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The BACTEC® MGIT™ 960 System is an instrumented system using a modified 7H9 growth medium for the detection of using a modifical specimens (except blood).
The BACTEC® MGIT™ 960 System is an in vitro diagnostic instrument designed and optimized for the rapid detection of mycobacterial and incouleted into RRI optimized for the rapid delection of informations processed and inoculated into BBL® and urine). Samples are collected from patients, processed and inoculation in CRBL® MGIT and urine). Samples are collected iront patients, procobod and incolance in the mail. MGIT™ 7mL tubes supplemented with BBL® MGIT™ and BBL® MGIT™ OADC.

The BACTEC® MGIT™ 960 instrument is a self-contained incubation/detection unit which contains three drawers; each drawer holding up to 320 tubes of growth medium containing fluorescent indicator. Inoculated tubes are monitored by the instrument continuously for growth, based on the detection of fluorescence. Mycobacteria matabolize nutrients and oxygen in the BBL" MGIT™ culture broth. The MGIT tubes contain a fluorescent indicator which reacts to the concentration of oxygen in the culture medium. As the microorganisms use the oxygen, the indicator begins to fluoresce when exposed to excitation light. The BACTEC® MGTT™ 960 instrument's photo detectors measure the level of fluorescence, which corresponds to microorganism growth. Clinical specimens (except blood) are collected from patients and processed, when necessary, using standard digestion/decontamination procedures. Specimens are inoculated (0.5 ml) into propared MGIT tubes (with MGIT OADC and MGIT PANTA. if necessary) and entered into the BACTEC® MGIT™ 960 System. All tubes entered into the system are read every sixty minutes. When a MOIT tube is detected as positive, the positive tube inclument for confirmation by front. Positive MGIT tubes are removed from the instrument for confirmation by acid-fast bacilli (AFB) smeal, foolation and feeniness and of protocol, the negative tubes are removed and discarded.

The BACTEC® MGIT™ 960 System is intended for the rapid detection of mycobacteria from clinical specimens (excluding blood and urine). The system uses fluorescent detection of oxygen consumption by microorganism growth in specially prepared MGIT tubes.

Here's a breakdown of the acceptance criteria and the study that demonstrates the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

The submission does not explicitly state quantitative acceptance criteria in a structured table. However, the study aims to demonstrate substantial equivalence to existing predicate devices (BACTEC® 460TB System and Conventional Media). The performance metrics presented are recovery rates and false positive/negative rates, allowing for comparison.

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

• Sample Size for Test Set: A total of 3330 specimens were tested during the external evaluation study.
• Data Provenance: The study was an external evaluation performed at six (6) sites. The country of origin is not explicitly stated, but given the submission to the US FDA, it is highly likely that these sites were in the United States. The study appears to be prospective as clinical specimens were "tested during the study" in a comparative manner.

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 states that "positive MGIT tubes are removed from the instrument for confirmation by acid-fast bacilli (AFB) smear, isolation and identification." This implies that trained laboratory personnel or microbiologists performed these confirmatory tests, which serve as the ground truth. However, specific expert qualifications are not detailed.

4. Adjudication Method for the Test Set

The document does not describe a formal "adjudication method" in terms of multiple expert reviews and reconciliation for the ground truth. Instead, confirmation of positive MGIT tubes was done through standard microbiological procedures (AFB smear, isolation, and identification). For "false positive" determinations for the MGIT 960, 27 tubes were found to be instrument-positive but negative by smear and/or subculture. For "false negative" determinations, terminal subcultures of approximately 15% of instrument-negative tubes were performed to confirm the absence of growth. This suggests a direct comparison to laboratory reference methods rather than an expert consensus adjudication process.

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

This is not applicable. The BACTEC® MGIT™ 960 System is an automated instrument for detecting microbial growth, not an AI system designed to assist human readers in image interpretation or diagnosis. Therefore, no MRMC study or assessment of human reader improvement with AI assistance was performed or is relevant.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Yes, the study primarily evaluates the standalone performance of the BACTEC® MGIT™ 960 System. The instrument itself detects fluorescence indicating growth. While subsequent manual confirmatory tests (AFB smear, isolation, identification) are performed on positive samples, the initial detection is performed solely by the algorithm/instrument without human intervention. The reported recovery rates and false positive/negative rates directly reflect the instrument's standalone performance in detecting mycobacterial growth.

7. The Type of Ground Truth Used

The ground truth used in this study was based on standard microbiological laboratory methods:

• For positive identification: Acid-fast bacilli (AFB) smear, isolation, and identification from positive MGIT tubes.
• For confirming negative status: Terminal subcultures of instrument-negative tubes.

These methods represent a combination of direct observation (smear) and culture-based growth as definitive evidence of mycobacterial presence or absence.

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" in the context of machine learning. The BACTEC® MGIT™ 960 System is a device for detecting growth based on an optical sensor and algorithm, not a learning-based AI model that requires a distinct training phase with a labeled dataset in the conventional sense. The development of the detection algorithm would have involved internal validation and calibration with various mycobacterial and non-mycobacterial samples, but this is not specified as a formal "training set" in the document.

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

As noted above, a formal "training set" and associated ground truth establishment for a machine learning model is not applicable here. The "training" or calibration of the instrument's detection algorithm would have been part of its internal development and validation, likely using well-characterized mycobacterial cultures and clinical samples confirmed by standard laboratory methods. However, the document does not provide details on this process.

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