MDx-Chex for BCY

K254167 · Streck, LLC · PMN · Mar 17, 2026 · Microbiology

Device Facts

• Record ID: K254167
• Device Name: MDx-Chex for BCY
• Applicant: Streck, LLC
• Product Code: PMN · Microbiology
• Decision Date: Mar 17, 2026
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.3920
• Device Class: Class 2

Indications for Use

MDx-Chex for BCY is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of yeast by the Diasorin LIAISON PLEX Yeast Blood Culture assay on the LIAISON PLEX System. The MDx-Chex for BCY 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: Yeast: Candida albicans, Candida dubliniensis, Candida glabrata, Candida krusei, Candida parapsilosis, Candida tropicalis, Candida auris, Candida kefyr, Candida lipolytica, Candida lusitaniae, Candida guilliermondii, Cryptococcus neoformans/gattii, Candida famata, Candida haemulonii/duobushamulonii. Negative Control: buffered solution only. This product is not intended to replace manufacturer controls provided with the device.

Device Story

MDx-Chex for BCY is a ready-to-use liquid quality control kit; contains positive and negative controls for the Diasorin LIAISON PLEX Yeast Blood Culture (BCY) assay. Positive control contains stabilized yeast pathogens (14 species) in a matrix of blood culture media, erythrocytes, and leukocytes; negative control contains buffered solution only. Used in clinical laboratories to monitor assay performance, including lysis, nucleic acid isolation/purification, PCR inhibitor removal, amplification, and detection. Processed like a patient sample. Provides healthcare providers with verification that the LIAISON PLEX system is functioning correctly; ensures reliability of qualitative yeast detection results. Also configured as a verification kit for equipment installation, workflow development, and operator proficiency.

Clinical Evidence

No clinical data. Performance was established via bench testing, including multi-site reproducibility (100% PPA/NPA, n=180), repeatability (100% PPA/NPA, n=120), lot-to-lot reproducibility, and closed-vial stability (75 days at 2-25°C). Shipping stability was validated under simulated winter and summer temperature extremes.

Technological Characteristics

Ready-to-use liquid control; buffered solution with stabilized erythrocytes and leukocytes in blood culture media matrix. Monitors lysis, nucleic acid isolation/purification, PCR inhibitor removal, amplification, and detection. Compatible with LIAISON PLEX System. No specific energy source or connectivity; 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 yeast by the Diasorin LIAISON PLEX Yeast Blood Culture assay on the LIAISON PLEX System. Intended for clinical laboratory use.

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 BCID2 (K212576)

Submission Summary (Full Text)

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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

K254167

B Applicant

Streck, LLC

C Proprietary and Established Names

MDx-Chex for BCY

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 BCY.

B Measurand:

Multi-analyte quality control materials

C Type of Test:

MDx-Chex for BCY is intended for in vitro diagnostic use as an external assayed quality control to monitor the performance of the qualitative detection of yeast by the Diasorin LIAISON PLEX Yeast Blood Culture assay on the LIAISON PLEX System. The MDx-Chex for BCY 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: Yeast: Candida

Food and Drug Administration

10903 New Hampshire Avenue

Silver Spring, MD 20993-0002

www.fda.gov

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albicans, Candida dubliniensis, Candida glabrata, Candida krusei, Candida parapsilosis, Candida tropicalis, Candida auris, Candida kefyr, Candida lipolytica, Candida lusitaniae, Candida guilliermondii, Cryptococcus neoformans/gattii, Candida famata, Candida haemulonii/duobushamulonii. Negative Control: buffered solution only.

## Intended Use/Indications for Use:

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

### B Indication(s) for Use:
MDx-Chex for BCY is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of yeast by the Diasorin LIAISON PLEX Yeast Blood Culture assay on the LIAISON PLEX System. The MDx-Chex for BCY 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: Yeast: Candida albicans, Candida dubliniensis, Candida glabrata, Candida krusei, Candida parapsilosis, Candida tropicalis, Candida auris, Candida kefyr, Candida lipolytica, Candida lusitaniae, Candida guilliermondii, Cryptococcus neoformans/gattii, Candida famata, Candida haemulonii/duobushamulonii. 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:
MDx-Chex for BCY is to be used on the Diasorin LIAISON PLEX system only.

## IV Device/System Characteristics:

### A Device Description:
MDx-Chex for BCY is a quality control kit consisting of positive and negative controls for the Diasorin LIAISON PLEX Yeast Blood Culture assay (BCY) on the LIAISON PLEX System. The MDx-Chex for BCY Positive Control is positive for 14 different yeast species (Table 1) that can cause bloodstream infections. The MDx-Chex for BCY Negative Control is negative for all yeast targets in the LIAISON PLEX BCY test.

Each control mix contains stabilized human blood components (erythrocytes and leukocytes) and blood culture media components that have been identified as inhibitors to nucleic acid purification and hybridization assays (e.g., hemoglobin, leukocyte DNA, and sodium polyanetholesulfonate anticoagulant). The MDx-Chex for BCY quality control kit contains stabilized blood components, simulated blood culture media components, and inactivated, intact yeast microorganisms resulting in a full-process, cellular-based control for the Diasorin

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LIAISON PLEX Yeast Blood Culture panel. Full-process controls evaluate the entire analytical workflow, including sample lysis, nucleic acid isolation and purification, hybridization, detection, and analysis, as well as the impact of inhibitors present in blood culture samples and pre-analytical variables.

Table 1: Yeast in MDx-Chex for BCY and detected by the Diasorin LIAISON PLEX Yeast Blood Culture assay on the LIAISON PLEX System

| Candida albicans | Candida krusei |
| --- | --- |
| Candida auris | Candida lipolytica |
| Candida dubliniensis | Candida lusitaniae |
| Candida famata | Candida parapsilosis |
| Candida glabrata | Candida tropicalis |
| Candida guilliermondii | Candida haemulonii/duobushaemulonii |
| Candida kefyr | Cryptococcus neoformans/gattii |

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): | K254167 (candidate device) | K212576 (predicate) |
| --- | --- | --- |
| Device Trade Name | MDx-Chex for BCY | MDx-Chex for BCID2 |
| General Device Characteristic Similarities | | |
| Intended Use/Indications For Use | MDx-Chex for BCY is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of yeast by the Diasorin LIAISON PLEX Yeast Blood Culture assay on the LIAISON PLEX System. The MDx-Chex for BCY Positive and Negative Controls are composed of a buffered solution with | MDx-Chex for BCID2 is intended for use as an external positive and negative assayed control to monitor the performance of the qualitative detection of yeast, Gram positive and Gram negative bacteria, as well as associated antimicrobial resistance genes, by the BioFire |

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| Device & Predicate Device(s): | K254167
(candidate device) | K212576
(predicate) |
| --- | --- | --- |
| | stabilized erythrocytes and leukocytes in a matrix of blood culture media components.
Positive Control: Yeast: *Candida albicans*, *Candida dubliniensis*, *Candida glabrata*, *Candida krusei*, *Candida parapsilosis*, *Candida tropicalis*, *Candida auris*, *Candida kefyr*, *Candida lipolytica*, *Candida lusitaniae*, *Candida guilliermondii*, *Cryptococcus neoformans/gattii*, *Candida famata*, *Candida haemulonii/duobushamulonii*.
Negative Control: buffered solution only. This product is not intended to replace manufacturer controls provided with the device. | 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 lugdunesis*, *Streptococcus agalactiae*, *Streptococcus pneumonia*, *Streptococcus pyogenes*; yeast: *Candida albicans*, *Candida auris*, *Candida glabrata*, *Candida krusei*, *Candida parapsilosis*, *Candida tropicalis*, *Cryptococcus neoformans/gatti*; antimicrobial resistance genes: *mecA/C* and MREJ, |

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| Device & Predicate Device(s): | K254167
(candidate device) | K212576
(predicate) |
| --- | --- | --- |
| | | vanA/B. This product is not intended to replace manufacturer controls provided with the device. |
| Physical Format | Ready-to-Use Liquid | Same |
| Direction for Use | Process like patient sample | Same |
| Assay Steps Monitored | Lysis, nucleic acid isolation/purification/PCR inhibitor removal, amplification, detection, identification/data reporting | Same |
| General Device Characteristic Differences | | |
| Number of targets monitored in one assay | Multiple - 14 yeast organisms | Multiple, >30 targets |
| Composition | Intact inactivated yeast, human erythrocytes and leukocytes, and relevant components of blood culture media | Intact inactivated bacteria, antimicrobial resistance genes, human erythrocytes and leukocytes, and relevant components of blood culture media |

VI Standards/Guidance Documents Referenced:

- ISO 14971,2019: Medical devices - Application of risk management to medical devices
- ISO 15223,2021: Medical devices - Symbols to be used with information to be supplied by the manufacturer - Part 1: General requirements.
- CLSI EP05-A3: Evaluation of Precision of Quantitative Measurement Procedures; Approved Guideline - Third Edition

VII Performance Characteristics (if/when applicable):

A Analytical Performance:

Note: The results for all analytical studies described below represent percent agreement based on comparing the expected call to the obtained test result (positive or negative). The terms, PPA (positive percent agreement) and NPA (negative percent agreement) were used to describe this agreement.

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1. Precision/Reproducibility:

Reproducibility

A multi-site reproducibility study was conducted with the MDx-Chex for BCY 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 BCY for a total of 30 samples per control type and 60 samples per lot. Both positive and negative controls were tested on different days (2 tubes 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 BCY control type) from all testing sites and all MDx-Chex for BCY lots.

All samples were prepared and analyzed on the DiaSorin LIAISON PLEX System per the Instructions for Use. This resulted in a positive percent agreement (PPA) of 100% (90/90) for the MDx-Chex for BCY Positive Control (Table 2) and a negative percent agreement (NPA) of 100% (90/90) for the MDx-Chex for BCY Negative Control (Table 3).

Table 2: MDx-Chex for BCY Positive Control Multi-Site Reproducibility Summary

| Category | Site #1 | | Site #2 | | Site #3 | | PPA for All Sites Combined | 95% Confidence Interval |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | # Observed/# Expected Results¹ | PPA | # Observed/# Expected Results¹ | PPA | # Observed/# Expected Results¹ | PPA | | |
| MDx-Chex for BCY Positive Control | 30/30 | 100% | 30/30 | 100% | 30/30 | 100% | 100% (90/90) | 96%-100% |

¹ Expected result for the Positive Control is positive.

Table 3: MDx-Chex for BCY Negative Control Multi-Site Reproducibility Summary

| Category | Site #1 | | Site #2 | | Site #3 | | NPA for All Sites Combined | 95% Confidence Interval |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | # Observed/# Expected Results¹ | NPA | # Observed/# Expected Results¹ | NPA | # Observed/# Expected Results¹ | NPA | | |
| MDx-Chex for BCY Negative Control | 30/30 | 100% | 30/30 | 100% | 30/30 | 100% | 100% (90/90) | 96%-100% |

¹ Expected result for the Negative Control is negative.

The results support the reproducibility of the MDx-Chex for BCY across three separately manufactured control lots between sites, days, and operators when used with the DiaSorin LIAISON PLEX BCY test on different DiaSorin LIAISON PLEX systems.

Repeatability

An internal repeatability study was conducted to assess performance of MDx-Chex for Blood Culture Yeast (BCY) using at least two DiaSorin LIAISON PLEX systems. The testing schedule consisted of evaluating two MDx-Chex for BCY control types (1 control type per day) from three lots over 20 days for a total of 120 runs. Samples were analyzed on the

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DiaSorin LIAISON PLEX System per the Instructions for Use. Three operators tested each control type using three LIAISON PLEX BCY test cartridge lots and two LIAISON PLEX systems. This resulted in a PPA of 100% (60/60) for the MDx-Chex for BCY Positive Control (Table 4) and a NPA of 100% (60/60) for the MDx-Chex for BCY Negative Control (Table 5).

Table 4: MDx-Chex for BCY Positive Control Repeatability Study Summary

| Category | # Observed/#Expected Results^{1} | PPA | 95% Confidence Interval |
| --- | --- | --- | --- |
| MDx-Chex for BCY Positive Control | 60/60 | 100% | 94%-100% |

1 Expected result for the Positive Control is positive.

Table 5: MDx-Chex for BCY Negative Control Repeatability Summary

| Category | # Observed/#Expected Results^{1} | NPA | 95% Confidence Interval |
| --- | --- | --- | --- |
| MDx-Chex for BCY Negative Control | 60/60 | 100% | 94%-100% |

1 Expected result for the Negative Control is negative.

The results support the conclusion that MDx-Chex for Blood Culture Yeast shows repeatability across three separately manufactured control lots when used with the LIAISON PLEX BCY Test on the DiaSorin LIAISON PLEX system.

## Lot-to-Lot Reproducibility

Lot-to-lot reproducibility was demonstrated by testing three lots of MDx-Chex for BCY. Samples were prepared per the control Instructions for Use and tested using the same DiaSorin LIAISON PLEX BCY test cartridge lot tested on one DiaSorin LIAISON PLEX system over ten days. Ten positive and ten negative MDx-Chex for BCY control tubes were tested on the same DiaSorin LIAISON PLEX system for 60 data points total (30 per lot per positive and negative control). All MDx-Chex for BCY positive and negative control lots passed with ≥ 90% positive or negative agreement with expected results, respectively. Results are presented in Tables 6 and 7.

Table 6: Lot-to-Lot Reproducibility for MDx-Chex for BCY Positive Controls

| Category | Lot # | # Observed/# Expected Results^{1} | PPA | 95% Confidence Interval |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCY Positive Control | 5202 | 10/10 | 100% | 69-100% |
| | 5209 | 10/10 | 100% | 69-100% |
| | 5223 | 10/10 | 100% | 69-100% |

1 Expected result for the Positive Control is positive.

Table 7: Lot-to-Lot Reproducibility for MDx-Chex for BCY Negative Controls

| Category | Lot # | # Observed/# Expected Results^{1} | PPA | 95% Confidence Interval |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCY Negative Control | 5202 | 10/10 | 100% | 69-100% |
| | 5209 | 10/10 | 100% | 69-100% |
| | 5223 | 10/10 | 100% | 69-100% |

1 Expected result for the Negative Control is negative.

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The results support that MDx-Chex for BCY is reproducible across three separately manufactured lots when used with the DiaSorin LIAISON PLEX BCY Test.

## Within-run Precision

A within-run precision study was conducted to assess performance of one MDx-Chex for BCY lot, using the same DiaSorin LIAISON PLEX BCY test cartridge lot tested on the same day with one DiaSorin LIAISON PLEX System. The study consisted of 10 tests for each positive and negative control tube generated from one MDx-Chex for BCY lot (total of 20 tests per control kit). All MDx-Chex for BCY positive and negative control lots passed with $\geq 90\%$ positive or negative agreement with expected results, respectively. Results are presented in Tables 8 and 9.

Table 8: Within-run Precision Summary for MDx-Chex for BCY Positive Controls

| Category | Lot # | # Observed/# Expected Results¹ | PPA | 95% Confidence Interval |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCY Positive Control | 5223 | 10/10 | 100% | 69-100% |

¹ Expected result for the Positive Control is positive.

Table 9: Within-run Precision Summary for MDx-Chex for BCY Negative Controls

| Category | Lot # | # Observed/# Expected Results¹ | PPA | 95% Confidence Interval |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCY Negative Control | 5223 | 10/10 | 100% | 69-100% |

¹ Expected result for the Negative Control is negative.

2. Linearity:

Not applicable.

3. Analytical Specificity/Interference:

Not applicable.

4. Detection Limit and 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 BCY with currently available data summarized below. Twenty positive and 20 negative control samples from each MDx-Chex for BCY lot were stored at room temperature (20-25 °C) and refrigerated temperature (2-8 °C) and collected at different timepoints for testing. The first

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data collection timepoint was on Day 0 (ship date), followed by Day 75 for each lot and storage condition. Samples were prepared and analyzed on the DiaSorin LIAISON PLEX System per the MDx-Chex for BCY Instructions for Use. Data collected on Days 0 and at a minimum of 75 days are presented in Tables 10 and 11.

Table 10: Closed-vial Stability of MDx-Chex for BCY Positive Control- PPA

| Shelf-Life | Storage Temperature | # Observed/# Expected Results^{1} | PPA | 95% Confidence Interval | PPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- | --- |
| Day 0 | N/A | 60/60 | 100% | 94-100% | Pass |
| Day 75+ | 2-8°C | 60/60 | 100% | 94-100% | Pass |
| | 20-25°C | 60/60 | 100% | 94-100% | Pass |

Expected result for the Positive Control is positive.
Indicates that lots stored at 2-8°C were tested for at least 75 days; Lot 5202 (80 days), Lot 5209 (83 days), Lot 5223 (78 days). Lots stored at 20-25°C were tested for at least 75 days; Lot 5202 (80 days), Lot 5209 (83 days), Lot 5223 (79 days).

Table 11: Closed-vial Stability of MDx-Chex for BCY Negative Control- NPA

| Shelf-Life | Storage Temperature | # Observed/# Expected Results^{1} | NPA | 95% Confidence Interval | NPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- | --- |
| Day 0 | N/A | 60/60 | 100% | 94-100% | Pass |
| Day 75+ | 2-8°C | 60/60 | 100% | 94-100% | Pass |
| | 20-25°C | 60/60 | 100% | 94-100% | Pass |

Expected result for the Negative Control is negative.
Indicates that lots stored at 2-8°C were tested for at least 75 days; Lot 5202 (80 days), Lot 5209 (83 days), Lot 5223 (79 days). Lots stored at 20-25°C were tested for at least 75 days; Lot 5202 (83 days), Lot 5209 (84 days), Lot 5223 (80 days).

The data for the ongoing closed-vial stability study support the conclusion that MDx-Chex for BCY has a closed-vial stability for 75 days when stored at 2-25°C. The study is ongoing to support the use of the MDx-Chex for BC-GN control kit throughout the labeled shelf life.

## Shipping Stability

A shipping stability study was performed to validate the stability of MDx-Chex for BCY during shipment. One MDx-Chex for BCY lot was subjected to simulated winter and summer shipping temperature profiles over 5 days. Temperature stress conditions for summer include a 120-hour exposure period with the following temperature profile: 5h at 22°C, 14h at 26°C, 5.5h at 22°C, 5.5h at 25°C, 10h at 22°C, 2h at 40°C, 15h at 29°C, 5h at 40°C, 17.5h at 26°C, 11.5h at 29°C, 10h at 22°C, 7.5h at 30°C, and 11.5h at 24°C. Temperature stress conditions for winter include a 120-hour exposure period with the following temperature profile: 5h at 22°C, 14h at 15°C, 5.5h at 22°C, 5.5h at 17°C, 10h at 22°C, 2h at -10°C, 15h at 10°C, 5h at -10°C, 17.5h at 15°C, 11.5h at 10°C, 10h at 22°C, 7.5h at 8°C, and 11.5h at 18°C.

Samples at each storage temperature (2°C and 25°C) were exposed to winter and summer temperature extremes and then were stored back at each respective storage temperature (2°C and 25°C) for a week prior to being tested using LIAISON PLEX BCY Test. Data were collected from 20 samples per positive and negative control for each simulated shipping profile within the 75-day closed-vial stability testing period. An additional 20 samples per control type will be tested at the end of shelf-life.

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All summer and winter shipping conditions passed with $\geq 90\%$ positive and negative agreement with expected results and presented in Tables 12 and 13.

Table 12: Shipping Stability Study Results for the MDx-Chex for BCY Positive Control

| Category | Storage Temperature^{1} | # Observed/# Expected Results^{2} | 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% |

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 DiaSorin LIAISON PLEX system.
2. Expected result for the positive Control is positive.
*Indicates initial dataset for shipping study which was collected within the 75-day CVS testing period.

Table 13: Shipping Stability Study Results for the MDx-Chex for BCY Negative Control

| Category | Storage Temperature^{1} | # Observed/# Expected Results^{2} | 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% |

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 DiaSorin LIAISON PLEX system.
2. Expected result for the negative Control is negative.
*Indicates initial dataset for shipping study which was collected within the 75-day CVS testing period.

Results support that the MDx-Chex for BCY control kit is stable and functional for 75 days after exposure to extreme summer and winter shipping temperature conditions. The study is ongoing to support the shipping stability of the MDx-Chex for BC-GN control kit throughout the labeled shelf life.

6. 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 BCY 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 DiaSorin LIAISON PLEX BCY 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 DiaSorin LIAISON PLEX BCY assay, Candida tropicalis (1×10⁶ cells/mL final

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concentration) was spiked into MDx-Chex for BCY 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 DiaSorin LIAISON PLEX BCY assay. Three replicates of each simulated matrix with no spike-in organism were also tested to serve as negative controls. The results presented in Tables 14 and 15 showed PPA and NPA of 100%, respectively.

Table 14: Matrix Equivalency Study Results for Control and Clinical Matrix Spiked with Candida tropicalis, tested on DiaSorin LIAISON PLEX BCY Assay

| Matrix Type | # Observed/# Expected Results^{1} | PPA | 95% Confidence Interval |
| --- | --- | --- | --- |
| MDx-Chex for BCY Matrix + Candida tropicalis | 3/3 | 100% | 29-100% |
| Clinical Matrix + Candida tropicalis | 3/3 | 100% | 29-100% |

1 Expected result for the Spiked-in matrices are positive for Candida tropicalis.

Table 15: Matrix Equivalency Study Results for Unspiked Control and Clinical Matrix, tested on DiaSorin LIAISON PLEX BCY Assay

| Matrix Type | # Observed/# Expected Results^{1} | NPA | 95% Confidence Interval |
| --- | --- | --- | --- |
| MDx-Chex for BCY Matrix | 3/3 | 100% | 29-100% |
| Clinical Matrix | 3/3 | 100% | 29-100% |

1 Expected result for non-spiked matrices are negative.

The results demonstrate that MDx-Chex for BCY matrix has no effect on target detection (i.e., no inhibition and/or false negative results) when tested with the LIAISON PLEX BCY Test. Data for MDx-Chex for BCY was identical to the results for the simulated clinical blood culture sample.

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.

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# D Expected Values/Reference Range:

MDx-Chex for BCY is a qualitative control and the expected results are listed in Table 16 below.

Table 16: Pathogens detected by MDx-Chex for BCY Control

| Pathogen | Positive Control | Negative control |
| --- | --- | --- |
| Candida albicans | Detected | Not detected |
| Candida auris | Detected | Not detected |
| Candida dubliniensis | Detected | Not detected |
| Candida famata | Detected | Not detected |
| Candida glabrata | Detected | Not detected |
| Candida guilliermondii | Detected | Not detected |
| Candida kefyr | Detected | Not detected |
| Candida krusei | Detected | Not detected |
| Candida lipolytica | Detected | Not detected |
| Candida lusitaniae | Detected | Not detected |
| Candida parapsilosis | Detected | Not detected |
| Candida tropicalis | Detected | Not detected |
| Candida haemulonii/duobushaemulonii | Detected | Not detected |
| Cryptococcus neoformans/gattii | 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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