(350 days)
The APTIMA COMBO 2 Assay is a target amplification nucleic acid probe test that utilizes target capture for the in vitro qualitative detection and differentiation of ribosomal RNA (rRNA) from Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (GC) to aid in the diagnosis of chlamydial and/or gonococcal urogenital disease using the PANTHER System as specified.
On the PANTHER System, the assay may be used to test the following specimens from symptomatic and asymptomatic individuals: clinician-collected endocervical, vaginal and male urethral swab specimens, clinician-collected gynecological specimens collected in the PreservCyt Solution, and patient-collected vaginal swab specimens.
The APTIMA Combo 2 Assay combines the technologies of target capture, TMA, and DKA. Specimens are collected and transferred into their respective specimen transport tubes. The transport solutions in these tubes release the rRNA targets and protect them from degradation during storage. When the APTIMA Combo 2 Assay is performed in the laboratory, the target rRNA molecules are isolated from specimens by use of capture oligomers via target capture that utilizes magnetic microparticles. The capture oligomers contain sequences complementary to specific regions of the target molecules as well as a string of deoxyadenosine residues. A separate capture oligomer is used for each target. During the hybridization step, the sequence specific regions of the capture oligomers bind to specific regions of the target molecules. The capture oligomer:target complex is then captured out of solution by decreasing the temperature of the reaction to room temperature. This temperature reduction allows hybridization to occur between the deoxyadenosine region on the capture oligomer and the poly-deoxythymidine molecules that are covalently attached to the magnetic particles. The microparticles, including the captured target molecules bound to them, are pulled to the side of the reaction vessel using magnets and the supernatant is aspirated. The particles are washed to remove residual specimen matrix that may contain amplification reaction inhibitors. After the target capture steps are completed, the specimens are ready for amplification. Target amplification assays are based on the ability of complementary oligonucleotide primers to specifically anneal and allow enzymatic amplification of the target nucleic acid strands. The APTIMA Combo 2 Assay replicates a specific region of the 23S rRNA from CT and a specific region of the 16S rRNA from GC via DNA intermediates. A unique set of primers is used for each target molecule. Detection of the rRNA amplification product sequences (amplicon) is achieved using nucleic acid hybridization. Single-stranded chemiluminescent DNA probes, which are complementary to a region of each target amplicon, are labeled with different acridinium ester molecules. The labeled DNA probes combine with amplicon to form stable RNA:DNA hybrids. The Selection Reagent differentiates hybridized from unhybridized probe, eliminating the generation of signal from unhybridized probe. During the detection step, light emitted from the labeled RNA:DNA hybrids is measured as photon signals in a luminometer, and are reported as Relative Light Units (RLU). In DKA, differences in the kinetic profiles of the CT and GC labeled probes allow for the differentiation of signal; kinetic profiles are derived from measurements of photon output during the detection read time. The chemiluminescent detection for CT signal has very rapid kinetics and has the "flasher" kinetic type. The chemiluminescent detection reaction for GC signal is relatively slower and has the "glower" kinetic type. Assay results are determined by a cut-off based on the total RLU and the kinetic curve type.
This FDA 510(k) summary describes the APTIMA Combo 2® Assay on the PANTHER System, a device for in vitro qualitative detection and differentiation of ribosomal RNA from Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (GC). The submission is for clearing the assay for use on the PANTHER System, as it was previously cleared on the TIGRIS System.
Here's an analysis of the provided information:
1. Acceptance Criteria and Reported Device Performance
The acceptance criteria for this device are implicitly tied to the performance characteristics, specifically sensitivity and specificity, as demonstrated in the clinical study. While explicit "acceptance criteria" values for sensitivity and specificity are not directly stated in the summary, the reported performance characteristics are presented with 95% confidence intervals, suggesting that the observed values met predefined thresholds for regulatory approval. The fact that the device received 510(k) clearance further indicates that its performance was deemed acceptable by the FDA.
Table of Performance for APTIMA Combo 2® Assay on the PANTHER System (Clinical Study Results)
| Specimen Type | Target | Reported Sensitivity % (95% CI) | Reported Specificity % (95% CI) |
|---|---|---|---|
| Male Urethral Swab | CT | 100 (96.3-100) | 99.1 (97.7-99.7) |
| Clinician-Collected/Patient-Collected Vaginal Swab | CT | 97.2 (92.1-99.0) | 98.5 (97.6-99.0) |
| PreservCyt Solution Liquid Pap | CT | 98.2 (93.8-99.5) | 100 (99.7-100) |
| Female Endocervical Swab | CT | 97.2 (92.1-99.0) | 99.3 (98.6-99.6) |
| Male Urethral Swab | GC | 100 (89.8-100) | 100 (99.3-100) |
| Vaginal Swab | GC | 97.7 (87.9-99.6) | 99.6 (99.0-99.8) |
| PreservCyt Solution Liquid Pap | GC | 100 (91.8-100) | 100 (99.7-100) |
| Female Endocervical Swab | GC | 100 (91.6-100) | 99.8 (99.4-100) |
Analytical Sensitivity (Limits of Detection):
- CT: Claimed 1 IFU/assay (7.25 IFU/swab, 9.75 IFU/mL, PreservCyt Solution liquid Pap). 100% positivity was observed in samples containing CT concentrations of 0.03 IFU/mL.
- GC: Claimed 50 cells/assay (362 cells/swab, 488 cells/mL PreservCyt Solution liquid Pap). 100% positivity was observed in samples containing GC concentrations of 0.04 CFU/mL.
Within Laboratory Precision (STM matrix, selected rows as an example):
| Target Concentration CT (IFU/mL) | GC (CFU/mL) | Agrmt (%) | Total SD (x1000) | Total CV (%) |
|---|---|---|---|---|
| 0 | 0 | 100 | 1.3 | 20.1 |
| 0.25 | 0 | 100 | 87.1 | 7.1 |
| 0 | 12.5 | 100 | 43.2 | 4.0 |
| 2.5 | 125 | 100 | 101.5 | 4.1 |
Carryover Study: Overall carryover rate was 0% with a 95% confidence interval of 0-0.1%. This meets an implicit acceptance criterion of negligible or acceptable carryover.
2. Sample Size Used for the Test Set and Data Provenance
The clinical study was a prospective, multicenter clinical study conducted across 7 geographically and ethnically diverse US clinical sites.
Test Set Sample Sizes:
- Male subjects: 580 enrolled, 567 evaluable male urethral swab samples.
- 18 male urethral swab specimens had final invalid results and were excluded.
- Female subjects: 1332 enrolled.
- 1319 evaluable vaginal swab samples (clinician-collected/patient-collected combined).
- 1330 evaluable PreservCyt Solution liquid Pap samples.
- 1310 evaluable endocervical swab samples.
- 1 vaginal swab and 1 endocervical swab had final CT equivocal results and were excluded.
- 1 PreservCyt and 1 endocervical swab had final GC equivocal results and were excluded.
- Female urine specimens were collected but used as part of the "infected status algorithm" (ground truth definition) rather than directly tested as a primary specimen type for performance against the APTIMA Combo 2 Assay on PANTHER for this 510(k).
Data Provenance: United States (7 US clinical sites). The study was prospective.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
The ground truth was established using an "infected status algorithm" based on results from two specimen types and two reference NAATs (Nucleic Acid Amplification Tests). The specific number and qualifications of experts directly involved in adjudicating the "infected status" or interpreting the reference NAATs are not explicitly stated in the provided text.
However, for a device like this, standard practice for establishing ground truth for NAATs in clinical trials typically involves:
- Use of one or more FDA-cleared and/or highly sensitive and specific reference NAATs.
- Concordance of positive results across multiple tests/specimens to define an "infected status."
- Discrepancies often resolved by a third, highly sensitive method or expert clinical review, though this detail is not provided.
The text states: "Subjects were categorized as infected if a positive result occurred in each of the 2 reference NAATs." This implies a rule-based algorithm for ground truth rather than individual expert adjudication for each case.
4. Adjudication Method for the Test Set
The adjudication method for determining the "infected status" (ground truth) was an algorithm-based approach:
- For male subjects and female subjects, if the positive NAAT results occurred only in the urine specimens and not in the PreservCyt specimens, the subject was categorized as infected; however, for the evaluation of the non-urine specimen types, the specimens were considered non-infected.
- "Subjects were categorized as infected if a positive result occurred in each of the 2 reference NAATs."
This indicates a 2-out-of-2 (or 2+0) concordance rule for positivity to establish infection status. The text doesn't mention a tie-breaking or expert review process if results were discordant between the two reference NAATs, but specimens with "invalid, equivocal, or error results" were retested, and those with final invalid/equivocal results were excluded from analysis.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done.
This device is an in vitro diagnostic test, specifically a nucleic acid amplification test (NAAT). These types of tests are designed to provide a qualitative result (positive/negative) based on an analytical assay run on an automated system, not to be interpreted by human readers in the same way an imaging device or pathology slide might be. Therefore, the concept of "human readers improve with AI vs. without AI assistance" does not apply to this type of device. The "AI" (algorithm) here is the test.
6. Standalone (Algorithm Only) Performance
Yes, standalone performance was done.
The entire clinical study described, including the sensitivity and specificity values provided in Tables 6, 7, 8, 9, 10, and 11, represents the standalone performance of the APTIMA Combo 2 Assay on the PANTHER System. The results are compared against an "infected status algorithm" which serves as the ground truth, not against human interpretation of raw assay data. The device's output is the final diagnostic result.
7. Type of Ground Truth Used
The ground truth used was an algorithm-based "infected status" derived from the results of two reference nucleic acid amplification tests (NAATs) on two different specimen types (e.g., male urethral swab and male urine for males, and PreservCyt and urine for females).
Specifically:
- "Male urethral swab, male and female urine, and PreservCyt samples were tested with cleared nucleic acid amplification tests (NAATs) to establish the infected status."
- "The infected status algorithm used results from two specimen types and two reference NAATs. Subjects were categorized as infected if a positive result occurred in each of the 2 reference NAATs."
- "For female subjects, if the positive NAAT results occurred only in the urine specimens and not in the PreservCyt specimens, the subject was categorized as infected; however, for the evaluation of the non-urine specimen types, the specimens were considered non-infected."
8. Sample Size for the Training Set
The provided text does not specify a sample size for a training set. This document is a 510(k) summary for a diagnostic test, not a submission for a de novo machine learning algorithm that typically requires a distinct training and test set with explicit disclosure of training data. The "device" in this context is the analytical assay and automated system. While the assay itself (APTIMA Combo 2) was developed and validated, the data tables presented relate to the performance evaluation (test set) for the new platform (PANTHER System).
9. How the Ground Truth for the Training Set Was Established
As no explicit training set is detailed for the purpose of a machine learning algorithm in this 510(k) summary, the process for establishing ground truth for a training set is not applicable here. The provided data focuses on the validation of the device on a new platform (PANTHER System) for regulatory clearance, where the clinical study (test set) is the primary evidence for performance.
§ 866.3390
Neisseria spp. direct serological test reagents.(a)
Identification. Neisseria spp. direct serological test reagents are devices that consist of antigens and antisera used in serological tests to identifyNeisseria spp. from cultured isolates. Additionally, some of these reagents consist ofNeisseria spp. antisera conjugated with a fluorescent dye (immunofluorescent reagents) which may be used to detect the presence ofNeisseria spp. directly from clinical specimens. The identification aids in the diagnosis of disease caused by bacteria belonging to the genusNeisseria, such as epidemic cerebrospinal meningitis, meningococcal disease, and gonorrhea, and also provides epidemiological information on diseases caused by these microorganisms. The device does not include products for the detection of gonorrhea in humans by indirect methods, such as detection of antibodies or of oxidase produced by gonococcal organisms.(b)
Classification. Class II (performance standards).