(223 days)
BD BACTECT™ Standard/10 Aerobic/F culture vials (enriched Soybean-Casein Digest broth with CO2) are for aerobic blood cultures. Principal use is with the BD BACTEC fluorescent series instruments for the qualitative culture and recovery of aerobic microorganisms (bacteria and yeast) from blood.
The sample to be tested is inoculated into one or more vials which are inserted into the BD BACTEC fluorescent series instrument for incubation and periodic reading. Each vial contains a chemical sensor which can detect increases in CO2 produced by the growth of microorganisms. The sensor is monitored by the instrument every ten minutes for an increase in its fluorescence, which is proportional to the amount of CO2 present. A positive reading indicates the presumptive presence of viable microorganisms in the vial. Detection is limited to microorganisms that will grow in a particular type of medium.
The provided document describes the BD BACTEC™ Standard/10 Aerobic/F Culture Vials (plastic version). The device is a culture vial for aerobic blood cultures, intended for use with BD BACTEC fluorescent series instruments for qualitative detection of microorganisms (bacteria and yeast) in blood. The study presented aims to demonstrate that the plastic version of the culture vial is substantially equivalent to the predicate device (glass version).
Here's an analysis of the acceptance criteria and study details based on the provided text, focusing on the comparisons between the modified (plastic) device and the predicate (glass) device:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Time to Detection (TTD): No relevant difference from current product (predicate device). | The estimated median TTD difference for 682 positive paired sets was -1.084 hours, favoring the modified device. Conclusion: The modified device meets the acceptance criteria, and the effect of differences between the modified and predicate devices on TTD was minimal; the modified device performs equivalently. |
| Percent Recovery: Equivalent between devices. | 984 paired sets evaluated. 948 were positive in both. 4 grew in predicate only, 9 grew in modified only. McNemar chi-square analysis: 0.2673, indicating no relevant difference. |
| Microbial Detection Limit: No relevant difference between devices. | 360 paired sets tested. 207 grew in both. 37 grew in predicate only, 48 grew in modified only. McNemar chi-square analysis: 0.2781, indicating no relevant difference. |
| False Positive Rate: No false positives in the modified device, or statistically insignificant difference from predicate. | 240 paired sets evaluated. No false positives in the modified device. One anomaly (a false positive) observed in the predicate device (positive at 16.98 hours without organism). A statistical analysis could not be performed due to insufficient failures in the test (only one failure in predicate and none in modified). Implicitly, the modified device met this better than the predicate. |
| False Negative Rate: No statistically significant difference in recovery between devices. | 91 paired sets were instrument negative. 41 modified devices and 57 predicate devices were instrument negative. Terminal subculture of instrument negatives identified 34 false negatives total. 18 were in the predicate device, 16 in the modified device. McNemar chi-square analysis (p=0.8638) indicates no statistically significant difference in recovery between the modified and predicate devices. |
| Reproducibility: No statistical difference across lots in TTD and recovery. | The modified device was evaluated for reproducibility across lots. No statistical difference in time to detection and recovery was observed between lot comparisons. |
2. Sample Size Used for the Test Set and Data Provenance
The document does not explicitly state the country of origin of the data or whether it was retrospective or prospective. It describes analytical studies comparing the modified device to a predicate device.
- Instrument Time to Detection: 682 paired sets recovered organisms in both devices.
- Percent Recovery: 984 paired sets.
- Microbial Detection Limit: 360 paired sets.
- False Positive Rate: 240 paired sets (comprised of 40 bottles from each of 3 lots).
- False Negative Rate: 91 paired sets that were instrument negative.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not provide any information regarding the number or qualifications of experts used to establish ground truth. The studies described are laboratory-based comparisons of detection capabilities, not evaluations of human interpretation.
4. Adjudication Method for the Test Set
The document does not describe any adjudication method involving human interpretation. The "ground truth" (or reference standard) in these studies appears to be based on whether microorganisms were successfully grown and detected, or confirmed by terminal subculture in the case of false negatives.
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 MRMC comparative effectiveness study was done. This device is a culture vial designed for automated detection by an instrument, not an AI-assisted diagnostic tool that requires human reader interpretation.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
The performance described in the document is effectively "standalone" in terms of the device's ability to detect microbial growth. The BD BACTEC fluorescent series instruments are automated systems that detect increases in CO2 produced by microorganisms. The studies evaluate the performance of the modified culture vial within this automated system, essentially demonstrating the algorithm (instrument's detection mechanism) only performance as it relates to the culture media. There is no human intervention in the detection process itself once the vials are loaded into the instrument.
7. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc.)
The ground truth for the analytical studies appears to be based on:
- Presence of microbial growth: Confirmed by instrument detection and/or terminal subculture for definitive growth determination.
- Known inoculum levels: For studies like Microbial Detection Limit and implied for Time to Detection and Percent Recovery, predefined organism concentrations are used to challenge the system.
8. The Sample Size for the Training Set
The document does not mention any "training set." The studies described are analytical performance evaluations of a medical device, not a machine learning model that requires a training phase.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there is no mention of a training set or machine learning model.
§ 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.