the training set was established:

   • Not applicable / not provided for the same reason as point 7.

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