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510(k) Data Aggregation
(271 days)
Antimicrobial Susceptibility Test Discs are indicated for the semi-quantitative susceptibility testing by agar diffusion test procedure of rapidly growing micro-organisms. These include : Staphylococcus spp., and modified by procedures, Haemophilus influenzae.
Oxoid Rifampicin Susceptibility Test Disc
This document is an FDA 510(k) clearance letter for an in vitro diagnostic device (IVD), specifically an antimicrobial susceptibility test disc. IVDs, especially those cleared under a 510(k), are often evaluated based on their performance characteristics compared to a predicate device, rather than a full clinical study with acceptance criteria like a drug or a novel medical device. The document itself does not contain the detailed study results or acceptance criteria.
However, based on the nature of antimicrobial susceptibility testing and the typical requirements for such devices, I can infer and generally describe the likely acceptance criteria and type of study. I will fill in the table and information, making educated assumptions where the specific details are not provided in the given text.
I must emphasize that the provided text does not include the detailed study results or acceptance criteria directly. This information would typically be in the 510(k) submission itself, which this document is a response to.
1. Table of Acceptance Criteria and Reported Device Performance
For an antimicrobial susceptibility test disc, the primary performance metrics are related to its ability to accurately classify bacterial isolates as susceptible, intermediate, or resistant to a given antibiotic (Rifampicin in this case). The acceptance criteria are typically established in comparison to a reference method (e.g., broth microdilution or agar dilution as described by CLSI/NCCLS standards).
| Acceptance Criteria (Inferred) | Reported Device Performance (Inferred/Typical for 510k IVD) |
|---|---|
| Essential Agreement (EA): Percentage of isolates where the disc diffusion category (S, I, R) matches the reference method category. | Typically >90% (often 95-99%) for each drug-bug combination. For the Oxoid Rifampicin disc, it would need to demonstrate high essential agreement across relevant Staphylococcus spp. and Haemophilus influenzae. The exact reported percentage is not in this document. |
| Category Agreement (CA): Percentage of isolates where the disc diffusion category (S, I, R) exactly matches the reference method category (similar to EA but sometimes used to denote a stricter match). | Typically >90% (often 95-99%). The exact reported percentage is not in this document. |
| Minor Discrepancies: Percentage of isolates with a one-off category difference (e.g., reference is Susceptible, disc is Intermediate). | Typically <5-10% (often <5%). The exact reported percentage is not in this document. |
| Major Discrepancies (False Susceptible): Percentage of isolates where the disc diffusion indicates Susceptible, but the reference method indicates Resistant. | Typically <1.5-3.0%. These are clinically critical errors and must be very low. The exact reported percentage is not in this document. |
| Very Major Discrepancies (False Resistant): Percentage of isolates where the disc diffusion indicates Resistant, but the reference method indicates Susceptible. | Typically <1.5-3.0%. These are also clinically critical errors. The exact reported percentage is not in this document. |
| Zone Diameter Reproducibility: Consistent zone diameters when tested repeatedly under controlled conditions. | Standard deviation or coefficient of variation for zone diameters within acceptable limits (e.g., within 1-2 mm for 95% of replicates). The exact reported percentage or values are not in this document. |
| Growth/Inhibition Characteristics: Clear zones of inhibition for susceptible organisms, and clear growth for resistant organisms. | Qualitative observation of distinct growth patterns. The document mentions "semi-quantitative susceptibility testing by agar diffusion test procedure." The exact reported qualitative assessment is not in this document. |
| Quality Control Ranges: Zone diameters for specified QC organisms fall within established ranges. | The document mentions "The technical product insert details the Quality Control organisms to be use with this disc." This implies that the device demonstrated performance within established QC ranges for those organisms. The specific ranges and results are not in this document. |
2. Sample size used for the test set and the data provenance
- Sample Size for Test Set: The document does not specify the exact sample size. However, for a 510(k) submission for an antimicrobial susceptibility test, the test set would typically involve a statistically significant number of clinical isolates (e.g., hundreds, sometimes thousands) representing the target organisms (Staphylococcus spp., Haemophilus influenzae) and covering a range of resistance mechanisms to Rifampicin. This would often include a good representation of susceptible, intermediate, and resistant strains.
- Data Provenance: The document does not explicitly state the country of origin or whether the data was retrospective or prospective. However, given Oxoid Limited is based in England, it is plausible that some or all of the clinical isolates used in the studies originated from European collections or clinical sites. Studies for 510(k) usually involve a combination of well-characterized reference strains and fresh clinical isolates, often collected prospectively or from well-maintained biobanks (making them retrospective by nature of collection but prospectively tested for the device).
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts
- Number of Experts & Qualifications: For antimicrobial susceptibility testing, the "ground truth" is typically established by performing a reference method (e.g., CLSI/NCCLS broth microdilution or agar dilution). This is a standardized laboratory procedure, not typically an expert consensus reading of images or clinical cases. The interpretation of the reference method results and the categorization into S/I/R is based on established clinical breakpoints published by organizations like CLSI. Therefore, "experts" in the sense of adjudicators are not usually involved in establishing the ground truth directly, beyond ensuring the reference method is performed and interpreted correctly by qualified microbiologists or laboratory scientists.
4. Adjudication method for the test set
- Adjudication Method: Not applicable in the traditional sense. As explained above, the "ground truth" is determined by a standardized reference method. Any discrepancies between the investigational device and the reference method would be analyzed, but typically not "adjudicated" by multiple human readers in the way diagnostic imaging or pathology might be. If there were significant discrepancies, the reference method result would stand, and the investigational device's performance would be evaluated against that.
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
- MRMC Study: Not applicable. This device is an in vitro diagnostic for antimicrobial susceptibility, not a device that involves human readers interpreting cases (like imaging devices aided by AI). Therefore, no MRMC study, AI assistance, or effect size related to human reader improvement would be relevant or performed for this type of product.
6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done
- Standalone Performance: Partially applicable. The device itself is a disc that produces a zone of inhibition. The reading of this zone diameter and its interpretation into S/I/R categories can be done manually by a human or potentially by an automated zone reader (which might involve an algorithm). The primary performance evaluation would be for the accuracy of the zone diameter measurement and its correlation with the reference method, regardless of how the zone is read. This document pertains to the disc itself, not an automated reader. Therefore, the "standalone" performance would be how accurately the disc produces a zone that, when correctly measured and interpreted, correlates with the reference method.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
- Type of Ground Truth: The ground truth would be established by a standardized microbiological reference method, specifically a quantitative method like broth microdilution or agar dilution, interpreted according to established clinical breakpoints (e.g., CLSI/NCCLS guidelines). This is considered the gold standard for antimicrobial susceptibility testing.
8. The sample size for the training set
- Sample Size for Training Set: The document does not provide information about a "training set." For an IVD like this, there isn't typically a "training set" in the machine learning sense. The device is a physical disc; its design (e.g., antibiotic concentration) is based on established microbiological principles and validated through performance studies. While developers might conduct initial studies to optimize disc concentration, this isn't usually termed a "training set" in regulatory submissions. The primary focus is on the performance evaluation (test set) against a gold standard.
9. How the ground truth for the training set was established
- Ground Truth for Training Set: Not applicable. As explained above, a "training set" as understood in AI/ML is not a concept typically applied to the development and validation of a simple physical IVD like an antimicrobial susceptibility disc. The ground truth for performance evaluation (the test set) is established using reference microbiological methods.
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