MDx-Chex for BCP

K260041 · Streck, LLC · PMN · Mar 27, 2026 · Microbiology

Device Facts

• Record ID: K260041
• Device Name: MDx-Chex for BCP
• Applicant: Streck, LLC
• Product Code: PMN · Microbiology
• Decision Date: Mar 27, 2026
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.3920
• Device Class: Class 2

Indications for Use

MDx-Chex for BCP is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of Gram-positive bacteria and associated antimicrobial resistance genes, by the Diasorin LIAISON PLEX Gram-Positive Blood Culture assay on the LIAISON PLEX System. The MDx-Chex BCP 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-positive bacteria: Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Streptococcus agalactiae, Streptococcus anginosus group, Streptococcus pneumoniae, Streptococcus pyogenes, Enterococcus faecalis, Enterococcus faecium; genus: Bacillus spp., Listeria spp., Staphylococcus spp., Streptococcus spp.; antimicrobial resistance genes: mecA/mecC, vanA, and vanB. Negative Control: buffered solution only. This product is not intended to replace manufacturer controls provided with the device.

Device Story

MDx-Chex for BCP is a ready-to-use liquid quality control kit; contains two controls (positive and negative) for the Diasorin LIAISON PLEX Gram-Positive Blood Culture assay. Positive control contains stabilized human erythrocytes, leukocytes, inactivated Gram-positive bacteria, and resistance genes in a simulated blood culture media matrix; negative control contains buffered solution only. Used by laboratory technicians to monitor assay performance, including lysis, nucleic acid isolation, purification, inhibitor removal, DNA hybridization, and detection. Processed like a patient sample on the LIAISON PLEX system. Output is a qualitative result (detected/not detected) for specific pathogens and resistance genes. Helps ensure system accuracy, operator proficiency, and equipment installation verification. Benefits patient care by providing confidence in the reliability of clinical diagnostic results for blood culture assays.

Clinical Evidence

No clinical data. Bench testing only. Precision evaluated at one site (60 results) and reproducibility at three sites (90 results per control type). Combined reproducibility percent agreement was 99% (89/90) for positive controls and 98% (88/90) for negative controls. Matrix effect study confirmed performance in MDx-Chex matrix compared to clinical blood culture matrix (100% agreement). Stability testing supports 365-day shelf-life at 2-25°C.

Technological Characteristics

Ready-to-use liquid control; contains stabilized human erythrocytes, leukocytes, and inactivated bacteria/components in simulated blood culture media. Monitors lysis, nucleic acid isolation/purification, DNA hybridization, and detection. No energy source; standalone material. Sterilization not specified. Software algorithm is inherent to the LIAISON PLEX system, not the control material.

Indications for Use

Indicated for use by trained laboratory professionals as an external positive and negative assayed control to monitor the performance of the qualitative detection of Gram-positive bacteria and associated antimicrobial resistance genes in blood culture samples using the DiaSorin LIAISON PLEX Gram-Positive Blood Culture assay.

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.”

Predicate Devices

• MDx-Chex for BC-GP (K231221)

Submission Summary (Full Text)

{0}

FDA U.S. FOOD & DRUG ADMINISTRATION

# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY

ASSAY ONLY

## I Background Information:

A 510(k) Number

K260041

B Applicant

Streck, LLC

C Proprietary and Established Names

MDx-Chex for BCP

D Regulatory Information

| Product Code(s) | Classification | Regulation Section | Panel |
| --- | --- | --- | --- |
| PMN | Class II | 21 CFR 866.3920 - Assayed Quality Control Material For Clinical Microbiology Assays | MI - Microbiology |

## II Submission/Device Overview:

A Purpose for Submission:

To obtain a substantial equivalence determination for the MDx-Chex for BCP.

B Measurand:

Multi-analyte external quality control materials for microbiology NAAT assays.

C Type of Test:

QC materials to monitor the performance of the DiaSorin LIAISON PLEX Gram-Positive Blood Culture assay on the LIAISON PLEX System.

Food and Drug Administration

10903 New Hampshire Avenue

Silver Spring, MD 20993-0002

www.fda.gov

{1}

K260041 - Page 2 of 8

## III Intended Use/Indications for Use:

### A Intended Use(s):

See Indications for Use below.

### B Indication(s) for Use:

MDx-Chex for BCP is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of Gram-positive bacteria and associated antimicrobial resistance genes, by the Diasorin LIAISON PLEX Gram-Positive Blood Culture assay on the LIAISON PLEX System. The MDx-Chex BCP 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-positive bacteria: *Staphylococcus aureus*, *Staphylococcus epidermidis*, *Staphylococcus lugdunensis*, *Streptococcus agalactiae*, *Streptococcus anginosus* group, *Streptococcus pneumoniae*, *Streptococcus pyogenes*, *Enterococcus faecalis*, *Enterococcus faecium*; genus: *Bacillus* spp., *Listeria* spp., *Staphylococcus* spp., *Streptococcus* spp.; antimicrobial resistance genes: mecA/mecC, vanA, and vanB. Negative Control: buffered solution only. 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:

DiaSorin LIAISON PLEX System.

## IV Device/System Characteristics:

### A Device Description:

MDx-Chex for BCP is a cellular-based external quality control containing stabilized blood components (erythrocytes and leukocytes), simulated blood culture media, and inactivated microorganisms. 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-result tests, including lysis, nucleic acid isolation/purification, hybridization, detection, and analysis, and provides assessment of the impact of inhibitors and pre-analytical variables. The device is intended to be used by trained laboratory professionals.

#### Kit configurations

MDx-Chex for BCP is packaged in a chipboard box containing a 10-hole insert. Each package contains five (5) Positive Control vials and five (5) Negative Control vials. Each control kit is

{2}

supplied with 5 violet-capped $0.5\mathrm{mL}$ microtubes, each containing $300\mu \mathrm{L}$ of the Positive Control formulation, and 5 white-capped $0.5\mathrm{mL}$ microtubes, each containing $300\mu \mathrm{L}$ of the Negative Control formulation. Each tube contains enough reagent for 1 test.

MDx-Chex for BCP Verification Kit is packaged in the same chipboard box and contains a 20-hole insert. Each package contains ten (10) Positive Sample vials and ten (10) Negative Sample vials. Each packaged verification kit is supplied with 10 violet-capped $0.5\mathrm{mL}$ microtubes, each containing $300\mu \mathrm{L}$ of the Positive Control formulation, and 10 white-capped $0.5\mathrm{mL}$ microtubes, each containing $300\mu \mathrm{L}$ of the Negative Control formulation.

| Catalog Number | Product Name | Kit Configuration |
| --- | --- | --- |
| 250084 | MDx-Chex for BCP | (5) Positive Control vials and (5) Negative Control vials |
| 250087 | MDx-Chex for BCP Verification Kit | (10) Positive Sample vials and (10) Negative Sample vials |

The analyte composition for the Control set is described in Table 1, below.

Table 1: MDx-Chex for BCP Positive Control and Negative Control Results Summary.

| Gram-Positive Bacteria* | | |
| --- | --- | --- |
| Target | Positive Control | Negative Control |
| Staphylococcus aureus | Detected | Not Detected |
| Staphylococcus epidermidis | Detected | Not Detected |
| Staphylococcus lugdunensis | Detected | Not Detected |
| Streptococcus agalactiae | Detected | Not Detected |
| Streptococcus anginosus group | Detected | Not Detected |
| Streptococcus pneumoniae | Detected | Not Detected |
| Streptococcus pyogenes | Detected | Not Detected |
| Enterococcus faecalis | Detected | Not Detected |
| Enterococcus faecium | Detected | Not Detected |
| Bacillus spp. | Detected | Not Detected |
| Listeria spp. | Detected | Not Detected |
| Staphylococcus spp. | Detected | Not Detected |
| Streptococcus spp | Detected | Not Detected |
| Antimicrobial Resistance Genes* | | |
| mecA/mecC | Detected | Not Detected |
| VanA | Detected | Not Detected |
| VanB | Detected | Not Detected |

*All Bacteria analytes are sourced from ATCC, American Type Culture Collection

# B Principle of Operation:

Not applicable.

K260041 - Page 3 of 8

{3}

V Substantial Equivalence Information:

A Predicate Device Name(s):

MDx-Chex for BC-GP

B Predicate 510(k) Number(s):

K231221

C Comparison with Predicate:

| Device & Predicate Device(s): | K260041 | K231221 |
| --- | --- | --- |
| Device Trade Name | MDx-Chex for BCP | MDx-Chex for BC-GP |
| General Device Characteristic Similarities | | |
| Intended Use/Indications For Use | MDx-Chex for BCP is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of Gram-positive bacteria and associated antimicrobial resistance genes, by the Diasorin LIAISON PLEX Gram-Positive Blood Culture assay on the LIAISON PLEX System. The MDx-Chex BCP 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-positive bacteria: Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Streptococcus agalactiae, Streptococcus anginosus group, Streptococcus pneumoniae, Streptococcus pyogenes, Enterococcus faecalis, Enterococcus faecium; genus: Bacillus spp., Listeria spp., Staphylococcus spp., Streptococcus spp.; antimicrobial resistance genes: mecA/mecC, vanA, and vanB. Negative Control: buffered solution only. This product is not | MDx-Chex for BC-GP is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of Gram-positive bacteria and associated antimicrobial resistance genes, by the Luminex VERIGENE ® Gram-Positive Blood Culture Nucleic Acid Test (BC-GP) on Luminex VERIGENE ® systems. The MDx-Chex for BC-GP 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-positive bacteria: Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Streptococcus agalactiae, Streptococcus pneumoniae, Streptococcus pyogenes, Enterococcus faecalis, Enterococcus faecium, Streptococcus anginosus; Species: Staphylococcus spp., Streptococcus spp., Listeria spp.; antimicrobial resistance genes: mecA, vanA, vanB. Negative Control: buffered solution only. This product is not intended to replace manufacturer controls provided with the device. |

K260041 - Page 4 of 8

{4}

| | intended to replace manufacturer controls provided with the device. | |
| --- | --- | --- |
| Physical Format | Ready-to-Use Liquid | Same |
| Indications for Use | Process like patient sample | Same |
| Composition | MDx-Chex for BCP contains stabilized human leukocytes and erythrocytes, and the inactivated bacteria and bacteria components in simulated blood culture media as identified on table 1 above. | Same |
| Assay Steps Monitored | Lysis, nucleic acid isolation/purification/inhibitor removal, DNA hybridization, detection, identification/data reporting | Same |
| General Device Characteristic Differences | | |
| Number of targets monitored in one assay | Multiple, 16 Targets | Multiple, 15 Targets |

VI Standards/Guidance Documents Referenced:

Special Controls under 21 CFR 866.3920

ISO 15223-1:2021. Symbols to be used with information to be supplied by the manufacturer.

ISO 14971:2019. Medical Devices-Application of risk management to medical devices.

CLSI EP05-A3. Evaluation of Precision of Quantitative Measurement Procedures

VII Performance Characteristics (if/when applicable):

A Analytical Performance:

1. Precision/Reproducibility:

A. Single-site precision.

Within-laboratory precision was evaluated at one site, using three lots of positive and negative QC material, over 20 days, producing a total of 60 results per control type. Samples were prepared according to the MDx-Chex for BCP Instructions for Use (IFU) and tested using at least three Liaison PLEX BCP test cartridges on at least two DiaSorin LIAISON PLEX systems by at least two operators. The results from the initial run were

K260041 - Page 5 of 8

{5}

analyzed as percent agreement between the observed and expected value (positive or negative) for each run, with one or more discordant analyte rendering “unexpected” result for the entire run. The results are summarized in Table 2 below.

Table 2. Single-site precision of MDx-Chex for Blood Culture GP QC material.

| Category | Observed / Expected Results | Percent Agreement | 95% Confidence Interval |
| --- | --- | --- | --- |
| MDx-Chex for Blood Culture GP Positive Control | 59/60 | 98% | 91%-100% |
| MDx-Chex for Blood Culture GP Negative Control | 60/60 | 100% | 94%-100% |

B. Multisite reproducibility.

Reproducibility was evaluated at three sites using three lots (one lot per site) of positive and negative QC material at each site and 10 samples per lot per control type, producing a total of 30 results per site per control type. Samples were prepared according to the MDx-Chex for BCP IFU and analyzed with the DiaSorin LIAISON PLEX BCP assay and DiaSorin LIAISON PLEX systems. The results from the initial run were analyzed as percent agreement between the observed and expected value (positive or negative) for each run, with one or more discordant analyte rendering “unexpected” result for the entire run. The results are summarized in Table 3 below.

Table 3. Multisite reproducibility of MDx-Chex for Blood Culture GP QC material.

| Category | Site #1 | | Site #2 | | Site #3 | | Combined Percent Agreement (observed/expected) | 95% Confidence Interval |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | Observed/Expected Results | Percent Agreement | Observed/Expected Results | Percent Agreement | Observed/Expected Results | Percent Agreement | | |
| MDx-Chex for BCP Positive Control | 29/30 | 97% | 30/30 | 100% | 30/30 | 100% | 99% (89/90) | 94% - 100% |
| MDx-Chex for BCP Negative Control | 30/30 | 100% | 29/30 | 97% | 29/30 | 97% | 98% (88/90) | 92% - 100% |

2. Linearity:
N/A

3. Analytical Specificity/Interference:
N/A

4. Assay Reportable Range:
N/A

K260041 - Page 6 of 8

{6}

5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):

## Closed-Vial Stability.

Closed-Vial Stability was evaluated using three lots of QC material, two conditions (storage temperature 2-8°C or 20-25°C), and 20 samples for each combination of lot, condition, and QC type. The results demonstrated at least 90% agreement with the expected outcomes, and supported a claimed shelf-life of 365 days when stored at 2-25°C.

## Shipping Stability.

Shipping Stability was evaluated using one lot of QC material, two conditions (simulated shipping during summer or winter), and 20-25 samples for each QC type. Samples were stored at 2-8°C or 20-25°C prior to shipping simulation, exposed to extreme temperature profiles (summer: between 22°C and 40°C; winter: between -10°C and -22°C) for five days, then returned to their respective storage temperatures for seven days. Samples were tested within the 75-day close-vial stability testing period. The results demonstrated at least 90% agreement with the expected outcomes. Additional stability assessment may be performed at end-of-shelf-life to confirm product shelf-life claim after exposure to extreme shipping temperatures.

6. Detection Limit:

N/A

7. Assay Cut-Off:

N/A

## B Comparison Studies:

1. Method Comparison with Predicate Device:

N/A

2. Matrix Effect:

To evaluate the effect of the simulated blood culture matrix on the performance of the DiaSorin LIAISON PLEX BCP assay, one lot of Staphylococcus aureus (4,000,000 cells/mL final concentration) was spiked into MDx-Chex for BCP matrix and into BD BACTEC Plus Aerobic/F culture medium supplemented with negative whole blood to simulate a clinical sample. The simulated samples were tested in triplicate using DiaSorin LIAISON PLEX BCP assay. Additionally, non-spiked simulated samples were tested in triplicate using BCP assay serving as negative controls. The results are summarized in Table 4 below.

Table 4. Matrix effect on results of MDx-Chex for Blood Culture GP QC material.

| Matrix type | Observed/Expected results | Percent Agreement | 95% Confidence Interval |
| --- | --- | --- | --- |
| MDx-Chex for BCP Matrix + Staphylococcus aureus | 3/3 | 100% | 29% - 100% |

K260041 - Page 7 of 8

{7}

| Clinical Matrix + Staphylococcus aureus | 3/3 | 100% | 29% - 100% |
| --- | --- | --- | --- |
| MDx-Chex for BCP Matrix | 3/3 | 100% | 29% - 100% |
| Clinical Matrix | 3/3 | 100% | 29% - 100% |

C Clinical Studies:

1. Clinical Sensitivity:
N/A

2. Clinical Specificity:
N/A

3. Other Clinical Supportive Data (When 1. and 2. Are Not Applicable):
N/A

D Clinical Cut-Off:
N/A

E Expected Values/Reference Range:
The expected values for each analyte are either “detected” or “not detected”. Refer to section IV.A. Device Description, Table 1.

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.

K260041 - Page 8 of 8