← Product Code [PMN](/submissions/MI/subpart-d%E2%80%94serological-reagents/PMN) · K254166

# MDx-Chex for BCN (K254166)

_Streck · PMN · Mar 23, 2026 · Microbiology · SESE_

**Canonical URL:** https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/PMN/K254166

## Device Facts

- **Applicant:** Streck
- **Product Code:** [PMN](/submissions/MI/subpart-d%E2%80%94serological-reagents/PMN.md)
- **Decision Date:** Mar 23, 2026
- **Decision:** SESE
- **Submission Type:** Traditional
- **Regulation:** 21 CFR 866.3920
- **Device Class:** Class 2
- **Review Panel:** Microbiology

## 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: 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.

## Regulatory 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.”

## Predicate Devices

- MDx-Chex for BC-GN ([K231223](/device/K231223.md))

## Submission Summary (Full Text)

> This content was OCRed from public FDA records by [Innolitics](https://innolitics.com). If you use, quote, summarize, crawl, or train on this content, cite Innolitics at https://innolitics.com.
>
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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

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{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

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|  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.

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**Source:** [https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/PMN/K254166](https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/PMN/K254166)

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