The Sensititre 18-24 hour MIC or Breakpoint Susceptibility System with Moxifloxacin in the dilution range of 0.008-16 ug/mL

K242658 · Thermo Fisher Scientific · JWY · Apr 15, 2025 · Microbiology

Device Facts

• Record ID: K242658
• Device Name: The Sensititre 18-24 hour MIC or Breakpoint Susceptibility System with Moxifloxacin in the dilution range of 0.008-16 ug/mL
• Applicant: Thermo Fisher Scientific
• Product Code: JWY · Microbiology
• Decision Date: Apr 15, 2025
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.1640
• Device Class: Class 2
• Attributes: PCCP

Indications for Use

The Sensititre MIC and Breakpoint Susceptibility system is an in vitro diagnostic product for clinical susceptibility testing of non-fastidious Gram negative isolates, comprising of Enterobacteriaceae, Pseudomonas aeruginosa, and other non-Enterobacteriaceae and of non-fastidious Gram positive isolates, comprising of Staphylococcus spp., Enterococcus spp., and beta-hemolytic Streptococci other than S. pneumoniae.

Device Story

Sensititre 18-24 hour MIC or Breakpoint Susceptibility System performs in vitro antimicrobial susceptibility testing. Device utilizes microbroth dilution method to determine Minimum Inhibitory Concentrations (MIC) or breakpoint results for moxifloxacin against non-fastidious gram-positive bacteria. System intended for use in clinical laboratory settings by trained personnel. Output provides quantitative MIC values or qualitative breakpoint interpretations, assisting clinicians in selecting appropriate antimicrobial therapy for patients with bacterial infections. System includes Predetermined Change Control Plan (PCCP) for future modifications.

Clinical Evidence

Performance evaluated using 546 clinical and 144 challenge gram-positive isolates (Staphylococcus spp. and E. faecalis). Comparison against CLSI broth microdilution reference method. For Staphylococcus spp. (ARIS HiQ/OptiRead), EA was 96.0% and CA was 93.6%. For E. faecalis (ARIS HiQ/OptiRead), combined clinical/challenge/supplemental data showed EA 97.8% and CA 99.3%. Vizion read method showed similar performance. Trending toward higher MIC values was noted for several species and addressed in labeling. No clinical sensitivity/specificity data provided as this is an AST device.

Technological Characteristics

Microbroth dilution susceptibility testing system. Dilution range: 0.008-16 μg/mL. Designed for non-fastidious gram-positive organisms. Operates as an in vitro diagnostic system.

Indications for Use

Indicated for clinical susceptibility testing of non-fastidious gram-positive isolates, specifically Staphylococcus spp. (S. aureus, S. epidermidis, S. haemolyticus, S. hominis, S. lugdunensis, S. saprophyticus) and Enterococcus faecalis, using moxifloxacin (0.008-16 μg/mL). Prescription use only.

Regulatory Classification

Identification

An antimicrobial susceptibility test powder is a device that consists of an antimicrobial drug powder packaged in vials in specified amounts and intended for use in clinical laboratories for determining in vitro susceptibility of bacterial pathogens to these therapeutic agents. Test results are used to determine the antimicrobial agent of choice in the treatment of bacterial diseases.

Submission Summary (Full Text)

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FDA U.S. FOOD & DRUG ADMINISTRATION

# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY

ASSAY ONLY

## I Background Information:

A 510(k) Number

K242658

B Applicant

Thermo Fisher Scientific

C Proprietary and Established Names

The Sensititre 18-24 hour MIC or Breakpoint Susceptibility System with Moxifloxacin in the dilution range of 0.008-16 µg/mL

D Regulatory Information

| Product Code(s) | Classification | Regulation Section | Panel |
| --- | --- | --- | --- |
| JWY | Class II | 21 CFR 866.1640 - Antimicrobial Susceptibility Test Powder | MI - Microbiology |
| LRG | Class II | 21 CFR 866.1640 - Antimicrobial susceptibility test powder | MI - Microbiology |
| LTT | Class II | 21 CFR 866.1640 - Antimicrobial susceptibility test powder | MI - Microbiology |

## II Submission/Device Overview:

### A Purpose for Submission:

To obtain substantial equivalence determination for The Sensititre 18-24 hour MIC or Breakpoint Susceptibility System with Moxifloxacin in the dilution range of 0.008-16 µg/mL with updated FDA-recognized breakpoints for Staphylococcus spp. and expand claims to include additional Staphylococcus species and E. faecalis.

### B Measurand:

Moxifloxacin in the dilution range of 0.008 to 16 µg/mL

Food and Drug Administration

10903 New Hampshire Avenue

Silver Spring, MD 20993-0002

www.fda.gov

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C Type of Test:

Quantitative Antimicrobial Susceptibility Test (AST) growth-based detection

III Intended Use/Indications for Use:

A Intended Use(s):

The Sensititre MIC and Breakpoint Susceptibility system is an in vitro diagnostic product for clinical susceptibility testing of non-fastidious Gram negative isolates, comprising of Enterobacteriaceae, Pseudomonas aeruginosa, and other non-Enterobacteriaceae and of non-fastidious Gram positive isolates, comprising of Staphylococcus spp., Enterococcus spp., and beta-hemolytic Streptococci other than S. pneumoniae.

B Indication(s) for Use:

The Sensititre 18-24 hour MIC or Breakpoint Susceptibility System is an in vitro diagnostic product for clinical susceptibility testing of non-fastidious isolates.

This 510(k) is for moxifloxacin in the dilution range of 0.008-16 µg/mL for testing non-fastidious gram-positive isolates on The Sensititre 18-24 hour MIC or Breakpoint Susceptibility System. Testing is indicated for Staphylococcus spp. and Enterococcus faecalis, as recognized by the FDA Susceptibility Test Interpretive Criteria (STIC) webpage.

The Sensititre 18-24 hour MIC or Breakpoint Susceptibility System with Moxifloxacin in the dilution range of 0.008-16 µg/mL demonstrated acceptable performance with the following organisms:

Staphylococcus spp. (S. aureus, S. epidermidis, S. haemolyticus, S. hominis, S. lugdunensis, and S. saprophyticus)

Enterococcus faecalis

C Special Conditions for Use Statement(s):

Rx - For Prescription Use Only

The following limitation was applied to moxifloxacin testing in the appropriate sections of the device labeling that reference other drugs:

Studies of the following drugs were performed with the AIM Autoinoculator and read using the ARIS HiQ/OptiRead and Vizion. The use of an alternative inoculation system or alternative read methods has not been evaluated.

Due to the insufficient number of resistant S. lugdunensis and S. saprophyticus isolates evaluated, the following limitation was applied to moxifloxacin testing in the appropriate section of the device labeling that references other drugs:

The ability of the Sensititre system to detect resistance or non-susceptibility to antimicrobials as shown below is unknown because an insufficient number of resistant or non-susceptible strains were available at the time of comparative testing. If such a strain is observed, it should be submitted to a reference laboratory.

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## D Special Instrument Requirements:

- Sensititre AIM for device inoculation
- Sensititre Vizion digital plate reader/viewer
- Sensititre ARIS HiQ/OptiRead automated plate reader

## IV Device/System Characteristics:

### A Device Description:

The Sensititre 18-24 hour MIC or Breakpoint Susceptibility Plate System is an antimicrobial susceptibility test. Each plate is dosed with dried, stabilized antimicrobial agents at appropriate dilutions. It is a micro-version of the classic broth dilution method and can provide both qualitative and quantitative susceptibility results. After inoculation, plates are sealed with an adhesive seal, incubated at $34 - 36^{\circ}\mathrm{C}$ for 18-24 hours and examined for bacterial growth.

### B Principle of Operation:

The Sensititre 18-24 hour MIC Susceptibility plates are multi-well plastic microtiter plates that contain doubled dilutions of antibacterial agents. Each plate includes antimicrobial agents at appropriate dilutions. Results can be read using the digital viewing device (Vizion) or by use of an automated plate reader (ARIS HiQ/OptiRead).

The Sensititre Vizion digital viewing device allows the panel image to be displayed on a touch screen directly from a video camera and allows the user to visually determine MIC results. The Sensititre OptiRead utilizes fluorescence technology to read the microbroth dilution plates after 18 to 24 hours incubation. The technology involves the detection of bacterial growth by monitoring the activity of specific surface enzymes produced by the test organism. Growth is determined by generating a fluorescent product from a fluorogenic substrate. The non-fluorescent substrate is prepared by conjugating a fluorescent compound to the specific enzyme substrates with a bond which prevents fluorescence. The enzymatic action of the bacterial surface enzymes on the bound non-fluorescent substrate cleaves the bond releasing fluorescence. The amount of fluorescence detected is directly related to the activity of bacterial growth. The MIC is determined by observing the lowest dilution of antimicrobial agent that inhibits growth of the organism. The non-fluorescent (fluorogenic) substrate can be added to the inoculum broth which is dispensed into the test plate at the same time as the test organism, or the plates can be prepared with the substrate already added to each micro-well.

Sensititre 18-24 hour MIC plates can either be read automatically on an ARIS HiQ/OptiRead using fluorescence or by visual reading of growth on the Vizion digital viewing device.

### V Substantial Equivalence Information:

### A Predicate Device Name(s):

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The Sensititre 18-24 Hour MIC or Breakpoint Susceptibility System with Lefamulin in the dilution range of 0.008-16 µg/mL

B Predicate 510(k) Number(s): K192729

C Comparison with Predicate(s):

| Device & Predicate Device(s): | Device: K242658 | Predicate: K192729 |
| --- | --- | --- |
| Device Trade Name | The Sensititre 18-24 Hour MIC or Breakpoint Susceptibility System with Moxifloxacin in the dilution range of 0.008-16 µg/mL | The Sensititre 18-24 Hour MIC or Breakpoint Susceptibility System with Lefamulin in the dilution range of 0.008-16 µg/mL |
| General Device Characteristic Similarities | | |
| Intended Use | The Sensititre 18-24 Hour MIC or Breakpoint Susceptibility System is an in vitro diagnostic product for clinical susceptibility testing of non-fastidious bacterial isolates. | Same |
| Test Panel | Each 96 well plate is precision dosed with selected antimicrobial agents and substrate for the fluorescent reads, then dried. The bacterial suspension in the appropriate broth is used to rehydrate the plate. | Same |
| Incubation | 18-24 hours | Same |
| Read Method | Results can be read using fluorescence with the ARIS HiQ/OptiRead or by visual reading of growth with the Vizion. | Same |
| General Device Characteristic Differences | | |
| Antibiotic and Dilution Range | Moxifloxacin 0.008-16 µg/mL | Lefamulin 0.008-16 µg/mL |
| Test Organisms | Staphylococcus spp. E. faecalis | Staphylococcus aureus (methicillin-susceptible isolates) |

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VI Standards/Guidance Documents Referenced:

CLSI M07, "Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard - Eleventh Edition", (January 2018)

CLSI M100, "Performance Standards for Antimicrobial Susceptibility Testing; 33rd Edition", (March 2023)

Guidance for Industry and FDA: Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems, August 28, 2009

VII Performance Characteristics (if/when applicable):

A Analytical Performance:

1. Precision/Reproducibility:

A reproducibility study of The Sensititre 18-24 hour MIC or Breakpoint Susceptibility System with Moxifloxacin was performed at three sites using a panel of thirteen (13) gram-positive isolates from indicated species (4 Staphylococcus aureus (MSSA), 4 Staphylococcus aureus (MRSA), 1 Staphylococcus epidermidis (MSSE), 1 Staphylococcus haemolyticus, 1 Staphylococcus lugdunensis, 1 Enterococcus faecalis (VSE), and 1 Enterococcus faecalis (VRE)). In addition, two E. faecium isolates were tested that do not have FDA-recognized STIC breakpoints and are not intended for testing with the device. All isolates were tested in triplicate over three days with each read method (i.e., automatically with the ARIS HiQ/OptiRead and visually with the Vizion). The Sensititre AIM Autoinoculator was used for Sensititre plate inoculation. The mode MIC value was determined, and the reproducibility of the 13 isolates was calculated based on MIC values falling within $\pm 1$ doubling dilution of the mode MIC value. The reproducibility studies for both the ARIS HiQ/OptiRead and Vizion read methods demonstrated acceptable performance of $\geq 95\%$.

2. Linearity:

Not applicable.

3. Analytical Specificity/Interference:

Not applicable.

4. Assay Reportable Range:

Not applicable.

5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):

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The CLSI-recommended quality control (QC) strains S. aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 were tested at four sites. The QC strains were tested a minimum of 20 times per site and read automatically with the ARIS HiQ/OptiRead and visually with the Vizion. The QC strains were also tested with the reference method. The results demonstrate that The Sensititre 18-24 hour MIC Susceptibility plates with Moxifloxacin produced quality control results within the recommended range >95% of the time (Table 1).

Table 1. Quality Control Results for S. aureus and E. faecalis with Moxifloxacin with the Reference Method, ARIS HiQ/OptiRead, and Vizion

| QC Organism | Expected Range (μg/mL) | Concentration (μg/mL) | Reference | ARIS HiQ/OptiRead | Vizion |
| --- | --- | --- | --- | --- | --- |
| Staphylococcus aureus ATCC 29213 | 0.15-0.12 μg/mL | ≤0.008 | 1 | - | - |
| | | 0.15 | 11 | - | - |
| | | 0.03 | 68 | 3 | 2 |
| | | 0.06 | 6 | 103 | 98 |
| | | 0.12 | - | | 4 |
| | | ≥0.25 | - | - | - |
| Enterococcus faecalis ATCC 29212 | 0.06-0.5 μg/mL | ≤0.03 | - | - | - |
| | | 0.06 | - | 1 | - |
| | | 0.12 | 86 | 69 | 10 |
| | | 0.25 | 2 | 37 | 97 |
| | | 0.5 | - | - | - |
| | | ≥1 | - | - | - |

Inoculum Density: Inoculum density checks were performed for all QC, reproducibility, challenge, and clinical isolates tested. Only results from cultures with appropriate inoculum densities were reported.

Purity Checks: Purity checks were performed for all QC, reproducibility, challenge, and clinical isolates tested. Only results from pure cultures were reported.

Growth Failure: There was one growth failure for Staphylococcus spp. There were no growth failures for E. faecalis.

ARIS HiQ/OptiRead Invalid (No fluorescence): There were two invalids for Staphylococcus spp. and one invalid for E. faecalis that did not produce adequate fluorescence by the ARIS HiQ/OptiRead.

6. Detection Limit:

Not applicable.

7. Assay Cut-Off:

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Not applicable.

## B Comparison Studies:

### 1. Method Comparison with Predicate Device:

Testing of The Sensititre 18-24 hour MIC or Breakpoint Susceptibility System with Moxifloxacin was performed at three external sites and additional testing was performed at one internal site. Results were compared to those obtained with the CLSI broth microdilution reference method. Sensititre panels were inoculated using only the AIM Autoinoculator and results were read automatically by the ARIS HiQ/OptiRead and visually by the Vizion. Reference panels were inoculated according to recommendations in the M07 CLSI document and results were read manually using a mirrored reader.

No inoculation system other than the AIM Autoinoculator and no read method other than ARIS HiQ/OptiRead and Vizion was used in the comparative study. To address the inoculation method and read method limitation, the following limitation was applied to moxifloxacin testing in the appropriate sections of the device labeling that references other drugs:

Studies of the following drugs were performed with the AIM Autoinoculator and read using the ARIS HiQ/OptiRead and Vizion. The use of an alternative inoculation system or alternative read methods has not been evaluated.

The testing conditions for the reference method consisted of the following:

- Media: per CLSI M07 guidelines for Staphylococcus spp. and Enterococcus spp.
- Inoculum: Inoculated per CLSI M07 guidelines
- Incubation: 34-36° C in a non-CO₂ incubator for 16-20 hours

Inoculation and incubation procedure for Staphylococcus spp. and Enterococcus spp.

- Media: cation-adjusted Mueller Hinton broth with TES buffer (CAMHBT)
- Inoculum: A suspension approximating a 0.5 McFarland standard was prepared in 5 mL sterile water. Ten (10) μL of the standardized suspension was transferred to 11 mL of CAMHBT. Susceptibility plates were inoculated with 50 μL of the final organism suspension using the Sensititre AIM Autoinoculator.
- Incubation: 34-36° C in a non-CO₂ incubator for 18-24 hours

A total of 546 gram-positive clinical isolates comprised of Staphylococcus spp. (334 S. aureus, 75 S. epidermidis, 11 S. haemolyticus, 10 S. hominis, 26 S. lugdunensis, and 24 S. saprophyticus isolates) and E. faecalis (66 isolates), as well as 144 challenge isolates comprised of Staphylococcus spp. (100 S. aureus, 7 S. epidermidis, 4 S. haemolyticus, 3 S. hominis, 6 S. lugdunensis, and 5 S. saprophyticus isolates) and E. faecalis (19 isolates) were evaluated with the ARIS HiQ/OptiRead and the results are provided in Table 2.

For Staphylococcus spp. read using the ARIS HiQ/OptiRead, the combined clinical and challenge results (605 isolates) were acceptable at 96.0% and 93.6% for EA and CA, respectively. There were 38 minor errors, 1 major error (1/434 = 0.2%), and no very major errors.

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For $E$ faecalis read by the ARIS/HiQ/OptiRead, the combined clinical and challenge results (85 isolates) were acceptable at $96.5\%$ and $98.8\%$ for EA and CA, respectively. There were no minor errors, no major errors, and one very major error $(1/24 = (4.2\%)$ , which is not acceptable. A supplemental study was performed to address the unacceptable very major error rate and is described below.

Table 2. Moxifloxacin Performance of Staphylococcus spp. and E. faecalis spp. Read by ARIS HiQ/OptiRead

| | Tot | EA N | EA % | Eval Tot | Eval EA N | Eval EA % | CA Tot | CA % | No. R | No. S | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Staphylococcus spp. [≤ 0.5 (S), 1 (I), ≥2 (R)] | | | | | | | | | | | | | |
| Clinical | 480 | 463 | 96.5 | 475 | 458 | 96.4 | 456 | 95.0 | 86 | 355 | 24 | 0 | 0 |
| Challenge | 125 | 118 | 94.4 | 117 | 110 | 94.0 | 110 | 88.0 | 32 | 79 | 14 | 1 | 0 |
| Total | 605 | 581 | 96.0 | 592 | 568 | 96.0 | 566 | 93.6 | 118 | 434 | 38 | 1 | 0 |
| E. faecalis [≤ 1 (S), 2 (I), ≥4 (R)] | | | | | | | | | | | | | |
| Clinical | 66 | 63 | 95.5 | 61 | 58 | 95.1 | 65 | 98.5 | 15 | 51 | 0 | 0 | 1 |
| Challenge | 19 | 19 | 100 | 17 | 17 | 100 | 19 | 100 | 9 | 10 | 0 | 0 | 0 |
| Total | 85 | 82 | 96.5 | 78 | 75 | 96.2 | 84 | 98.8 | 24 | 61 | 0 | 0 | 1 |

EA - Essential Agreement
CA - Categorical Agreement
S - Susceptible
Maj - Major Discrepancies
EVAL - Evaluable MICs
R - Resistant
min - Minor Discrepancies
vmj - Very Major Discrepancies

Essential agreement (EA) occurs when the result of the reference method and that of the Sensititre panel are within plus or minus one serial two-fold dilution of the antibiotic. Evaluable results are those that are on scale for both the reference method and the Sensititre panel or those in which an off-scale result is at least two doubling dilutions from the on-scale result. Category agreement (CA) occurs when the interpretation of the result of the reference method agrees exactly with the interpretation of the Sensititre panel.

A total of 548 gram-positive clinical isolates comprised of Staphylococcus spp. (334 S. aureus, 75 S. epidermidis, 11 S. haemolyticus, 10 S. hominis, 27 S. lugdunensis, and 24 S. saprophyticus isolates) and E. faecalis (67 isolates), as well as 144 challenge isolates comprised of Staphylococcus spp. (100 S. aureus, 7 S. epidermidis, 4 S. haemolyticus, 3 S. hominis, 6 S. lugdunensis, and 5 S. saprophyticus isolates) and E. faecalis (19 isolates) were evaluated with the Vizion and the results are provided in Table 3.

For Staphylococcus spp. read using the Vizion, the combined clinical and challenge results (606 isolates) were acceptable at $94.4\%$ and $93.4\%$ for EA and CA, respectively. There were 39 minor errors, 1 major error $(1/435 = 0.2\%)$ , and no very major errors.

For $E.$ faecalis read by the Vizion, the combined clinical and challenge results (86 isolates) were acceptable at $93.0\%$ and $98.8\%$ for EA and CA, respectively. There were no minor errors, no major errors, and one very major error $(1/24 = (4.2\%)$ , which was not acceptable.

Table 3. Moxifloxacin Performance of Staphylococcus spp. and E. faecalis spp. Read by Vizion

| | Tot | EA N | EA % | Eval Tot | Eval EA N | Eval EA % | CA Tot | CA % | No. R | No. S | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Staphylococcus spp. [≤ 0.5 (S), 1 (I), ≥2 (R)] | | | | | | | | | | | | | |
| Clinical | 481 | 454 | 94.4 | 477 | 450 | 94.3 | 455 | 94.6 | 86 | 356 | 26 | 0 | 0 |
| Challenge | 125 | 118 | 94.4 | 117 | 110 | 94.0 | 111 | 88.8 | 32 | 79 | 13 | 1 | 0 |
| Total | 606 | 572 | 94.4 | 594 | 560 | 94.3 | 566 | 93.4 | 118 | 435 | 39 | 1 | 0 |
| E. faecalis [≤ 1 (S), 2 (I), ≥4 (R)] | | | | | | | | | | | | | |
| Clinical | 67 | 61 | 91.0 | 62 | 56 | 90.3 | 66 | 98.5 | 15 | 52 | 0 | 0 | 1 |

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| | Tot | EA N | EA % | Eval Tot | Eval EA N | Eval EA % | CA Tot | CA % | No. R | No. S | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Challenge | 19 | 19 | 100 | 16 | 16 | 100 | 19 | 100 | 9 | 10 | 0 | 0 | 0 |
| Total | 86 | 80 | 93.0 | 78 | 72 | 92.3 | 85 | 98.8 | 24 | 62 | 0 | 0 | 1 |

EA - Essential Agreement

CA - Categorical Agreement

S - Susceptible

Maj - Major Discrepancies

EVAL - Evaluable MICs

R - Resistant

min - Minor Discrepancies

vmj - Very Major Discrepancies

Essential agreement (EA) occurs when the result of the reference method and that of the Sensititre panel are within plus or minus one serial two-fold dilution of the antibiotic. Evaluable results are those that are on scale for both the reference method and the Sensititre panel or those in which an off-scale result is at least two doubling dilutions from the on-scale result. Category agreement (CA) occurs when the interpretation of the result of the reference method agrees exactly with the interpretation of the Sensititre panel.

To address the unacceptable VMJ rate for $E$ faecalis read by ARIS HiQ/OptiRead and Vizion, a supplemental study was performed at one internal site. Additional $E$ faecalis challenge isolates (52) were tested and read by the ARIS/HiQ/OptiRead and Vizion. The original clinical and challenge data were combined with the supplemental testing. Final results demonstrated an acceptable very major error rate of $1.6\%$ (1/63) with the ARIS/HiQ/OptiRead and $1.6\%$ (1/64) with the Vizion (Table 4).

Table 4. Combined (Original and Supplemental) Moxifloxacin Performance of $E$ . faecalis spp. Read by ARIS HiQ/OptiRead and Vizion

| | Tot | EA N | EA % | Eval Tot | Eval EA N | Eval EA % | CA Tot | CA % | No. R | No. S | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| E. faecalis [≤1 (S), 2 (I), ≥4 (R)] | | | | | | | | | | | | | |
| ARIS HiQ/OptiRead | | | | | | | | | | | | | |
| Clinical | 66 | 63 | 95.5 | 61 | 58 | 95.1 | 65 | 98.5 | 15 | 51 | 0 | 0 | 1 |
| Challenge | 19 | 19 | 100 | 17 | 17 | 100 | 19 | 100 | 9 | 10 | 0 | 0 | 0 |
| Supplemental | 51 | 51 | 100 | 48 | 48 | 100 | 51 | 100 | 39 | 12 | 0 | 0 | 0 |
| Total | 136 | 133 | 97.8 | 126 | 123 | 97.6 | 135 | 99.3 | 63 | 73 | 0 | 0 | 1 |
| Vizion | | | | | | | | | | | | | |
| Clinical | 67 | 61 | 91.0 | 62 | 56 | 90.3 | 66 | 98.5 | 15 | 52 | 0 | 0 | 1 |
| Challenge | 19 | 19 | 100 | 16 | 16 | 100 | 19 | 100 | 9 | 10 | 0 | 0 | 0 |
| Supplemental | 52 | 52 | 100 | 41 | 41 | 100 | 52 | 100 | 40 | 12 | 0 | 0 | 0 |
| Total | 138 | 132 | 95.7 | 119 | 113 | 95.0 | 137 | 99.3 | 64 | 74 | 0 | 0 | 1 |

EA - Essential Agreement

CA - Categorical Agreement

S - Susceptible

Maj - Major Discrepancies

EVAL - Evaluable MICs

R - Resistant

min - Minor Discrepancies

vmj - Very Major Discrepancies

Essential agreement (EA) occurs when the result of the reference method and that of the Sensititre panel are within plus or minus one serial two-fold dilution of the antibiotic. Evaluable results are those that are on scale for both the reference method and the Sensititre panel or those in which an off-scale result is at least two doubling dilutions from the on-scale result. Category agreement (CA) occurs when the interpretation of the result of the reference method agrees exactly with the interpretation of the Sensititre panel.

Due to the insufficient number of non-susceptible S. lugdunensis and S. saprophyticus isolates evaluated, the following limitation was applied to moxifloxacin testing in the appropriate section of the device labeling that references other drugs:

The ability of the Sensititre system to detect resistance or non-susceptibility to antimicrobics as shown below is unknown because an insufficient number of

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resistant or non-susceptible strains were available at the time of comparative testing. If such a strain is observed, it should be submitted to a reference laboratory.

# MIC Trending

A trending analysis was conducted using the combined data (clinical and challenge) obtained for both the ARIS HiQ/OptiRead and the Vizion for Staphylococcus spp. and E. faecalis. This trending calculation takes into account MIC values that are determined to be one or more doubling dilutions lower or higher than the reference method irrespective of whether the device MIC values are on-scale or not. Results that are not clearly at least one dilution lower at least one dilution higher or in exact agreement with the CLSI reference method are not considered in the trending analysis.

Species for which the difference between the percentage of isolates with higher vs. lower readings was > 30% and for which the confidence interval was determined to be statistically significant were considered to show evidence of trending. Trending that shows higher or lower MIC values compared to the reference is addressed in the labeling.

Evaluation of results for Staphylococcus spp. and E. faecalis with moxifloxacin using the ARIS HiQ/OptiRead and Vizion are summarized in Table 5. A trend toward higher MIC values was observed for S. aureus, S. epidermidis, S. hominis, and S. saprophyticus using the ARIS/HiQ/OptiRead when compared to the CLSI broth microdilution reference method. A trend toward higher MIC values was observed for S. aureus, S. epidermidis, S. hominis, S. lugdunensis, S. saprophyticus, and E. faecalis using the Vizion when compared to the CLSI broth microdilution reference method.

To address the MIC trending, the sponsor includes the following footnotes in the performance table:

For ARIS HiQ/OptiRead:
Moxifloxacin MIC values tended to be in exact agreement or at least one doubling dilution higher when testing S. aureus, S. epidermidis, S. hominis, and S. saprophyticus with the ARIS HiQ/OptiRead compared to the CLSI reference broth microdilution method.

For Vizion:
Moxifloxacin MIC values tended to be in exact agreement or at least one doubling dilution higher when testing S. aureus, S. epidermidis, S. hominis, S. lugdunensis, S. saprophyticus, and E. faecalis with the Vizion compared to the CLSI reference broth microdilution method.

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Table 5. Moxifloxacin Trending Analysis for Staphylococcus spp. and E. faecalis with ARIS HiQ/OptiRead and Vizion

| Read Method | Organism | Total Evaluable for Trending | ≥ 1 Dilution lower No. (%) | Exact No. (%) | ≥ 1 Dilution Higher No. (%) | Percent Difference (95% CI) | Trending Noted |
| --- | --- | --- | --- | --- | --- | --- | --- |
| ARIS HiQ/OptiRead | S. aureus | 426 | 4, (0.9) | 116 | 306 (71.8) | 71% (66% to 75%) | Yes, high |
| | S. epidermidis | 82 | 2, (2.4) | 35 | 45, (54.9) | 52% (40% to 62%) | Yes, high |
| | S. haemolyticus | 13 | 1, (7.7) | 11 | 1, (7.7) | 0% (-26% to 26%) | No |
| | S. hominis | 13 | 0, (0) | 4 | 9, (69.2) | 69% (34% to 87%) | Yes, high |
| | S. lugdunensis | 32 | 0, (0) | 27 | 5, (15.6) | 16% (2% to 32%) | No |
| | S. saprophyticus | 29 | 0, (0) | 17 | 12, (41.4) | 41% (22% to 59%) | Yes, high |
| | E. faecalis | 129 | 22 (17.1) | 84 | 23 (17.8) | 1% (-9% to 10%) | No |
| Vizion | S. aureus | 426 | 2, (0.5) | 122 | 302 (70.8) | 70% (66% to 75%) | Yes, high |
| | S. epidermidis | 81 | 0, (0) | 19 | 62, (76.5) | 77% (65% to 84%) | Yes, high |
| | S. haemolyticus | 13 | 0, (0) | 11 | 2, (15.4) | 15% (-10% to 42%) | No |
| | S. hominis | 13 | 0, (0) | 13 | 13, (100) | 100% (68% to 100%) | Yes, high |
| | S. lugdunensis | 33 | 0, (0) | 6 | 27, (81.8) | 82% (63% to 91%) | Yes, high |
| | S. saprophyticus | 29 | 0, (0) | 14 | 15, (51.7) | 52% (31% to 69%) | Yes, high |
| | E. faecalis | 129 | 4 (3.1) | 58 | 67, (51.9) | 49% (39% to 57%) | Yes, high |

Testing/Reporting MICs for Non-indicated Species.

For this review, the interpretive criteria are applied to the organisms/organism groups according to the FDA STIC website. As required under 511A(2)(2)(B) of the Federal Food, Drug and Cosmetic Act, the following statement is included in the Warnings and Precautions section of the device labeling to address testing and reporting of non-indicated species:

The safety and efficacy of antimicrobial drugs, for which antimicrobial susceptibility is tested by this AST device, may or may not have been established in adequate and well controlled clinical trials for treating clinical infections due to microorganisms outside of those found in the indications and usage in the drug label. The clinical significance of susceptibility information in those instances is unknown. The approved labeling for specific antimicrobial drugs provides the uses for which the antimicrobial drug is approved.

2. Matrix Comparison:

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Not applicable.

## C Clinical Studies:

1. Clinical Sensitivity:
Not applicable.

2. Clinical Specificity:
Not applicable.

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

## D Clinical Cut-Off:

Not applicable.

## E Expected Values/Reference Range:

Table 6: FDA-Recognized Interpretive Criteria for Moxifloxacin

| | Minimum Inhibitory Concentrations (μg/mL)a | | |
| --- | --- | --- | --- |
| Organisms | Susceptible | Intermediate | Resistant |
| Staphylococcus spp. | ≤0.5 | 1 | ≥2 |
| Enterococcus faecalis | ≤1 | 2 | ≥4 |

aAccording to FDA STIC Webpage

## VIII Proposed Labeling:

The labeling supports the finding of substantial equivalence for this device.

## IX Conclusion:

The submitted information in this premarket notification is complete and supports a substantial equivalence decision.

To support the implementation of changes to FDA-recognized susceptibility test interpretive criteria (i.e., breakpoints), this submission incorporated by reference a breakpoint change protocol that was reviewed and accepted by FDA in submission K231994 cleared on August 25, 2023. This referenced protocol addresses future revisions to device labeling in response to breakpoint changes that are recognized on the FDA STIC webpage (https://www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/ucm410971.htm). The referenced protocol outlined the specific procedures and acceptance criteria that Thermo Fisher Scientific intends to use to evaluate The Sensititre 18-24 hour MIC or Breakpoint

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Susceptibility System with Moxifloxacin when revised breakpoints for moxifloxacin are published on the FDA STIC webpage. The breakpoint change protocol included with the submission indicated that if specific criteria are met, Thermo Fisher Scientific will update the moxifloxacin device label to include (1) the new breakpoints, (2) an updated performance section after re-evaluation of data in this premarket notification with the new breakpoints, and (3) any new limitations as determined by their evaluation.

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