MDx-Chex® for BCN is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of gram-negative bacteria and associated antimicrobial resistance genes, by the Diasorin LIAISON PLEX® Gram-Negative Blood Culture assay on the LIAISON PLEX System. MDx-Chex for BCN Control 1 and Control 2 are composed of a buffered solution with stabilized erythrocytes and leukocytes in a matrix of blood culture media components. Control 1: gram-negative bacteria: Acinetobacter baumannii, Haemophilus influenzae, Neisseria meningitidis, Pseudomonas aeruginosa, Stenotrophomonas maltophilia; genus: Acinetobacter spp., Pseudomonas spp.; antimicrobial resistance genes: KPC, NDM, and VIM. Control 2: gram-negative bacteria: Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Morganella morganii, Serratia marcescens; family/genus: Enterobacteriaceae/Morganellaceae, Citrobacter spp., Enterobacter spp., Proteus spp., Salmonella spp.; antimicrobial resistance genes: CTX-M, IMP, MCR, OXA, and SME. This product is not intended to replace manufacturer controls provided with the device.
Device Story
MDx-Chex for BCN is a ready-to-use liquid quality control kit; contains two controls (Control 1 and Control 2) composed of buffered solution with stabilized human erythrocytes, leukocytes, and inactivated bacteria; monitors assay performance for Gram-negative bacteria and antimicrobial resistance genes; used in clinical laboratories to verify LIAISON PLEX Gram-Negative Blood Culture assay performance; processed like a patient sample; monitors entire assay workflow including lysis, nucleic acid isolation/purification, inhibitor removal, DNA hybridization, and detection; provides healthcare providers with confidence in assay accuracy; helps ensure reliable detection of pathogens and resistance genes; benefits patients by supporting accurate diagnostic results for blood culture testing.
Clinical Evidence
No clinical data. Performance established via bench testing, including multi-site reproducibility (n=180 runs, 99% PPA, 100% NPA), repeatability (n=120 replicates, 98% PPA, 100% NPA), lot-to-lot reproducibility, closed-vial stability (75 days), and shipping stability (summer/winter profiles). Matrix equivalency study confirmed no inhibition compared to clinical blood culture matrix.
Technological Characteristics
Ready-to-use liquid control; contains intact inactivated bacteria, human erythrocytes, and leukocytes in blood culture media matrix. Monitors lysis, nucleic acid isolation/purification, DNA hybridization, and detection. Stable at 2-25°C for 75 days. Standalone control material.
Indications for Use
Indicated for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of Gram-negative bacteria and associated antimicrobial resistance genes by the Diasorin LIAISON PLEX Gram-Negative Blood Culture assay on the LIAISON PLEX System. For prescription use only.
Regulatory Classification
Identification
An assayed quality control material for clinical microbiology assays is a device indicated for use in a test system to estimate test precision or to detect systematic analytical deviations that may arise from reagent or analytical instrument variation. This type of device consists of single or multiple microbiological analytes intended for use with either qualitative or quantitative assays.
Special Controls
An assayed quality control material for clinical microbiology assays must comply with the following special controls: (1) Premarket notification submissions must include detailed device description documentation and information concerning the composition of the quality control material, including, as appropriate: (i) Analyte concentration; Expected values: (ii) Analyte source: (iii) (iv) Base matrix; (v) Added components; (vi) Safety and handling information; and, (vii) Detailed instructions for use. (2) Premarket notification submissions must include detailed documentation, including line data as well as detailed study protocols and a statistical analysis plan used to establish performance, including: (i) Description of the process for value assignment and validation. (ii) Description of the protocol(s) used to establish stability. (iii) Line data establishing precision/reproducibility. (iv) Where applicable, assessment of matrix effects and any significant differences between the quality control material and typical patient samples in terms of conditions known to cause analytical error or affect assay performance. (v) Where applicable, identify or define traceability or relationship to a domestic or international standard reference material and/or method. (vi) Where applicable, detailed documentation related to studies for surrogate controls. (3) Premarket notification submissions must include an adequate mitigation (e.g., realtime stability program) to the risk of false results due to potential modifications to the assays specified in the device's 21 CFR 809.10 compliant labeling. (4) Your 21 CFR 809.10 compliant labeling must include the following: (i) The intended use in your 21 CFR 809.10(a)(2) and 21 CFR 809.10(b)(2) compliant labeling must include the following: (A) Assayed control material analyte(s); (B) Whether the material is intended for quantitative or qualitative assays: (C) Stating if the material is a surrogate control; (D)The system(s), instrument(s), or test(s) for which the quality control material is intended. (ii) The intended use in your 21 CFR 809.10(a)(2) and 21 CFR 809.10(b)(2) compliant labeling must include the following statement: "This product is not intended to replace manufacturer controls provided with the device." (iii)A limiting statement that reads "Quality control materials should be used in accordance with local, state, federal regulations, and accreditation requirements."
*Classification.* Class II (special controls). The special controls for this device are:(1) Premarket notification submissions must include detailed device description documentation and information concerning the composition of the quality control material, including, as appropriate:
(i) Analyte concentration;
(ii) Expected values;
(iii) Analyte source;
(iv) Base matrix;
(v) Added components;
(vi) Safety and handling information; and
(vii) Detailed instructions for use.
(2) Premarket notification submissions must include detailed documentation, including line data as well as detailed study protocols and a statistical analysis plan used to establish performance, including:
(i) Description of the process for value assignment and validation.
(ii) Description of the protocol(s) used to establish stability.
(iii) Line data establishing precision/reproducibility.
(iv) Where applicable, assessment of matrix effects and any significant differences between the quality control material and typical patient samples in terms of conditions known to cause analytical error or affect assay performance.
(v) Where applicable, identify or define traceability or relationship to a domestic or international standard reference material and/or method.
(vi) Where applicable, detailed documentation related to studies for surrogate controls.
(3) Premarket notification submissions must include an adequate mitigation (e.g., real-time stability program) to the risk of false results due to potential modifications to the assays specified in the device's 21 CFR 809.10 compliant labeling.
(4) Your 21 CFR 809.10 compliant labeling must include the following:
(i) The intended use of your 21 CFR 809.10(a)(2) and (b)(2) compliant labeling must include the following:
(A) Assayed control material analyte(s);
(B) Whether the material is intended for quantitative or qualitative assays;
(C) Stating if the material is a surrogate control; and
(D) The system(s), instrument(s), or test(s) for which the quality control material is intended.
(ii) The intended use in your 21 CFR 809.10(a)(2) and (b)(2) compliant labeling must include the following statement: “This product is not intended to replace manufacturer controls provided with the device.”
(iii) A limiting statement that reads “Quality control materials should be used in accordance with local, state, federal regulations, and accreditation requirements.”
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FDA U.S. FOOD & DRUG ADMINISTRATION
# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY
ASSAY ONLY
## I Background Information:
A 510(k) Number
K254166
B Applicant
Streck
C Proprietary and Established Names
MDx-Chex for BCN
D Regulatory Information
| Product Code(s) | Classification | Regulation Section | Panel |
| --- | --- | --- | --- |
| PMN | Class II | 866.3920 | MI |
## II Submission/Device Overview:
A Purpose for Submission:
To obtain a substantial equivalence determination for the MDx-Chex for BCN.
B Measurand:
Multi-analyte external quality control materials for microbiology NAAT assays.
C Type of Test:
The MDx-Chex for BCN is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of Gram-negative bacteria and associated antimicrobial resistance genes by the DiaSorin LIAISON PLEX Gram-Negative Blood Culture assay on the LIAISON PLEX System. MDx-Chex for BCN Control 1 and Control 2 are composed of a buffered solution with stabilized erythrocytes and leukocytes in a matrix of blood culture media components. Control 1: Gram-negative bacteria: Acinetobacter baumannii, Haemophilus influenzae, Neisseria meningitidis, Pseudomonas aeruginosa, Stenotrophomonas
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
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maltophilia; genus: Acinetobacter spp., Pseudomonas spp.; antimicrobial resistance genes: KPC, NDM, and VIM. Control 2: Gram-negative bacteria: Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Morganella morganii, Serratia marcescens; family/genus: Enterobacteriaceae/Morganellaceae, Citrobacter spp., Enterobacter spp., Proteus spp., Salmonella spp.; antimicrobial resistance genes: CTX-M, IMP, MCR, OXA, and SME. This product is not intended to replace manufacturer controls provided with the device.
## Intended Use/Indications for Use:
### A Intended Use(s):
See Indications for Use below.
### B Indication(s) for Use:
MDx-Chex for BCN is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of Gram-negative bacteria and associated antimicrobial resistance genes, by the DiaSorin LIAISON PLEX Gram-Negative Blood Culture assay on the LIAISON PLEX System. MDx-Chex for BCN Control 1 and Control 2 are composed of a buffered solution with stabilized erythrocytes and leukocytes in a matrix of blood culture media components. Control 1: Gram-negative bacteria: Acinetobacter baumannii, Haemophilus influenzae, Neisseria meningitidis, Pseudomonas aeruginosa, Stenotrophomonas maltophilia; genus: Acinetobacter spp., Pseudomonas spp.; antimicrobial resistance genes: KPC, NDM, and VIM. Control 2: Gram-negative bacteria: Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Morganella morganii, Serratia marcescens; family/genus: Enterobacteriaceae/Morganellaceae, Citrobacter spp., Enterobacter spp., Proteus spp., Salmonella spp.; antimicrobial resistance genes: CTX-M, IMP, MCR, OXA, and SME. This product is not intended to replace manufacturer controls provided with the device.
### C Special Conditions for Use Statement(s):
Rx – For Prescription Use Only
### D Special Instrument Requirements:
LIAISON Analyzer
## IV Device/System Characteristics:
### A Device Description:
MDx-Chex for BCN is a cellular-based external quality control containing stabilized blood components (erythrocytes and leukocytes), simulated blood culture media, inactivated microorganisms, and antimicrobial resistance gene targets. The control simulates positive and negative blood culture samples and is processed in "control mode" per the assay IFU. Use of full-process cellular controls enables evaluation of the entire analytical workflow for sample-to-
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result tests, including lysis, nucleic acid isolation/purification, hybridization, detection, and analysis, and provides assessment of the impact of inhibitors and pre-analytical variables.
MDx-Chex for BCN is supplied as two controls packaged as follows:
- Control 1 (pink cap), 5 microtubes $\times 0.5$ mL each, containing $300~\mu \mathrm{L}$ per tube.
- Control 2 (black cap), 5 microtubes $\times 0.5$ mL each, containing $300~\mu \mathrm{L}$ per tube. Each tube contains sufficient volume for a single test.
The kit has two configurations:
- Package containing five Control 1 vials and five Control 2 vials
- Package containing 10 Control 1 vials and 10 Control 2 vials
The analyte composition for the Control set is described in Table 1, below.
Table 1. Analyte composition for Control 1 and Control 2
| Gram-Negative Bacteria* | | |
| --- | --- | --- |
| Target | Control 1 | Control 2 |
| Enterobacteriaceae/Morganellaceae | Not Detected | Detected |
| Acinetobacter spp. | Detected | Not Detected |
| Acinetobacter baumannii | Detected | Not Detected |
| Citrobacter spp. | Not Detected | Detected |
| Enterobacter spp. | Not Detected | Detected |
| Escherichia coli | Not Detected | Detected |
| Haemophilus influenzae | Detected | Not Detected |
| Klebsiella oxytoca | Not Detected | Detected |
| Klebsiella pneumoniae | Not Detected | Detected |
| Klebsiella variicola | Not Detected | Detected |
| Morganella morganii | Not Detected | Detected |
| Neisseria meningitidis | Detected | Not Detected |
| Proteus spp. | Not Detected | Detected |
| Pseudomonas spp. | Detected | Not Detected |
| Pseudomonas aeruginosa | Detected | Not Detected |
| Salmonella spp. | Not Detected | Detected |
| Serratia marcescens | Not Detected | Detected |
| Stenotrophomonas maltophilia | Detected | Not Detected |
| Antimicrobial Resistance Genes* | | |
| Gene | Control 1 | Control 2 |
| CTX-M | Not Detected | Detected |
| IMP | Not Detected | Detected |
| KPC | Detected | Not Detected |
| MCR | Not Detected | Detected |
| NDM | Detected | Not Detected |
| OXA | Not Detected | Detected |
| SME | Not Reviewed | Detected |
| VIM | Detected | Not Detected |
*All bacteria analytes are sourced from ATCC, American Type Culture Collection
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B Principle of Operation:
Not applicable.
V Substantial Equivalence Information:
A Predicate Device Name(s):
MDx-Chex for BC-GN
B Predicate 510(k) Number(s):
K231223
C Comparison with Predicate(s):
| Device & Predicate Device(s): | K254166 | K231223 |
| --- | --- | --- |
| Device Trade Name | MDx-Chex for BCN | MDx-Chex for BC-GN |
| General Device Characteristic Similarities | | |
| Intended Use/Indications For Use | MDx-Chex for BCN is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of Gram-negative bacteria and associated antimicrobial resistance genes, by the DiaSorin LIAISON PLEX Gram-Negative Blood Culture assay on the LIAISON PLEX System. MDx-Chex for BCN Control 1 and Control 2 are composed of a buffered solution with stabilized erythrocytes and leukocytes in a matrix of blood culture media components. Control 1: Gram-negative bacteria: Acinetobacter baumannii, Haemophilus influenzae, Neisseria meningitidis, Pseudomonas aeruginosa, Stenotrophomonas maltophilia; genus: | MDx-Chex for BC-GN is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of Gram-negative bacteria and associated antimicrobial resistance genes, by the Luminex VERIGENE Gram-Negative Blood Culture Nucleic Acid Test (BC-GN) on Luminex VERIGENE systems. The MDx-Chex for BC-GN Positive and Negative Controls are composed of a buffered solution with stabilized erythrocytes and leukocytes in a matrix of blood culture media components. Positive Control: Gram-negative bacteria: Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa; Species: |
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VI Standards/Guidance Documents Referenced:
Not applicable
| | Acinetobacter spp.,
Pseudomonas spp.;
antimicrobial resistance genes:
KPC, NDM, and VIM. Control
2: Gram-negative bacteria:
Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Morganella morganii, Serratia marcescens;
family/genus:
Enterobacteriaceae/
Morganellaceae, Citrobacter spp., Enterobacter spp., Proteus spp., Salmonella spp.;
antimicrobial resistance genes:
CTX-M, IMP, MCR, OXA, and SME. This product is not intended to replace manufacturer controls provided with the device. | Acinetobacter spp., Citrobacter spp., Enterobacter spp., Proteus spp.; antimicrobial resistance genes: CTX-M, IMP, KPC, NDM, OXA, and VIM.
Negative Control: buffered solution only.
This product is not intended to replace manufacturer controls provided with the device. |
| --- | --- | --- |
| Physical Format | Same | Ready-to-Use Liquid |
| Indications for Use | Same | Process like a patient sample |
| Composition | Buffered solution with stabilized human erythrocytes and leukocytes, simulated blood culture media components, and inactivated microorganisms. | Intact inactivated bacteria, human erythrocytes and leukocytes, and relevant components of blood culture media |
| Assay Steps Monitored | Same | Lysis, nucleic acid isolation/purification/inhibitor removal, DNA hybridization, detection, identification/data reporting |
| General Device Characteristic Differences | | |
| Number of targets monitored in one assay | Multiple, 26 targets
18 Gram-negative organisms
8 Resistance genes | Multiple, 14 targets
8 Gram-negative organisms
6 Resistance genes |
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VII Performance Characteristics (if/when applicable):
A Analytical Performance:
1. Reproducibility:
A multi-site reproducibility study was conducted for the MDx-Chex for BCN where testing was completed at three different sites, with three operators and consisted of ten Control 1 samples and ten Control 2 samples for each of three lots of MDx-Chex for BCN, for a total of 30 samples per control type (i.e., Control 1 and Control 2) and 60 samples per lot. Both Control 1 and Control 2 were tested on different days (2 MDx-Chex for BCN control types x 1 lot x 1 day, for 10 days and 3 different sites) for a total of 180 runs (90 runs per MDx-Chex for BCN control type) generated for data analysis from all testing sites and all MDx-Chex for BCN sites.
All samples were prepared and analyzed using the LIAISON PLEX System per the controls Instructions for Use. This resulted in a positive percent agreement (PPA) of 99% (178/180) and a negative percent agreement (NPA) of 100% (180/180) for the MDx-Chex for BCN Control 1 and Control 2. Results are summarized in Table 2 and Table 3, below.
Table 2. MDx-Chex for BCN: Positive Percent Agreement Multi-Site Reproducibility Summary
| Category | Site 1 | | Site 2 | | Site 3 | | Percent Agreement | 95% CI |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | Observed /Expected Results | PPA | Observed /Expected Results | PPA | Observed/ Expected Results | PPA | | |
| MDx-Chex for BC-GN Positive Control 1 and Control 2 | 58*/60 | 97% | 60/60 | 100% | 60/60 | 100% | 99% (178/180) | 96-100% |
* One Positive Control 1 and one Positive Control Level 2 produced unexpected results
Table 3. MDx-Chex for BCN: Negative Percent Agreement Multi-Site Reproducibility Summary
| Category | Site 1 | | Site 2 | | Site 3 | | Percent Agreement | 95% CI |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | Observed/ Expected Results | NPA | Observed /Expected Results | NPA | Observed /Expected Results | NPA | | |
| MDx-Chex for BC-GN Negative Control 1 and Control 2 | 60/60 | 100% | 60/60 | 100% | 60/60 | 100% | 100% (180/180) | 98-100% |
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The results support the reproducibility of the MDx-Chex for BCN Controls 1 and 2 across three separately manufactured control lots, days, and operators when used with the DiaSorin LIAISON PLEX BCN panels on three different LIAISON PLEX Systems.
## 2. Repeatability:
An internal repeatability study was conducted to assess performance of MDx-Chex for BCN using at least two LIAISON PLEX Systems, three MDx-Chex for BCN lots, at least three LIAISON PLEX BCN test cartridge lots, and a minimum of two operators. Testing consisted of evaluating 20 samples per control type (Control 1 and Control 2), 40 samples per MDx-Chex for BCN lot, tested over 20 different days (2 MDx-Chex for BCN control types x 1 control type/day x 3 lots x 20 days), for a total of 120 replicates generated for data analysis.
Samples were prepared according to MDx-Chex for BCN control instructions, and tested using the LIAISON PLEX BCN system, per the Instructions for Use of the assay. This testing resulted in a PPA of 98% (118/120) for both MDx-Chex for BCN controls (Table 4) and a NPA of 100% (120/120) for both MDx-Chex for BCN controls (Table 5).
Table 4. MDx-Chex for BCN: Positive Percent Agreement Repeatability Summary
| Category | Observed/Expected Results | PPA | 95% CI |
| --- | --- | --- | --- |
| MDx-Chex for BCN Positive Control 1 and Control 2 | 118/120* | 98% | 94% - 100% |
*One Positive Control 1 and one Positive Control 2 produced unexpected results.
Table 5. MDx-Chex for BCN: Negative Percent Agreement Repeatability Summary
| Category | Observed/Expected Results | NPA | 95% CI |
| --- | --- | --- | --- |
| MDx-Chex for BCN Negative Control 1 and Control 2 | 120/120 | 100% | 97% - 100% |
The results support the repeatability of the MDx-Chex for BCN across three separately manufactured control lots when used with the Luminex BCN panels on the LIAISON PLEX system.
## 3. Lot-to-Lot Reproducibility
A lot-to-lot reproducibility study assessed the performance of the MDx-Chex for BCN across three lots. Ten Control 1 and 10 Control 2 tubes were tested per lot, for three lots, using one lot of LIAISON PLEX BCN testing cartridge lot, for a total of 60 replicates (30 per lot per control type). Samples were prepared per the control Instructions for Use (IFU) prior to testing. The study resulted in 100% PPA and 100% NPA for both Control 1 and Control 2 MDx-Chex for BCN, as shown in Table 6 and Table 7 below.
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Table 6. MDx-Chex for BCN: Positive Percent Agreement Lot-to-Lot Reproducibility Summary
| Category | MDx-Chex for BC-GN | Observed/Expected Results | PPA | 95% CI |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCN
Positive Control 1 and Control 2 | 5202 | 20/20 | 100% | 83% – 100% |
| | 5209 | 20/20 | 100% | 83% – 100% |
| | 5223 | 20/20 | 100% | 83% – 100% |
Table 7. MDx-Chex for BCN: Negative Percent Agreement Lot-to-Lot Reproducibility Summary
| Category | MDx-Chex for BC-GN | Observed/Expected Results | NPA | 95% CI |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCN
Negative Control 1 and Control 2 | 5202 | 20/20 | 100% | 83% – 100% |
| | 5209 | 20/20 | 100% | 83% – 100% |
| | 5223 | 20/20 | 100% | 83% – 100% |
The results support lot-to-lot reproducibility of the MDx-Chex for BCN across three separately manufactured lots when used with the LIAISON PLEX BCN panel.
4. Linearity:
Not applicable
5. Analytical Specificity/Interference:
Not applicable
6. Detection Limit and Assay Reportable Range:
Not applicable
7. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):
a. Closed vial Stability
A closed-vial stability study was conducted using three lots of MDx-Chex for BCN with the LIAISON PLEX BCN using the LIAISON PLEX system. Twenty Control 1 and 20 Control 2 samples representing three different lots of MDx-Chex for BCN were stored at room (25°C) and refrigerated temperatures (2°C) and collected at different timepoints for testing. Samples were tested at day zero (ship date) and at day 75 for each lot and storage condition. Samples were prepared and analyzed on the LIAISON PLEX BCN system per MDx-Chex for BCN Instructions for Use. The results of the closed vial stability testing are presented in Tables 8 and 9 below.
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Table 8. Closed-vial stability of MDx-Chex for BCN Control 1 and Control 2 - Positive Percent Agreement
| | Storage Temperature | # Lot | Observed/Expected Results | PPA | 95% Confidence Interval |
| --- | --- | --- | --- | --- | --- |
| Day 0 | NA | 5202 | 39/40* | 98% | 87% - 100% |
| | | 5209 | 40/40 | 100% | 91% - 100% |
| | | 5223 | 39/40* | 98% | 87% - 100% |
| Day 75* | 2 - 8°C | 5202 | 40/40 | 100% | 91% - 100% |
| | | 5209 | 40/40 | 100% | 91% - 100% |
| | | 5223 | 40/40 | 100% | 91% - 100% |
| | 20 - 25°C | 5202 | 40/40 | 100% | 91% - 100% |
| | | 5209 | 40/40 | 100% | 91% - 100% |
| | | 5223 | 40/40 | 100% | 91% - 100% |
* Indicates that lots stored at 2-8°C were tested for at least 75 days; Lot 5202 (Control 1: 82 days, Control 2: 83 Days), Lot 5209 (Control 1: 80 days, Control 2: 83 Days), Lot 5223 (Control 1: 84 days, Control 2: 85 Days). Lots stored at 20-25°C were tested for at least 75 days; Lot 5202 (Control 1: 82 days, Control 2: 83 Days), Lot 5209 (Control 1: 83 days, Control 2: 84 Days), Lot 5223 (Control 1: 85 days, Control 2: 88 Days).
* One MDx-Chex for BCN Control 1 from Lot 5202 and one MDx-Chex for BCN Control 1 from Lot 5223 produced unexpected results.
Table 9. Closed-vial stability of MDx-Chex for BCN Control 1 and Control 2 - Negative Percent Agreement
| | Storage Temperature | # Lot | Observed/Expected Results | NPA | 95% Confidence Interval |
| --- | --- | --- | --- | --- | --- |
| Day 0 | NA | 5202 | 40/40 | 100% | 91% - 100% |
| | | 5209 | 40/40 | 100% | 91% - 100% |
| | | 5223 | 40/40 | 100% | 91% - 100% |
| Day 75 | 2 - 8°C | 5202 | 40/40 | 100% | 91% - 100% |
| | | 5209 | 40/40 | 100% | 91% - 100% |
| | | 5223 | 40/40 | 100% | 91% - 100% |
| | 20 - 25°C | 5202 | 40/40 | 100% | 91% - 100% |
| | | 5209 | 40/40 | 100% | 91% - 100% |
| | | 5223 | 40/40 | 100% | 91% - 100% |
* Indicates that lots stored at 2-8°C were tested for at least 75 days; Lot 5202 (Control 1: 82 days, Control 2: 83 Days), Lot 5209 (Control 1: 80 days, Control 2: 83 Days), Lot 5223 (Control 1: 84 days, Control 2: 85 Days). Lots stored at 20-25°C were tested for at least 75 days; Lot 5202 (Control 1: 82 days, Control 2: 83 Days), Lot 5209 (Control 1: 83 days, Control 2: 84 Days), Lot 5223 (Control 1: 85 days, Control 2: 88 Days).
The data supports that MDx-Chex for BCN Control kit is stable for a minimum of 75 days for use with the LIAISON PLEX BCN panel, when stored at $2^{\circ}\mathrm{C} - 25^{\circ}\mathrm{C}$ .
b. Shipping Stability
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A shipping stability study was performed to determine the stability of MDx-Chex for BCN during shipment. Twenty samples of each control type (Control 1 and Control 2) were prepared from one lot of the MDx-Chex for BCN and stored at both ends of the storage temperature recommendations (i.e., $2^{\circ}\mathrm{C}$ and $25^{\circ}\mathrm{C}$ ). Control samples were then shipped under simulated winter and summer conditions for a period of five days (i.e., 120 hours). After the end of simulation period, the control samples were stored at the recommended temperatures, and data were then collected for each simulated shipping profile within the 75-day closed-vial stability testing period. Temperature stress conditions for summer and winter include a 120-hour exposure period with the following temperature profile, as presented in Table 10, below.
Table 10. Temperature Stress conditions
| Intervals | Interval Time (h) | Summer | | Winter | |
| --- | --- | --- | --- | --- | --- |
| | | Initial Temperature | Final Temperature | Initial Temperature | Final Temperature |
| 1 | 5 | 22 | 22 | 22 | 22 |
| 2 | 0 | 22 | 26 | 22 | 15 |
| 3 | 14 | 26 | 26 | 15 | 15 |
| 4 | 5.5 | 26 | 22 | 15 | 22 |
| 5 | 5.5 | 22 | 25 | 22 | 17 |
| 6 | 10 | 25 | 22 | 17 | 22 |
| 7 | 2 | 22 | 40 | 22 | -10 |
| 8 | 7.5 | 40 | 29 | -10 | 10 |
| 9 | 7.5 | 29 | 29 | 10 | 10 |
| 10 | 5 | 29 | 40 | 10 | -10 |
| 11 | 9 | 40 | 26 | -10 | 15 |
| 12 | 8.5 | 26 | 26 | 15 | 15 |
| 13 | 0 | 26 | 29 | 15 | 10 |
| 14 | 11.5 | 29 | 29 | 10 | 10 |
| 15 | 0 | 29 | 22 | 10 | 22 |
| 16 | 10 | 22 | 22 | 22 | 22 |
| 17 | 7.5 | 22 | 30 | 22 | 8 |
| 18 | 7.5 | 30 | 24 | 8 | 18 |
| 19 | 4 | 24 | 24 | 18 | 18 |
Samples at each storage temperature (2-8°C and 20-25°C) were exposed to winter and summer temperature extremes and then were stored back at each respective temperature for a week prior to being tested using LIAISON PLEX BCN panel. All results met the predefined acceptance criteria of PPA or NPA ≥90% and are presented in Table 11 and 12, below.
Table 11. Shipping Study of MDx-Chex for BCN - Positive Percent Agreement
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| Category | Storage Temperature1 | Observed/Expected Results | PPA | 95% CI |
| --- | --- | --- | --- | --- |
| Summer | 2-8°C | 40/40 | 100% | 91 – 100% |
| | 20-25°C | 40/40 | 100% | 91 – 100% |
| Winter | 2-8°C | 39/40* | 98% | 87 – 100% |
| | 20-25°C | 40/40 | 100% | 91 – 100% |
Samples were stored at each respective temperature prior to exposure to simulated summer or winter conditions and incubated back at each respective storage temperature prior to testing on the LIASON PLEX system.
* One Positive Control Level 1 had unexpected result.
Table 12. Shipping Study of MDx-chex for BCN - Negative Percent Agreement
| Category | Storage Temperature1 | Observed/Expected Results | PPA | 95% CI |
| --- | --- | --- | --- | --- |
| Summer | 2-8°C | 40/40 | 100% | 91 – 100% |
| | 20-25°C | 40/40 | 100% | 91 – 100% |
| Winter | 2-8°C | 40/40 | 100% | 91 – 100% |
| | 20-25°C | 40/40 | 100% | 91 – 100% |
1 Samples were stored at each respective temperature prior to exposure to simulated summer or winter conditions and incubated back at each respective storage temperature prior to testing on the LIAISON PLEX system.
Results demonstrate the MDx-Chex for BCN control kit is stable after exposure to summer and winter shipping temperature conditions.
8. Assay Cut-Off:
Not applicable
B Comparison Studies:
1. Method Comparison with Predicate Device:
Not applicable
2. Matrix Comparison:
The matrix of MDx-Chex for BCN contains stabilized blood components (erythrocytes and leukocytes) as well as components found in blood culture media. Since the matrix is not identical to that of the routine LIAISON PLEX BCN assay sample, blood culture media, a study was conducted to evaluate the effect of the matrix on the assay.
To demonstrate that the simulated blood culture matrix does not impact performance of the LIAISON PLEX BCN assay, Escherichia coli $(3.0 \times 10^{8}$ cells/mL final concentration) was spiked into MDx-Chex for BCN matrix as well as into BD BACTEC Plus Aerobic/F culture medium supplemented with negative whole blood to simulate a clinical sample. These samples were then tested in triplicate using the LIAISON PLEX BCN assay. Three replicates of each simulated
K254166 - Page 11 of 13
{11}
matrix with no spike-in organism were also tested to serve as negative controls. The results presented in Table 13 and Table 14 showed PPA and NPA of 100%, respectively.
Table 13. Matrix Equivalency Study Results for Control and Clinical Matrix Spiked with E. coli
| Matrix type | Expected/Tested | PPA | 95% CI |
| --- | --- | --- | --- |
| MDx-Chex for BCN matrix + E. coli | 3/3 | 100% | 29% - 100% |
| Clinical Matrix + E. coli | 3/3 | 100% | 29% - 100% |
Table 14. Matrix Equivalency Study Results for Unspiked Control and Clinical Matrix
| Matrix type | Expected/Tested | PPA | 95% CI |
| --- | --- | --- | --- |
| MDx-Chex for Blood Culture GN matrix | 3/3 | 100% | 29% - 100% |
| Clinical Matrix | 3/3 | 100% | 29% - 100% |
The results demonstrate that MDx-Chex for BCN matrix has no effect on target detection (no inhibition and/or false negative results) when tested with the LIAISON PLEX BCN panel.
C Clinical Studies:
1. Clinical Sensitivity:
Not applicable
2. Clinical Specificity:
Not applicable
3. Clinical Cut-Off:
Not applicable
4. Other Clinical Supportive Data (When 1. and 2. Are Not Applicable):
Not applicable
D Expected Values/Reference Range:
MDx-Chex for BCN is a qualitative control and the expected results are listed in Table 15, below.
Table 15. Bacterial Pathogens and Antimicrobial Resistance Genes Detected by MDx-Chex for BCN Control Types
K254166 - Page 12 of 13
{12}
| Gram-Negative Bacteria* | | |
| --- | --- | --- |
| Target | Control 1 | Control 2 |
| Enterobacteriaceae/Morganellaceae | Not Detected | Detected |
| Acinetobacter spp. | Detected | Not Detected |
| Acinetobacter baumannii | Detected | Not Detected |
| Citrobacter spp. | Not Detected | Detected |
| Enterobacter spp. | Not Detected | Detected |
| Escherichia coli | Not Detected | Detected |
| Haemophilus influenzae | Detected | Not Detected |
| Klebsiella oxytoca | Not Detected | Detected |
| Klebsiella pneumoniae | Not Detected | Detected |
| Klebsiella variicola | Not Detected | Detected |
| Morganella morganii | Not Detected | Detected |
| Neisseria meningitidis | Detected | Not Detected |
| Proteus spp. | Not Detected | Detected |
| Pseudomonas spp. | Detected | Not Detected |
| Pseudomonas aeruginosa | Detected | Not Detected |
| Salmonella spp. | Not Detected | Detected |
| Serratia marcescens | Not Detected | Detected |
| Stenotrophomonas maltophilia | Detected | Not Detected |
| Antimicrobial Resistance Genes* | | |
| Gene | Control 1 | Control 2 |
| CTX-M | Not Detected | Detected |
| IMP | Not Detected | Detected |
| KPC | Detected | Not Detected |
| MCR | Not Detected | Detected |
| NDM | Detected | Not Detected |
| OXA | Not Detected | Detected |
| SME | Not Reviewed | Detected |
| VIM | Detected | Not Detected |
# VIII Proposed Labeling:
The labeling supports the finding of substantial equivalence for this device.
# IX Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
K254166 - Page 13 of 13
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Learn the FDA Browser
Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.
