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Granada Medium is a selective and differential agar which is intended for the qualitative detection of Group B Streptococus (GBS) from LIM Broth enrichment cultures of vaginal/rectal swabs from antepartum women following 18-24 hours of incubation.

Recovery of orange colored colonies on Granada Medium is a positive result for presence of β-hemolytic GBS. Results can be interpreted after 18-24 hours of anaerobic incubation. Due to the properties of Granada Medium, white colonies recovered on Granada Medium must undergo additional testing to confirm absence of GBS colonies must be performed for conducting susceptibility testing as recommended for penicillin- allergic women. A lack of growth or the absence of orange colonies on Granada Medium does not presence of GBS. Granada Medium is not intended to diagnose infection, or to guide or monitor treatment for infections.

Hardy Diagnostics Granada Medium agar utilizes the Granada reaction and contains the necessary components for pigment detection of beta-hemolytic GBS. The production of a light orange to dark orange pigmented colony is a unique characteristic of hemolytic GBS on Granada Medium due to a reaction with substrates such as starch, peptone, serum, and folate pathway inhibitors.

Here's a breakdown of the acceptance criteria and study details for the Granada Medium device:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as numerical targets in the provided document, but rather implied by the overall performance comparison to the reference method and the conclusion of substantial equivalence. The key performance metrics reported are sensitivity and specificity for GBS detection.

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

• Sample Size (Clinical Study): A total of 771 valid clinical specimens were tested (out of 884 initially collected, with 113 excluded for not meeting enrollment criteria).
• Data Provenance: The study was conducted at four geographically diverse hospitals with routine GBS specimens in the form of vaginal/rectal swabs. This suggests a multi-center, potentially prospective (implied by "routine GBS specimen") collection of real-world clinical samples. It does not explicitly state the country of origin, but "US Food & Drug Administration" context usually refers to studies conducted in the USA or accepted for the US market. The nature of the study (comparing to a reference method) indicates it's a diagnostic accuracy study.

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

The document does not specify the number of experts or their qualifications for establishing the ground truth. It describes the "reference method" as:

• Selective enrichment of specimen in LIM Broth
• Followed by subculture to blood agar
• Confirmation of Group B Streptococci by: hemolytic reaction on blood agar, gram-stain, catalase test, and StrepPRO™ latex agglutination.

This indicates a standard microbiology laboratory workflow, where trained laboratory personnel (e.g., medical technologists, microbiologists) would be performing and interpreting these established diagnostic tests. The discrepant analysis involved isolates being returned to Hardy Diagnostics for re-testing and confirmation of identity, implying expertise at the manufacturer's facility as well.

4. Adjudication Method for the Test Set

The document primarily describes a comparison against a "reference method" and subsequent "discrepant analysis."

• For the initial comparison (Table 1 and 2), the "reference method" was considered the ground truth.
• For Discrepant Analysis: All discrepant isolates (False Positives and False Negatives) were re-tested and confirmed using the reference method described above (hemolytic reaction, gram-stain, catalase, StrepPRO™ latex agglutination). This serves as an adjudication method where initial discrepancies are resolved by re-examination using definitive laboratory tests.

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

• No, an MRMC comparative effectiveness study was not explicitly described in the provided text. The study focuses on the standalone performance of the Granada Medium compared to a traditional reference laboratory method.
• A brief mention under Reproducibility states: "The testing was done with at least one operator and two readers, blinded to each other's results, per site." This element incorporated some "multi-reader" aspects for reproducibility checks but this was for concordance of interpretations of Granada Medium itself, not a comparative effectiveness study of human readers with vs. without AI assistance. The device is a culture medium, not an AI-assisted diagnostic tool for interpretation.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

• Yes, a standalone study was performed. The clinical performance data (Tables 1 and 2) directly compares the results of the Granada Medium (interpreted visually for orange colonies, which is a human interpretation step, but without assistance from another diagnostic tool) against the established laboratory reference method. The device's "performance" is its ability to produce a visual indicator (orange colonies) corresponding to GBS presence. This is its "standalone" performance in its intended use. There is no AI algorithm involved.

7. The Type of Ground Truth Used

The ground truth used was expert consensus / established laboratory methods which identified specific bacterial species. Specifically:

• The "reference method" involved selective enrichment in LIM Broth, subculture to blood agar, and confirmation based on hemolytic reaction, gram-stain, catalase test, and StrepPRO™ latex agglutination. This is a highly accurate and accepted method for identifying Group B Streptococci in clinical microbiology.
• For analytical studies (reactivity, specificity, LoD), well-characterized ATCC, NCIMB, NCTC reference strains and clinical GBS isolates were used, which represent a known ground truth.

8. The Sample Size for the Training Set

• The document does not explicitly mention a separate "training set" as would be typical for machine learning or AI models.
• For a diagnostic device like a culture medium, the development and initial optimization (which parallels a "training" phase) would typically involve internal laboratory testing with known bacterial strains and challenging conditions. While not quantified as a "training set" in the context of this document, the Analytical Reactivity, Specificity, Recovery Rate, Microbial Interference, and Incubation studies collectively represent the robust characterization and "training" of the medium's performance during development. These studies involved specific numbers of ATCC/reference strains and non-target organisms (e.g., 54 GBS strains for reactivity, 84 non-target organisms for specificity).

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

Given that a specific "training set" with separate ground truth establishment wasn't explicitly defined for an AI model, for the developmental and analytical studies (which function similarly to training data for the medium's design):

• The ground truth was established by using well-characterized, identified bacterial strains (ATCC, NCIMB, NCTC reference strains, and clinical isolates).
• For these strains, their identity (e.g., S. agalactiae, specific serotypes, or other bacterial species) was already established through standard microbiological identification techniques.
• The "expected color development" (orange for β-hemolytic GBS, white for non-hemolytic GBS, negative for non-GBS organisms) served as the pre-defined target for the medium's differentiation capabilities, based on the known Granada reaction.

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Strep B Carrot Broth™ One-Step is a selective and differential medium which is intended for the detection of Group B Streptococcus (GBS) from anovaginal specimen collected from pregnant women. The medium is used as an aid in the qualitative determination of GBS colonization in pregnant women. The color change reaction from white to orange is representative of a positive result for presence of GBS. The medium requires 24 hours of incubation but positive results can be interpreted as early as 16 hours. Due to the properties of Strep B Carrot Broth™ One-Step, non-hemolytic GBS cannot be detected by the medium's color change and require subculture for identification. Any presumptive negative indicated by lack of color change at the incubation period must be subcultured to a non-selective medium (e.g. Tryptic Soy Agar with 5% Sheep Blood) to confirm absence of GBS. Subculture must also be performed to recover isolates for conducting susceptibility testing as recommended for penicillin-allergic women.

Strep B Carrot Broth™ One-Step is a selective and differential medium with selective components designed to enrich for Group B Streptococci. The production of a light orange, or red-orange pigment is a unique characteristic of hemolytic GBS due to reaction with substrates such as starch, peptone, serum, and folate pathway inhibitors. GBS detection with Strep B Carrot Broth™ One-Step is only possible with β-hemolytic Group B Streptococci colonies, providing evidence of a direct genetic linkage between pigment production in this media and hemolysin production. Non-hemolytic GBS can be recovered from Strep B Carrot Broth™ One-Step upon subculture to 5% sheep blood agar plates.

The provided text describes the performance evaluation of the "Strep B Carrot Broth™ One-Step" device. Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" in a separate section with numerical targets. However, the performance data presented (sensitivity and specificity) is implicitly the criteria the device met for substantial equivalence. The predicate device's performance is not provided in numerical values, but the comparison is implied through the overall "Substantially Equivalent?" column.

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

• Test Set Sample Size: A total of 884 specimens were initially collected, but 113 were excluded, resulting in 771 valid samples for the primary comparison.
  • Data Provenance: The study was conducted at four geographically diverse hospitals with routine GBS specimens (anovaginal swabs). This indicates a prospective collection within normal clinical practice. The country of origin is not explicitly stated but implied to be the US given the FDA submission.

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

• The document does not explicitly state the number of experts or their specific qualifications (e.g., "radiologist with 10 years of experience") for establishing ground truth.
• Ground Truth Establishment: For the primary comparison, the reference method was "routine culture," defined as:
  • Selective enrichment in LIM Broth.
  • Followed by subculture to Blood Agar.
  • Confirmed by biochemical testing.
  • Organisms grown on Blood Agar were confirmed using gram-stain, catalase test, and latex agglutination.
  • Discrepant isolates underwent re-testing and confirmation at Hardy Diagnostics using a "discrepant analysis protocol." This re-testing included confirming identity (β-hemolytic GBS, non-hemolytic GBS, or non-GBS) and testing at the Limit of Detection (LoD).

4. Adjudication Method for the Test Set

• The document implies a form of adjudication for discrepant results. All discrepant isolates (false positives and false negatives) were re-tested and confirmed at Hardy Diagnostics using a specific "discrepant analysis protocol." This suggests a process where initial disagreements between the test device and the reference method were further investigated to establish the definitive ground truth. It is not explicitly described as a 2+1 or 3+1 method; rather, it appears to be a single "expert site" (Hardy Diagnostics) reviewing discrepancies.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

• No, an MRMC comparative effectiveness study was not explicitly done as described. The study evaluates a culture medium, not an imaging AI diagnostic device. The "reproducibility" section mentions "at least one operator and two readers, blinded to each other's results, per site" for the reproducibility panel of 12 isolates, but this is to demonstrate proficiency and reproducibility of the device itself, not to compare human reader performance with and without AI assistance on a large test set. Therefore, no effect size of human readers improving with AI vs. without AI assistance is reported.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done

• Yes, a standalone performance was done for the "Strep B Carrot Broth™ One-Step" in its primary mode of operation. The device is a culture medium designed to produce a visual color change. The performance metrics (sensitivity and specificity in Table 1) directly reflect the device's ability to produce this color change as a standalone indicator of GBS presence, compared to the reference method. The subsequent subculture for negatives or non-hemolytic GBS is part of the overall diagnostic workflow, but the initial "color reaction" is a standalone readout.

7. The Type of Ground Truth Used

• The ground truth used was expert consensus informed by a reference culture method (LIM Broth + subculture to Blood Agar) and confirmed by biochemical testing, gram-stain, catalase test, and latex agglutination. For discrepant cases, further re-testing and confirmation at a central lab (Hardy Diagnostics) was performed. This is a form of laboratory reference standard.

8. The Sample Size for the Training Set

• The document does not mention a training set sample size. This is common for traditional culture media, which are developed based on established microbiological principles and validated rather than "trained" in the machine learning sense. The performance data presented is for validation.

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

• As there is no explicit mention of a training set, the method for establishing ground truth for a training set is not applicable or provided.

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Strep B Carrot Broth™ Kit is a selective and differential medium which is intended for the detection of Group B Streptococus (GBS) from anovaginal specimens collected from pregnant women. The medium is used as an aid in the qualitative determination of GBS colonization in pregnant women. The color change reaction from white to orange is representative of a positive result for presence of GBS. The medium requires 24 hours of incubation but positive results can be interpreted and reported as early as 16 hours. Due to the properties of Strep B Carrot Broth™ Kit, non-hemolytic GBS cannot be detected by the medium's color change and require subculture for identification. Any presumptive negative indicated by lack of color change at the end of the incubation period must be subcultured to a non-selective medium (e.g., Tryptic Soy Agar with 5% Sheep Blood) to confirm absence of GBS. Subculture must also be performed to recover isolates for conducting susceptibility testing as recommended for penicillin-allergic women.

Strep B Carrot Broth™ is a selective and differential medium with selective components designed to enrich for Group B Streptococci. The production of a light orange, or red-orange pigment is a unique characteristic of β-hemolytic GBS due to reaction with substrates such as starch, and folate pathway inhibitors. GBS detection by color with Strep B Carrot Broth™ is only possible with β-hemolytic Group B Streptococci colonies, which provides evidence of a direct genetic linkage between pigment production in this media and hemolysin production. Non-hemolytic GBS can be recovered Strep B Carrot Broth™ upon subculture to 5% sheep blood agar plates.

The device in question is the Strep B Carrot Broth™ Kit, a selective and differential medium intended for the detection of Group B Streptococcus (GBS) from anovaginal specimens collected from pregnant women. It aids in the qualitative determination of GBS colonization.

Here's an analysis of the acceptance criteria and the study proving the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state pre-defined acceptance criteria in terms of specific sensitivity or specificity thresholds. However, the performance data presented implies a comparison against a reference method (LIM Broth with subculture and biochemical testing). The "Substantially Equivalent?" column in the comparison table (page 4) suggests that similar performance for "Intended Use," "Methodology," "Inoculation," and "Sample Type" were considered for equivalence. For quantitative performance, the comparison against the reference method served as the implicit acceptance benchmark.

Based on the provided performance tables, here's a summary of the device's performance:

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

• Sample Size for Clinical Performance Study: 771 valid specimens. An initial 884 specimens were collected, but 113 were excluded.
• Data Provenance:
  • Country of Origin: Not explicitly stated, but the study was conducted at "four geographically diverse hospitals with routine GBS specimen." Given the FDA submission from a US company (Hardy Diagnostics, Santa Maria, CA), it is highly probable the data is from the United States.
  • Retrospective or Prospective: The study describes evaluating the performance of the Strep B Carrot Broth™ "against routine culture," using "routine GBS specimens." This phrasing, along with the collection of specimens and subsequent testing, suggests a prospective collection and testing of new specimens, though the document does not explicitly state "prospective study."

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

The document does not explicitly specify the number of experts used or their qualifications for establishing the "ground truth" for the clinical test set. The ground truth was established by:

• "routine culture, defined as the selective enrichment of specimen in LIM Broth, followed by subculture to Blood Agar and confirmed by biochemical testing."
• Organisms that grew on Blood Agar were confirmed using "gram-stain, catalase test, and latex agglutination."
• For discrepant analysis, isolates were sent back to Hardy Diagnostics for confirmation, where their identity was confirmed (β GBS, NH GBS, or non-GBS).

This suggests standard microbiology laboratory procedures were followed, implying trained microbiologists or laboratory technicians were involved in establishing the ground truth.

4. Adjudication Method for the Test Set

The data indicates an adjudication process for discrepant isolates.

• "All discrepant isolates were frozen in CryoSavers™ with Brucella Broth and returned to Hardy Diagnostics for testing."
• "The identity of each isolate was confirmed (β Group B Streptococi, NH Group B Streptococi, or non-Group B Streptococi)."
• "Once the identity was confirmed, positive organisms (β Group B Streptococi or NH Group B Streptococi) were tested at LoD (10^0 CFU/mL) in donated negative-vaginal rectal matrix for their recovery from the LIM reference method, color development in Carrot Broth™ Kit, and recovery from the Carrot Broth™ Kit to Blood Agar System."
• Footnotes 1 and 2 on page 5 further detail the re-testing and confirmation process for false positives and false negatives based on the initial comparison.

This represents a form of independent adjudication performed by Hardy Diagnostics on all discrepant samples to determine the true status of the sample.

5. 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 conducted. This device is a culture medium, not an AI-assisted diagnostic tool interpreted by human readers. The clinical study compares the performance of the new culture medium (Strep B Carrot Broth™ Kit) against a predicate culture medium (LIM Broth) and standard microbiological confirmatory tests.

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

The device is a standalone diagnostic tool in the sense that its primary output (color change and/or subculture) is directly interpreted. There is no "algorithm only" performance as it's a biochemical reaction in a broth medium. The interpretation of the color change is visual, and subsequent subculture and biochemical testing for negatives are laboratory procedures. Its performance as a standalone culture medium for GBS detection is what was evaluated.

7. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc.)

The ground truth for the clinical performance study was established by standard microbiological culture methods and confirmatory tests. Specifically:

• Selective enrichment in LIM Broth.
• Subculture to Blood Agar.
• Confirmation by biochemical testing (gram-stain, catalase test, and latex agglutination).
• For discrepant analysis, full re-testing and confirmation of isolates at Hardy Diagnostics.

This represents a robust, laboratory-based "reference standard" or "gold standard" for GBS detection.

8. The Sample Size for the Training Set

This type of product (a culture medium) does not typically involve a "training set" in the machine learning sense. Its performance is based on its inherent biochemical and selective properties. Therefore, there is no training set for this device.

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

As there is no training set for a culture medium, this question is not applicable. The "ground truth" principles applied to its development would stem from established scientific principles of bacteriology, media formulation, and GBS characteristics rather than a data-driven training process.

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chromID® Strepto B agar is a selective chromogenic medium that is intended to aid in the qualitative determination of Group B Streptococcus (GBS) colonization in pregnant women. This medium supports the growth of, but does not differentiate between, hemolytic and non-hemolytic GBS strains. The test is performed on 18-24 hour LIM broth enrichments of vaginal/rectal swabs obtained from pregnant women. chromID® Strepto B agar results can be interpreted after 24 hours incubation with confirmation of characteristic GBS colonies from the media.

chromID® Strepto B agar is not intended to diagnose infection nor to guide or monitor treatment for infections. chromID® Strepto B agar does not provide susceptibility results. Subculture to non-selective media should be performed as needed for susceptibility testing. chromID® Strepto B agar is intended for use by laboratory health practitioners in a clinical laboratory.

chromID Strepto B agar consists of a nutritive base combining different peptones, chromogenic substrates and antibiotics. These components enable the screening of S. agalactiae by the spontaneous appearance of pale pink to red colonies. Most other bacterial species and yeasts do not grow on this medium or do not produce typical colonies.

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

1. Table of Acceptance Criteria and Reported Device Performance:

Note: The document only provides the reported performance and implies that these values are acceptable as it concludes substantial equivalence. Explicit numerical acceptance criteria for sensitivity and specificity are not directly stated in the text.

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

• Sample Size: A total of 681 vaginal/rectal specimens enriched in LIM broth were analyzed during the clinical trial.
• Data Provenance: The data was collected from fresh clinical specimens at three external sites. This indicates that the data is prospective and originates from a clinical setting (likely within the USA, given the FDA filing).

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

• The document does not explicitly state the number of experts or their specific qualifications (e.g., "radiologist with 10 years of experience").
• It mentions that for the Reference Culture Method, "all suspicious colonies were screened to confirm or rule-out the presence of GBS using established laboratory methods: gram stain, catalase, PYR testing, and latex agglutination. VITEK® MS was also used to confirm the identification of GBS by the Reference Method." This implies that laboratory health practitioners (as stated in the intended use for the device) with relevant microbiology expertise were responsible for establishing the ground truth.

4. Adjudication Method for the Test Set:

• The document does not describe an explicit adjudication method (like 2+1 or 3+1).
• Instead, for the Reference Culture Method, it states that "all suspicious colonies were screened to confirm or rule-out the presence of GBS using established laboratory methods: gram stain, catalase, PYR testing, and latex agglutination. VITEK® MS was also used to confirm the identification of GBS by the Reference Method." This suggests a sequential confirmation process using multiple established laboratory tests to arrive at a confirmed ground truth, rather than an adjudication among independent readers.

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

• No, an MRMC comparative effectiveness study was not done.
• This study evaluates a culture medium (chromID® Strepto B agar) against a "Reference Culture Method" for detecting Group B Streptococcus. It's a comparison of diagnostic methods, not human reader performance with and without AI assistance. Therefore, there is no effect size reported for human readers improving with AI.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) was Done:

• Yes, a standalone performance evaluation was done. The "device" in this context is the chromID® Strepto B agar medium.
• The clinical study directly compares the results obtained from the chromID® Strepto B agar (interpreting characteristic colonies after 24 hours, followed by confirmation) to a "Reference Culture Method." The reported sensitivity and specificity values represent the standalone performance of the chromID® Strepto B agar in identifying GBS from clinical specimens.
• It's important to note that the device's intended use specifies "chromID® Strepto B agar results can be interpreted after 24 hours incubation with confirmation of characteristic GBS colonies from the media," indicating that a human laboratory health practitioner is always in the loop for confirmation, but the primary sensitivity and specificity reported directly reflect the medium's ability to selectively grow and display characteristic GBS colonies.

7. The Type of Ground Truth Used:

• The ground truth used was expert consensus / established laboratory methods for microbiology.
• The "Reference Culture Method" served as the gold standard, involving:
  • Subculture to CNA agar.
  • Screening suspicious colonies with gram stain, catalase, PYR testing, and latex agglutination.
  • Confirmation with VITEK® MS.

8. The Sample Size for the Training Set:

• The document does not explicitly mention a "training set" for the chromID® Strepto B agar. This is typical for traditional in-vitro diagnostic devices like culture media, which are developed and validated through analytical studies and then assessed in clinical studies, rather than "trained" like AI algorithms.
• The design and formulation of the medium come from developmental work, but there isn't a "training set" in the machine learning sense.

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

• As there is no explicit "training set" mentioned in the context of an algorithm, the concept of establishing ground truth for a training set is not directly applicable to this device description. The performance is assessed against established laboratory practices and known bacterial strains for analytical studies.

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