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510(k) Data Aggregation
(252 days)
BD BBL™ CHROMagar™ 0157 is a selective medium for the isolation, differentiation and presumptive identification of Escherichia coli 0157:H7 from clinical human stool specimens.
BBL™ CHROMagar™ O157 formulation incorporates chromogenic substrates, which allow colonies of E. coli O157:H7 to produce a mauve color for presumptive identification from the primary isolation plate and differentiation from other organisms. Specially selected Difco™ peptones are incorporated to supply nutrients. The addition of potassium tellurite, cefixime and cefsulodin reduces the number of bacteria other than E. coli O157:H7 that grow on this medium. The chromogen mix consists of artificial substrates (chromogens), which release an insoluble colored compound when hydrolyzed by a specific enzyme. E. coli O157:H7 utilizes one of the chromoqenic substrates producing mauve colonies. The growth of mauve colonies is considered presumptive for E. coli 0157:H7 on BBL™ CHROMagar™ 0157. Non-E. coli O157:H7 bacteria may utilize other chromogenic substrates resulting in blue-green colored colonies or, if none of the chromogenic substrates are utilized, colonies may appear as their natural color. These visually distinct colored colonies facilitate the detection and differentiation of E. coli 0157:H7 from other organisms.
Here's an analysis of the provided text regarding the acceptance criteria and study for the BBL™ CHROMagar™ O157 device:
BBL™ CHROMagar™ O157 Device Study Summary
1. Acceptance Criteria and Reported Device Performance
The direct acceptance criteria are not explicitly stated as numerical thresholds in the provided text. However, the study aims to demonstrate that BBL™ CHROMagar™ O157 performs "as well as" the predicate device (SMAC) and another commercially available medium (SMAC-CT) in presumptively identifying E. coli O157:H7. The results from the external clinical study provide the performance metrics against the predicate device.
Table of Performance:
| Metric | Reported Device Performance (BBL™ CHROMagar™ O157 vs. SMAC) |
|---|---|
| Positive Percent Agreement | 86.4% |
| Negative Percent Agreement | 99.8% |
2. Sample Size and Data Provenance
- Test Set Sample Size: 3,136 stool specimens were initially cultured, with 2,855 providing acceptable results for the study.
- Data Provenance: The external clinical study was conducted at "an external centralized regional clinical laboratory that routinely tests for E. coli O157:H7 in stool specimens." The country of origin is not explicitly stated, but the context (FDA 510(k) submission, Department of Health & Human Services USA) strongly suggests it was conducted in the United States.
- Retrospective or Prospective: The study describes specimens being "inoculated onto Sorital-MacConkey (SMAC) and BBL CHROMagar O157 media," implying a prospective collection and testing of new specimens at the time of the study, rather than analyzing existing archived data.
3. Number of Experts and Qualifications for Ground Truth
- Number of Experts: "Each Plate was read by an independent technologist." The exact number of technologists involved is not specified, but it implies at least two (one for SMAC, one for CHROMagar, though it might have been the same technologist reading both, followed by confirmatory testing). It doesn't appear that multiple experts independently read the same plates to establish a consensus ground truth at the reading stage.
- Qualifications of Experts: The experts are referred to as "independent technologist(s)." Specific qualifications (e.g., years of experience, certifications) are not detailed in the provided text.
4. Adjudication Method for the Test Set
The primary method for establishing the definitive ground truth (beyond the initial technologist reading) was: "confirmatory testing (indole and serotyping) was conducted on all suspected colony samples." This indicates that any suspected positive result from either the SMAC or BBL CHROMagar O157 plates underwent further definitive laboratory testing. This is a form of confirmatory testing adjudication, where definitive lab tests serve as the ultimate arbiter, rather than a consensus among human readers of the primary plates.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not conducted in the typical sense of measuring human reader improvement with or without AI assistance. This device is a culture medium, not an AI-powered diagnostic tool for interpretation. The comparison is between the BBL™ CHROMagar™ O157 medium and predicate media, both of which are interpreted manually by a technologist.
6. Standalone Performance Study
Yes, a standalone study was performed in the sense that the performance of the BBL™ CHROMagar™ O157 medium was evaluated independently. The "External Studies" section details its performance (Positive Percent Agreement and Negative Percent Agreement) in comparison to the SMAC medium based on the final confirmatory testing. The "Internal Studies" also included a Limit of Detection study and a cross-reactivity study, which assess the medium's inherent performance.
7. Type of Ground Truth Used
The ground truth used for the external clinical study was primarily confirmatory laboratory testing, specifically "indole and serotyping" performed on "all suspected colony samples." This represents a high-level, definitive laboratory identification of E. coli O157:H7.
8. Sample Size for the Training Set
The document does not mention a training set size. This is because the BBL™ CHROMagar™ O157 is a traditional in-vitro diagnostic culture medium, not a machine learning or artificial intelligence algorithm that requires a training set.
9. How Ground Truth for the Training Set Was Established
As there is no training set for this type of device, this question is not applicable. The device's formulation and chromogenic properties are based on biological principles, not on learned patterns from a dataset.
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(248 days)
The Novamed, Ltd. DipStreak Urine Culture Device is used for the isolation and enumeration of bacteria in urine. A set of plastic prongs on the end of the device are dipped into the urine sample. The drops of urine which adhere to the prongs are then streaked across two different agar surfaces (CLED agar on one side, MacConkey agar on the other). A dilution effect takes place which allows the isolation of single colonies.
DipStreak comprises a plastic paddle with two types of agar attached back-to-back, housed in a closed transparent plastic tube. A ring with elongated prongs is attached to the end of the paddle so that there are prongs on each side of the slide. The ends of the prongs are dipped into the urine sample. Upon re-insertion into the plastic tube, the prongs are prevented from moving and the agar surfaces are inoculated with bacteria from the urine sample as the agar-coated paddle passes over the prongs. The result is a series of streaks of decreasing bacterial concentration which permits isolation of single colonies even when the original bacterial population of the sample was as high as 10' organisms per milliliter.
The provided text describes the DipStreak Urine Culture Device and studies supporting its performance. Here's a breakdown of the requested information:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria Category | Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Bacterial Detection Range | Pathogenic bacteria found in urine samples at levels from 10^3 to 10^7 CFU/ml are detected accurately and consistently. | Precision Study: Experimental evidence to support this claim is given in the application's "Precision Study." (Specific numerical results for this range are not explicitly provided in the excerpt, but the claim is made that it's detected accurately and consistently.) |
| Agreement with Predicate Device | Not explicitly stated as a numerical acceptance criterion, but implied to be high due to substantial equivalence. | Study 1 & 2 (vs. Predicate Device): Overall agreement of 96.4% at the cutoff level of 10^5 CFU/ml and 96.9% at the cutoff level of 10^4 CFU/ml when compared to the Savyon Diaslide Urine Culturing Device (K921045) in two studies comprising 522 clinical samples. |
| Sensitivity and Specificity (Standalone) | Not explicitly stated as numerical acceptance criteria, but implied to be high for standalone performance. | Study 3 (vs. Traditional Petri Dish Culture): Sensitivity and specificity values for cutoff levels of 10^5 and 10^4 CFU/ml were all above 98.6% when compared to traditional petri dish culture in a study of 1000 clinical samples. |
| Quality Control Tests | Device must support the expected growth of organisms. Failure indicates deterioration. | User Quality Control: Specific "Typical Culture Response" table provided for E. coli, S. aureus, and P. vulgaris with expected growth rates and colony appearances after 24 hours at 37°C. (This serves as an in-use acceptance criterion, not a study outcome, but demonstrates a defined performance expectation for functionality). |
2. Sample Size Used for the Test Set and the Data Provenance
- Sample Size for Predicate Device Comparison: 522 clinical samples (across two studies).
- Sample Size for Traditional Petri Dish Comparison: 1000 clinical samples (one study).
- Data Provenance: The text does not explicitly state the country of origin of the data or whether the studies were retrospective or prospective. It refers to "clinical samples," implying human-derived samples.
3. 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 given text.
4. Adjudication Method for the Test Set
This information is not provided in the given text.
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 done. The device being described is a urine culture device (a diagnostic tool for bacterial enumeration and isolation), not an AI-powered diagnostic imaging or interpretation tool. Therefore, "human readers improving with AI vs without AI assistance" is not applicable to this device type.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done
- Yes, a standalone performance study was done. The comparison of the DipStreak device to "traditional petri dish culture" in a study of 1000 clinical samples, yielding sensitivity and specificity values, represents a standalone performance evaluation of the device itself. The device is designed to be used independently to grow and identify bacteria, without an "algorithm only" component in the modern AI sense. Its "standalone" performance is its direct ability to detect and enumerate bacteria.
7. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc.)
- The ground truth for the comparison studies was traditional petri dish culture and the predicate device (Savyon Diaslide Urine Culturing Device). These methods are considered standard clinical practices for urine culture and bacterial enumeration, and thus serve as the reference standard or "ground truth" against which the DipStreak device's performance was measured.
8. The Sample Size for the Training Set
- This information is not provided in the given text. The description focuses on performance studies (test sets) rather than development or training data. Being a physical diagnostic device, it likely did not have a "training set" in the machine learning sense. The "Precision Study" likely refers to internal development and validation work rather than a data training phase.
9. How the Ground Truth for the Training Set Was Established
- This information is not provided and is likely not applicable in the context of a physical diagnostic device like the DipStreak. The "ground truth" for its design and manufacturing would be based on established microbiology principles and standard culturing techniques.
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