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

Intended 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)

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FDA U.S. FOOD & DRUG ADMINISTRATION

03/27/2026

Streck, LLC
Iris Servellon
Regulatory Affairs Coordinator
7002 S 109th St.
La Vista, Nebraska 68128

Re: K260041
Trade/Device Name: MDx-Chex for BCP
Regulation Number: 21 CFR 866.3920
Regulation Name: Assayed Quality Control Material For Clinical Microbiology Assays
Regulatory Class: Class II
Product Code: PMN
Dated: January 2, 2026
Received: January 6, 2026

Dear Iris Servellon:

We have reviewed your section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (the Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

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K260041 - Iris Servellon
Page 2

Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device" (https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).

Your device is also subject to, among other requirements, the Quality Management System Regulation (QMSR) (21 CFR Part 820), which includes, but is not limited to, ISO 13485 clause 7.3 (Design controls), ISO 13484 clause 8.3 (Nonconforming product), and ISO 13485 clause 8.5 (Corrective and preventative action). Please note that regardless of whether a change requires premarket review, the QMSR requires device manufacturers to review and approve changes to device design and production (ISO 13485 clause 7.3 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801 and Part 809); medical device reporting (reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reporting-combination-products); good manufacturing practice requirements as set forth in the Quality Management System Regulation (QMSR) (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.

All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rule"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance/unique-device-identification-system-udi-system.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-devices/medical-device-safety/medical-device-reporting-mdr-how-report-medical-device-problems.

For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-

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K260041 - Iris Servellon
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assistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email ([e-mail]) or phone [phone] or 301-796-7100).

Sincerely,
BRYAN M. GRABIAS-S
2026.03.27 07:33:48
-04'00"
Bryan Grabias, Ph. D.
Acting Branch Chief
Bacterial Respiratory and Medical Countermeasures Branch
Division of Microbiology Devices
OHT7: Office of In Vitro Diagnostics
Office of Product Evaluation and Quality
Center for Devices and Radiological Health

Enclosure

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DEPARTMENT OF HEALTH AND HUMAN SERVICES
Food and Drug Administration
Indications for Use
Form Approved: OMB No. 0910-0120
Expiration Date: 07/31/2026
See PRA Statement below.

510(k) Number (if known)
K260041

Device Name
MDx-Chex for BCP

Indications for Use (Describe)

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.

Type of Use (Select one or both, as applicable)
☑ Prescription Use (Part 21 CFR 801 Subpart D)
☐ Over-The-Counter Use (21 CFR 801 Subpart C)

CONTINUE ON A SEPARATE PAGE IF NEEDED.

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STRECK

# 510(k) Summary

510(k) Submitter: Streck 7002 S. 109th Street La Vista, NE 68128

Official Correspondent Address: Iris Servellon 7002 S. 109th Street La Vista, NE 68128

Phone: [phone]

Email: [e-mail]

Date Prepared: December 05, 2025

Names, Trade Name: MDx-Chex for BCP

Common Name: Quality Control Material for Microbiology Assays

Device Type: Assayed external control material for microbiology nucleic acid amplification (NAT) assays

Product Code: PMN

Panel: Microbiology

Predicate Device: MDx-Chex for BC-GP (K231221)

Device Description:

MDx-Chex® for BCP is a quality control kit consisting of two controls for the Diasorin LIAISON-PLEX® Gram-Positive Blood Culture Assay (BCP). The MDx-Chex for BCP Positive Control is positive for pathogens and resistance mechanisms in the LIAISON-PLEX Gram-Positive Blood Culture assay (See Table 1). The MDx-Chex for BCP Negative Control is negative for pathogen and antimicrobial resistance genes in the LIAISON-PLEX Gram-Positive Blood Culture assay. Each control mix also contains and controls for blood and blood culture media components that have been identified as assay inhibitors, namely hemoglobin, leukocyte DNA, and anticoagulants.

MDx-Chex® for BCP is also configured as a verification kit (MDx-Chex® for BCP Verification Kit) for use at equipment installation, in the development of workflow procedures and for operator proficiency evaluation.

7002 S. 109th STREET, LA VISTA, NE 68128

P 800.843.0912

streck.com

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STRECK

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

| Gram-Positive Bacteria | | |
| --- | --- | --- |
| Pathogen/Species | Positive Control | Negative Control |
| Bacillus spp. | 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 |
| Enterococcus faecalis | Detected | Not Detected |
| Enterococcus faecium | Detected | Not Detected |
| Antimicrobial Resistance Genes | | |
| Gene | Positive Control | Negative Control |
| mecA/mecC | Detected | Not Reviewed |
| vanA | Detected | Not Reviewed |
| vanB | Detected | Not Reviewed |

## Intended 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.

7002 S. 109th STREET, LA VISTA, NE 68128

P 800.843.0912

streck.com

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STRECK

Comparison to Predicate Device

| Characteristics | Candidate Device: MDx-Chex for BCP | Predicate Device: Streck MDx-Chex for BC-GP (K231221) |
| --- | --- | --- |
| Device & Predicate Device(s): | | K231221 |
| Device Trade Name | MDx-Chex for BCP | MDx-Chex for BC-GP |
| Device 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 for 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. | 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. |
| Physical Format | Ready-to-Use Liquid | Same |
| Direction for Use | Process like patient sample | Same |

7002 S. 109th STREET, LA VISTA, NE 68128

P 800.843.0912

streck.com

{7}

STRECK

| Number of targets monitored in one assay | Multiple, 16 Targets | Multiple, 15 Targets |
| --- | --- | --- |
| Assay Steps Monitored | Lysis, nucleic acid isolation/purification/inhibitor removal, DNA hybridization, detection, identification/data reporting | 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 |

# Discussion of Tests and Test Results

To substantiate the product performance claims for MDx-Chex for BCP, Streck collected product performance data for the following studies. Results of studies are summarized below:

- Multi-Site Precision (Reproducibility)
- Single-Site Precision (Repeatability)
- Lot-to-Lot Within Run Precision
- Closed-Vial Stability and Shipping Stability
- Matrix Effect

# Multi-Site Precision (Reproducibility)

A multi-site reproducibility study assessed performance of MDx-Chex for BCP, with the DiaSorin LIAISON PLEX BCP assay, using DiaSorin LIAISON PLEX systems at three separate sites. Three MDx-Chex for BCP lots, at least three LIAISON PLEX BCP test cartridge lots, and at least three operators were included in the study. Testing at each site consisted of 10 positive control samples and 10 negative control samples for each MDx-Chex for BCP lot for a total of 30 samples per control type (positive and negative control tubes), 60 samples per lot, tested on different days (2 tubes x 1 lot x 1 day, for 10 days and 3 different lots). A total of 180 runs (90 runs per MDx-Chex for BCP control type; control type = positive or negative control) were generated for data analysis from all testing sites and all MDx-Chex for BCP lots.

An effective statistical sample size of $n = 90$ tests per control type (positive or negative) produced a two-sided $95\%$ confidence interval with a width equal to 0.058 and a lower limit of $93.2\%$ when the positive or negative percent agreement with expected results was assumed $99\%$. The total sample size for this multi-site evaluation was $N = 180$ samples tested using the DiaSorin LIAISON PLEX system.

All MDx-Chex for BCP Positive and Negative Control lots passed with $\geq 90\%$ agreement with expected results. The results support the conclusion that MDx-Chex for BCP shows reproducibility across three separately manufactured control lots between sites, days, and operators when used with the LIAISON PLEX BCP assay on different DiaSorin LIAISON PLEX system.

7002 S. 109th STREET, LA VISTA, NE 68128

P 800.843.0912

streck.com

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STRECK

Table 1: Reproducibility of MDx-Chex for BCP - Positive Control: Positive Percent Agreement

| Category | Site #1 | | Site #2 | | Site #3 | | Percent Agreement (all sites combined) | 95% Confidence Interval |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | # Observed Results/# Expected Results 1 | Positive Percent Agreement | # Observed Results/# Expected Results 1 | Positive Percent Agreement | # Observed Results/# Expected Results 1 | Positive Percent Agreement | | |
| MDx-Chex for BCP Positive Control | 29/30* | 97% | 30/30 | 100% | 30/30 | 100% | 99% (89/90 total runs) | 94% - 100% |

1 Expected result for the Positive Control is positive.
*One Positive Control produced an unexpected result.

Table 2: Reproducibility of MDx-Chex for BCP - Negative Control: Negative Percent Agreement

| Category | Site #1 | | Site #2 | | Site #3 | | Percent Agreement (all sites combined) | 95% Confidence Interval |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | # Observed Results/# Expected Results 1 | Negative Percent Agreement | #Observed Results/# Expected Results 1 | Negative Percent Agreement | # Observed Results/# Expected Results 1 | Negative Percent Agreement | | |
| MDx-Chex for BCP Negative Control | 30/30 | 100% | 29/30* | 97% | 29/30* | 97% | 98% (88/90 total runs) | 92% - 100% |

1 Expected result for the Negative Control is negative.
*Two Negative Controls produced unexpected results.

# Single-Site Precision (Repeatability)

An internal repeatability study was conducted to assess performance of MDx-Chex for BCP using at least two DiaSorin LIAISON PLEX systems. Three MDx-Chex for BCP lots, at least three LIAISON PLEX BCP test cartridge lots and a minimum of two operators were included in the study. Testing consisted of 20 samples per control type (positive and negative control tubes), 40 samples per MDx-Chex for BCP lot, tested over 20 days. A total of 120 runs (20 runs per MDx-Chex for BCP control type; control type = positive or negative control) were generated for data analysis for all MDx-Chex for BCP lots (2 BCP control types/day x 3 lots x 20 days = 120 runs). Controls were stored at 2-25°C prior to testing.

An effective statistical sample size of $n = 60$ tests for each control vials produced a two-sided 95% confidence interval with width equal to 0.077 and a lower limit of 90.3% when the percent positive or negative agreement with expected results was 98%. The total sample size for this study was $N = 120$ samples tested using the DiaSorin LIAISON PLEX system. Repeatability data collected from three MDx-Chex for BCP Positive and Negative Control lots passed with ≥ 90% positive agreement with expected results.

All results met predefined acceptance criteria. The results support the conclusion that MDx-Chex for BCP shows repeatability across three separately manufactured control lots when used with the LIAISON PLEX BCP Test.

7002 S. 109th STREET, LA VISTA, NE 68128

P 800.843.0912

streck.com

{9}

STRECK

Table 1: Repeatability of MDx-Chex for BCP - Positive Control: Positive Percent Agreement

| Category | # Observed Results/ # Expected Results 1 | Positive Percent Agreement | 95% Confidence Interval | PPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCP Positive Control | 59/60* | 98% | 91%-100% | Pass |

1 Expected result for the Positive Control is positive.
*One Positive Control produced an unexpected result.

Table 2: Repeatability of MDx-Chex for BCP - Negative Control: Negative Percent Agreement

| Category | # Observed Results/ # Expected Results 1 | Negative Percent Agreement | 95% Confidence Interval | NPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCP Negative Control | 60/60 | 100% | 94%-100% | Pass |

1 Expected result for the Negative Control is negative.

## Lot-to-Lot Reproducibility

A lot-to-lot reproducibility study was conducted to assess performance of three MDx-Chex for BCP lots, using the same DiaSorin LIAISON PLEX BCP test cartridge lot for two of the MDx-Chex for BCP lots (due to unavailability of that lot for procurement, a second test cartridge lot was used for one lot of MDx-Chex for BCP) tested on one DiaSorin LIAISON PLEX system over multiple days. The within-run precision study was conducted to assess performance of one MDx-Chex for BCP lot, using the same DiaSorin LIAISON PLEX BCP test cartridge lot tested on the same day with one DiaSorin LIAISON PLEX System.

For the Lot-to-lot study, data from 10 positive and 10 negative control tubes, tested on the same DiaSorin LIAISON PLEX System, was used for data analysis for each control tube per MDx-Chex for BCP lot (30 data points per control type) for a total of 60 data points from three MDx-Chex for BCP lots. The Within-Run Precision study consisted of 10 tests for each positive and negative control tube generated from one MDx-Chex for BCP lot (total of 20 tests per control kit). For this study, closed-vial stability data was used to demonstrate the within-run precision.

All MDx-Chex for BCP Positive and Negative Control lots passed with ≥ 90% positive agreement with expected results. All results met predefined acceptance criteria. The results support that MDx-Chex for BCP is reproducible across three separately manufactured lots when used with the DiaSorin LIAISON PLEX BCP Test. The results also demonstrate that there are no significant differences in results within runs of a control lot.

7002 S. 109th STREET, LA VISTA, NE 68128

P 800.843.0912

streck.com

{10}

STRECK

Table 1: Lot-to-Lot Precision Summary of MDx-Chex for BCP - Positive Control: Positive Percent Agreement

| Category | MDx-Chex for BCP Lot | # Observed Results/# Expected Results 1 | Positive Percent Agreement | 95% Confidence Interval |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCP 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 2: Lot-to-Lot Precision Summary of MDx-Chex for BCP - Negative Control: Negative Percent Agreement

| Category | MDx-Chex for BCP Lot | # Observed Results/# Expected Results 1 | Negative Percent Agreement | 95% Confidence Interval |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCP 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.

Table 3: Within-run Precision Summary of MDx-Chex for BCP - Positive Control: Positive Percent Agreement

| Category | MDx-Chex for BCP Lot | # Observed Results/# Expected Results 1 | Positive Percent Agreement | 95% Confidence Interval |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCP Positive Control | 5223 | 10/10 | 100% | 69% - 100% |

1 Expected result for the Positive Control is positive.

Table 4: Within-run Precision Summary of MDx-Chex for BCP - Negative Control: Negative Percent Agreement

| Category | MDx-Chex for BCP Lot | # Observed Results/# Expected Results 1 | Negative Percent Agreement | 95% Confidence Interval |
| --- | --- | --- | --- | --- |
| MDx-Chex for BCP Negative Control | 5223 | 10/10 | 100% | 69% - 100% |

1 Expected result for the Negative Control is negative.

## Closed-Vial Stability and Shipping Stability

For closed-vial stability, three (3) MDx-Chex for BCP lots were tested using the LIAISON PLEX BCP Test. Testing consisted of 20 positive and 20 negative control samples from each MDx-Chex for BCP lot, collected at various timepoints at room temperature (25 °C) and refrigerated temperature (2 °C). The first data collection timepoint was on Day 0 (ship date) and Day 75. Day 0 and Day 75 are being submitted for FDA review. Note: Data will be collected on three previously manufactured lots using the final product formulation to substantiate a one-year shelf-life prior to product launch.

Closed-vial stability (Day 0 and Day 75): All MDx-Chex for BCP Positive and Negative Control lots passed with ≥ 90% positive agreement with expected results at Day 0 and Day 75. The data support MDx-Chex for BCP is stable for at least 75 days and results meet acceptance criteria.

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Table 1. Closed-vial stability of MDx-Chex for BCP Positive Control: Positive Percent Agreement

| Shelf-Life | Storage Temperature | #Observed Results/#Expected Results^{1} | Positive Percent Agreement | 95% Confidence Interval | PPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- | --- |
| Day 0 | NA | 57/60* | 95 % | 86% - 99% | Pass |
| Day 110+ | 2-8°C | 60/60 | 100 % | 94% - 100% | Pass |
| | 20-25°C | 60/60 | 100 % | 94% - 100% | Pass |

1 Expected result for the Positive Control is positive. Denominator = total number of expected positive results for BCP Positive Control.
*Three Positive Controls produced unexpected results.
+ Indicates that lots stored at 2-8°C were tested for at least 110 days; Lot 5202 (124 days), Lot 5209 (127 days), Lot 5223 (113 days). Lots stored at 20-25°C were tested for at least 110 days; Lot 5202 (124 days), Lot 5209 (127 days), Lot 5223 (114 days).

Table 2. Closed-vial stability of MDx-Chex for BCP Negative Control: Negative Percent Agreement

| Shelf-Life | Storage Temperature | #Observed Results/#Expected Results^{1} | Negative Percent Agreement | 95% Confidence Interval | NPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- | --- |
| Day 0 | NA | 60/60 | 100% | 94% - 100% | Pass |
| Day 110+ | 2-8°C | 58/60* | 97% | 88% - 100% | Pass |
| | 20-25°C | 60/60 | 100% | 94% - 100% | Pass |

1 Expected result for the Negative Control is negative. Denominator = total number of expected negative results for BCP Negative Control.
*Two Negative Controls produced unexpected results.
+ Indicates that lots stored at 2-8°C were tested for at least 110 days; Lot 5202 (125 days), Lot 5209 (128 days), Lot 5223 (118 days). Lots stored at 20-25°C were tested for at least 110 days; Lot 5202 (125 days), Lot 5209 (128 days), Lot 5223 (118 days).

Table 3. Closed-vial stability of MDx-Chex for BCP Positive Control: Positive Percent Agreement for each MDx-Chex Lot.

| Category | Storage Temperature | # Lot | #Observed Results/#Expected Results^{1} | Positive Percent Agreement | 95% Confidence Interval | PPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- | --- | --- |
| Day 0 | NA | 5202 | 20/20 | 100% | 83% - 100% | Pass |
| | | 5209 | 18/20* | 90% | 68% - 99% | Pass |
| | | 5223 | 19/20** | 95% | 75% - 100% | Pass |
| Day 110+ | 2-8°C | 5202 | 20/20 | 100% | 83% - 100% | Pass |
| | | 5209 | 20/20 | 100% | 83% - 100% | Pass |
| | | 5223 | 20/20 | 100% | 83% - 100% | Pass |
| | 20-25°C | 5202 | 20/20 | 100% | 83% - 100% | Pass |
| | | 5209 | 20/20 | 100% | 83% - 100% | Pass |
| | | 5223 | 20/20 | 100% | 83% - 100% | Pass |

1 Expected result for the Positive Control is positive. Denominator = total number of expected positive results for BCP Positive Control.
*Two Positive Controls produced unexpected results.
**One Positive Control produced an unexpected result.
+ Indicates that lots stored at 2-8°C were tested for at least 110 days; Lot 5202 (124 days), Lot 5209 (127 days), Lot 5223 (113 days). Lots stored at 20-25°C were tested for at least 110 days; Lot 5202 (124 days), Lot 5209 (127 days), Lot 5223 (114 days).

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Table 4. Closed-vial stability of MDx-Chex for BCP Negative Control: Negative Percent Agreement for each MDx-Chex Lot.

| Category | Storage Temperature | # Lot | #Observed Results/#Expected Results 1 | Negative Percent Agreement | 95% Confidence Interval | NPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- | --- | --- |
| Day 0 | NA | 5202 | 20/20 | 100% | 83% - 100% | Pass |
| | | 5209 | 20/20 | 100% | 83% - 100% | Pass |
| | | 5223 | 20/20 | 100% | 83% - 100% | Pass |
| Day 110 * | 2-8°C | 5202 | 20/20 | 100% | 83% - 100% | Pass |
| | | 5209 | 19/20* | 95% | 75% - 100% | Pass |
| | | 5223 | 19/20* | 95% | 75% - 100% | Pass |
| | 20-25°C | 5202 | 20/20 | 100% | 83% - 100% | Pass |
| | | 5209 | 20/20 | 100% | 83% - 100% | Pass |
| | | 5223 | 20/20 | 100% | 83% - 100% | Pass |

1 Expected result for the Negative Control is negative. Denominator = total number of expected negative results for BCP Negative Control.
*One Negative Control produced an unexpected result.
* Indicates that lots stored at 2-8°C were tested for at least 110 days; Lot 5202 (125 days), Lot 5209 (128 days), Lot 5223 (118 days). Lots stored at 20-25°C were tested for at least 110 days; Lot 5202 (125 days), Lot 5209 (128 days), Lot 5223 (118 days).

## Shipping Stability (Control)

For shipping study, one MDx-Chex for BCP lot was subjected to simulated winter and summer shipping temperature profiles over 5 days. For each simulated shipping condition (Summer and Winter), 20 samples per control type (i.e., positive and negative) were tested within the 75-day CVS testing period. Additional 20 samples per control type will be tested at the end of shelf-life. Temperature stress conditions for Summer and Winter include a 120-hour exposure periods. Samples at each storage temperature (2C and 25C) were exposed to Winter and Summer Temperature extremes and then were stored back at each respective storage temperature (2C and 25C) for a week prior to being tested using LIAISON PLEX BCP Test.

All summer and winter shipping conditions passed with ≥ 90% positive and negative agreement with expected results.

The data support that MDx-Chex for BCP Control kit is stable for 75 days for use with the DiaSorin LIAISON PLEX BCP Test when stored at 2-25°C. In addition, data support that the Control kit is stable and functional for 75 days after exposure to extreme summer and winter shipping temperature conditions.

Table 1. Shipping Study of MDx-Chex for BCP Positive Control: Positive Percent Agreement.

| Category | Storage Temperature1 | #Observed Results/#Expected Results 2 | Positive Percent Agreement | 95% Confidence Interval | PPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- | --- |
| Summer+ | 2-8°C | 19/20* | 95% | 75% - 100% | Pass |
| | 20-25°C | 20/20 | 100% | 83% - 100% | Pass |
| Winter+ | 2-8°C | 20/20 | 100% | 83% - 100% | Pass |
| | 20-25°C | 20/20 | 100% | 83% - 100% | Pass |

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.

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^{}[]

$^{2}$ Expected result for the Positive Control is positive.
* Indicates initial dataset for shipping study which was collected within the 110-day CVS testing period.
*One Positive Control produced an unexpected result.

Table 2. Shipping Study of MDx-Chex for BCP Negative Control: Negative Percent Agreement.

| Category | Storage Temperature^{1} | #Observed Results/#Expected Results^{2} | Negative Percent Agreement | 95% Confidence Interval | NPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- | --- |
| Summer + | 2-8°C | 20/20 | 100% | 83% - 100% | Pass |
| | 20-25°C | 20/20 | 100% | 83% - 100% | Pass |
| Winter + | 2-8°C | 20/20 | 100% | 83% - 100% | Pass |
| | 20-25°C | 20/20 | 100% | 83% - 100% | Pass |

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 110-day CVS testing period.

# Shipping Stability (MDx-Chex for BCP Verification Kit)

To verify simulated shipping performance, one lot of MDx-Chex for BCP Verification Kit was subjected to simulated shipping conditions. Vials were packaged in the MDx-Chex for BCP Verification Kit configuration (see Design Input section for details) and exposed to winter and summer shipping temperature profiles over a 5-day period. Data were collected from 5 samples per control type under each simulated profile within the 75-day CVS testing window. Data may be collected again at end-of-shelf-life to confirm product stability.

All summer and winter shipping conditions passed with ≥ 90% positive and negative agreement with expected results. The data supports that the MDx-Chex for BCP Verification Kit is stable for 75 days for use with the DiaSorin LIAISON PLEX BCP Test when stored at 2-25°C. In addition, data supports that the MDx-Chex for BCP Verification Kit is stable and functional for 75 days after exposure to extreme summer and winter shipping temperature conditions.

Table 1. Shipping Study of MDx-Chex for BCP Verification Kit Positive Control: Positive Percent Agreement.

| Category | Storage Temperature^{1} | #Observed Results/#Expected Results^{2} | Positive Percent Agreement | 95% Confidence Interval | PPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- | --- |
| Summer + | 2-8°C | 5/5 | 100% | 48% - 100% | Pass |
| | 20-25°C | 9/10* | 90% | 55% - 100% | Pass |
| Winter + | 2-8°C | 5/5 | 100% | 48% - 100% | Pass |
| | 20-25°C | 5/5 | 100% | 48% - 100% | Pass |

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 110-day CVS testing period.
*One Positive Control produced an unexpected result. The entire dataset (5 replicates) was re-tested, and all runs passed confirming the stability of product exposed to shipping conditions (refer to study protocol # 24-0004-1 Revision 1 under "Study Design and Sample Size" section".

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Table 2. Shipping Study of MDx-Chex for BCP Verification Kit Negative Control: Negative Percent Agreement.

| Category | Storage Temperature^{1} | #Observed Results/#Expected Results^{2} | Negative Percent Agreement | 95% Confidence Interval | NPA ≥ 90% Acceptance |
| --- | --- | --- | --- | --- | --- |
| Summer * | 2-8°C | 5/5 | 100% | 48% - 100% | Pass |
| | 20-25°C | 5/5 | 100% | 48% - 100% | Pass |
| Winter * | 2-8°C | 5/5 | 100% | 48% - 100% | Pass |
| | 20-25°C | 5/5 | 100% | 48% - 100% | Pass |

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 110-day CVS testing period.

## Matrix Effect

To verify that the simulated blood culture matrix does not impact performance of the DiaSorin LIAISON PLEX BCP assay, one lot of Staphylococcus aureus (4E6 cells/mL final concentration) was spiked into MDx-Chex for BCP matrix and also into BD BACTEC Plus Aerobic/F culture medium supplemented with negative whole blood to simulate a clinical sample (note: spike-in concentration is within the clinical bottle positivity range of approximately 1E7-1E9 CFU/mL). 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 simulated positive and negative MDx-Chex for BCP matrix and simulated positive clinical sample passed with ≥ 90% agreement for positive detection of analyte. All results met predefined acceptance criteria. The results demonstrate that MDx-Chex for BCP matrix has no effect on target detection (i.e., no inhibition and/or false negative results) when tested with the LIAISON PLEX BCP Test. Data for MDx-Chex for BCP was identical to the results for the simulated clinical blood culture sample.

Table 1: Comparison of MDx-Chex for BCP Matrix and Clinical Sample matrix tested on DiaSorin LIAISON PLEX BCP Assay – Spiked-in samples

| Matrix type | # Expected results / # tested^{1} | Positive Percent Agreement | 95% Confidence Interval |
| --- | --- | --- | --- |
| MDx-Chex for BCP Matrix + Staphylococcus aureus | 3/3 | 100% | 29% - 100% |
| Clinical Matrix + Staphylococcus aureus | 3/3 | 100% | 29% - 100% |

1 Expected result for the Spiked-in matrices are positive for Staphylococcus aureus.

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Table 2: Comparison of MDx-Chex for BCP Matrix and Clinical Sample matrix tested on DiaSorin LIAISON PLEX BCP Assay – Non-spiked samples

| Matrix type | # Expected results / # tested 1 | Negative Percent Agreement | 95% Confidence Interval |
| --- | --- | --- | --- |
| MDx-Chex for BCP Matrix | 3/3 | 100% | 29% - 100% |
| Clinical Matrix | 3/3 | 100% | 29% - 100% |

1 Expected result for non-spiked matrices are negative.

## Conclusion of Performance Tests

The study results demonstrate MDx-Chex for BCP to be consistently stable, to demonstrate reproducibility, repeatability, and is substantially equivalent to the predicate device (MDx-Chex for BC-GP) through product expiration dating. MDx-Chex for BCP is a safe and effective product, which fulfills its intended use when used as instructed in the Instructions for Use.

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