(300 days)
MB/BacT Process bottles are used with the MB/BacT Mycobacteria Detection System in qualitative procedures for recovery and detection of mycobacteria in clinical specimens other than blood.
Automated system for growth and detection of mycobacteria organisms in clinical specimens other than blood.
Here's a breakdown of the acceptance criteria and study information for the BacT/Alert MB/BacT Mycobacteria Detection System, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The provided text does not explicitly state formal "acceptance criteria" for performance metrics like sensitivity or specificity with predefined numerical thresholds. Instead, the study aims to demonstrate substantial equivalence by comparing the MB/BacT system's recovery rates and time to detection with predicate devices.
The "reported device performance" is presented through recovery rates for various mycobacteria species compared to the predicate devices.
| Metric | Acceptance Criteria (Implicit) | Reported Device Performance (MB/BacT vs BACTEC) | Reported Device Performance (MB/BacT vs Solid Media) |
|---|---|---|---|
| Overall Mycobacteria Recovery | Comparable to predicate devices (BACTEC 460 and solid media) | MB/BacT recovered 151/179 isolates (84.4%) vs BACTEC 460 recovering 150/179 (83.8%) | MB/BacT recovered 335/395 isolates (84.8%) vs Solid Media recovering 307/395 (77.7%) |
| MB/BacT "Positives Only" (vs BACTEC) | Should show instances where MB/BacT detects growth that BACTEC 460 does not. | 22 isolates unique to MB/BacT | Not applicable |
| BACTEC "Positives Only" (vs MB/BacT) | Should show instances where BACTEC 460 detects growth that MB/BacT does not. | 18 isolates unique to BACTEC 460 | Not applicable |
| Solid Media "Positives Only" (vs MB/BacT) | Should show instances where Solid Media detects growth that MB/BacT does not. | Not applicable | 60 isolates unique to Solid Media |
| MB/BacT "Positives Only" (vs Solid Media) | Should show instances where MB/BacT detects growth that Solid Media does not. | Not applicable | 88 isolates unique to MB/BacT |
| Time to Detection | Comparable to predicate devices. | Ranged from 7.9 to 17.1 days for MB/BacT (vs 5 to 14 days for BACTEC 460) | Not explicitly quantified for solid media in this summary. |
| Ability to Grow Mycobacteria Strains In Vitro | Must demonstrate support for growth of a variety of mycobacteria organisms. | Demonstrated growth of several ATCC strains and clinical strains from CDC. | Demonstrated. |
| Level of Growth to Trigger Positive Reading | Instrument capable of detecting growth at relevant concentrations. | Triggered positive reading at 10^0 to 10^6 CFU/ml. | Demonstrated. |
Summary of Device Performance based on the Tables provided:
- MB/BacT vs BACTEC 460: The overall recovery rates are very similar (MB/BacT: 151, BACTEC: 150). Both systems also detected isolates that the other did not (MB/BacT only: 22, BACTEC only: 18).
- MB/BacT vs Solid Media: MB/BacT showed a higher overall recovery rate (335) compared to solid media (307). MB/BacT also uniquely identified more isolates (88) than solid media did uniquely (60).
- Time to Detection: The time to detection for MB/BacT was slightly longer on average (7.9 to 17.1 days) compared to BACTEC 460 (5 to 14 days).
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size:
- For the MB/BacT vs BACTEC comparison, the total number of unique mycobacteria isolates recovered across all methods was 179.
- For the MB/BacT vs Solid Media comparison, the total number of unique mycobacteria isolates recovered across all methods was 395.
- The total number of clinical specimens is not explicitly stated, only the number of isolates recovered.
- Data Provenance: Clinical specimens were collected from 4 clinical sites. The country of origin is not specified, but given the context of a US FDA 510(k) submission, it is highly likely to be United States data. The data is prospective, as it involved direct comparison studies conducted at clinical sites.
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 qualifications for establishing ground truth. However, the ground truth for identifying "mycobacteria species" and "total recovered" would have been established by standard microbiology laboratory procedures at the four clinical sites, likely by trained microbiologists using recognized culture and identification methods.
4. Adjudication Method for the Test Set
The document does not describe an adjudication method. The comparison tables present aggregated results for organisms recovered by each method, implying that if an organism was recovered by any of the methods, it was considered a "total recovered" isolate. This suggests a "Union" approach where any positive result from a validated method contributes to the ground truth of presence, rather than a specific adjudication process between conflicting results.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- No, an MRMC comparative effectiveness study was not done. This device is an automated system for detecting microbial growth, not an imaging diagnostic requiring human interpretation. The study compares the performance of the automated system to other laboratory methods (both manual and automated), not the performance of human readers with or without AI assistance.
6. Standalone Performance Study
- Yes, a standalone study was done for the algorithm (device). The entire clinical study is a standalone performance evaluation of the MB/BacT system compared to predicate devices. The system operates independently to detect growth and provide a positive reading. The results in the tables reflect the performance of the MB/BacT system on its own.
7. Type of Ground Truth Used
The ground truth used was microbiological culture and identification. The "Total recovered" column in the tables represents the ground truth for the presence of mycobacteria, meaning that if a mycobacterium species was successfully isolated and identified by any of the comparative methods (MB/BacT, BACTEC 460, or solid media), it was counted as a recovered isolate. The specific type of mycobacteria (e.g., M. tuberculosis, M. avium) would be confirmed through further laboratory identification methods.
8. Sample Size for the Training Set
The document does not specify a separate "training set" sample size. This is typical for device submissions of this nature, especially in 1996, where the "training" (development and refinement) of the device's
detection algorithm would have involved various in-house studies (growth promotion, colony count determination) rather than a distinct, prospectively collected clinical "training set" dataset as understood in modern AI/ML contexts. The "ATCC strains were used and clinical strains not commonly encountered were obtained from CDC for testing" for growth promotion studies, which could be considered part of the development/training process.
9. How the Ground Truth for the Training Set Was Established
For the "growth promotion studies" which served a similar purpose to training:
- For ATCC strains and CDC clinical strains: The ground truth for the presence and identity of these mycobacteria strains would have been established by standard microbiological techniques and culture verification methods inherent to their source (ATCC, CDC). This typically involves culturing, microscopy, biochemical tests, and potentially molecular methods to confirm the species and viability of the organisms.
- Colony counts: For determining the level of growth to trigger a positive reading (10^0 to 10^6 CFU/ml), the ground truth for CFU/ml would have been established by standard quantitative microbiology techniques, such as pour plating or spread plating dilutions of known bacterial suspensions.
§ 866.2560 Microbial growth monitor.
(a)
Identification. A microbial growth monitor is a device intended for medical purposes that measures the concentration of bacteria suspended in a liquid medium by measuring changes in light scattering properties, optical density, electrical impedance, or by making direct bacterial counts. The device aids in the diagnosis of disease caused by pathogenic microorganisms.(b)
Classification. Class I. With the exception of automated blood culturing system devices that are used in testing for bacteria, fungi, and other microorganisms in blood and other normally sterile body fluids, this device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter.