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The BDProbeTec™ ET Chlamydia trachomatis and Neisseria gonorrhoeae Amplified DNA Assays, when tested with the BDProbeTec™ ET System, use Strand Displacement Amplification (SDA) technology for the direct, qualitative detection of Chlamydia trachomatis and Neisseria gonorrhoeae DNA in endocervical swabs, male urethral swabs, and in female and male urine specimens as evidence of infection with C. trachomatis, N. gonorrhoeae, or of co-infection with C. trachomatis and N. gonorrhoeae. Specimens may be from symptomatic or asymptomatic males and females. A separate Amplification Control is an option for inhibition testing (BDProbeTec™ ET CT/GC/AC Reagent Pack).

The BDProbeTecTM ET Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) amplified DNA assays utilize homogeneous SDA technology as the amplification method and fluorescent energy transfer (ET) as the detection method to test for the presence of CT and GC in clinical specimens.

For each assay, the SDA reagents are dried in two separate microwell strips. First, the processed sample is added to the Priming Microwell which contains the amplification primers, fluorescent labeled detector probe, and other reagents necessary for amplification. However, because no enzymes are present in the priming microwell strips, no amplification occurs at this step. After incubation, the reaction mixture is transferred to the Amplification Microwell, which contains two enzymes (a DNA polymerase and a restriction endonuclease) necessary for SDA. It is in this latter microwell in which amplification and detection occurs. The Amplification Microwells are sealed to prevent contamination and then incubated in a thermally controlled fluorescent reader which monitors each test well for the generation of amplified products. The presence or absence of CT and GC is determined by relating the BDProbeTec™ ET MOTA (Method Other Than Acceleration) scores for the sample to pre-determined cutoff values. The MOTA score is a metric used to assess the magnitude of signal generated as a result of the reaction.

If the CT/GC Reagent Pack is used, each sample and control are tested in two discrete microwells: C. trachomatis and N. gonorrhoeae. Results are reported through an algorithm as positive or negative. If the CT/GC/AC Reagent Pack is used, each sample and control are tested in three discrete microwells: C. trachomatis, N. gonorrhoeae, and the Amplification Control. The purpose of the Amplification Control is to identify a sample that may inhibit the SDA reaction. Results are reported through an algorithm as positive, negative, or indeterminate.

Here's a breakdown of the acceptance criteria and study details for the BDProbeTec™ ET Chlamydia trachomatis and Neisseria gonorrhoeae Amplified DNA Assays based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The 510(k) summary focuses specifically on the Neisseria gonorrhoeae (GC) assay for asymptomatic males, comparing it to culture methods and a predicate device (Abbott LCx® N. gonorrhoeae assay). While explicit "acceptance criteria" are not listed numerically in the same way modern regulatory submissions often delineate them, the summary presents the performance metrics that were deemed sufficient for "substantial equivalence."

Note: The document states the results were "substantially equivalent" to GC culture methods and the Abbott LCx® assay, implying these performance values met the threshold for that determination.

2. Sample Size Used for the Test Set and Data Provenance

The study was a multicenter study, indicating data from various geographical locations in the US. It was a retrospective and prospective study, as it first describes an initial multicenter study and then a supplementary study to gather more asymptomatic male GC data, which was then "pooled."

• Initial Multicenter Study:

  • 2109 patients
  • 4108 C. trachomatis (CT) specimens
  • 4105 N. gonorrhoeae (GC) specimens
  • Collected from seven geographically diverse clinical sites (e.g., sexually transmitted disease clinics, OB/GYN clinics, family planning clinics, adolescent clinics, emergency rooms).
  • Included 183 asymptomatic male GC swab specimens.
  • Included 184 asymptomatic male GC urine specimens.

• Supplementary Study (Asymptomatic Male GC Data):

  • 519 patients
  • 987 specimens (asymptomatic male urethral swab and urine specimens)
  • Conducted at three clinical sites (one of which participated in the original evaluation).
  • Results were pooled with the original study's asymptomatic male GC specimens.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications

The document does not explicitly state the number or qualifications of experts involved in establishing the ground truth. However, the ground truth for N. gonorrhoeae in the study was based on:

• Culture: This implies laboratory personnel with expertise in microbiological culture techniques would have performed and interpreted these assays.
• Patient Infected Status (GC Culture): This indicates that a positive GC culture was the determinant of infection for comparing the BDProbeTec™ ET assay.

4. Adjudication Method for the Test Set

The document does not describe an adjudication method for conflicting results between the investigational device and the ground truth. The comparison was reported as direct sensitivity and specificity against the established ground truth (culture or patient infected status based on culture).

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

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This study is for an in vitro diagnostic (IVD) device, not an imaging device typically evaluated with MRMC studies. The device is for direct detection of DNA, and its performance is assessed against a gold standard, not by human reader interpretation.

6. Standalone Performance

Yes, a standalone performance study was done. The reported sensitivity and specificity values (95.5%, 100%, 99.4%, 99.5%) represent the unaided, algorithm-only performance of the BDProbeTec™ ET assay compared to the ground truth. There is no human-in-the-loop component mentioned in these performance metrics.

7. Type of Ground Truth Used

The ground truth used for N. gonorrhoeae was:

• Culture: For comparing the BDProbeTec™ ET GC assay to traditional methods.
• Patient Infected Status (defined as a positive GC culture): This was the primary definition of infection used to calculate sensitivity and specificity for the BDProbeTec™ ET assay.

8. Sample Size for the Training Set

The document does not provide a separate sample size for a "training set." The performance data presented (sensitivity and specificity) is from the clinical studies described, which would typically be considered the "test set" for regulatory submission. It's possible that internal development and optimization used other data, but that is not detailed in this 510(k) summary.

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

Since a separate training set is not explicitly detailed, the method for establishing ground truth for the clinical studies (which act as the definitive test set here) was based on GC culture as described above.

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