(231 days)
BD BACTEC Peds Plus™/F culture vials (enriched Soybean-Casein Digest broth with CO2) are for aerobic blood cultures. Principal use is with the BACTEC fluorescent series instruments for the qualitative culture and recovery of aerobic microorganisms (mainly bacteria and yeast) from pediatric and non-pediatric blood specimens which are generally less than 5 mL in volume.
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 document describes the BD BACTEC Peds Plus™/F Culture Vials (plastic), which is an aerobic blood culture medium. It compares this modified device to its predicate, the BD BACTEC Peds Plus/F medium (glass). The purpose of the studies is to demonstrate that the modified device performs equivalently to the predicate device.
Here's an analysis of the acceptance criteria and study information:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly state formal "acceptance criteria" in a quantitative format for each performance metric. Instead, it aims to demonstrate equivalence or non-inferiority to the predicate device. The reported performance is generally framed as "no statistically significant difference" or "performs equivalently."
| Performance Metric | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Instrument Time to Detection (TTD) | Equivalence to predicate device. | The Wilcoxon estimated median TTD difference for 473 positive sets is -0.250 hours (15 minutes), favoring the modified device. The data indicate that the effect of differences between the modified and predicate devices on TTD under these test conditions was minimal and that the modified device performs equivalently to the predicate device. |
| Percent Recovery | No statistically significant difference in recovery compared to the predicate device. | A total of 1344 paired sets were evaluated. 953 paired sets were positive in both devices. The McNemar p-value for this data set equals 0.2673, indicating no statistically significant difference in recovery. The document notes a "significant difference in recovery...favoring the modified device contained in plastic vials," which seemingly contradicts the p-value unless it refers to a non-statistical observation or a different comparison. Assuming the p-value is the statistical conclusion, it suggests no significant difference. |
| Microbial Detection Limit | No statistically significant difference in recovery compared to the predicate device. | A total of 360 inoculated cultures. 196 grew and detected in both. 42 in predicate only, 57 in modified only. McNemar chi-square analysis (p=0.1594) indicates no statistically significant difference in recovery between the modified and predicate devices. Of 164 sets, 62.2% had plate counts of 0 CFU per vial. |
| False Positive Rate | No false positives within specified blood volumes (0.5 to 1 mL). | A total of 288 paired sets (96 bottles/lot across 3 lots) inoculated with fresh human blood. There were no false positive bottles of the modified device observed within blood volumes (0.5 to 1 mL). |
| False Negative Rate | No statistically significant difference in false negative rates compared to the predicate device. | 83 paired sets were end of protocol negative in both. 129 sets were predicate-only detected, 146 sets were modified-only detected. Terminal subculture of non-detected vials showed 45 false negative bottles (25 in predicate, 20 in modified). A Chi-square analysis (p=0.456) indicates no significant difference favoring the modified in the plastic bottle. Retesting of Haemophilus influenzae strains initially leading to high false negatives resulted in detection in both vials. |
| Antimicrobial Neutralization Capability | No statistically significant difference in recovery when antimicrobials are present, compared to the predicate device. | Eleven drugs evaluated at MIC level. A total of 51 paired sets tested. Predicate detected 48 times (94%), modified detected 49 times (96%). McNemar's test p-value = 1.000, indicating no statistically significant difference in recovery between the modified and predicate devices. |
| Reproducibility | No statistical difference across lots in Time to Detection and Percent Recovery. | Tested across three lots for TTD and Percent Recovery. There was no statistical difference observed across lots comparison. |
2. Sample Size Used for the Test Set and Data Provenance
- Instrument Time to Detection: 473 paired sets (positive in both devices).
- Percent Recovery: 1344 paired sets.
- Microbial Detection Limit: 360 inoculated cultures (196 grew and detected in both).
- False Positive Rate: 288 paired sets (96 bottles from each of 3 lots).
- False Negative Rate: 83 paired sets (end-of-protocol negative in both), and other sets where only one device detected (129 predicate-only, 146 modified-only).
- Antimicrobial Neutralization Capability: 51 paired sets.
- Reproducibility: Tested across three lots (implied using subsets of the TTD and Percent Recovery data).
Data Provenance: The document does not specify the country of origin. The studies appear to be prospective analytical studies conducted in a laboratory setting, involving the inoculation of culture media with specific microorganisms and human blood.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
This information is not provided in the document. The studies described are analytical performance studies of a culture medium, not diagnostic studies involving interpretation by human experts. The "ground truth" for these tests (e.g., presence/absence of microbial growth, CFU counts) would have been established through standard microbiology laboratory techniques (e.g., subculture, plate counts) rather than expert consensus on diagnostic images or clinical data.
4. Adjudication Method for the Test Set
This information is not applicable/provided. As mentioned above, these are analytical performance studies where the outcome is objectively measured (e.g., instrument detection of CO2, colony counts from subcultures), not subjective interpretations requiring adjudication by human experts.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, an MRMC comparative effectiveness study was not done. The device is a culture medium, and the studies assess its analytical performance (e.g., time to detection, recovery rates) directly from instrument readings and laboratory methods, not human reader performance with or without AI assistance.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, the studies reflect standalone performance of the device in conjunction with the BACTEC fluorescent series instruments. The instrument automatically detects growth based on CO2 production. Human intervention would be for initial sample loading, result interpretation (positive/negative), and subsequent microbiological workup, but the "detection" itself is algorithmic. The document states: "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." This describes the standalone algorithmic detection by the instrument.
7. The Type of Ground Truth Used
The ground truth used for these analytical studies includes:
- Microbiological Culture and Growth: The presence or absence of viable microorganisms, confirmed by growth in culture or subculture, and typically quantified by plate counts (e.g., CFU per vial shown in the Microbial Detection Limit section).
- Instrument Readings: The BACTEC fluorescent series instruments provide quantitative data on CO2 production and time to detection.
- Terminal Subculture: Used to confirm true positive/negative status where the instrument did not detect growth, particularly for false negative assessments.
8. The Sample Size for the Training Set
This information is not provided as this is not an AI/ML device that requires a distinct "training set" in the conventional sense. The device is a culture medium where performance is evaluated through a series of analytical experiments with known microbial inocula and clinical samples (human blood). There is no "training phase" for an algorithm in the context of this product.
9. How the Ground Truth for the Training Set Was Established
Not applicable as there is no training set for an AI/ML algorithm involved with this device. The product is a physical culture medium, and its performance is evaluated against established microbiological methods and instrument readings as ground truth.
§ 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.