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The BACTEC® MYCO/F Lytic culture vials when used with the 9000 Blood Culture series of instrumentation are intended as an adjunct to routine blood culture for patients suspected of having mycobacteria, yeast and fungi septicemia. Extended incubation times (7 days for yeast, 30 days for fungi, and 42 days for mycobacteria) will permit recovery of mycobacteria and fungi when more rapidly growing organisms are not present. This medium may also be used for the culture of sterile body fluids when yeast or fungi are suspected.

BACTEC MYCO/F LYTIC Culture medium is a Middlebrook 7H9 and Brain Heart Infusion broth formulation for the recovery of mycobacteria from blood specimens and fungi from blood and sterile body fluids. The range of specimen volume which can be cultured is one to five mL. with optimum recovery obtained at three to five mL. Specific modifications were made to enhance the growth and recovery of mycobacteria, veast, and fungi. These modifications include ferric ammonium citrate to provide an iron source for specific strains of mycobacteria and fungi, the addition of saponin as a blood lysing agent and the addition of specific proteins and sugars to provide nutritional supplements. Each vial contains a sensor which can detect decreases in oxygen concentration in the vial resulting from microorganism and growth. The sensor is monitored by the BACTEC 9000 Blood Culture Systems for increasing fluorescence which is proportional to the decrease in oxygen. A positive determination indicates the presumptive presence of viable microorganisms in the vial.

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

Acceptance Criteria and Device Performance

The BACTEC MYCO/F LYTIC Blood Culture Medium is deemed substantially equivalent to predicate devices (BACTEC 13A for mycobacteria and BACTEC NR FUNGAL for yeast/fungi) based on internal and clinical studies demonstrating "equivalent performance." While explicit numerical acceptance criteria for recovery rates or time to detection are not provided as fixed thresholds, the studies aim to show that the new device performs comparably or better than the predicate devices across various clinically relevant scenarios.

Table of Acceptance Criteria and Reported Device Performance

Study Details

2. Sample sizes used for the test set and the data provenance:

• Clinical Studies (Test Set):
  • Mycobacteria: 1,100 blood culture specimens.
  • Yeast and Fungi (Blood): 748 blood culture specimens.
  • Overall Clinical Evaluation (Mycobacteria, Yeast, Fungi, Other Bacteria): 1,488 blood cultures.
• Internal Performance Studies (Test Set - In Vitro):
  • Yeast and Fungi: A variety of species at different CFU levels (e.g., TNTC, 170, 16, 80, 6 CFU/vial) and specimen volumes (0 mL, 1 mL, 5 mL blood). Each value is the average of "all vials per test condition" (specific number of vials per condition not detailed).
  • Mycobacteria: A variety of species at different CFU levels (e.g., 0, 1, 2, 3, 5, 7, 12, 13, 16, 20, 31, 44, 45, 49, 53, 58, 68 CFU/vial) and specimen volumes (1 mL, 3 mL, 5 mL blood). Two replicates ("Replicate" and original reading) are shown for each condition.
• Data Provenance:
  • Clinical Studies: Conducted at "two clinical sites considered large tertiary care teaching hospitals in geographically diverse areas" (for mycobacteria) and "four clinical sites considered large tertiary care teaching hospitals" (for fungi). Patient populations included HIV, immunocompromised, transplant patients, and those suspected of mycobacterial or fungal infections. This indicates prospective clinical data from diverse, real-world patient samples.
  • Internal Performance Studies: Conducted by Becton Dickinson Microbiology Systems. These are retrospective/in-vitro laboratory studies using controlled inoculums of specific organism strains.

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

The document does not explicitly state the number of experts or their specific qualifications (e.g., radiologists with X years of experience). However, for the clinical studies, ground truth was established by:

• Determining the "total number of pathogenic mycobacteria isolates recovered" and "total number of pathogenic yeast and fungal isolates recovered" from the various culture media.
• For false positive/negative rates, instrument results were compared to "smear and/or subculture-negative" or "smear and/or subculture-positive." This implies standard microbiological techniques and interpretation by laboratory professionals, rather than image interpretation by radiologists.

4. Adjudication method for the test set:

The document does not describe a formal adjudication method (like 2+1 or 3+1). The ground truth for the clinical studies appears to be based on the established clinical laboratory results from the two or four tertiary care hospitals involved, likely following standard diagnostic protocols of the time. For false positives/negatives, smear and/or subculture results served as the determinant.

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 to this device. The BACTEC MYCO/F LYTIC system is a blood culture medium used with an automated instrument for microbial growth detection, not an AI-assisted diagnostic imaging device that involves "human readers" in the traditional sense of image interpretation. The comparison is between different culture media/systems and their ability to recover and detect microorganisms.

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

The BACTEC MYCO/F LYTIC is a culture medium used with an instrument (BACTEC 9000 Blood Culture Series). The instrument automates the detection of growth (based on oxygen metabolism), but the "algorithm only" concept usually refers to AI in image analysis or similar fields. The performance measured is that of the medium and instrument system in detecting growth. While automated, human intervention is still required for specimen collection, inoculation, and interpretation of positive results (e.g., Gram stain, subculture for identification). Therefore, it's a device-only performance rather than a standalone algorithm in the AI sense.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

• Clinical Studies: Ground truth was established by microbiological culture results from the comparative methods (BACTEC 13A, ISOLATOR™ System) and confirmed by subculture and/or smear for positive/negative determinations. For identifying pathogenic isolates, standard laboratory identification methods would have been used.
• Internal Performance Studies: Ground truth was established by known inoculum levels of specific microbial strains (CFU/vial) in a controlled laboratory setting.

8. The sample size for the training set:

• The document does not explicitly describe a "training set" in the context of machine learning. The studies are traditional clinical and internal performance evaluations demonstrating the device's efficacy and substantial equivalence.
• The "Substantial Equivalence" section mentions "Internal and clinical studies demonstrated equivalent performance with all predicate devices," implying these studies were used to demonstrate performance rather than to "train" an algorithm.

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

• As there's no explicitly defined "training set" in the AI/ML context, this question is not applicable in the sense of how an algorithm's ground truth was established by experts for training.
• The "ground truth" for the overall evaluation involves the known presence/absence of microorganisms and their identification through standard microbiological laboratory procedures and controlled laboratory inoculations, as described in point 7.

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The BACTEC ® MYCO/F LYTIC Culture vial when used with the BACTEC 9000MB System is a qualitative test for the culture and recovery of mycobacteria in human blood speciments from patients who are suspected of having septicemia.

BACTEC MYCO/F LYTIC blood culture medium is a non-selective growth medium intended for the culture and recovery of mycobacteria and designed for blood volumes of one to five mL. BACTEC MYCO/F LYTIC culture medium is a Middlebrook 7H9 and Brain Heart Infiusion broth formulation with specific formulation modifications made to enhance the growth of mycobacteria. It is used specifically with the BACTEC 9000MB instrument in the monitoring of clinical blood specimens for the presence of microorganisms. This medium contains the same fluorescence senor as the BACTEC MYCO/F Sputa culture medium and detection is based on changes in oxygen concentration in the vial resulting from metabolism and growth of microorganisms. The sensor is monitored by the BACTEC 9000MB System for increasing fluorescence which is proportinal to the decrease in oxygen. A positive determination indicates the presumptive presence of viable microorganisms in the vial.

Here's an analysis of the acceptance criteria and study details for the BACTEC MYCO/F LYTIC Culture Medium, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly define formal "acceptance criteria" with specific thresholds (e.g., "sensitivity must be >X%"). However, it implies acceptance criteria by comparing the performance of the BACTEC MYCO/F LYTIC medium to a predicate device (BACTEC 13A) and by reporting internal performance characteristics.

The implied objective is that the BACTEC MYCO/F LYTIC medium should be at least comparable to, or ideally better than, the predicate device in terms of mycobacteria recovery and detection, with acceptable false positive and false negative rates.

Since explicit acceptance criteria are missing as numerical targets, I will present the key performance metrics reported in the studies.

2. Sample Size and Data Provenance

• Clinical Test Set Sample Size: 284 blood specimens.
• Data Provenance: Prospective clinical study conducted at "two clinical sites considered large tertiary care teaching hospitals in geographically diverse areas." The specific country of origin is not mentioned but typically for FDA submissions of this era, the studies would be conducted in the United States.

3. Number of Experts and Qualifications for Ground Truth

The document does not explicitly state the number of experts or their specific qualifications for establishing the "ground truth" (e.g., "smear and/or subculture-negative/positive") for the clinical test set. It mentions "microbiological workup" and validation against "smear and/or subculture." This implies standard laboratory practices performed by qualified laboratory personnel, but details on expertise (e.g., years of experience, specific certifications) are absent.

4. Adjudication Method

The document does not describe an explicit adjudication method (like 2+1 or 3+1) for resolving discrepancies in the ground truth for the clinical test set. The ground truth ("smear and/or subculture-negative/positive") appears to be determined by confirmed laboratory results.

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

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not conducted. This study compares a device (the BACTEC MYCO/F LYTIC medium) directly against a predicate device (BACTEC 13A medium) in a clinical evaluation, but it is not a "human reader" study; it's a comparison of culture media performance. Therefore, an effect size of human readers improving with or without AI assistance is not applicable.

6. Standalone (Algorithm Only) Performance Study

Yes, a standalone performance study was conducted. The "INTERNAL PERFORMANCE" section and "Table 2: Detection of Mycobacteria in the Myco/F Lytic Medium" represent a standalone evaluation. This study assessed the recovery and time to detection of various mycobacteria species at different CFU levels specifically with the BACTEC MYCO/F LYTIC medium and the BACTEC 9000MB instrument, without direct comparison to human reading or other media as the primary objective.

7. Type of Ground Truth Used

• Clinical Study: The ground truth for the clinical performance evaluation was established through laboratory confirmation (smear and/or subculture results). This represents definitive microbiological results, which would fall under a form of "pathology" in a broader sense of laboratory diagnostics.
• Internal Study: The ground truth for the internal performance study (Table 2) was based on known mycobacteria strains and quantified CFU/bottle (Colony Forming Units per bottle), with the outcome being the time to detection by the BACTEC 9000MB instrument.

8. Sample Size for the Training Set

The document does not mention a training set for the BACTEC MYCO/F LYTIC culture medium. This type of device (a culture medium for microbial growth detection) does not typically involve machine learning algorithms that require explicit "training sets" in the conventional sense. The "internal performance" study (Table 2) could be considered an initial validation or characterization of the medium's performance with known isolates under controlled conditions, serving a similar purpose to testing the device's inherent capabilities before clinical evaluation.

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

Since there is no explicit mention of a "training set" in the context of machine learning, this question is not directly applicable. If the "internal performance" study is considered a foundational or characterization study, the ground truth was established by using known, cultured mycobacteria strains with quantified concentrations (CFU/bottle).

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