← Product Code [PMN](/submissions/MI/subpart-d%E2%80%94serological-reagents/PMN) · K231221

# MDx-Chex for BC-GP (K231221)

_Streck · PMN · Jul 27, 2023 · Microbiology · SESE_

**Canonical URL:** https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/PMN/K231221

## Device Facts

- **Applicant:** Streck
- **Product Code:** [PMN](/submissions/MI/subpart-d%E2%80%94serological-reagents/PMN.md)
- **Decision Date:** Jul 27, 2023
- **Decision:** SESE
- **Submission Type:** Traditional
- **Regulation:** 21 CFR 866.3920
- **Device Class:** Class 2
- **Review Panel:** Microbiology

## Indications for Use

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, Streptoccus pneumoniae, Streptococcus pyogenes, Enterococcus faecalis, Enterococcus faecium, Streptococcus anginosus group; 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.

## Device Story

MDx-Chex™ for BC-GP is a ready-to-use liquid quality control kit; contains stabilized human erythrocytes, leukocytes, blood culture media components, and inactivated intact microorganisms. Used in clinical laboratories to monitor the entire analytical process of the Luminex VERIGENE® BC-GP test, including sample lysis, nucleic acid isolation, DNA hybridization, and detection. Controls for potential inhibitors like hemoglobin, leukocyte DNA, and anticoagulants. Operators process control vials like patient samples. Output is qualitative detection of specific Gram-positive pathogens and resistance genes. Routine use helps identify test system variations, preanalytical errors, or reagent degradation, ensuring reliable clinical results for blood culture diagnostics.

## Clinical Evidence

No clinical data. Analytical performance was established via multi-site reproducibility and repeatability studies. Reproducibility study (n=180 runs) across three sites, seven operators, and three lots yielded 100% PPA and 100% NPA. Repeatability study (n=120 runs) yielded 100% PPA and 100% NPA. Lot-to-lot reproducibility (n=60) confirmed performance consistency. Shipping stability studies (summer/winter profiles) confirmed stability. Matrix equivalency study confirmed the simulated matrix does not inhibit target detection compared to clinical blood culture matrix.

## Technological Characteristics

Ready-to-use liquid control; contains stabilized human erythrocytes, leukocytes, and inactivated intact microorganisms in blood culture media matrix. Monitors lysis, nucleic acid isolation, DNA hybridization, and detection. No energy source; standalone product. Not a software-based device.

## 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 BCID2 ([K212576](/device/K212576.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

K231221

B Applicant

Streck

C Proprietary and Established Names

MDx-Chex for BC-GP

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 BC-GP.

B Measurand:

Multi-analyte quality control materials

C Type of Test:

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

Food and Drug Administration

10903 New Hampshire Avenue

Silver Spring, MD 20993-0002

www.fda.gov

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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 group; Species: Staphylococcus spp., Streptococcus spp., Listeria spp.; antimicrobial resistance genes: mecA, vanA, vanB. Negative Control: buffered solution only.

## III Intended Use/Indications for Use:

A. Intended Use(s): See Indications for Use below.

B. Indication(s) for Use: 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 group; 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.

C. Special Conditions for Use Statement(s): Rx - For Prescription Use Only

For in vitro diagnostic use only

D. Special Instrument Requirements:

The MDx-Chex for BC-GP is only for use on the Luminex VERIGENE system.

## IV Device/System Characteristics:

A. Device Description:

MDx-Chex for BC-GP is a quality control kit consisting of positive and negative controls for the Luminex VERIGENE Gram-Positive Blood Culture Test (BC-GP). The MDx-Chex for BC-GP Positive Control is positive for Gram-positive bacterial pathogens and antimicrobial resistance gene markers in the VERIGENE BC-GP test (Table 1). The MDx-Chex for BC-GP Negative Control is negative for Gram-positive bacterial pathogens and antimicrobial resistance gene markers in the VERIGENE BC-GP test. The MDx-Chex for BC-GP matrix consists of blood and blood culture media components that have been identified as inhibitors to DNA hybridization assays (e.g., hemoglobin, leukocyte DNA, and anticoagulants).

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Table 1: Bacterial pathogens and antimicrobial resistance genes found in MDx-Chex for BC-GP and detected by the Luminex VERIGENE Gram-Negative Blood Culture Test on the Luminex VERIGENE system

|  Gram-Positive Bacterial Pathogens  |   |
| --- | --- |
|  Enterococcus faecalis | Enterococcus faecium  |
|  Listeria species | Streptococcus species  |
|  Staphylococcus species | Streptococcus agalactiae  |
|  Staphylococcus aureus | Streptococcus anginosus group  |
|  Staphylococcus epidermis | Streptococcus pneumoniae  |
|  Staphylococcus lugdunensis | Streptococcus pyogenes  |
|  Resistance Genes  |   |
|  mecA (methicillin) | vanB (vancomycin)  |
|  vanA (vancomycin) |   |

The MDx-Chex for BC-GP quality control kit contains stabilized blood components, blood culture media components, and inactivated, intact microorganisms resulting in a full-process, cellular-based control for the Luminex VERIGENE BC-GP panel. Full-process controls evaluate the entire analytical process, including sample lysis, nucleic acid isolation, DNA hybridization detection, and analysis, as well as the impact of inhibitors present in blood culture samples and pre-analytical variables.

# B Principle of Operation:

Not applicable.

# V Substantial Equivalence Information:

A Predicate Device Name(s):

MDx-Chex for BCID2

B Predicate 510(k) Number(s):

K212576

C Comparison with Predicate(s):

|  Device & Predicate Device(s): | K231221 | K212576  |
| --- | --- | --- |
|  Device Trade Name | MDx-Chex for BC-GP | MDx-Chex for BCID2  |
|  General Device Characteristic Similarities |  |   |
|  Intended Use/Indications For Use | MDx-Chex for BC-GP is intended for use as an external positive and negative assayed control to monitor the performance of the | MDx-Chex for BCID2 is intended for use as an external positive and negative assayed control to monitor the performance of the  |

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|   | 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 group; Species: Staphylococcus spp., Streptococcus spp., Listeria spp.; antimicrobial resistance genes: mecA, vanA, vanB. This product is not intended to replace manufacturer controls provided with the device. | qualitative detection of yeast, Gram positive and Gram-negative bacteria, as well as associated antimicrobial resistance genes, by the BioFire FilmArray Blood Culture Identification 2 (BCID2) Panel on FilmArray systems. Control 1 - GN: Gram negative bacteria: Acinetobacter colcoaceticus-baumannii complex, Bacteroides fragilis, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae group, Proteus spp., Salmonella spp., Serratia marcescens, Haemophilus influenza, Neisseria meningitides, Pseudomonas aeruginosa, Stenotrophomonas maltophilia; antimicrobial resistance genes: KPC, CTX-M, IMP, NDM, OXA-48-like, VIM, mcr-1. Control 2 - GPY: Gram positive bacteria: Enterococcus faecalis, Enterococcus faecium, Listeria monocytogenes, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Streptococcus agalactiae, Streptococcus pneumonia, Streptococcus pyogenes; yeast: Candida albicans, Candida auris, Candida glabrata, Candida  |
| --- | --- | --- |

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K231221 - Page 5 of 11

|   |  | krusei, Candida parapsilosis, Candida tropicalis, Cryptococcus neoformans/gatti; antimicrobial resistance genes: mecA/C and MREJ, vanA/B. This product is not intended to replace manufacturer controls provided with the device.  |
| --- | --- | --- |
|  Physical Format | Ready-to-Use Liquid | Same  |
|  Directions for Use | Process like a patient sample | Same  |
|  Composition | Intact inactivated bacteria, human erythrocytes and leukocytes, and relevant components of blood culture media | Same  |
|  General Device Characteristic Differences |  |   |
|  Assay Steps Monitored | Lysis, nucleic acid isolation/purification/inhibitor removal, DNA hybridization, detection, identification/data reporting | Lysis, nucleic acid isolation/purification/PCR inhibitor removal, amplification, detection, identification/data reporting  |
|  Number of Targets monitored in one assay | 15 targets | >30 targets  |

VI Standards/Guidance Documents Referenced:

None.

VII Performance Characteristics (if/when applicable):

A Analytical Performance:

1. Precision/Reproducibility:

Reproducibility

A multi-site reproducibility study was conducted with the MDx-Chex for BC-GP where testing was completed at three sites with seven operators and consisted of ten positive control samples and ten negative control samples for each of three lots of MDx-Chex for BC-GP for a total of 30 samples per control and 60 samples per lot. Both positive and negative controls

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were tested on different days (2 vials x 1 lot x 1 day, for 10 days and 3 different lots) for a total of 180 runs (90 runs per MDx-Chex for BC-GP positive and negative control) were generated for data analysis from all testing sites and all MDx-Chex for BC-GP lots.

All samples were prepared and analyzed on the Luminex VERIGENE System Instrument per the control Instructions for Use. This resulted in a positive percent agreement (PPA) of 100% (90/90) for the MDx-Chex for BC-GP Positive Control (Table 1) and a negative percent agreement (NPA) of 100% (90/90) for the MDx-Chex for BC-GP Negative Control (Table 2).

Table 1: MDx-Chex for BC-GP Positive Control Multi-Site Reproducibility Summary

|  Category | Site #1 |   | Site #2 |   | Site #3 |   | PPA for All Sites Combined | 95% Confidence Interval  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|   |  # Observed/# Expected Results | PPA | # Observed/# Expected Results | PPA | # Observed/# Expected Results | PPA  |   |   |
|  MDx-Chex for BC-GP Positive Control | 30/30 | 100% | 30/30 | 100% | 30/30 | 100% | 100% (90/90) | 96%-100%  |

Table 2: MDx-Chex for BC-GP Negative Control Multi-Site Reproducibility Summary

|  Category | Site #1 |   | Site #2 |   | Site #3 |   | NPA for All Sites Combined | 95% Confidence Interval  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|   |  # Observed/# Expected Results | NPA | # Observed/# Expected Results | NPA | # Observed/# Expected Results | NPA  |   |   |
|  MDx-Chex for BC-GP Negative Control | 30/30 | 100% | 30/30 | 100% | 30/30 | 100% | 100% (90/90) | 96%-100%  |

The results support the reproducibility of the MDx-Chex for BC-GP across three separately manufactured control lots between sites, days, and operators when used with the Luminex BC-GP panels on different Luminex VERIGENE systems.

## Repeatability

An internal repeatability study was conducted to assess performance of MDx-Chex for BC-GP using at least two Luminex VERIGENE systems. The testing schedule consisted of evaluating MDx-Chex for BC-GP positive and negative controls across three lots for over 20 days for a total of 120 runs. Samples were prepared according to MDx-Chex for BC-GP control instructions. Samples were analyzed on the Luminex VERIGENE System per the Instructions for Use. Five to six operators tested each control using 3-4 Luminex BC-GP panel lots and 4 Luminex VERIGENE systems. This resulted in a PPA of 100% (60/60) for the MDx-Chex for BC-GP Positive Control (Table 3) and a NPA of 100% (60/60) for the MDx-Chex for BC-GP Negative Control (Table 4).

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Table 3: MDx-Chex for BC-GP Positive Control Repeatability Study Summary

|  Category | # Observed/#Expected Results | PPA | 95% Confidence Interval  |
| --- | --- | --- | --- |
|  MDx-Chex for BC-GP Positive Control | 60/60 | 100% | 94%-100%  |

Table 4: MDx-Chex for BC-GP Negative Control Repeatability Summary

|  Category | # Observed/#Expected Results | NPA | 95% Confidence Interval  |
| --- | --- | --- | --- |
|  MDx-Chex for BC-GP Negative Control | 60/60 | 100% | 94%-100%  |

The results support repeatability of the MDx-Chex for BC-GP across three separately manufactured control lots when used with the Luminex BC-GP panels on the Luminex VERIGENE system.

## Lot-to-Lot Reproducibility

Lot-to-lot reproducibility was demonstrated by testing three lots of MDx-Chex for BC-GP. Samples were prepared per the control Instructions for Use (IFU) prior to testing with the same Luminex BC-GP panel lot on one Luminex VERIGENE System over multiple days. Ten positive and negative MDx-Chex for BC-GP control tubes were tested on the same VERIGENE System for 60 data points total (30 per lot per positive and negative control). All MDx-Chex for BC-GP positive and negative control lots passed with $\geq 90\%$ positive or negative agreement with expected results, respectively. Results are presented in Tables 5 and 6.

Table 5: Lot-to-Lot Reproducibility for MDx-Chex for BC-GP Positive Controls

|  Category | Lot # | # Observed/#Expected Results | PPA | 95% Confidence Interval  |
| --- | --- | --- | --- | --- |
|  MDx-Chex for BC-GP, Positive Control | 22343 | 9/10* | 90% | 55-100%  |
|   |  22353 | 10/10 | 100% | 69-100%  |
|   |  22355 | 9/10* | 90% | 55-100%  |

* One positive control for lots #22343 and #22355 produced initial false negative results which upon a single retest produced the expected results. The retest runs are not included in the above calculations.

Table 6: Lot-to-Lot Reproducibility for MDx-Chex for BC-GP Negative Controls

|  Category | Lot # | # Observed/#Expected Results | PPA | 95% Confidence Interval  |
| --- | --- | --- | --- | --- |
|  MDx-Chex for BC-GP, Negative Control | 22343 | 10/10 | 100% | 69-100%  |
|   |  22353 | 10/10 | 100% | 69-100%  |
|   |  22355 | 10/10 | 100% | 69-100%  |

The results support reproducibility of the MDx-Chex for BC-GP across three separately manufactured lots when used with the Luminex VERIGENE BC-GP panel.

2. Linearity:

Not applicable.

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3. Analytical Specificity/Interference: Not applicable.
4. Assay Reportable Range: Not applicable.
5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):

# Closed-vial Stability

A real-time closed-vial stability study is ongoing using three lots of MDx-Chex for BC-GP with currently available data summarized below. Twenty positive and negative control samples representing three different lots of MDx-Chex for BC-GP were stored at room  $(25^{\circ}\mathrm{C})$  and refrigerated temperatures  $(2 - 8^{\circ}\mathrm{C})$  and collected at different timepoints for testing. Samples were tested at day zero (ship date) and later time points for each lot and storage condition. Samples were prepared and analyzed on the Luminex VERIGENE systems per MDx-Chex for BC-GP assay Instructions for Use.

The study is ongoing and will support the use of the MDx-Chex for BC-GP control kit throughout their labeled shelf life.

# Shipping Stability

A shipping stability study was performed to validate the stability of MDx-Chex for BC-GP during shipment. One of the MDx-Chex for BC-GP lots from each storage temperature  $(2^{\circ}\mathrm{C}$  and  $25^{\circ}\mathrm{C})$  was subjected to simulated winter and summer shipping temperature profiles over 5 days. Data was collected from 20 samples per positive and negative control for each simulated shipping profile within the 60-day closed-vial stability testing period. Temperature stress conditions for summer and winter include a 120-hour exposure period with the following temperature profile presented in Table 7:

Table 7: Temperature Stress Conditions

|  Duration of Incubation (hours) | Summer Temperature | Winter Temperature  |
| --- | --- | --- |
|  5h | 22°C | 22°C  |
|  14h | 26°C | 15°C  |
|  5.5h | 22°C | 22°C  |
|  5.5h | 25°C | 17°C  |
|  10h | 22°C | 22°C  |
|  2h | 40°C | -10°C  |
|  15h | 29°C | 10°C  |
|  5h | 40°C | -10°C  |
|  17.5h | 26°C | 15°C  |
|  11.5h | 29°C | 10°C  |
|  10h | 22°C | 22°C  |
|  7.5h | 30°C | 8°C  |
|  11.5h | 24°C | 18°C  |

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Samples at each storage temperature (2-8°C and 20-25°C) were exposed to either winter or summer temperature extremes and then were stored back at each respective temperature for a week prior to being tested using Luminex BC-GP panel. All results met the predefined acceptance criteria of PPA or NPA ≥90% and are presented in Tables 8 and 9.

Table 8: Shipping Stability Study Results for the MDx-Chex for BC-GP Positive Control

|  Category | Storage Temperature | # Observed/# Expected Results | PPA | 95% Confidence Interval  |
| --- | --- | --- | --- | --- |
|  Summer | 2-8°C | 20/20 | 100% | 83-100%  |
|   |  20-25°C | 20/20 | 100% | 83-100%  |
|  Winter | 2-8°C | 20/20 | 100% | 83-100%  |
|   |  20-25°C | 20/20 | 100% | 83-100%  |

Table 9: Shipping Stability Study Results for the MDx-Chex for BC-GP Negative Control

|  Category | Storage Temperature# | # Observed/# Expected Results | NPA | 95% Confidence Interval  |
| --- | --- | --- | --- | --- |
|  Summer | 2-8°C | 20/20 | 100% | 83-100%  |
|   |  20-25°C | 20/20 | 100% | 83-100%  |
|  Winter | 2-8°C | 20/20 | 100% | 83-100%  |
|   |  20-25°C | 20/20 | 100% | 83-100%  |

Results demonstrate the MDx-Chex for BC-GP control kit is stable and functional after exposure to extreme summer and winter shipping temperature conditions.

6. Detection Limit:
Not applicable.

7. 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 BC-GP is made of stabilized blood components (erythrocytes and leukocytes) in a simulated blood culture media. Since the matrix is not identical to that of the routine Luminex BC-GP assay sample, blood culture media, a test was performed to investigate the effect of the matrix on the assay.

To confirm that the simulated blood culture matrix does not impact performance of the Luminex BC-GP panel, Streptococcus agalactiae (5.0 x 10⁷ cells/mL final concentration)

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was spiked into one lot of MDx-Chex for BC-GP matrix as well as into BD BACTEC Plus Aerobic/F culture vial with negative whole blood to simulate a clinical sample. These samples were then tested in triplicate using the Luminex BC-GP. Three replicates of each simulated matrix with no spike-in organism were also tested to serve as negative controls. The results presented in Tables 10 and 11 showed PPA and NPA of 100%, respectively.

Table 10: Matrix Equivalency Study Results for Control and Clinical Matrix Spiked with Streptococcus agalactiae
|  Matrix Type | # Observed/# Expected Results | PPA | 95% Confidence Interval  |
| --- | --- | --- | --- |
|  MDx-Chex for BC-GP Matrix, Positive Control | 3/3 | 100% | 29-100%  |
|  Clinical Matrix, Positive Control | 3/3 | 100% | 29-100%  |

Table 11: Matrix Equivalency Study Results for Unspiked Control and Clinical Matrix
|  Matrix Type | # Observed/# Expected Results | NPA | 95% Confidence Interval  |
| --- | --- | --- | --- |
|  MDx-Chex for BC-GP Matrix, Negative Control | 3/3 | 100% | 29-100%  |
|  Clinical Matrix, Negative Control | 3/3 | 100% | 29-100%  |

The results demonstrate that MDx-Chex for BC-GP matrix has no effect on target detection (no inhibition and/or false negative results) when tested with the Luminex BC-GP panel.

C Clinical Studies:

1. Clinical Sensitivity:
Not applicable.

2. Clinical Specificity:
Not applicable.

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

D Clinical Cut-Off:
Not applicable.

E Expected Values/Reference Range:
MDx-Chex for BC-GP is a qualitative control and the expected results are listed in Table 12 below.

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Table 12: Bacterial Pathogens and Antimicrobial Resistance Genes Detected by MDx-Chex for BC-GP Positive and Negative Controls

|  Gram-Positive Bacteria  |   |   |
| --- | --- | --- |
|  Pathogen | Positive Control | Negative Control  |
|  Enterococcus faecalis | Detected | Not Detected  |
|  Enterococcus faecium | Detected | Not Detected  |
|  Listeria spp. | Detected | Not Detected  |
|  Staphylococcus spp. | Detected | Not Detected  |
|  Staphylococcus aureus | Detected | Not Detected  |
|  Staphylococcus epidermidis | Detected | Not Detected  |
|  Staphylococcus lugdunensis | Detected | Not Detected  |
|  Streptococcus spp. | Detected | Not Detected  |
|  Streptococcus agalactiae | Detected | Not Detected  |
|  Streptococcus anginosus group | Detected | Not Detected  |
|  Streptococcus pneumoniae | Detected | Not Detected  |
|  Streptococcus pyogenes | Detected | Not Detected  |
|  Antimicrobial Resistance Genes  |   |   |
|  Gene | Positive Control | Negative Control  |
|  mecA (methicillin) | Detected | Not Detected  |
|  vanA (vancomycin) | Detected | Not Detected  |
|  vanB (vancomycin) | 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.

K231221 - Page 11 of 11

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**Source:** [https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/PMN/K231221](https://fda.innolitics.com/submissions/MI/subpart-d%E2%80%94serological-reagents/PMN/K231221)

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