Intended Use:
The Selux AST System is intended to be used for the automated quantitative susceptibility testing for most clinically significant aerobic microorganisms. The Selux AST System does not provide organism identification.

Indications for Use:
The Selux Gram-Negative Panel is intended for use with the Selux AST System as an in vitro test to determine the susceptibility of isolated colonies of specific gram-negative bacilli to specific antimicrobial agents when used as instructed.

The Selux Gram-Negative Panel is a quantitative test for the following antimicrobial agents with the specific organisms identified below:

Amikacin: Pseudomonas aeruginosa
Amoxicillin-Clavulanate: Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae), Proteus mirabilis
Ampicillin: Escherichia coli, Proteus mirabilis
Ampicillin-Sulbactam: Acinetobacter baumannii complex, Escherichia species (including K. oxytoca, K. pneumoniae), Proteus mirabilis, Proteus vulgaris
Aztreonam: Escherichia coli
Cefazolin: Escherichia coli, Klebsiella pneumoniae
Cefepime: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
Cefoxitin: Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae), Morganii
Ceftazidime: Citrobacter species (including C. freundii complex, C. koseri), Enterobacter cloacae complex, Escherichia coli, Klebsiella species (including K. aerogenes, K. pneumoniae), Proteus mirabilis, Proteus vulgaris, Serratia marcescens
Ceftazidime-Avibactam: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens
Ceftriaxone: Citrobacter freundii complex, Citrobacter koseri, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis
Ciprofloxacin: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa
Eravacycline: Citrobacter freundii complex, Enterobacter cloacae complex, Escherichia oxytoca
Ertapenem: Citrobacter freundii complex, Citrobacter koseri, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
Gentamicin: Citrobacter species (including C. freundii complex, C. koseri), Enterobacter cloacae complex, Escherichia coli, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae), Proteus species (including P. mirabilis, P. vulgaris), Pseudomonas aeruginosa, Serratia marcescens
Imipenem-Relebactam: Citrobacter freundii complex, Citrobacter koseri, Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa
Levofloxacin: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
Meropenem: Citrohacter freundii complex. Citrobacter cloacae complex. Escherichia coli. Klebsiella oxvtoca, Klebsiella pneumoniae, Morganella morganii. Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens
Meropenem-Vaborbactam: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, Serratia marcescens
Minocycline: Escherichia coli, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae)
Piperacillin-Tazobactam: Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris
Tobramycin: Pseudomonas aeruginosa
Trimethoprim-Sulfamethoxazole: Enterobacter cloacae complex, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae)

Device Description

The Selux AST System for antimicrobial susceptibility testing (AST) consists of a Sample Prep Station, an Inoculator, an Analyzer, a computer workstation, and the reagents and consumables required to perform AST testing. The system is operated via software that guides users through the manual sample preparation process and operates the automated Inoculator and Analyzer. The software includes an algorithm that enables the system to determine the susceptibilities of an organism to the variety of antimicrobials under test.

The system is designed so that only Gram stain information is required to initiate testing (to select the proper antimicrobial panel, gram-negative or gram-positive). While complete system testing can be performed without species-level identification (ID), this information is required for the system to report susceptibility results. Species ID can be performed by any appropriate method and this information can be either manually input to the Selux system or automatically downloaded from the laboratory information system (LIS) at any time, once the sample ID is entered into the system.

The system utilizes 384-well panels to provide parallel results for a large number of antimicrobials. Its average time-to-result is under 6 hours, as demonstrated in various studies.

Principle of Operation
The Selux platform performs AST similarly to the reference broth microdilution method by first incubating samples, then quantifying microbial growth in each well of an antimicrobial dilution series after a growth period, and finally determining the MIC by comparing growth data in each well. The Selux AST test requires that the Gram type (Classification) of the organism be known prior to testing as the information is necessary to select the proper AST panel to use. The organism identification (ID) need not be known for Selux AST processing to be performed. However, the organism ID is necessary for a result to be obtained because the MIC-determining algorithm is species-specific as is the interpretative Susceptible, Intermediate, or Resistant (SIR) determination. Any FDA-cleared method may be used to provide an ID including biochemical techniques, matrixassisted laser desorption/isotherm mass spectrometry, and multiplex genetic assays.

To ensure accurate results, the Selux method initiates antimicrobial susceptibility assays only after sufficient microorganism replication has occurred. Following determination of sufficient growth, two complementary metabolic assays are performed that quantify microbial growth, namely an indicator assay to estimate the number of bacteria present and a surface binding assay. These data are input to an MIC-determining algorithm that provides results when organism IDs are available. The sufficient growth assay ensures that the metabolic reagents used for the high-sensitivity organism quantification assays are not added until after sufficient microbial growth has occurred. To get an accurate reading of microbial replication, the sufficient growth assay monitors growth in dedicated AST panel wells that contain organisms and cation-adjusted Mueller-Hinton Broth but no antimicrobials or probes. Sufficient growth assay wells are monitored by fluorescence to those wells which the standard viability assay pair resazurin/methylene blue have been added and/or by optical absorbance.

Two probe-based assays, a viability assay and a surface area assay, commence across all wells in the panel after the sufficient growth threshold has been met. Both of these assays are performed in each AST panel well, providing two complementary datasets for each well.

AI/ML Overview

Here's a summary of the acceptance criteria and study details for the Selux AST System, based on the provided FDA 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for the Selux AST System are based on the comparison of its results with triplicate broth microdilution results from an independent reference laboratory. The specific performance metrics are "Essential Agreement" (EA) and "Category Agreement" (CA), along with an analysis of Very Major Errors (VMJ), Major Errors (MAJ), and Minor Errors (MIN). While the exact numerical acceptance criteria are not explicitly stated as "X% EA and Y% CA," the table below presents the reported performance, which implicitly met the FDA's requirements for substantial equivalence. The document states that the "Selux AST System meets performance criteria for each indication."

Antimicrobial	Targeted Organism	Reported Essential Agreement (EA)	Reported Category Agreement (CA)	Very Major Errors (VMJ)	Major Errors (MAJ)	Minor Errors (MIN)
Amikacin	Pseudomonas aeruginosa	90.9% (150/165)	98.2% (162/165)	0	0	3
Amoxicillin-Clavulanate	Enterobacterales	95.6% (437/457)	92.6% (423/457)	1	2	31
Ampicillin	Enterobacterales	94.9% (241/254)	98.8% (251/254)	1	1	1
Ampicillin-Sulbactam	Acinetobacter baumannii complex, Enterobacterales	91.9% (113/123)	92.7% (114/123)	1	2	6
Aztreonam	Enterobacterales	97.8% (179/183)	97.3% (178/183)	0	0	5
Cefazolin	Enterobacterales	94.7% (339/358)	80.2% (287/358)	1	0	70
Cefepime	Enterobacterales	94.4% (833/882)	95.8% (845/882)	2	10	25
Cefoxitin	Enterobacterales	92.3% (538/583)	79.1% (461/583)	3	8	111
Ceftazidime	Enterobacterales	95.6% (752/787)	96.4% (759/787)	1	1	26
Ceftazidime-Avibactam	Enterobacterales, Pseudomonas aeruginosa	97.3% (793/815)	99.4% (810/815)	0	5	0
Ceftriaxone	Enterobacterales	97.3% (650/668)	98.4% (657/668)	1	4	3
Ciprofloxacin	Enterobacterales, Pseudomonas aeruginosa	96.7% (791/818)	96.2% (787/818)	2	3	26
Eravacycline	Enterobacterales	98.2% (478/487)	98.6% (480/487)	2	1	0
Ertapenem	Enterobacterales	96.3% (849/882)	98.4% (868/882)	0	8	6
Gentamicin	Enterobacterales, Pseudomonas aeruginosa	96.2% (713/741)	98.9% (733/741)	1	1	6
Imipenem-Relebactam	Enterobacterales, Pseudomonas aeruginosa	93.4% (440/471)	97.5% (459/471)	0	3	9
Levofloxacin	Enterobacterales	96.0% (753/784)	94.9% (744/784)	1	6	33
Meropenem	Enterobacterales, Pseudomonas aeruginosa	96.2% (801/833)	98.0% (816/833)	1	12	4
Meropenem-Vaborbactam	Enterobacterales	95.7% (727/760)	98.9% (752/760)	1	1	6
Minocycline	Enterobacterales	90.3% (353/391)	95.1% (372/391)	1	3	16
Piperacillin-Tazobactam	Enterobacterales	92.1% (644/699)	97.3% (680/699)	2	3	13
Tobramycin	Pseudomonas aeruginosa	93.4% (155/166)	97.6% (162/166)	0	1	3
Trimethoprim-Sulfamethoxazole	Enterobacterales	96.9% (435/449)	98.4% (442/449)	4	1	0
Ceftazidime-Avibactam (P. aeruginosa)	Pseudomonas aeruginosa	92.6% (151/163)	96.9% (158/163)	0	2	0
Ciprofloxacin (P. aeruginosa)	Pseudomonas aeruginosa	95.9% (162/169)	94.7% (160/169)	0	4	5
Gentamicin (P. aeruginosa)	Pseudomonas aeruginosa	96.8% (211/218)	97.2% (212/218)	0	0	6
Imipenem-Relebactam (P. aeruginosa)	Pseudomonas aeruginosa	96.4% (159/165)	98.2% (162/165)	0	0	3
Meropenem (P. aeruginosa)	Pseudomonas aeruginosa	93.1% (163/175)	96.0% (168/175)	0	0	7

2. Sample Size Used for the Test Set and Data Provenance

Sample Size:
- A total of 1401 clinical isolates (426 contemporary and 975 stock) and 222 challenge isolates were used.
- This totals 1623 isolates across 12 Enterobacterales species, Acinetobacter baumannii complex, and Pseudomonas aeruginosa.
- The number of data points for various antimicrobial-organism combinations ranged from 165 to 977, depending on the specific combination.
Data Provenance: Clinical isolates were from "diverse geographic locations across the US." The study included both contemporary and frozen clinical isolates, as well as banked challenge isolates (selected for resistance profiles). This indicates a prospective and retrospective collection for clinical isolates and potentially retrospective for banked challenge isolates.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

The document does not specify the number or qualifications of experts. However, it states that the ground truth was established by "triplicate broth microdilution results performed at an independent reference laboratory." This implies that the standard reference method for antimicrobial susceptibility testing was used, which is typically conducted by trained microbiologists.

4. Adjudication Method for the Test Set

The document does not explicitly describe an adjudication method for discrepancies between the device and the reference method. The comparison methodology is directly stated as: "Selux AST System performance was determined by comparing Selux AST System results with triplicate broth microdilution results performed at an independent reference laboratory." This suggests a direct comparison rather than an adjudication process by additional experts for discordant results.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No, an MRMC comparative effectiveness study involving human readers with and without AI assistance was not done. This device is an automated antimicrobial susceptibility testing system, not an imaging or diagnostic device that typically involves human interpretation of outputs aided by AI. Its performance is compared directly to a reference laboratory method for accuracy.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Yes, the study described is a standalone performance evaluation of the Selux AST System. The system "determines the susceptibilities of an organism to the variety of antimicrobials under test" using its integrated software and algorithm. While human input is required for initial sample preparation and entry of organism identification (which can be manual or LIS-automated), the core susceptibility determination by the system is automated ("algorithm only"). The results are then compared to the reference method (broth microdilution).

7. The Type of Ground Truth Used

The ground truth used was broth microdilution results, specifically "triplicate broth microdilution results performed at an independent reference laboratory." Broth microdilution is considered a gold standard reference method for antimicrobial susceptibility testing.

8. The Sample Size for the Training Set

The document does not explicitly state the sample size for the training set. The provided details focus on the validation/test set used for clinical performance evaluation.

9. How the Ground Truth for the Training Set Was Established

Since the training set size and details are not provided, information on how its ground truth was established is also not available in this document.

Summary

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April 19, 2023

Selux Diagnostics, Inc % Patricia Shrader Regulatory Consultant PBO Consulting 2212 East Pratt Street Baltimore, Maryland 21231

Re: K211748

Trade/Device Name: Selux AST System; Model AST Gen 1.0 Regulation Number: 21 CFR 866.1645 Regulation Name: Fully Automated Short-Term Incubation Cycle Antimicrobial Susceptibility System Regulatory Class: Class II Product Code: LON, LTT, LTW Dated: June 4, 2021 Received: June 7, 2021

Dear Patricia Shrader:

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 (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 located 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.

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

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requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801 and Part 809); medical device reporting of medical device-related adverse events) (21 CFR 803) for devices or postmarketing safety reporting (21 CFR 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (OS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 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-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about mediation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/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-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).

Sincerely,

Ribhi Shawar -S

Ribhi Shawar, Ph.D. (ABMM) Branch Chief. General Bacteriology and Antimicrobial Susceptibility 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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Indications for Use

510(k) Number (if known) K211748

Device Name Selux AST System

Indications for Use (Describe)

Intended Use:

The Selux AST System is intended to be used for the automated quantitative susceptibility testing for most clinically significant aerobic microorganisms. The Selux AST System does not provide organism identification.

Indications for Use:

The Selux Gram-Negative Panel is intended for use with the Selux AST System as an in vitro test to determine the susceptibility of isolated colonies of specific gram-negative bacilli to specific antimicrobial agents when used as instructed.

The Selux Gram-Negative Panel is a quantitative test for the following antimicrobial agents with the specific organisms identified below:

Amikacin: Pseudomonas aeruginosa
Amoxicillin-Clavulanate: Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae), Proteus ● mirabilis
Ampicillin: Escherichia coli, Proteus mirabilis ●
Ampicillin-Sulbactam: Acinetobacter baumannii complex, Escherichia species (including K. oxytoca, ● K. pneumoniae), Proteus mirabilis, Proteus vulgaris
Aztreonam: Escherichia coli ●
Cefazolin: Escherichia coli, Klebsiella pneumoniae ●
Cefepime: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, . Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
Cefoxitin: Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae), Morganii
Ceftazidime: Citrobacter species (including C. freundii complex, C. koseri), Enterobacter cloacae complex, ● Escherichia coli, Klebsiella species (including K. aerogenes, K. pneumoniae), Proteus mirabilis, Proteus vulgaris, Serratia marcescens
Ceftazidime-Avibactam: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, ● Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens
Ceftriaxone: Citrobacter freundii complex, Citrobacter koseri, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis
. Ciprofloxacin: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa
Eravacycline: Citrobacter freundii complex, Enterobacter cloacae complex, Escherichia oxytoca ●
Ertapenem: Citrobacter freundii complex, Citrobacter koseri, Klebsiella oxytoca, Klebsiella ● pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
Gentamicin: Citrobacter species (including C. freundii complex, C. koseri), Enterobacter cloacae complex, Escherichia coli, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae), Proteus species (including P. mirabilis, P. vulgaris), Pseudomonas aeruginosa, Serratia marcescens
Imipenem-Relebactam: Citrobacter freundii complex, Citrobacter koseri, Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa

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Levofloxacin: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
. Meropenem: Citrohacter freundii complex. Citrobacter cloacae complex. Escherichia coli. Klebsiella oxvtoca, Klebsiella pneumoniae, Morganella morganii. Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens
Meropenem-Vaborbactam: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, Serratia marcescens
Minocycline: Escherichia coli, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae)
Piperacillin-Tazobactam: Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Morganii, ● Proteus mirabilis, Proteus vulgaris
Tobramycin: Pseudomonas aeruginosa .
Trimethoprim-Sulfamethoxazole: Enterobacter cloacae complex, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae)

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)

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510(k) Summary for the Selux AST System, Antimicrobial Susceptibility Test System

Date prepared: April 9, 2023

Submitter:

Selux Diagnostics, Inc. 56 Roland St Suite 106 Charlestown, MA 02129 Tel. 617-945-9383

Contact:

Eric Stern, Ph.D. Tel. 617-945-9383

Subject Device

Trade Name:	Selux AST System
Common Name:	Antimicrobial Susceptibility Test System
Regulation Number:	21 CFR 866.1645
Regulation Name:	Fully automated short-term incubation cycle antimicrobial susceptibilitysystem
Regulatory Class:	Class II
Product Code:	LON, LTT, LTW
Classification Panel:	83 (Microbiology)

Primary Predicate Device(s)

Trade Name:	BD Phoenix Automated Microbiology System- Ceftaroline 0.0156-4µg/mL
Manufacturer:	Becton, Dickinson and Company
510(k) Reference:	K190905
Common Name:	Antimicrobial Susceptibility Test System
Regulation Number:	21 CFR 866.1645
Regulation Name:	Fully automated short-term incubation cycle antimicrobial susceptibilitysystem
Regulatory Class:	Class II
Product Code:	LON
Classification Panel:	83 (Microbiology)

Device Description

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The system utilizes 384-well panels to provide parallel results for a large number of antimicrobials. Its average time-to-result is under 6 hours, as demonstrated in various studies.

Principle of Operation

The Selux platform performs AST similarly to the reference broth microdilution method by first incubating samples, then quantifying microbial growth in each well of an antimicrobial dilution series after a growth period, and finally determining the MIC by comparing growth data in each well. The Selux AST test requires that the Gram type (Classification) of the organism be known prior to testing as the information is necessary to select the proper AST panel to use. The organism identification (ID) need not be known for Selux AST processing to be performed. However, the organism ID is necessary for a result to be obtained because the MIC-determining algorithm is species-specific as is the interpretative Susceptible, Intermediate, or Resistant (SIR) determination. Any FDA-cleared method may be used to provide an ID including biochemical techniques, matrixassisted laser desorption/isotherm mass spectrometry, and multiplex genetic assays.

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Intended Use and Indications for Use

The Selux AST System is intended to be used for the automated quantitative or qualitative susceptibility testing for most clinically significant aerobic microorganisms. The Selux AST System does not provide organism identification.

The Selux Gram-Negative Panel is intended for use with the Selux AST System as an in-vitro test to determine the susceptibility of isolated colonies of specific gram-negative bacilli to specific antimicrobial agents when used as instructed.

The Selux Gram-Negative Panel is a quantitative test for the following antimicrobial agents with the specific organisms identified below:

. Amikacin: Pseudomonas aeruginosa
. Amoxicillin-Clavulanate: Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae). Proteus mirabilis
Ampicillin: Escherichia coli, Proteus mirabilis
. Ampicillin-Sulbactam: Acinetobacter baumannii complex, Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae), Proteus mirabilis, Proteus vulgaris
Aztreonam: Escherichia coli
Cefazolin: Escherichia coli, Klebsiella pneumoniae
Cefepime: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae . complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
. Cefoxitin: Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae), Morganella morganii
. Ceftazidime: Citrobacter species (including C. freundii complex, C. koseri), Enterobacter cloacae complex, Escherichia coli, Klebsiella species (including K. aerogenes, K. oxvtoca, K. pneumoniae), Proteus mirabilis, Proteus vulgaris, Serratia marcescens
. Ceftazidime-Avibactam: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens
. Ceftriaxone: Citrobacter freundii complex, Citrobacter koseri, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis
Ciprofloxacin: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa
. Eravacycline: Citrobacter freundii complex, Enterobacter cloacae complex, Escherichia coli, Klebsiella oxytoca
. Ertapenem: Citrobacter freundii complex, Citrobacter koseri, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens

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Gentamicin: Citrobacter species (including C. freundii complex, C. koserì), . Enterobacter cloacae complex, Escherichia coli, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae), Proteus species (including P. mirabilis, P. vulgaris), Pseudomonas aeruginosa, Serratia marcescens
. Imipenem-Relebactam: Citrobacter freundii complex, Citrobacter koseri, Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa
. Levofloxacin: Citrobacter freundii complex. Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
. Meropenem: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens
. Meropenem-Vaborbactam: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxvtoca. Klebsiella pneumoniae, Morganella morganii, Serratia marcescens
. Minocycline: Escherichia coli, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae)
. Piperacillin-Tazobactam: Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris
. Tobramycin: Pseudomonas aeruginosa
. Trimethoprim-Sulfamethoxazole: Enterobacter cloacae complex, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae)

Comparison of Technological Characteristics with the Predicate Device

The technological characteristics of the Selux AST System are substantially equivalent to the predicate, the BD Phoenix Automated Microbiology System- Ceftaroline 0.0156-4 ug/mL (K190905) in terms of intended use, application, user population, basic design, performance, and labeling.

Specification	Selux AST System	K190905
Device Trade Name	Selux AST System	BD Phoenix AutomatedMicrobiology System-Ceftaroline 0.0156-4 µg/mL
Indication for Use	The Selux AST System is intended to beused for the automated quantitative orqualitative susceptibility testing for mostclinically significant aerobicmicroorganisms. The Selux AST Systemdoes not provide organism identification.The Selux Gram-Negative Panel isintended for use with the Selux ASTSystem as an in vitro test to determine thesusceptibility of isolated colonies ofspecific gram-negative bacilli to specific	The BD Phoenix AutomatedMicrobiology System is intendedfor the in vitro rapid identification(ID) of aerobic and facultativeanaerobic Gram-negativebacteria. The BD PhoenixAutomated Microbiology System isalso intended for the quantitativedetermination of antimicrobialsusceptibility by minimal inhibitoryconcentration (MIC) of aerobic andfacultative anaerobic Gram-
Specification	Selux AST System	K190905
	antimicrobial agents when used asinstructed.	negative bacteria isolates from pureculture.
Sources ofMicroorganisms	Bacterial colonies isolated from culture	Same
Technology	Automated growth-based detection	Same
Methodology	Determinations of MIC using serial two-fold dilution format	Same
Read Method	Automated	Same
Inoculation Method	Automated	Same
Result Reported	Report results as minimum inhibitoryconcentration (MIC) and categoricalinterpretation (S, I, R, NS)	Report results as minimuminhibitory concentration (MIC) andcategorical interpretation (S, I, R)
General Device Characteristic Differences
Antimicrobial Agent andReporting Range	Amikacin: ≤2 to ≥256 µg/mLAmoxicillin-Clavulanate: ≤0.5 to ≥128µg/mLAmpicillin: ≤0.25 to ≥128 µg/mLAmpicillin-Sulbactam: ≤0.5 to ≥128µg/mLAztreonam: ≤0.03 to ≥128 µg/mLCefazolin: ≤0.12 to ≥128 µg/mLCefepime: ≤0.25 to ≥128 µg/mLCefoxitin: ≤1 to ≥128 µg/mLCeftazidime: ≤2 to ≥64 µg/mLCeftazidime-Avibactam: ≤0.12 to ≥64µg/mLCeftriaxone: ≤0.25 to ≥32 µg/mLCiprofloxacin: ≤0.03 to ≥16 µg/mLEravacycline: ≤0.016 to ≥4 µg/mLErtapenem: ≤0.03 to ≥16 µg/mLGentamicin: ≤0.06 to ≥64 µg/mLImipenem-Relebactam: ≤0.03 to ≥128µg/mLLevofloxacin: ≤0.06 to ≥32 µg/mLMeropenem: ≤0.5 to ≥64 µg/mLMeropenem-Vaborbactam: ≤0.06 to≥64 µg/mLMinocycline: ≤1 to ≥64 µg/mLPiperacillin-Tazobactam: ≤4 to ≥512µg/mLTobramycin: ≤0.12 to ≥128 µg/mLTrimethoprim-Sulfamethoxazole:≤0.12 to ≥32 µg/mL	Ceftaroline: ≤0.0156 to ≥8 µg/mL
IVD Functions	AST	ID and AST
Instrument	Selux AST System	BD Phoenix AutomatedMicrobiology System

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Despite the differences between the Selux AST System and the predicate, the overall risk and safety of system use is not affected.

Reproducibility

Inter-site reproducibility was evaluated by testing a minimum of 25 isolates for each of the 24 antimicrobials at each of three test sites that participated in the clinical study. Each isolate was tested once at each site for a total of three results per isolate (minimum of 75 results per antimicrobial). Best-case inter-site reproducibility was ≥95% and worst-case inter-site reproducibility was ≥89% (see following table).

Selux AST System Inter-site Reproducibility
	All organisms (combined)		Indicated organisms only
Antimicrobial	Best-case (%)	Worst case (%)	Best-case (%)	Worst case (%)
Amikacin	98/104 (94.2%)	98/104 (94.2%)	92/98 (93.9%)	92/98 (93.9%)
Amoxicillin-Clavulanate	71/72 (98.6%)	70/72 (97.2%)	71/72 (98.6%)	70/72 (97.2%)
Ampicillin	72/75 (96.0%)	72/75 (96.0%)	68/69 (98.6%)	68/69 (98.6%)
Ampicillin-Sulbactam	74/75 (98.7%)	74/75 (98.7%)	66/66 (100%)	66/66 (100%)
Aztreonam	77/78 (98.7%)	75/78 (96.2%)	77/78 (98.7%)	75/78 (96.2%)
Cefazolin	77/81 (95.1%)	76/81 (93.8%)	68/72 (94.4%)	67/72 (93.1%)
Cefepime	77/78 (98.7%)	76/78 (97.4%)	77/78 (98.7%)	76/78 (97.4%)
Cefoxitin	70/72 (97.2%)	69/72 (95.8%)	70/72 (97.2%)	69/72 (95.8%)
Ceftazidime1	77/81 (95.1%)	71/81 (87.7%)	77/81 (95.1%)	71/81 (87.7%)
Ceftazidime-Avibactam	140/144 (97.2%)	139/144 (96.5%)	140/144 (97.2%)	139/144 (96.5%)
Ceftriaxone	140/141 (99.3%)	140/141 (99.3%)	140/141 (99.3%)	140/141 (99.3%)
Ciprofloxacin	74/75 (98.7%)	71/75 (94.7%)	74/75 (98.7%)	71/75 (94.7%)
Eravacycline	78/78 (100%)	78/78 (100%)	78/78 (100%)	78/78 (100%)
Ertapenem	143/145 (98.6%)	143/145 (98.6%)	143/145 (98.6%)	143/145 (98.6%)
Gentamicin	77/80 (96.3%)	77/80 (96.3%)	77/80 (96.3%)	77/80 (96.3%)
Imipenem	145/149 (97.3%)	140/149 (94.0%)	145/149 (97.3%)	140/149 (94.0%)
Imipenem-Relebactam	72/75 (96.0%)	72/75 (96.0%)	72/75 (96.0%)	72/75 (96.0%)
Levofloxacin	76/78 (97.4%)	76/78 (97.4%)	76/78 (97.4%)	76/78 (97.4%)
Meropenem	75/78 (96.2%)	73/78 (93.6%)	70/72 (97.2%)	68/72 (94.4%)
Meropenem-Vaborbactam	142/145 (97.9%)	132/145 (91.0%)	133/143 (93.0%)	133/143 (93.0%)
Minocycline	73/75 (97.3%)	73/75 (97.3%)	64/66 (97.3%)	64/66 (97.3%)
Piperacillin-Tazobactam	72/75 (96.0%)	69/75 (92.0%)	63/66 (95.5%)	60/66 (90.9%)
Tobramycin	74/78 (94.9%)	73/78 (93.6%)	74/78 (94.9%)	73/78 (93.6%)
Trimethoprim-Sulfamethoxazole	143/148 (96.6%)	142/148 (95.9%)	143/148 (96.6%)	142/148 (95.9%)

Intra-site reproducibility was evaluated at a single site that participated in the inter-site reproducibility testing and the clinical study. A minimum of 5 isolates for each antimicrobial were tested in triplicate at the site from three separate inoculums on three separate days for a minimum total of 45 results per antimicrobial. Best-case intra-site reproducibility was ≥95% and worst-case intra-site reproducibility was ≥89% (see following table).

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Selux AST System Intra-site Reproducibility
	All organisms (combined)		Indicated organisms only
Antimicrobial	Best-case (%)	Worst case (%)	Best-case (%)	Worst case (%)
Amoxicillin-Clavulanate	63/63 (100%)	63/63 (100%)	63/63 (100%)	63/63 (100%)
Ampicillin	45/45 (100%)	45/45 (100%)	45/45 (100%)	45/45 (100%)
Ampicillin-Sulbactam	72/72 (100%)	72/72 (100%)	72/72 (100%)	72/72 (100%)
Aztreonam	71/74 (95.9%)	68/74 (91.9%)	71/74 (95.9%)	68/74 (91.9%)
Cefazolin	61/63 (96.8%)	61/63 (96.8%)	61/63 (96.8%)	61/63 (96.8%)
Cefepime	45/47 (95.7%)	45/47 (95.7%)	45/47 (95.7%)	45/47 (95.7%)
Cefoxitin	54/54 (100%)	54/54 (100%)	54/54 (100%)	54/54 (100%)
Ceftazidime	92/93 (98.9%)	91/93 (97.8%)	92/93 (98.9%)	91/93 (97.8%)
Ceftazidime-Avibactam	47/47 (100%)	43/47 (91.5%)	47/47 (100%)	43/47 (91.5%)
Eravacycline	103/103 (100%)	99/103 (96.1%)	103/103 (100%)	99/103 (96.1%)
Gentamicin	116/121 (95.9%)	116/121 (95.9%)	116/121 (95.9%)	116/121 (95.9%)
Imipenem-Relebactam	72/76 (94.7%)	72/76 (94.7%)	72/76 (94.7%)	72/76 (94.7%)
Levofloxacin	179/181 (98.9%)	174/181 (96.1%)	179/181 (98.9%)	174/181 (96.1%)
Meropenem	57/58 (98.3%)	56/58 (96.6%)	57/58 (98.3%)	56/58 (96.6%)
Meropenem-Vaborbactam	45/47 (95.7%)	43/47 (91.5%)	45/47 (95.7%)	43/47 (91.5%)
Piperacillin-Tazobactam	54/56 (96.4%)	54/56 (96.4%)	54/56 (96.4%)	54/56 (96.4%)
Trimethoprim-Sulfamethoxazole	62/65 (95.4%)	61/65 (93.8%)	62/65 (95.4%)	61/65 (93.8%)

Clinical Studies

The following table gives the antimicrobial-organism combinations tested and includes the reporting range and breakpoints of each combination.

Antimicrobial	Abbreviation	Targeted Organism	Reporting Range	Breakpoints	Antimicrobial	Organism Group	TotalTested	# in EA	% EA	# in CA	% CA	# R	# VMJ	# MAJ	# MIN
Amikacin	AMK	Pseudomonasaeruginosa	≤0.12 to ≥256µg/mL	≤16 / 32 / ≥64	Amikacin	Pseudomonas aeruginosa	165	150	90.9	162	98.2	7	0	0	3
Amoxicillin-Clavulanate	AMC	Enterobacterales	≤0.5 to ≥128µg/mL	≤8 / 16 / ≥32	Amoxicillin-Clavulanate	Enterobacterales	457	437	95.6	423	92.6	110	1	2	31
Ampicillin	AMP	Enterobacterales	≤0.25 to ≥128µg/mL	≤8 / 16 / ≥32	Ampicillin	Enterobacterales	254	241	94.9	251	98.8	118	1	1	1
Ampicillin-Sulbactam	SAM	Acinetobacterbaumannii complexEnterobacterales	≤0.5 to ≥128µg/mL	≤8 / 16 / ≥32	Ampicillin-Sulbactam	Acinetobacter baumannii complex	123	113	91.9	114	92.7	52	1	2	6
Aztreonam	ATM	Enterobacterales	≤0.03 to ≥128µg/mL	≤4 / 8 / ≥16	Aztreonam	Enterobacterales	183	179	97.8	178	97.3	46	0	0	5
Cefazolin	CFZ	Enterobacterales	≤0.12 to ≥128µg/mL	≤1 / 2 / ≥4	Cefazolin	Enterobacterales	358	339	94.7	287	80.2	215	1	0	70
Cefepime	FEP	Enterobacterales	≤0.25 to ≥128µg/mL	≤2 / 4-8 / ≥16	Cefepime	Enterobacterales	882	833	94.4	845	95.8	127	2	10	25
Cefoxitin	FOX	Enterobacterales	≤1 to ≥128 µg/mL	≤4 / 8 / ≥16	Cefoxitin	Enterobacterales	583	538	92.3	461	79.1	103	3	8	111
Ceftazidime	CAZ	Enterobacterales	≤0.25 to ≥64µg/mL	≤4 / 8 / ≥16	Ceftazidime	Enterobacterales	787	752	95.6	759	96.4	208	1	1	26
Antimicrobial	Abbreviation	Targeted Organism	Reporting Range	Breakpoints	Ceftazidime-Avibactam	Enterobacterales	815	793	97.3	810	99.4	32	0	5	0
Ceftazidime-Avibactam	CZA	EnterobacteralesPseudomonasaeruginosa	≤0.12 to ≥64μg/mL	≤8 / ≥16	Ceftriaxone	Pseudomonas aeruginosa	163	151	92.6	158	96.9	10	0	2	0
Ceftriaxone	CRO	Enterobacterales	≤0.25 to ≥32μg/mL	≤1 / 2 / ≥4	Ceftriaxone	Enterobacterales	668	650	97.3	657	98.4	188	1	4	3
Ciprofloxacin	CIP	EnterobacteralesPseudomonasaeruginosa	≤0.03 to ≥16μg/mL	Enterobacterales:≤0.25 / 0.5 / ≥1P. aeruginosa :≤0.5 / 1 / ≥2	Ciprofloxacin	Enterobacterales	818	791	96.7	787	96.2	177	2	3	26
Eravacycline	ERV	Enterobacterales	≤0.016 to ≥4μg/mL	≤0.5 / -		Pseudomonas aeruginosa	169	162	95.9	160	94.7	33	0	4	5
Ertapenem	ETP	Enterobacterales	≤0.03 to ≥16μg/mL	≤0.5 / 1 / ≥2	Eravacycline	Enterobacterales	487	478	98.2	480	98.6	54	2	1	0
Gentamicin	GEN	Enterobacterales	≤0.06 to ≥64μg/mL	≤4 / 8 / ≥16	Ertapenem	Enterobacterales	882	849	96.3	868	98.4	101	0	8	6
Imipenem-Relebactam	IMR	EnterobacteralesPseudomonasaeruginosa	≤0.03 to ≥128μg/mL	Enterobacterales:≤1 / 2 / ≥4P. aeruginosa :≤2 / 4 / ≥8	Gentamicin	Enterobacterales	741	713	96.2	733	98.9	113	1	1	6
Levofloxacin	LVX	Enterobacterales	≤0.06 to ≥32μg/mL	≤0.5 / 1 / ≥2		Pseudomonas aeruginosa	218	211	96.8	212	97.2	15	0	0	6
Meropenem	MEM	EnterobacteralesPseudomonasaeruginosa	≤0.12 to ≥64μg/mL	Enterobacterales:≤1 / 2 / ≥4P. aeruginosa :≤2 / 4 / ≥8	Imipenem-Relebactam	Enterobacterales	471	440	93.4	459	97.5	33	0	3	9
Meropenem-Vaborbactam	MEV	Enterobacterales	≤0.06 to ≥64μg/mL	≤4 / 8 / ≥16		Pseudomonas aeruginosa	165	159	96.4	162	98.2	6	0	0	3
Minocycline	MIN	Enterobacterales	≤0.25 to ≥64μg/mL	≤4 / 8 / ≥16	Levofloxacin	Enterobacterales	784	753	96	744	94.9	161	1	6	33
Piperacillin-Tazobactam	TZP	Enterobacterales	≤0.25 to ≥512μg/mL	≤16 / 32-64 / ≥128	Meropenem	Enterobacterales	833	801	96.2	816	98	83	1	12	4
Tobramycin	TOB	Pseudomonasaeruginosa	≤0.12 to ≥128μg/mL	≤4 / 8 / ≥16		Pseudomonas aeruginosa	175	163	93.1	168	96	38	0	0	7
Trimethoprim-Sulfamethoxazole	SXT	Enterobacterales	≤0.12 to ≥32μg/mL	≤2 / ≥4	Meropenem-Vaborbactam	Enterobacterales	760	727	95.7	752	98.9	41	1	1	6
Minocycline	Enterobacterales	391	353	90.3	372	95.1	37	1	3	16
Piperacillin-Tazobactam	Enterobacterales	699	644	92.1	680	97.3	108	2	3	13
Tobramycin	Pseudomonas aeruginosa	166	155	93.4	162	97.6	14	0	1	3
Trimethoprim-Sulfamethoxazole	Enterobacterales	449	435	96.9	442	98.4	142	4	1	0

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Clinical performance testing on the Selux AST System was performed at three test sites. Contemporary and frozen clinical isolates from diverse geographic locations across the US were evaluated for performance as were banked challenge isolates, which were selected for their resistance profiles. A total of 1401 clinical (426 contemporary and 975 stock) and 222 challenge isolates from 12 Enterobacterales species, Acinetobacter baumannii complex, and Pseudomonas aeruginosa were tested to evaluate the Selux AST System performance for 24 antimicrobials. Depending on the spectrum of activity, breakpoints, and the claimed organisms (species/group)

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for each antimicrobial on the panel, the number of datapoints for the various antimicrobialorganisms tested varied and ranged from 165 (e.g. P. aeruginosa/Imipenem-Relebactam) to 977 (e.g. Enterobacterales/Ertapenem).

Selux AST System performance was determined by comparing Selux AST System results with triplicate broth microdilution results performed at an independent reference laboratory. The Selux AST System meets performance criteria for each indication and is given in the following table, where performance is summarized by reporting group. Additionally, QC testing was performed every day testing was performed at each site and met the 95% performance criteria for all antimicrobials.

Conclusion

Based on our studies and testing, the Selux AST System was determined to be substantially equivalent to the predicate device (K190905).

Regulation Number and Section

§ 866.1645 Fully automated short-term incubation cycle antimicrobial susceptibility system.

(a)
Identification. A fully automated short-term incubation cycle antimicrobial susceptibility system is a device that incorporates concentrations of antimicrobial agents into a system for the purpose of determining in vitro susceptibility of bacterial pathogens isolated from clinical specimens. Test results obtained from short-term (less than 16 hours) incubation are used to determine the antimicrobial agent of choice to treat bacterial diseases.(b)
Classification. Class II (special controls). The special control for this device is FDA's guidance document entitled “Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA.”