The eQUANT System is an automated inoculum preparation system that uses potentiometric sensing of oxidation-reduction potential changes due to pathogen metabolism to generate a 0.5 McFarland-equivalent suspension (the eMcFarland or eMcF) from positive blood culture samples that can be used for direct, qualitative in vitro susceptibility testing by the agar disk diffusion test method (Kirby-Bauer). Samples are processed directly from blood culture samples identified as positive by a continuous monitoring blood culture system and confirmed as Gram-negative rods by Gram stain. Organism identification must be confirmed by an FDA cleared device for direct testing from positive blood culture before processing samples on the eQUANT System.

Evaluation of the eQUANT System's inoculum preparation was conducted for use with agar disk diffusion susceptibility testing and performance was demonstrated for the following antimicrobial agents with Enterobacterales species, Acinetobacter species and Pseudomonas aeruginosa as identified below:

Amoxicillin/clavulanate- Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis

Ampicillin- Escherichia coli

Aztreonam- Citrobacter freundii, Enterobacter cloacae, Escherichia aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Cefazolin- Klebsiella pneumoniae

Cefepime- Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Ceftriaxone- Citrobacter freundii, Enterobacter cloacae, Escherichia aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens

Ertapenem- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella axytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens

Gentamicin- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella axytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Levofloxacin- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Meropenem- Acinetobacter spp., Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Piperacillin/tazobactam- Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Tobramycin- Citrobacter freundii, Enterobacter cloacae, Escherichia aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Susceptibility test results are intended to be used in conjunction with other clinical and laboratory findings. Standard laboratory protocols for processing positive blood cultures should be followed to ensure availability of isolates for supplemental testing as needed. Additionally, subculture of positive blood culture is necessary for the susceptibility testing of organisms present in polymicrobial samples, for testing antimicrobial agents and species not indicated for testing with the device, for epidemiologic testing, and for recovery of organisms present in microbial samples.

Device Description

The eQUANT™ System is an automated system that uses potentiometric sensing of changes in oxidationreduction potential (ORP) during pathogen metabolism to prepare an organism concentration equivalent to a 0.5 McFarland (1-2e8 CFU/ml ± 0.6 log) directly from a positive blood culture. The eQUANT™ System consists of four components: the eQUANT™ Instrument, a single use eTube™ Disposable, a single use eQUANT™ Reagent tube (CAMHB with antifoam), and a workflow tray.

The eQUANT™ System processes a single positive blood culture sample at a time. Before processing on the eQUANT™ System, the positive blood culture is confirmed as Gram-negative rods by Gram stain, and a rapid FDA-cleared identification (ID) method for testing from positive blood culture is performed to confirm organism ID. Mixed cultures or organisms identified that are not included in the eQUANT™ System indications for use should not be processed on the eQUANT™ System. Positive blood cultures must be processed immediately on the eQUANT™ System or within 12 hours of blood culture bottle positivity should delays be unavoidable. Once the organism ID is confirmed, 1 mL of eQUANT™ Reagent (cation-adjusted Mueller Hinton broth (CAMHB) supplemented with antifoam (0.0015%) to reduce air bubble formation) is added to the eTube™ Disposable, followed by the addition of 34 µL of the positive blood culture. The eTube™ Disposable with diluted sample is vortexed and then placed in the eQUANT™ System for incubation.

Once inserted, the eTube™ Disposable sits in a thermal module which is heated to 37°C ± 2°C to grow the bacteria to a concentration equivalent to a 0.5 McFarland, or eMcF). The eQUANT™ Sensor located in the eTube™ Disposable is an ORP sensor consisting of two electrode components, which both come into direct contact with the diluted positive blood culture sample. The eQUANT™ ORP sensor responds to changes in the ORP during pathogen growth/metabolism. As the concentration of microorganisms in the sample increases, the growth media becomes reduced, and the voltage measured by the ORP sensor becomes more negative. With the organism ID of the tested sample and the blood culture bottle type as inputs to the system, the algorithm is applied to the real-time voltage measurements to determine the point in time at which the organism concentration reaches a level equivalent to a standard 0.5 McFarland. At the endpoint, the sample immediately starts to cool down to 15°C ± 2°C to inhibit further growth. The sample can be held for up to one (1) hour on the instrument, before being used for downstream Disk Diffusion AST testing.

AI/ML Overview

Here's a breakdown of the acceptance criteria and study information for the eQUANT System, based on the provided document:

Acceptance Criteria and Device Performance

Acceptance Criteria (eQUANT System)	Reported Device Performance
Reproducibility of eMcFarland Concentration: ≥95% agreement that the eMcFarland concentration falls within 2.51e7 – 7.96e8 CFU/mL.	98.9% overall agreement based on eMcFarland concentration across sites, operators, runs, instruments, and lots. (Table 1)
Sample Stability (Positive Blood Culture): eMcFarland concentration meets 2.51e7 – 7.96e8 CFU/mL after specified holding times.	All eMcFarland colony counts met defined acceptance criteria. Positive blood culture bottles are stable for use on the eQUANT System for up to 12 hours when held on the blood culture instrument (35°C) or benchtop (room temperature). (Table 2)
eMcFarland Stability: eMcFarland concentration meets 2.51e7 – 7.96e8 CFU/mL after specified holding times post-processing.	eQUANT System generated eMcFarlands are stable for up to one (1) hour on the eQUANT Instrument, held at 15°C, and for up to 10 minutes after removal, held at room temperature. (Table 3)
Blood Culture Bottle Equivalency (eMcFarland Concentration): All eMcFarland concentrations meet 2.51e7 – 7.96e8 CFU/mL from various blood culture bottle media types.	All eMcFarland colony counts for all organisms and bottle types evaluated met defined acceptance criteria (2.51e7 – 7.96e8 CFU/mL). (Table 4)
Blood Culture Bottle Equivalency (Disk Diffusion AST): >95% CA when compared to standard 0.5 McFarland inoculum AST for A. baumannii and P. aeruginosa. >95% CA for Enterobacterales (exceptions noted).	Performed as follows: - A. baumannii: >95% CA for all bottle types assessed (100% CA).- P. aeruginosa: >95% CA for all bottle types except BD BACTEC Aero Plus (90.5% CA, with two minor errors). The two minor error eQUANT™ zone diameters were less than 3 mm difference compared to the standard method, considered acceptable.- Enterobacterales: >95% CA only obtained for BACT/ALERT SN (96.9% CA). Other bottle types showed 90-93% CA due to minor errors. The majority (93.8%) of error results had zone diameters ≤3 mm difference compared to the standard method, considered acceptable. 63/64 minor errors were due to a single K. pneumoniae isolate. (Table 4)
Interfering Substances (eMcFarland Concentration): All eMcFarland concentrations meet 2.51e7 – 7.96e8 CFU/mL in the presence of interferents.	All resulting eMcFarland concentrations met defined acceptance criteria (2.51e7 – 7.96e8 CFU/mL). (Tables 5-6)
Interfering Substances (Downstream AST): No reproducible interference observed in downstream AST testing.	No reproducible interference was observed. (Tables 5-6). High concentrations of hemoglobin (A. baumannii, P. aeruginosa) and platelets (P. aeruginosa) initially caused aborted runs. At decreased interferent concentrations, valid eMcFarlands were generated, and AST results were as expected. Minor errors in Ampicillin and Chloramphenicol were deemed acceptable due to zone diameter differences ≤ 3 mm.
Carryover: No bacterial carryover between runs.	No carryover was observed, as evidenced by monomicrobial cultures and the expected organism morphology during alternating runs of E. coli and P. aeruginosa.
Method Comparison (eMcFarland Concentration): ≥95% of eMcFarland colony counts fall within 2.51e7 – 7.96e8 CFU/mL.	99.1% of PBC samples were within the expected colony count range (219/221 samples). Two samples (one A. spp., one P. aeruginosa) were outside the range, but showed no errors in Disk Diffusion results. (Table 8)
Method Comparison (Disk Diffusion AST): - Overall CA: ≥95%- VME: ≤1%- ME: ≤1.5%(for each antimicrobial agent/organism group combination)	Most antibiotic/group combinations met overall acceptance criteria. - Exceptions to ≥95% CA: Amoxicillin/Clavulanate/Enterobacterales (94%), Cefazolin/Enterobacterales (85% - removed from Indications for Use for E. coli and P. mirabilis due to <90% CA), Cefepime/Enterobacterales (92% - removed from Indications for Use for C. freundii and K. aerogenes due to <90% CA), Piperacillin/Tazobactam/Enterobacterales (94%). These were considered acceptable if zone diameter differences were ≤3mm. - Exceptions to ≤1% VME: Gentamicin/Enterobacterales (3.85% - considered acceptable as zone diameters for major errors were ≤3 mm difference compared to standard). - Exceptions to ≤1.5% ME: Cefepime/Pseudomonas aeruginosa (9.52%). (Table 9) Other specific instances of minor/major errors were deemed acceptable based on zone diameter differences (≤3mm) or being single occurrences.

Study Details

The document describes five main studies to prove the device meets acceptance criteria: Reproducibility, Sample Stability, Blood Culture Bottle Equivalency, Interfering Substances, and Method Comparison.

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

Reproducibility Study:
- Sample Size: 462 eMcFarlands (72 replicates per organism for 5 organisms, and 102 replicates for Acinetobacter baumannii due to repeat testing). A panel of six organisms was used.
- Data Provenance: Contrived positive blood culture samples (contrived in blood culture bottles with human blood added).
Sample Stability Study:
- Sample Size: A panel of five organisms. The number of samples for each condition (organism, storage condition, time point) was tested in triplicate. Total samples not explicitly stated but implied to be 5 organisms x 2 storage conditions x 3 time points per condition x 3 replicates = 90 PBC stability tests. eMcFarland stability was also tested for these 5 organisms at various post-removal time points.
- Data Provenance: Contrived positive blood culture samples (contrived in blood culture bottles with human blood added).
Blood Culture Bottle Equivalency Study:
- Sample Size: A panel of eight organisms was contrived into various blood culture bottle types. Each organism/bottle type was tested in triplicate. (e.g., Enterobacterales: 9 bottle types * 96 total results = 864 results; P. aeruginosa: 4 bottle types * 21 total results = 84 results; A. baumannii: 4 bottle types * 24 total results= 96 results).
- Data Provenance: Contrived positive blood culture samples (contrived in blood culture bottles with human blood added).
Interfering Substances Study:
- Sample Size: A panel of nine organisms. Tests were conducted with and without potential interferents. Interferents include 10 endogenous substances and 10 antibiotics. When acceptance criteria were not met, repeat testing was performed in triplicate. (e.g., Table 5 shows overall CA results for endogenous substances ranging from 172-191 total tests, and Table 6 for antibiotics ranging from 6-66 tests.)
- Data Provenance: Contrived positive blood culture samples (contrived in blood culture bottles with human blood added).
Method Comparison Study:
- Sample Size: 567 positive blood culture samples included in performance analysis (out of 578 enrolled). Colony counts were performed on 221 samples of these.
- Data Provenance:
  - 42 (7.4%) prospective clinical samples: Leftover, de-identified. Confirmed by Gram stain (Gram-negative rods) and an FDA-cleared ID method.
  - 515 (90.8%) contrived with stock isolates.
  - 10 (1.8%) contrived with challenge isolates (with known antimicrobial resistance, provided by Avails Medical).

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

The document does not explicitly state the number of experts used or their specific qualifications for establishing ground truth, especially for the method comparison study. However, the ground truth for AST performance (method comparison) was established by comparing eQUANT System results to results generated from a traditional 0.5 McFarland standard prepared from isolated colonies according to CLSI guidelines (CLSI M02-A12). This implies standard laboratory practices using trained personnel, but not necessarily "experts" in the sense of external adjudicators.

4. Adjudication Method for the Test Set

The document does not mention an explicit adjudication method like 2+1 or 3+1. The ground truth for AST results in the method comparison study was based on comparison to a "standard (std) inoculum" prepared according to CLSI guidelines. Any discrepancies would likely have been analyzed by the study team, but an formal adjudication process involving multiple external experts is not described.

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

No, an MRMC comparative effectiveness study was not done. The studies focused on the performance of the device's inoculum preparation and its impact on subsequent in vitro AST results, not on how human readers' diagnostic accuracy improves with or without AI assistance. The eQUANT System is a tool for preparing inoculum for AST, not an AI-assisted diagnostic tool interpreted by human readers.

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

Yes, the primary performance evaluation of the eQUANT System is a standalone (algorithm only) assessment of its ability to produce a 0.5 McFarland equivalent inoculum. The system automatically processes the blood culture sample and its algorithm determines when the target concentration is reached. The downstream Disk Diffusion AST is then performed by laboratory personnel using the eMcFarland generated by the system. The performance metrics (eMcFarland concentration, CA, VME, ME rates) directly reflect the device's accuracy in generating an appropriate inoculum that yields reliable AST results.

7. The Type of Ground Truth Used

For eMcFarland Concentration: The ground truth was colony counts (CFU/mL) obtained by plating the prepared eMcFarlands and enumerating colonies. The target range was 2.51e7 – 7.96e8 CFU/mL, which corresponds to the 0.5 McFarland standard.
For Disk Diffusion AST: The ground truth was the AST results generated from a traditional 0.5 McFarland standard prepared from isolated colonies according to CLSI guidelines (CLSI M02-A12). This serves as the reference standard for categorical interpretations (Susceptible/Intermediate/Resistant - S/I/R) using FDA-recognized breakpoints (Antimicrobial Susceptibility Test Interpretive Criteria/STIC) and CLSI M100.

8. The Sample Size for the Training Set

The document does not explicitly describe a "training set" in the context of machine learning model training. The eQUANT System uses an algorithm based on potentiometric sensing of oxidation-reduction potential changes. While this algorithm would have been developed and optimized, the document focuses on validation studies rather than the specifics of algorithm development data. There's no specific mention of a separate, distinct "training set" for an AI aspect used by the device that would be typically reported alongside a test set. The algorithm uses "species-specific and blood culture bottle-specific algorithms" as inputs to determine the endpoint.

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

As noted above, a distinct "training set" with established ground truth, as defined in a typical AI/ML context, is not explicitly detailed. The fundamental principle of the eQUANT system is to match a 0.5 McFarland equivalent concentration. Therefore, any "training" or development of its algorithms would have involved generating inoculum suspensions and verifying their concentration through methods like direct colony counts (CFU/mL) to ensure the algorithm correlates ORP changes to the desired bacterial density.

Summary

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February 8, 2024

Regulatory Affairs Specialist MDC Associates 180 Cabot Street Beverly, Massachusetts 01915

Re: K231536

Trade/Device Name: eQUANT System Regulation Number: 21 CFR 866.1650 Regulation Name: A Cellular Analysis System For Multiplexed Antimicrobial Susceptibility Testing Regulatory Class: Class II Product Code: OZX, JTN Dated: May 26, 2023 Received: May 30, 2023

Dear Katie Hahnemann:

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.

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).

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Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30, Design controls; 21 CFR 820.90, Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review, the QS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 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 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-safetyreporting-combination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (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.

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-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

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Indications for Use

510(k) Number (if known) K231536

Device Name eQUANT System

Indications for Use (Describe)

The eQUANT System is an automated inoculum preparation system that uses potentiometric sensing of oxidationreduction potential changes due to pathogen metabolism to generate a 0.5 McFarland-equivalent suspension (the eMcFarland or eMcF) from positive blood culture samples that can be used for direct, qualitative in vitro susceptibility testing by the agar disk diffusion test method (Kirby-Bauer). Samples are processed directly from blood culture samples identified as positive by a continuous monitoring blood culture system and confirmed as Gram-negative rods by Gram stain. Organism identification must be confirmed by an FDA cleared device for direct testing from positive blood culture before processing samples on the eQUANT System.

Amoxicillin/clavulanate- Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis

Ampicillin- Escherichia coli

Cefazolin- Klebsiella pneumoniae

Cefepime- Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Ceftriaxone- Citrobacter freundii, Enterobacter cloacae, Escherichia aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens

Ertapenem- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella axytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens

Piperacillin/tazobactam- Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Tobramycin- Citrobacter freundii, Enterobacter cloacae, Escherichia aerogenes, Klebsiella oxytoca,

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Klebsiella pneumoniae, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Type of Use (Select one or both, as applicable)
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X Prescription Use (Part 21 CFR 801 Subpart D)

Over-The-Counter Use (21 CFR 801 Subpart C)

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510(k) Summary

The summary of the 510(k) safety and effectiveness information is being submitted in accordance with the requirements of SMDA 1990 and 21 CFR 807.92.

1. Contact Details

Sponsor: Avails Medical, Inc. 1455 Adams Drive Menlo Park, CA 94025 Correspondent: MDC Associates, Inc. Katie Hahnemann, Ph.D. 48 Dunham Ridge Road, Suite 4000 Beverly, MA 01915 (978) 927-3808 avails@mdcassoc.com

2. Device

Device Trade Name:	eQUANTTM System
Common Name:	eQUANTTM System
Classification Name:	Class II (special controls)
Regulation Number:	866.1650
Device Type:	A cellular analysis system for multiplexed antimicrobial susceptibility testing
Product Code:	QZX, JTN
Predicate Device:	Accelerate Pheno System, Accelerate PhenoTest BC Kit (K192665)

3. Device Description Summary

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The eQUANT™ System processes a single positive blood culture sample at a time. Before processing on the eQUANT™ System, the positive blood culture is confirmed as Gram-negative rods by Gram stain, and a rapid FDA-cleared identification (ID) method for testing from positive blood culture is performed to confirm organism ID. Mixed cultures or organisms identified that are not included in the eQUANT™ System indications for use should not be processed on the eQUANT™ System. Positive blood cultures must be processed immediately on the eQUANT™ System or within 12 hours of blood culture bottle positivity should delays be unavoidable. Once the organism ID is confirmed, 1 mL of eQUANT™ Reagent (cationadjusted Mueller Hinton broth (CAMHB) supplemented with antifoam (0.0015%) to reduce air bubble formation) is added to the eTube™ Disposable, followed by the addition of 34 µL of the positive blood culture. The eTube™ Disposable with diluted sample is vortexed and then placed in the eQUANT™ System for incubation.

4. Intended Use/Indications for Use

Intended Use:

The eQUANT™ System is an automated inoculum preparation system that uses potentiometric sensing of oxidation-reduction potential changes due to pathogen metabolism to generate a 0.5 McFarlandequivalent suspension (the eMcFarland or eMcF) from positive blood culture samples are processed directly from blood culture samples identified as positive by a continuous monitoring blood culture system and confirmed as Gram-negative rods by Gram stain. Organism identification, as determined by an FDA cleared device for direct testing from positive blood culture, must be available before processing samples on the eQUANT™ System.

Indications for Use:

The eQUANT™ System is an automated inoculum preparation system that uses potentiometric sensing of oxidation-reduction potential changes due to pathogen metabolism to generate a 0.5 McFarlandequivalent suspension (the eMcFarland or eMcF) from positive samples that can be used for direct, qualitative in vitro susceptibility testing by the agar disk diffusion test method (Kirby-Bauer). Samples are processed directly from blood culture samples identified as positive by a continuous

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monitoring blood culture system and confirmed as Gram-negative rods by Gram stain. Organism identification must be confirmed by an FDA cleared device for direct testing from positive blood culture before processing samples on the eQUANT™ System.

Evaluation of the eQUANT™ System's inoculum preparation was conducted for use with agar disk diffusion susceptibility testing and performance was demonstrated for the following antimicrobial agents with Enterobacterales species, Acinetobacter species and Pseudomonas aeruginosa as identified below:

Amoxicillin/clavulanate- Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis

Ampicillin- Escherichia coli

Cefazolin- Klebsiella pneumoniae

Cefepime- Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens and Pseudomonas aeruginosa

Ceftriaxone- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens

Ertapenem- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens

Gentamicin- Citrobacter freundii, Enterobacter cloacae, Escherichia aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens and Pseudomonas aeruginosa

Piperacillin/tazobactam- Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

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Tobramycin- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa

Feature	Subject Device	Predicate Device
	Avails Medical, Inc. eQUANT™ SystemK231536	Accelerate PhenoSystem, AcceleratePhenoTest BC Kit K192665
Intended Use	The eQUANT™ System is an automatedinoculum preparation system that usespotentiometric sensing of oxidation-reduction potential changes due topathogen metabolism to generate a 0.5McFarland-equivalent suspension (theeMcFarland or eMcF) from positiveblood culture samples. Samples areprocessed directly from blood culturesamples identified as positive by acontinuous monitoring blood culturesystem and confirmed as Gram-negative rods by Gram stain. Organismidentification, as determined by an FDAcleared device for direct testing frompositive blood culture, must beavailable before processing samples onthe eQUANT™ System.	The Accelerate PhenoTest BC kit is amultiplexed in vitro diagnostic testutilizing both qualitative nucleic acidfluorescence in situ hybridization (FISH)identification and quantitative,antimicrobial susceptibility testing (AST)methods and is intended for use with theAccelerate Pheno system. The AcceleratePhenoTest BC kit is capable ofsimultaneous detection andidentification of multiple microbialtargets followed by susceptibility testingof the appropriate detected bacterialorganisms. The Accelerate PhenoTest BCkit is performed directly on blood culturesamples identified as positive by acontinuous monitoring blood culturesystem. Results are intended to beinterpreted in conjunction with Gramstain results.
Similarities
Antibiotics	Amoxicillin/clavulanateAmpicillinAztreonamCefazolinCefepime	AmikacinAmpicillinAmpicillin/SulbactamAztreonamCeftazidime
Feature	Subject Device	Predicate Device
	Avails Medical, Inc. eQUANT™ System	Accelerate PhenoSystem, Accelerate
	K231536	PhenoTest BC Kit K192665
	CeftriaxoneErtapenemGentamicinLevofloxacinMeropenemPiperacillin/TazobactamTobramycin	CeftarolineCefepimeCeftriaxoneCiprofloxacinDaptomycinErtapenemGentamicinLinezolidMeropenemPiperacillin/TazobactamTobramycinVancomycin
IndicatedOrganisms	Acinetobacter spp.Citrobacter freundiiEnterobacter cloacaeEscherichia coliKlebsiella aerogenesKlebsiella pneumoniaeKlebsiella oxytocaProteus mirabilisProteus vulgarisPseudomonas aeruginosaSerratia marcescens	Gram-negative species:Acinetobacter baumanniiCitrobacter spp.Enterobacter spp.Escherichia coliKlebsiella spp.Proteus spp.Pseudomonas aeruginosaSerratia marcescensAdditional Gram-positive bacteria andyeast are also included on the AcceleratePhenoTest BC kit.
Sample	Positive blood culture aliquot	Positive blood culture aliquot
Differences
Technology	Measure pathogen concentration viapotentiometric sensing of changes inoxidation-reduction potential (ORP)during pathogen metabolism. Usesspecies-specific and blood culture	Microscopy-based, single cell analysis.Identification via fluorescence in situhybridization (FISH); AST via microscopicobservation of individual growingbacterial cells in the presence of
Feature	Subject Device	Predicate Device
Output/ResultsReporting	Avails Medical, Inc. eQUANT™ SystemK231536	Accelerate PhenoSystem, AcceleratePhenoTest BC Kit K192665
	Liquid suspension of bacteria (0.5McFarland equivalent) suitable for DiskDiffusion susceptibility testing; noresult reported	Microbial identification and MIC-basedsusceptibility test results

5. Technology Comparison with the Predicate Device

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antimicrobial agents.

bottle specific algorithms to determine

when a 0.5 McFarland equivalent

concentration is reached.

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Any differences between the subject device and the predicate device shown in the table above do not affect the safety and effectiveness of the subject device.

6. Performance Characteristics

Reproducibility

The Reproducibility Study was performed to demonstrate that the eQUANT™ System reproducibly prepares an 0.5 McFarland equivalent inoculum, the eMcFarland, at an organism concentration of 2.51e7 – 7.96e8 CFU/mL from a positive blood culture (PBC). The reproducibility of the eQUANT™ System was assessed across sites (one internal and two external), operators (6), instruments (12), and consumable lots. A panel of six (6) organisms was contrived in blood culture bottles with human blood added and incubated on a blood culture monitoring system until positivity. From each positive blood culture, eQUANT™ System testing was performed in duplicate by two (2) operators at each site for a total of four (4) eMcFarlands per PBC. The resulting eMcFarlands were plated to confirm colony counts met the defined concentration specifications. Due to agreement below defined acceptance criteria (≥95%) for A. boumannii in initial testing (93.1%), an additional 30 replicates were tested at the internal site (5 days x 3 replicates x 2 operators). All repeat testing passed. Final overall agreement based on eMcFarland concentration across sites, operators, runs, instruments, and lots was 98.9%, demonstrating that the eQUANT™ System prepares a 0.5 McFarland equivalent inoculum with a high degree of reproducibility (see Table 1 below).

Organism	Isolate ID	Agreement
Escherichia coli	ATCC 25922	72/72 (100%)
Pseudomonas aeruginosa	ATCC 27853	72/72 (100%)
Klebsiella pneumoniae	ATCC 700603	72/72 (100%)
Acinetobacter baumannii	ATCC 19606	97/102 (95.1%)
Proteus vulgaris	ATCC 6380	72/72 (100%)
Serratia marcescens	ATCC 14756	72/72 (100%)
Total		457/462 (98.9%)

Table 1. eQUANT™ System Reproducibility Results Summary
---------------------------------------------------------	--	--	--

Sample Stability

The Sample Stability Study was performed to determine the stability of positive samples when testing on the eQUANT™ System and to establish the stability of the eQUANT™ System generated eMcFarland. A panel of five (5) organisms was contrived in blood culture bottles with human blood added

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and incubated on a blood culture monitoring system until positive blood culture bottles were held for different lengths of time either on the blood culture instrument (35°C) or on the benchtop (room temperature) until processing on the eQUANT™ System. From the T0 bottles, the resulting eMcFarlands were held for one (1) hour on the eQUANT™ Instrument at 15°C, then removed and plated to confirm colony counts. Additionally, colony count plates were prepared at various timepoints (up to 30 minutes) after removal from the eQUANT™ Instrument when stored at room temperature. All conditions were tested in triplicate. A sample was considered stable if the eMcFarland concentration met the defined acceptance criteria of 2.51e7 – 7.96e8 CFU/mL. All eMcFarland colony counts met defined acceptance criteria, supporting that positive blood culture bottles are stable for use on the eQUANT™ System for up to 12 hours (Table 2). eQUANT™ System generated eMcFarlands are stable for up to one (1) hour on the eQUANT™ Instrument, held at 15°C, and for up to 10 minutes after removal, held at room temperature (Table 3).

Organism	PBC StorageCondition	Time Point(hours)	Average eMcFarlandConcentration after 1 hour holdat 15°C(CFU/mL)
E. coli	RT	TO	1.04 x 108
E. coli	RT	T12	1.19 x 108
E. coli	RT	T14	1.09 x 108
E. coli	35°C	TO	9.80 x 107
E. coli	35°C	T12	1.09 x 108
E. coli	35°C	T14	1.00 x 108
E. cloacae	RT	TO	1.71 x 108
E. cloacae	RT	T12	1.38 x 108
E. cloacae	RT	T14	1.59 x 108
E. cloacae	35°C	TO	1.71 x 108
E. cloacae	35°C	T12	1.77 x 108
E. cloacae	35°C	T14	1.79 x 108
S. marcescens	RT	TO	1.83 x 108
S. marcescens	RT	T12	1.92 x 108
S. marcescens	RT	T14	2.14 x 108
S. marcescens	35°C	TO	1.71 x 108
S. marcescens	35°C	T12	1.83 x 108
S. marcescens	35°C	T14	1.90 x 108
P. aeruginosa	RT	TO	8.76 x 107
P. aeruginosa	RT	T12	8.89 x 107
P. aeruginosa	RT	T14	9.14 x 107
P. aeruginosa	35°C	TO	8.92 x 107
P. aeruginosa	35°C	T12	9.61 x 107
P. aeruginosa	35°C	T14	9.27 x 107

Table 2. eQUANT™ System PBC Stability Results

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Organism	PBC StorageCondition	Time Point(hours)	Average eMcFarlandConcentration after 1 hour holdat 15°C(CFU/mL)
A. baumannii	RT	T0	$8.82 x 10^7$
A. baumannii	RT	T12	$9.06 x 10^7$
A. baumannii	RT	T14	$8.05 x 10^7$
A. baumannii	35°C	T0	$1.32 x 10^8$
A. baumannii	35°C	T12	$8.62 x 10^7$
A. baumannii	35°C	T14	$8.76 x 10^7$

Table 3. eQUANT™ System eMcFarland Stability Results

Organism	Avg. eMcFConcentrationafter 0 minhold(CFU/mL)	Avg. eMcFConcentrationafter 5 minhold(CFU/mL)	Avg. eMcFConcentrationafter 10 minhold(CFU/mL)	Avg. eMcFConcentrationafter 15 minhold(CFU/mL)	Avg. eMcFConcentrationafter 20 minhold(CFU/mL)	Avg. eMcFConcentrationafter 30 minhold(CFU/mL)
E. coli	1.01 × 108	1.06 × 108	1.02 × 108	1.06 × 108	1.08 × 108	1.24 × 108
E. cloacae	1.71 × 108	1.69 × 108	1.79 × 108	1.90 × 108	1.99 × 108	2.24 × 108
S. marcescens	1.77 × 108	1.80 × 108	1.90 × 108	1.94 × 108	2.12 × 108	2.14 × 108
P. aeruginosa	8.84 × 107	9.28 × 107	1.09 × 108	9.57 × 107	1.02 × 108	9.33 × 107
A. baumannii	1.10 × 108	1.48 × 108	1.33 × 108	1.60 × 108	1.80 × 108	1.33 × 108

Blood Culture Bottle Equivalency

The Blood Culture Bottle Equivalency Study was performed to demonstrate that the eQUANT™ System generates a standardized inoculum, the eMcFarland, meeting the defined concentration specifications, from a variety of blood culture bottle media types (Table 4). A panel of eight (8) organisms was contrived into various bioMérieux BACT/ALERT® and BD BACTEC™ blood culture bottle types with human blood added and incubated on the respective blood culture monitoring system until positivity. Each organism/blood culture bottle type was tested in triplicate on the eQUANT™ System within 12 hours of positivity, and the resulting eMcFarlands were plated to confirm colony counts met defined concentration specifications. The concentrations of all eMcFarlands for all organisms and bottle types evaluated met defined acceptance criteria (2.51e7 – 7.96e8 CFU/mL).

The eMcFarlands were also used for downstream Disk Diffusion AST testing, and results were compared to results generated from a standard 0.5 McFarland inoculum prepared from isolated colonies (Table 4). For A. baumannii, disk diffusion was performed and expected AST results (>95% CA) were obtained for all bottle types assessed. For P. aeruginosa, disk diffusion was performed and >95% CA was obtained for all bottle types except BD BACTEC Aero Plus, which demonstrated performance of 90.5% CA with two minor errors with levofloxacin. However, the two minor error eQUANT™ zone diameters were less than 3 mm difference when compared to the zone diameters obtained by the standard method, which was considered acceptable. For Enterobacterales, >95% CA was only obtained for the bottle type BACT/ALERT

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SN; the remaining CA performance was 90-93% CA. The minor errors were spread across all bottle types. The zone diameter of the majority (60/64 = 93.8%) of the error results were ≤3 mm compared to the standard method zone diameter, which was considered acceptable. In addition, 63/64 of the minor errors were due to a single isolate of K. pneumoniae with minor errors detected across bottle types and among 6 of the 12 tested drugs (i.e., levofloxacin, piperacillin/tazobactam, cefepime, gentamicin, tobramycin). These results demonstrate that all blood culture bottle types evaluated are suitable for use with the eQUANT™ System.

Org. Group	Bottle System	Bottle Type	Total	CA #	CA %	VME	mE
Enterobacteralesa	BD BACTEC	Aero Plus	96	87	90.6*	0	9
		STD AERO	96	88	91.7*	0	8
		STD ANA	96	89	91.7*	0	7
		LYTIC	96	89	92.7*	0	7
		ANA PLUS	96	88	91.7*	0	8
	BACT/ALERT	SA	96	89	92.7*	0	7
		FA	96	89	92.7*	0	7
		FN	96	88	91.7*	0	8
		SN	96	93	96.9	0	3
P. aeruginosab	BD BACTEC	Aero Plus	21	19	90.5*	0	2
		STD AERO	21	20	95.2	0	1
	BACT/ALERT	SA	21	21	100	0	0
		FA	21	20	95.2	0	1
A. baumanniic	BD BACTEC	Aero Plus	24	24	100	0	0
		STD AERO	24	24	100	0	0
		BACT/ALERT	SA	24	24	100	0
			FA	24	24	100	0

Table 4. Compatibility of the eQUANT™ System with Different Blood Culture Bottle Types

ªDisk diffusion results with amoxicillin/clavulanate, ampicillin, aztreonam, cefazolin, ceferiaxone, ertapenem, gentamicin, levofloxacin, meropenem, piperacillin/tazobactam, and tobramycin

ণDisk diffusion results with aztreonam, cefepime, gentamicin, levofloxacin, meropenem, piperacillin/tazobactam and tobramycin

°Meropenem and piperacillin/tazobactam disk diffusion results

*<95% CA due to minor errors of which the majority were from eQUANT™ zone diameters that were ≤3mm difference compared to the zone diameters obtained by the standard method

Interfering Substances

The Interfering Substances Study was performed to determine if the eQUANT™ System generates a standard inoculum (eMcFarland) suitable for downstream AST testing in the presence of substances commonly found in positive blood cultures. A panel of nine (9) organisms was contrived into blood culture bottles with and without potential interferents at high concentrations, including endogenous substances, exogenous substances, and a representative antibiotic from each of the main classes of antibiotics that target Gram-negative organisms (Tables 5-6). Antibiotic interferents were tested on one (1) test isolate resistant to the test interferent to allow for growth in the PBC. Contrived blood culture bottles were

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incubated on a blood culture monitoring system until positivity and tested on the eQUANT™ System within 12 hours. The resulting eMcFarlands were plated to confirm colony counts met defined concentration specifications and were also used for downstream Disk Diffusion AST testing. Results from eMcFarlands prepared from positive blood culture bottles containing interferents were compared to results from eMcFarlands prepared from PBCs without interferents. When acceptance criteria were not met, repeat testing was performed in triplicate. All resulting eMcFarland concentrations met defined acceptance criteria (2.51e7 – 7.96e8 CFU/mL). No reproducible interference was observed in downstream AST testing. High concentrations of two substances, hemoglobin (A. baumannii, P. aeruginosa) and platelets (P. aeruginosa), resulted in aborted eQUANT™ System runs due to aeration blockage errors detected by the instrument. At decreased interferent concentrations, valid eMcFarlands were successfully generated and AST results were as expected.

Interferent	Concentration	Overall CA
Conjugated Bilirubin	475 μmol/L	97.8%(176/180)
Gamma Globulin*	50 mg/mL	100%(177/177)
Hemoglobin*	20 g/dL (Enterobacterales)2 g/dL – 8 g/dL ( A. baumannii and P. aeruginosa )	98.9%(175/177)
Hematocrit*	50%	97.2%(172/177)
Heparin	3 units/mL	98.3%(174/177)
Platelets	1,000,000/μL900,000/μL ( P. aeruginosa )	100%(191/191)
Sodium Polyanetholesulfonate (SPS)	0.1% w/v	99.4%(176/177)
Triglycerides	37 mmol/L	97.7%(173/177)
Unconjugated Bilirubin	684 μmol/L	98.3%(174/177)
WBCs (Buffy Coat)*	12,000/μL	100%(177/177)

	Table 5. eQUANT TM System Interfering Substances Disk Diffusion Results
--	-------------------------------------------------------------------------	--

*Endogenous substances added directly into the eTube as acceptable interferent concentrations in the blood culture bottle were not achieved.

Interferent	Drug Class	Concentration	Overall CA
Ampicillin	Penicillins	75 µg/mL	95.2% (63/66)
Cefazolin	1st generation Cephalosporins	1201 µg/mL	100% (33/33)
Cefepime	4th generation Cephalosporins	492 µg/mL	100% (36/36)
Ceftriaxone	3rd generation Cephalosporins	837 µg/mL	100% (36/36)

Table 6. eQUANT™ System Interfering Antibiotics Disk Diffusion Results

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Chloramphenicol	Macrolides	78 µg/mL	90.9%1 (33/36)
Ciprofloxacin	Fluroquinolones	1.2 µg/mL	100% (36/36)
Gentamicin	Aminoglycosides	3 µg/mL	100% (6/6)
Piperacillin/Tazobactam	Beta-lactam combination agents	1100/31 µg/mL	100% (36/36)
Tetracycline	Tetracyclines	2.4 µg/mL	100% (27/27)
Trimethoprim/Sulfamethoxazole	Sulfonamides	41/405 µg/mL	100% (33/33)

1 Acceptable performance since 3/3 minor errors ≤ 3 mm difference in zone diameter when compared to the control replicate (i.e., no potential interferent).

Carryover

The Carryover Study was performed to demonstrate that no bacterial carryover occurs between runs on the eQUANT™ System. Two organisms with distinct morphologies, E. coli and P. aeruginosa, were contrived into blood culture bottles with human blood added and incubated on a blood culture system until positivity. The resulting positive blood cultures were run on the same eQUANT™ System within 12 hours of positivity in an alternating pattern for a total of three (3) runs per species. The resulting eMcFarlands were subcultured to ensure no carryover occurred between runs. No carryover was observed, as evidenced by monomicrobial cultures and the expected organism morphology.

Method Comparison

A method comparison study was performed to evaluate the performance of the eQUANT™ System in preparing a 0.5 McFarland equivalent inoculum (eMcFarland) from positive blood cultures containing Gram-negative bacteria for use in downstream Disk Diffusion AST testing. Performance was based on eQUANT™ System-generated eMcFarland concentrations meeting defined specifications (2.51e7 – 7.96e8 CFU/mL) and on AST results (categorical interpretations and error rates) generated from the eMcFarland as compared to AST results generated from a traditional 0.5 McFarland standard prepared from isolated colonies.

Samples were enrolled and tested at three (3) US clinical sites and one (1) internal site. Samples enrolled in the study included leftover, deidentified clinical positive samples (prospective) and contrived positive blood culture samples, contrived with either stock or challenge isolates. Prior to enrollment, prospective positive blood culture samples were confirmed by Gram strain Gramnegative rods followed by organism identification (ID) using an ID method FDA-cleared for use with positive blood cultures. Polymicrobial samples or those identified as containing species not supported by the eQUANT™ System were not eligible for enrollment. Contrived stock isolates were provided by the clinical site or Avails Medical and contrived challenge isolates with known antimicrobial resistance were provided by Avails Medical. All positive blood cultures were processed on the eQUANT™ System within 12 hours of positivity.

For comparative testing, the positive blood culture sample was subcultured overnight, and isolated colonies were used to prepare a standard 0.5 McFarland equivalent inoculum for Disk Diffusion testing

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according to CLSI guidelines (CLSI M02-A12). For eQUANT™ System testing, 34 µL of the positive blood culture sample was diluted into 1 mL of eQUANT™ Reagent in the eTube Disposable and processed on the eQUANT™ System according to Instructions for Use. After the run was successfully completed, the resulting eMcFarland was used to prepare colony count plates for select samples and for direct Disk Diffusion testing for all samples.

Performance of the eQUANT™ System was based on both eMcFarland concentrations and on Disk Diffusion AST results. eMcFarland concentrations were assessed based on the defined concentration range of 2.51e7 – 7.96e8 CFU/mL. AST performance was assessed by comparing the results generated from the eMcFarland inoculum to results generated from the standard (std) inoculum. Agreement and acceptance criteria were defined based on FDA guidance. The primary endpoints were Categorical Agreement (CA) and error rates (Very Major Error (ME) and Minor Error (ME) and Minor Error (MIN)) for antimicrobial agent (≥95% CA, ≤1% VME, ≤1.5% ME). Categorical agreement each (Susceptible/Intermediate/Resistant, S/I/R) was assessed using FDA-recognized breakpoints (Antimicrobial Susceptibility Test Interpretive Criteria/STIC) and CLSI M100, when applicable.

A total of 578 positive blood culture sampled in the study with 567 (98.1%) included in performance analysis. Eleven (11) samples were excluded for the following reasons: not meeting eQUANT™ System stability requirements for testing (4), non-target organism (2), eQUANT™ runtime exceeded (2), polymicrobial sample (1), insufficient growth (1), or sample mix-up (1).

Of the 567 samples included in clinical performance analysis, 42 were prospective blood cultures (7.4%), 515 were contrived with stock isolates (90.8%) and 10 were contrived with challenge isolates (1.8%). There was broad representation of the organisms that can be processed on the eQUANT™ System. These included 41 Acinetobacter spp., 41 Citrobacter spp., 45 Enterobacter spp., 45 Enterobacter cloacae, 182 Escherichia coli, 43 Klebsiella aerogenes, 19 Klebsiella pneumoniae, 52 Proteus mirabilis, 18 Proteus vulgaris, 1 Proteus spp., 41 Serratia marcescens, and 41 Pseudomonas aeruginosa.

Of the 567 samples included in clinical performance analysis, colony counts were performed on 221 samples. eMcFarland colony counts from eQUANT™ System samples were within the expected colony count range of 2.51e7 to 7.96e8 CFU/mL for 99.1% of PBC samples and therefore met the acceptance criteria for overall samples of ≥95% (Table 8). The two (2) samples outside the expected colony count range were one (1) contrived Acinetobacter spp. and one (1) contrived P. aeruginosa sample. For these two (2) samples, there were no errors observed with Disk Diffusion results.

*Target range is between 2.51e7 and 7.96e8 CFU/mL; colony counts were not performed on all samples enrolled
	eMcFarland Colony Counts# in Expected Range/Total (%)
Organism Group	Site #1	Site #2	Site #3	Site #4	Overall
Enterobacterales	50/50	36/36	25/25	54/54	165/165

Table 8. eQUANT™ System Colony Count Performance (All Sites)

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	(100.0)	(100.0)	(100.0)	(100.0)	(100.0)
Acinetobacter spp.	7/8(87.5)	8/8(100.0)	3/3(100.0)	6/6(100.0)	24/25(96.0)
P. aeruginosa	4/4(100.0)	12/13(92.3)	8/8(100.0)	6/6(100.0)	30/31(96.8)
Total	61/62(98.4)	56/57(98.2)	36/36(100.0)	66/66(100.0)	219/221(99.1)

Qualitative AST performance for Disk Diffusion was assessed with 12 antimicrobials and overall performance is summarized in Table 9, below. All antibiotic/group combinations met overall acceptance criteria of ≥95% CA with the following exceptions: amoxicillin_clavulanate/Enterobacterales, cefazolin/Enterobacterales, cefepime/Enterobacterales, and piperacillin_tazobacterales. One combination did not meet acceptance criteria for %VME, gentamicin/Enterobacterales, and one combination did not meet acceptance criteria for %ME, cefepime/Pseudomonas aeruginosa. The following combinations were removed from the eQUANT™ System Indications for Use based on performance <90% CA: cefazolin/Escherichia coli, cefazolin/Proteus mirabilis, cefepime/Citrobacter freundii, and cefepime/Klebsiella aerogenes. Limitations are included in product labeling, as appropriate.

Antimicrobial Agent	Organism Group	N	Std S	Std I	Std R	Total CA	CA	% CA	VMJ	MAJ	MIN
Amoxicillin/Clavulanate	Enterobacterales	223	150	13	60	223	210	94%1	0 (0.00%)	1 (0.67%)	12(5.38%)
Ampicillin	Enterobacterales	33	9	1	23	33	33	100%	0 (0.00%)	0 (0.00%)	0(0.00%)
Aztreonam	Enterobacterales	189	141	3	45	189	183	97%	0 (0.00%)	1 (0.71%)	5(2.65%)
	Pseudomonas aeruginosa	25	10	4	11	25	24	96%	0 (0.00%)	0 (0.00%)	1(4.00%)
Cefazolin	Enterobacterales2	213	71	44	98	213	181	85%1	0 (0.00%)	1 (1.41%)	31(14.55%)
Cefepime	Enterobacterales3	237	162	33	42	237	218	92%1	0 (0.00%)	1 (0.62%)	18(7.59%)
	Pseudomonas aeruginosa	41	21	0	20	41	39	95%	0 (0.00%)	24 (9.52%)	0(0.00%)
Ceftriaxone	Enterobacterales	223	134	5	84	223	216	97%	0 (0.00%)	25 (1.49%)	5(2.24%)
Ertapenem	Enterobacterales	187	153	5	29	187	183	98%	0 (0.00%)	0 (0.00%)	4(2.14%)
Gentamicin	Enterobacterales	255	226	3	26	255	248	97%	1 (3.85%)	1 (0.44%)	5(1.96%)
	Pseudomonas aeruginosa	41	23	1	17	41	39	95%	0 (0.00%)	0 (0.00%)	2(4.88%)
Levofloxacin	Enterobacterales	206	146	11	49	206	198	96%	0 (0.00%)	0 (0.00%)	8(3.88%)
	Pseudomonas aeruginosa	25	8	6	11	25	24	96%	0 (0.00%)	0 (0.00%)	1(4.00%)
Meropenem	Acinetobacter spp.	16	6	1	9	16	16	100%	0 (0.00%)	0 (0.00%)	0(0.00%)
	Enterobacterales	206	180	3	23	206	200	97%	0 (0.00%)	26 (1.11%)	4(1.94%)
	Pseudomonas aeruginosa	25	8	0	17	25	25	100%	0 (0.00%)	0 (0.00%)	0(0.00%)

		Table 9. eQUANT™ System Disk Diffusion Performance Summary by Antimicrobial - All Sites, All Samples
--	--	------------------------------------------------------------------------------------------------------	--	--

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Antimicrobial Agent	Organism Group	N	Std S	Std I	Std R	Total CA	CA	% CA	VMJ	MAJ	MIN
Piperacillin/Tazobactam	Acinetobacter spp.	41	16	0	25	41	39	95%	0 (0.00%)	0 (0.00%)	2(4.88%)
	Enterobacterales	239	166	27	46	239	225	94%1	0 (0.00%)	0 (0.00%)	14(5.86%)
	Pseudomonas aeruginosa	25	14	2	9	25	24	96%	0 (0.00%)	0 (0.00%)	1(4.00%)
Tobramycin	Enterobacterales	203	164	6	33	203	196	97%	0 (0.00%)	0 (0.00%)	7(3.45%)
	Pseudomonas aeruginosa	25	16	1	8	25	25	100%	0 (0.00%)	0 (0.00%)	0(0.00%)

1 Categorical agreement was 90-95% due to minor errors for the following drug/organism combinations and considered acceptable since the eQUANT™ zone diameters of a significant number of the errors were ≤3 mm difference compared to the standard disk diffusion zone diameters:

Amoxiciliin/Clavulanate: Escherichia coli, Proteus mirabilis; Cefazolin: Klebsiella pneumoniae; Cefepime: Enterobacter clocce, Klebsiella oxytoca, Proteus mirabilis; Ceftriaxone: Klebsiella aerogenes, Proteus mirabilis; Piperacillin/Tazobactam: Escherichia coli.

2 Two combinations are removed from product labeling due to %CA <90%: cefazolin/E. coli and cefazolin/P. mirabilis.

3 Two combinations are removed from product labeling due to %CA <90%: cefepime/C. freundii and cefepime/K. aerogenes.

4The major error rate was ≥1.5% and considered acceptable since the eQUANT™ zone diameters for the major errors were ≤3 mm difference compared to the standard disk diffusion zone diameters.

් A single major error was observed for the following drug/organism combinations which may be due to eQUANT™ zone diameters tending to be smaller than the standard disk diffusion zone diameters: Ceftriaxone/Klebsiella aerogenes, Proteus mirabilis.

6 The categorical agreement was ≥95% for the following drug/organism combination; however, a single major error was observed which may be due to eQUANT™ zone diameters tending to be smaller than the standard disk diffusion zone diameters: Meropenem/Serratia marcescens.

7. Conclusion

The conclusions drawn from the nonclinical and clinical tests demonstrate that the device is as safe, as effective, and performs as well as or better than the legally marketed predicate device (807.92(b)(3)).

Regulation Number and Section

§ 866.1650 A cellular analysis system for multiplexed antimicrobial susceptibility testing.

(a)
Identification. A cellular analysis system for multiplexed antimicrobial susceptibility testing is a multiplex qualitative and/or quantitative in vitro diagnostic device intended for the identification and determination of the antimicrobial susceptibility results of organisms detected in samples from patients with suspected microbial infections. This device is intended to aid in the determination of antimicrobial susceptibility or resistance when used in conjunction with other laboratory findings.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Design verification and validation must include:
(i) Detailed device description documentation, including the device components, ancillary reagents required but not provided, a detailed explanation of the methodology, including primer/probe sequence, design, rationale for sequence selection, and details of the antimicrobial agents, as applicable.
(ii) Detailed documentation from the following analytical and clinical performance studies: limit of detection, inclusivity, precision, reproducibility, interference, cross-reactivity, carryover, and cross-contamination, quality control and additional studies, as applicable to specimen type and assay intended use.
(iii) Detailed documentation from an appropriate clinical study. The study, performed on a study population consistent with the intended use population, must compare the device performance to results obtained from well-accepted reference methods.
(iv) Detailed documentation for device software, including software applications and hardware-based devices that incorporate software.
(2) The labeling required under § 809.10(b) of this chapter must include:
(i) Limitations and protocols regarding the need for correlation of results by standard laboratory procedures, as applicable.
(ii) A detailed explanation of the interpretation of results and acceptance criteria.
(iii) A detailed explanation of the principles of operation and procedures for assay performance and troubleshooting.