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The BD MAX™ Enteric Bacterial Panel performed on the BD MAX™ System is an automated in vitro diagnostic test for the direct qualitative detection and differentiation of enteric bacterial pathogens. The BD MAX Enteric Bacterial Panel detects nucleic acids from:

• Salmonella spp. .
• Campylobacter spp. (jejuni and coli) .
• Shigella spp. / Enteroinvasive E. coli (EIEC) .
• Shiga toxin 1 (stx1) / Shiga toxin 2 (stx2) genes (found in Shiga toxin-producing . E. coli [STEC]) as well as Shigella dysenteriae, which can possess a Shiga toxin gene (stx) that is identical to the stx1 gene of STEC.

Testing is performed on unoreserved soft to diarrheal stool specimens or Cary-Blair preserved stool specimens from symptomatic patients with suspected acute gastroenteritis, enteritis or colitis. The test is performed directly on the specimen, utilizing real-time polymerase chain reaction (PCR) for the amplification of SpaO, a Campylobacter specific tuf gene sequence, ipaH and stx1/stx2. The test utilizes fluorogenic sequence-specific hybridization probes for detection of the amplified DNA.

This test is intended for use, in conjunction with clinical presentation, laboratory findings, and epidemiological information, as an aid in the differential diagnosis of Salmonella, Shigella/EIEC, Campylobacter and Shiga toxin-producing E. coli (STEC) infections. Results of this test should not be used as the sole basis for diagnosis, treatment, or other patient management decisions. Positive results do not rule out co-infection with other organisms that are not detected by this test, and may not be the sole or definitive cause of patient illness. Negative results in the setting of clinical illness compatible with gastroenteritis may be due to infection by pathogens that are not detected by this test or non-infectious causes such as ulcerative colitis, irritable bowel syndrome, or Crohn's disease.

The BD MAX™ System and the BD MAX™ Enteric Bacterial Panel are comprised of an instrument with associated hardware and accessories, disposable microfluidic cartridges. master mixes, unitized reagent strips, extraction reagents, and sample buffer tubes. The instrument automates sample preparation including target lysis, DNA extraction and concentration, reagent rehydration, and target nucleic acid amplification and detection using real-time PCR. The assay includes a Sample Processing Control (SPC) that is present in the Extraction Tube. The SPC monitors DNA extraction steps, thermal cycling steps, reagent integrity and the presence of inhibitory substances. The BD MAX™ System software automatically interprets test result may be called as POS. NEG or UNR for each of the assay's targets, based on the amplification status of the target and of the Sample Processing Control. IND (Indeterminate) or INC (Incomplete) results are due to BD MAX™ System failure.

Here's a breakdown of the acceptance criteria and study details for the BD MAX™ Enteric Bacterial Panel, based on the provided document:

Acceptance Criteria and Device Performance

The document describes various analytical and clinical performance studies, each with inherent acceptance criteria demonstrated by the reported results. The explicit acceptance criteria are outlined in the "Precision" section for analytical performance. For clinical performance, the acceptance is implied by the achieved PPA (Positive Percent Agreement) and NPA (Negative Percent Agreement) values with corresponding confidence intervals.

Table of Acceptance Criteria and Reported Device Performance

Study Details

The provided document describes both Analytical Performance and Clinical Performance studies.

Analytical Performance Studies

These studies evaluate the device's technical capabilities in detecting the target pathogens.

• Sample Size Used for the Test Set and Data Provenance:
  • Precision:
    • Within-laboratory: For each of 4 different target types (Shiga toxins, Campylobacter, Shigella, Salmonella), 4 sample categories (TN, HN, LP, MP) were tested in triplicate over 12 days, with 2 runs per day. This results in 72 replicates per category per target.
    • Site-to-Site Reproducibility: 3 clinical sites were provided with 10 panels, each with 12 tubes. Each site performed the study over 5 distinct days, with 2 panels tested per day by 2 technologists. This results in 90 replicates per category per target across all sites (though specific numbers vary slightly when looking at site-by-site data for positive/negative agreement).
    • Lot-to-Lot Reproducibility: Data from 5 days of an accuracy and precision study, using 12 panel members per lot, with two users for each of two lots, was used. This equates to 90 replicates per category per target across the lots.
  • Data Provenance: Not explicitly stated as real-world patient data. These appear to be spiked samples (engineered to be near LoD, etc.) into negative stool matrix. The origin of the negative stool matrix is stated as "from patients".
• Number of Experts and Qualifications for Ground Truth: Not applicable for analytical studies, as ground truth is established by spiked concentrations of known organisms.
• Adjudication Method: Not applicable for analytical studies.
• Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study: Not applicable. These are analytical studies of the device's performance, not comparative effectiveness of human readers with/without AI assistance.
• Standalone Performance: Yes, these studies evaluate the standalone performance of the BD MAX™ Enteric Bacterial Panel system.
• Type of Ground Truth Used: For precision and reproducibility, known concentrations of target strains were used (e.g., "5 CFU/mL" for HN, "≥1 and <2 x LoD" for LP, etc.) Spiked samples into negative stool matrix.
• Sample Size for Training Set: Not applicable. These are analytical validation studies, not machine learning model training.
• How Ground Truth for Training Set was Established: Not applicable.

Clinical Performance Studies

These studies evaluate the device's accuracy in a real-world clinical setting.

• Sample Size Used for the Test Set and Data Provenance:
  • Prospective Specimens (Fresh): 3457 specimens were enrolled (2112 Cary-Blair preserved, 1345 unpreserved). The compliant dataset used for PPA and NPA calculations included a total of:
    • Campylobacter: 3038 (48 positive, 2990 negative)
    • Shigella: 3069 (41 positive, 3028 negative)
    • Salmonella: 3067 (44 positive, 3023 negative)
    • Shigatoxins: 2502 (10 positive, 2492 negative)
  • Retrospective Specimens (Frozen): 785 specimens were enrolled (464 Cary-Blair preserved, 321 unpreserved). 104 retrospective specimens were excluded from performance calculations because historical results were not confirmed. The compliant dataset used for PPA and NPA calculations included a total of:
    • Campylobacter: 507 (133 positive, 374 negative)
    • Shigella: 543 (92 positive, 451 negative)
    • Salmonella: 618 (167 positive, 451 negative)
    • Shigatoxins: 156 (66 positive, 90 negative)
  • Data Provenance:
    • Country of Origin: Geographically diverse clinical centers (8 sites) and collection centers (unspecified number, but imply multiple locations in the US given FDA submission). The document states "United States, European Union, Canada, other geographical regions" for analytical inclusivity, suggesting a broad scope, but for clinical trials, it only refers to "geographically diverse clinical centers."
    • Retrospective/Prospective: Both retrospective (collected March 2012 - August 2013, and archived June-Sept 2007, Oct-Dec 2011) and prospective (collected June-September 2013 on an "all-comers" basis) specimens were used.
• Number of Experts and Qualifications for Ground Truth:
  • The "reference method" involved historical culture results (for retrospective samples) which were confirmed by alternate PCR and bi-directional amplicon sequencing. For prospective samples, the reference method is also implied to be culture (not explicitly detailed, but standard for these pathogens).
  • The document does not specify the number or qualifications of experts (e.g., microbiologists, lab technicians) involved in performing the reference methods or interpreting the sequencing results. It refers to "clinical centers utilizing methodologies that did not have a high degree of similarity sent specimens to a central laboratory for reference method testing," suggesting specialized labs for the reference methods.
• Adjudication Method: For discrepant prospective specimens (where the device result differed from the reference method), further investigation was conducted using an "alternate PCR assay followed by bi-directional sequencing." This acts as a form of "tie-breaker" or confirmatory adjudication.
• Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study: No, this study evaluates the standalone diagnostic accuracy of the device against a reference method, not the impact of AI on human reader performance.
• Standalone Performance: Yes, the clinical performance study evaluated the device in a standalone capacity (algorithm only, against a reference standard).
• Type of Ground Truth Used:
  • Clinical Culture/Reference Method: For prospective samples, the reference method is indicated as clinical presentation, laboratory findings, and epidemiological information, along with culture.
  • Composite Reference Method: For retrospective samples, the ground truth was established by historical culture results confirmed using an alternate PCR and bi-directional amplicon sequencing. Discrepant prospective specimens were also adjudicated using alternate PCR and bi-directional sequencing.
• Sample Size for the Training Set: Not applicable. These are clinical validation studies. The device itself (BD MAX™ Enteric Bacterial Panel) is a nucleic acid-based assay (PCR), not an AI algorithm that would typically require a separate training set of clinical images/data.
• How Ground Truth for the Training Set was Established: Not applicable.

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