VITEK 2 AST-GN Cefepime (<=0.12->=32 ug/mL)

K161227 · bioMerieux, Inc. · LON · Jul 20, 2016 · Microbiology

Device Facts

• Record ID: K161227
• Device Name: VITEK 2 AST-GN Cefepime (<=0.12->=32 ug/mL)
• Applicant: bioMerieux, Inc.
• Product Code: LON · Microbiology
• Decision Date: Jul 20, 2016
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.1645
• Device Class: Class 2

Indications for Use

VITEK® 2 AST-Gram Negative Cefepime is designed for antimicrobial susceptibility testing of Gram negative bacilli and is intended for use with the VITEK® 2 Compact Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents. VITEK® 2 AST-Gram Negative Cefepime is a quantitative test. Cefepime has been shown to be active against most strains of the microorganisms listed below. according to the FDA label for this antimicrobial. Active in vitro and in clinical infections: Enterobacter spp. Escherichia coli Klebsiella pneumoniae Proteus mirabilis Pseudomonas aeruginosa In vitro data available but clinical significance is unknown: Citrobacter koseri (formerly Citrobacter diversus) Citrobacter freundii Pantoea agglomerans (formerly Enterobacter agglomerans) Klebsiella oxytoca Proteus vulgaris Providencia rettgeri Providencia stuartii Serratia marcescens The VITEK @ 2 Antimicrobial Susceptibility Test (AST) is intended to be used with the VITEK® 2 Systems for the automated quantitative or qualitative susceptibility testing of isolated colonies for the most clinically significant aerobic gram-negative bacilli, Staphylococus spp., Enterococcus spp., Streptococcus spp. and clinically significant yeast.

Device Story

VITEK® 2 AST-GN Cefepime card; miniaturized version of broth microdilution technique. Input: isolated bacterial colonies diluted in 0.45-0.50% saline. Operation: automated filling/sealing (VITEK 2) or manual (VITEK 2 Compact); card incubation/reading for up to 18 hours. System monitors growth in card wells; calculates Minimum Inhibitory Concentration (MIC) and interpretive category. Output: automated report of MIC and susceptibility category. Used in clinical laboratories; operated by laboratory technicians. Results assist clinicians in selecting appropriate antimicrobial therapy for patients with bacterial infections.

Clinical Evidence

Performance evaluated using 824 clinical isolates and 100 challenge isolates. Combined performance for Enterobacteriaceae and P. aeruginosa showed 93.8% Essential Agreement and 96.1% Category Agreement. Adjusted major discrepancy rate 0.5%; adjusted very major discrepancy rate 1.6%. Reproducibility 99.6-100%. Growth failure rate 0.2%.

Technological Characteristics

Miniaturized broth microdilution card; contains antimicrobial concentrations equivalent to standard mcg/mL concentrations. Automated incubation and optical growth monitoring. Compatible with VITEK 2 and VITEK 2 Compact systems. Software-based automated analysis of growth kinetics to determine MIC.

Indications for Use

Indicated for antimicrobial susceptibility testing of isolated colonies of clinically significant aerobic Gram-negative bacilli, Staphylococcus spp., Enterococcus spp., Streptococcus spp., and yeast. Specifically for Cefepime, targets include Enterobacter spp., E. coli, K. pneumoniae, P. mirabilis, P. aeruginosa, and various other Gram-negative species.

Regulatory Classification

Identification

A fully automated short-term incubation cycle antimicrobial susceptibility system is a device that incorporates concentrations of antimicrobial agents into a system for the purpose of determining in vitro susceptibility of bacterial pathogens isolated from clinical specimens. Test results obtained from short-term (less than 16 hours) incubation are used to determine the antimicrobial agent of choice to treat bacterial diseases.

Special Controls

*Classification.* Class II (special controls). The special control for this device is FDA's guidance document entitled “Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA.”

Predicate Devices

• VITEK® 2 GN Doxycycline (K121546)

Submission Summary (Full Text)

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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION MEMORANDUM ASSAY ONLY TEMPLATE

A. 510(k) Number:
K161227

B. Purpose for Submission:
To obtain a substantial equivalence determination for Cefepime for testing of gram negative bacilli on the VITEK® 2 and VITEK® 2 Compact Antimicrobial Susceptibility Test (AST) Systems.

C. Measurand:
The VITEK® 2 AST-Gram Negative card contains the following concentrations of cefepime: 0.25, 1, 4, 16 and 32 µg/mL (equivalent standard method concentration by efficacy in µg/mL). The MIC result reporting range for the card is ≤0.12 - ≥32 µg/mL.

D. Type of Test:
Automated quantitative or qualitative antimicrobial susceptibility test for Cefepime

E. Applicant:
bioMérieux, Inc.

F. Proprietary and Established Names:
VITEK® 2 AST- GN Cefepime (≤0.12 - ≥32 µg/mL)
VITEK 2® AST- Gram Negative Cefepime (≤0.12 - ≥32 µg/mL)

G. Regulatory Information:
1. Regulation section:
21 CFR 866.1645 Fully Automated Short-Term Incubation Cycle Antimicrobial Susceptibility System
2. Classification:
Class II

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3. Product code:
LON - Fully automated short-term incubation cycle antimicrobial susceptibility system
LTW - Susceptibility Test Cards, Antimicrobial
LTT - Panels, Test, Susceptibility, Antimicrobial

4. Panel:
83 Microbiology

H. Intended Use:

1. Intended use(s):
The VITEK 2 Antimicrobial Susceptibility Test (AST) is intended to be used with the VITEK 2 Systems for the automated quantitative or qualitative susceptibility testing of isolated colonies for the most clinically significant aerobic gram-negative bacilli, Staphylococcus spp., Enterococcus spp., Streptococcus spp. and clinically significant yeast.

2. Indication(s) for use:
VITEK 2 Gram Negative Cefepime is designed for antimicrobial susceptibility testing of Gram negative bacilli and is intended for use with the VITEK 2 and VITEK 2 Compact Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents. VITEK 2 Gram Negative Cefepime is a quantitative test. Cefepime has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for the antimicrobial.

Active in vitro and in clinical infections:
Enterobacter spp.
Escherichia coli
Klebsiella pneumoniae
Proteus mirabilis
Pseudomonas aeruginosa

In vitro data available but clinical significance is unknown:
Citrobacter koseri (formerly Citrobacter diversus)
Citrobacter freundii
Pantoea agglomerans (formerly Enterobacter agglomerans)
Klebsiella oxytoca
Proteus vulgaris
Providencia rettgeri
Providencia stuartii
Serratia marcescens

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3. Special conditions for use statement(s):

Prescription use only

The following limitations are included in the device labeling:

Although within Essential Agreement, the lack of an intermediate category has shown major and very major discrepancies when compared to the reference method. Testing should be repeated using an alternative testing/reference method prior to reporting results for the following antibiotic/organism:

- Cefepime: Pseudomonas aeruginosa when the VITEK 2 MIC is 8μg/mL or 16μg/mL

Perform an alternative method of testing prior to reporting of results for the following antibiotic/organism combination(s):

- Cefepime: Hafnia alvei, Morganella spp.

Users outside the U.S. should perform an alternative method of testing prior to reporting of results for the following antibiotic/organism combination(s):

- Cefepime: Bordetella bronchiseptica

4. Special instrument requirements:

VITEK 2 Systems 7.01 (PC version) software for VITEK 2 and VITEK 2 Compact Systems

I. Device Description:

The VITEK 2 AST card is a miniaturized, abbreviated and automated version of the doubling dilution technique for determining the minimum inhibitory concentration (MIC). Each VITEK 2 test card contains 64 microwells. A control well containing only culture medium is included on all cards, with the remaining wells containing premeasured amounts of a specific antimicrobial agent in a culture medium base. A suspension of organism from a pure culture is prepared in a tube containing 0.45-0.5% sterile saline and standardized to a McFarland 0.5 using the DensiCHEK Plus. The VITEK 2 System automatically fills, seals and places the card into the incubator/reader; manual methods can also be used for the inoculation of test cards for use in the VITEK 2 System. The VITEK 2 Compact has a manual filling and sealing operation. The VITEK 2 Systems monitor the growth of each well in the card over a defined period of time (up to 18 hours). At the completion of the incubation cycle, a report is generated that contains the MIC value along with the interpretive category result for each antimicrobial contained on the card.

VITEK 2 AST-GN Cefepime has the following concentrations in the card: 0.25, 1, 4, 16 and 32 μg/mL (equivalent standard method concentration by efficacy in μg/mL). The MIC result reporting range for the card is ≤0.12 - ≥32 μg/mL.

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# J. Substantial Equivalence Information:

1. Predicate device name(s):

VITEK 2 AST- GN Doxycycline

2. Predicate $510(\mathrm{k})$ number(s):

K121546

3. Comparison with predicate:

Table 1: Comparison with the Predicate Device

| Similarities | | |
| --- | --- | --- |
| Item | Device VITEK 2 AST- GN Cefepime | Predicate VITEK 2 AST- GN Doxycycline (K121546) |
| Intended Use | The VITEK 2 Antimicrobial Susceptibility Test (AST) is intended to be used with the VITEK 2 Systems for the automated quantitative or qualitative susceptibility testing of isolated colonies for the most clinically significant aerobic gram-negative bacilli, Staphylococcus spp., Enterococcus spp., Streptococcus spp. and clinically significant yeast. | Same |
| Test Method | Automated quantitative antimicrobial susceptibility test for use with the VITEK 2 and VITEK 2 Compact Systems to determine the in vitro susceptibility of Gram negative bacilli | Same |
| Inoculum | Saline suspension of organisms | Same |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Antimicrobial | Cefepime | Doxycycline |
| Antimicrobial Concentration | 0.25, 1, 4, 16, 32 | 1, 4, 16 |
| Reading Algorithm | Growth pattern analysis-Unique to Cefepime | Discriminate analysis-Unique to Doxycycline |

# K. Standard/Guidance Document Referenced (if applicable):

- CLSI M100-S25: Performance Standards for Antimicrobial Susceptibility Testing
- CLSI M07-A10: Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria

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That Grow Aerobically
- Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems

L. Test Principle:

The VITEK 2 and VITEK 2 Compact Systems utilize automated growth-based detection using attenuation of light measured by an optical scanner. The optics used in the systems use visible light to directly measure organism growth. Transmittance optics are based on an initial light reading of a well before significant growth has begun. Periodic light transmittance samplings of the same well measure organism growth by how much light is prevented from going through the well. The VITEK 2 System monitors the growth of each well in the card over a defined period of time. An interpretive call is made between 4 and 16 hours for a “rapid” read but may be extended to 18 hours in some instances. At the completion of the incubation cycle, a report is generated that contains the MIC value along with the interpretive category result for each antibiotic on the card.

M. Performance Characteristics (if/when applicable):

1. Analytical performance:

a. Precision/Reproducibility:

A reproducibility study was conducted at three sites using ten isolates of gram negative bacilli that were consistent with the intended use. Isolates were tested in triplicate over three days for a total of 270 data points. The isolates tested in the reproducibility study included Klebsilla pneumoniae (three isolates), Pseudomonas aeruginosa (two isolates), Enterobacter cloacae (two isolates), Serratia marcescens (two isolates), and E. coli (one isolate). Inocula were prepared using both manual and automatic dilution methods for testing in the VITEK 2. Inocula were prepared by the manual testing method only in the VITEK 2 Compact. The mode MIC value was determined and the reproducibility was calculated based on MIC values falling within ± 1 dilution of the mode MIC value.

Using VITEK 2 and automatic dilution, all results were on scale and the reproducibility was 100%.

Using VITEK 2 and manual dilution, there was one off-scale result. Reproducibility was at 99.6% for best an worst case scenarios.

Using VITEK 2 Compact and manual dilution, all results were on-scale and the reproducibility was 100%.

The reproducibility results were acceptable.

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b. Linearity/assay reportable range:

Not Applicable

c. Traceability, Stability, Expected values (controls, calibrators, or methods):

Inoculum Density Check: The inoculum density was monitored using the DensiCHEK Plus™ instrument. The DensiCHEK Plus™ was standardized daily with all results recorded and within expected range.

Purity Check: A purity check of all organisms was performed at the time of VITEK2 card inoculation. Only results obtained with pure cultures were evaluated.

Growth Failure Rate: There were two isolates that failed to grow in the clinical study. Complete test results were available for 822 isolates in a total of 824 clinical isolates. The growth failure rate was 0.2% and was acceptable.

Quality Control Testing: The FDA recommended QC organisms (E. coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) were tested using both the VITEK 2 card and the reference method at each site. Both the automatic dilution and manual dilution methods were used for the VITEK 2 and the manual dilution method was used for the VITEK 2 Compact.

The expected range for E. coli ATCC 25922 with cefepime is 0.015 – 0.12 µg/mL. Even though the cefepime concentrations included in the VITEK 2 AST-Gram Negative card are 0.25, 1, 4, 16 and 32 µg/mL, the reporting range is ≤0.12 – ≥32 µg/mL. Therefore, all results for the QC strain E. coli ATCC 25922 were off scale for the VITEK 2 and VITEK 2 Compact Systems as both VITEK systems report the lowest end of the scale as ≤0.12 µg/mL (Table 2). However, Pseudomonas aeruginosa ATCC 27853 was tested where the expected range is 0.5–4 µg/mL and all results were on-scale. All results were within the expected range.

Table 2: Quality Control Results for VITEK 2 (Automatic and Manual Dilution Methods) and for VITEK 2 Compact (Manual Dilution Method)

| | | VITEK 2 Automatic-Dilution | | VITEK 2 Manual Dilution | | VITEK 2 Compact Manual Dilution | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Organism | Conc. (μg/mL) | Ref. | Test | Ref. | Test | Ref. | Test |
| E. coli
ATCC 25922
Expected Range:
0.015- 0.12μg/mL | ≤0.008 | | | | | | |
| | 0.016 | 1 | | 1 | | 1 | |
| | 0.03 | 166 | | 120 | | 117 | |
| | 0.06 | 66 | | 44 | | 43 | |
| | (≤)0.125* | | 233 | | 165 | | 161 |
| | 0.25 | | | | | | |
| | 0.5 | | | | | | |
| | 1 | | | | | | |

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| | | VITEK 2 Automatic-Dilution | | VITEK 2 Manual Dilution | | VITEK 2 Compact Manual Dilution | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Organism | Conc. (μg/mL) | Ref. | Test | Ref. | Test | Ref. | Test |
| | 2 | | | | | | |
| | 4 | | | | | | |
| | 8 | | | | | | |
| | 16 | | | | | | |
| | 32 | | | | | | |
| | ≥64 | | | | | | |
| | | | | | | | |
| P. aeruginosaATCC 27853Expected Range:0.5-4μg/mL | 0.125 | | | | | | |
| | 0.25 | | | | | | |
| | 0.5 | 15 | 1 | 6 | 1 | 6 | 1 |
| | 1 | 178 | | 130 | 1 | 129 | |
| | 2 | 40 | 231 | 28 | 163 | 26 | 161 |
| | 4 | 1 | 2 | 1 | | 1 | |
| | 8 | | | | | | |
| | 16 | | | | | | |
| | 32 | | | | | | |
| | ≥64 | | | | | | |

* The lowest end point of the VITEK 2 Cefepime MIC range is ≤0.12 μg/mL. Obtaining this value was considered as an indicator that the quality control test results were acceptable.

Inoculum Density Check. The inoculum density was monitored using the DensiCHEK Plus instrument. The DensiCHEK Plus was standardized weekly with all results recorded and in expected range.

d. Detection limit:

Not Applicable

e. Analytical specificity:

Not Applicable

f. Assay cut-off:

Not Applicable

2. Comparison studies:

a. Method comparison with predicate device:

Results obtained with the bioMérieux VITEK 2 AST - Gram Negative card with cefepime were compared to results obtained with the CLSI broth microdilution reference panel. The VITEK 2 AST-Gram Negative card with cefepime contains the

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following concentrations of cefepime: 0.25, 1, 4, 16, and $32\mu \mathrm{g / mL}$ (equivalent standard method concentration by efficacy in $\mu \mathrm{g / mL}$ ) and the reporting range is $\leq 0.12 - \geq 32\mu \mathrm{g / mL}$ (i.e. $\leq 0.125$ , 0.25, 0.5, 1, 2, 4, 8, 16, and $\geq 32$ ). The reference panel contained two-fold serial dilutions with a range of 0.008 to $128\mu \mathrm{g / mL}$ . The testing conditions for the reference method were:

Medium: Mueller Hinton broth (Cation-Adjusted) with the appropriate dilutions of antimicrobial solution added
Inoculum: Direct colony suspension
- Incubation: $35^{\circ}\mathrm{C}$ ; 16-20 hours

Test inocula were standardized using the DensiCHEK Plus instrument. VITEK 2 AST - Gram Negative cards were inoculated using automatic dilution (for reading on the VITEK 2 instrument) or using a manual dilution method (for reading on the VITEK 2 instrument or on the VITEK 2 COMPACT instrument). Reference panels were inoculated as outlined in the CLSI document M07-A10.

A total of 824 clinical isolates were evaluated at three external sites with VITEK 2 AST - Gram Negative cards inoculated by automatic dilution and interpreted using the VITEK 2 instrument. There were two isolates that failed to grow (99.8% growth rate). The majority of isolates were fresh (641 isolates, 78.0%); 181 isolates (22.0%) were stock isolates. There were 531 Enterobacteriaceae and 291 Pseudomonas aeruginosa isolates tested in the clinical studies.

A total of 100 challenge isolates (80 Enterobacteriaceae and 20 Pseudomonas aeruginosa) were evaluated at one external site. The challenge set was tested with both automatic dilution and manual dilution methods on the VITEK 2 System and with the manual dilution method on the VITEK2 Compact System. The performance is provided in Table 3-A below:

Table 3-A: Performance† of Clincal and Challenge Isolates, VITEK 2 Auto-Dilution

| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA N | CA % | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Enterobacteriaceae ≤2 (S), 4-8 (I), ≥16 (R) | | | | | | | | | | | | |
| Clinical | 531 | 513 | 96.6 | 41 | 31 | 75.6 | 519 | 97.7 | 81 | 10 | 1 | 1 |
| Challenge | 80 | 77 | 96.3 | 12 | 9 | 75.0 | 80 | 100 | 0 | 0 | 0 | 0 |
| Combined | 611 | 590 | 96.6 | 53 | 40 | 75.5 | 599 | 98.0 | 81 | 10 | 1 | 1 |
| Pseudomonas aeruginosa ≤8 (S), --, ≥16 (R) | | | | | | | | | | | | |
| Clinical | 291 | 256 | 88.0 | 273 | 239 | 87.5 | 268 | 92.1 | 41 | 0 | 20 | 3 |
| Challenge | 20 | 19 | 95.0 | 20 | 19 | 95.0 | 19 | 95.0 | 2 | 0 | 0 | 1 |
| Combined | 311 | 275 | 88.4 | 293 | 258 | 88.1 | 287 | 92.3 | 43 | 0 | 20 | 4 |
| Enterobacteriaceae + P. aeruginosa | 922 | 865 | 93.8 | 346 | 298 | 86.1 | 886 | 96.1 | 124 | 10 | 21 (2.7%) | 5 (4.0%) |

$\dagger$ EA - Essential Agreement (+/- 1 dilutions)
CA - Category Agreement
EVAL - Evaluable isolates
R or NS - Resistant or non-susceptible isolates
Essential Agreement (EA) occurs when there is agreement between the result of the reference method and min - minor discrepancies
maj - major discrepancies
vmj - very major discrepancies

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that of VITEK 2 test card within plus or minus one serial two-fold dilution of the antibiotic. Evaluable results are those that are on scale for both the VITEK 2 test card and the reference method. Category Agreement (CA) occurs when the interpretation of the result of the reference method agrees exactly with the interpretation of the VITEK 2 test card.

## Enterobacteriaceae, ≤2 (S), 4-8 (I), ≥16 (R)

The performance of Enterobacteriaceae was acceptable at 96.6% EA, 98.0% CA, major discrepancy rate of 0.2% (1/523), and very major discrepancy rate of 1.2% (1/81).

## Pseudomonas aeruginosa, ≤8 (S), --, ≥16 (R)

### i. Category Agreement

Major and very major discrepancies were observed when P. aeruginosa results were analyzed separately. Of the 20 major discrepancies, 17 were within essential agreement [i.e. VITEK 2: 16 (R), Reference: 8 (S)]. Of the four very major discrepancies, three were within essential agreement [i.e. VITEK 2: 8 (S), Reference: 16 (R)]. These 17 major and 3 very major discrepancies would have been considered minor discrepancies if there was an "intermediate" interpretation category for cefepime/P. aeruginosa.

Because of the lack of "intermediate" interpretation category, an adjustment was made in the overall performance evaluation of the discrepancy (error) rates by conducting an analysis to determine whether the MIC values for these isolates were within essential agreement or not.

As a result of this analysis, the adjusted major discrepancy rate for P. aeruginosa became 1.1% (3/268). The combined major discrepancy rate for Enterobacteriaceae and P. aeruginosa became 0.5% (4/791). Similarly, the adjusted very major discrepancy rate for P. aeruginosa became 2.3% (1/43). The combined very major discrepancy rate for Enterobacteriaceae and P. aeruginosa became 1.6% (2/124). These performance data are acceptable based on the criteria outlined in the AST Special Controls guidance document.

The adjusted performance is noted in Tables 3-B and 3-C below:

| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA N | CA % | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Clinical | 291 | 256 | 88.0 | 273 | 239 | 87.5 | 268 | 92.1 | 41 | 0 | 3
1.2%
(3/250) | 1
2.4%
(1/41) |
| Challenge | 20 | 19 | 95.0 | 20 | 19 | 95.0 | 19 | 20 | 2 | 0 | 0 | 0 |
| Combined | 311 | 275 | 88.4 | 293 | 258 | 88.1 | 287 | 92.3 | 43 | 0 | 3
1.1%
(3/268) | 1
2.3%
(1/43) |

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Table 3-C: Combined Performance (Original Enterobacteriaceae plus Adjusted P. aeruginosa)

| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA N | CA % | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Enterobacteriaceae + P. aeruginosa | 922 | 865 | 93.8 | 346 | 298 | 86.1 | 886 | 96.1 | 124 | 10 | 4 0.5% (4/791) | 2 1.6%† (2/124) |

† The acceptable number of discrepancies is 3 when 124 of resistant organisms are tested (Table 8, AST Special Controls Guidance)

The original $P$ aeruginosa performance with 20 major and 4 very discrepancies was mitigated by adding a limitation to address the need for repeat testing $P$ aeruginosa by alternative methods when the VITEK 2 Systems MIC is $8\mu \mathrm{g} / \mathrm{mL}$ or $16\mu \mathrm{g} / \mathrm{mL}$ . The limitation is noted below:

Although within Essential Agreement, the lack of an intermediate category has shown major and very major discrepancies when compared to the reference method. Testing should be repeated using an alternative testing/reference method prior to reporting results for the following antibiotic/organism:

- Cefepime: Pseudomonas aeruginosa when the VITEK 2 MIC is $8\mu \mathrm{g} / \mathrm{mL}$ or $16\mu \mathrm{g} / \mathrm{mL}$

For implementation of the repeat testing limitation, bioMerieux indicated that they will issue a customer communication requesting VITEK 2 uers to create a BioART rule stating the limitation in the VITEK 2 System for Pseudomonas aeruginosa when testing cefepime. Implementation of this BioART rule will assure that alternative testing is performed in accordance with the above limitation. The limitation will be included in the next software update release.

# ii. Essential Agreement

The essential agreement for $P$ aeruginosa in the comparative studies was lower than the acceptance criterion of $90\%$ when analyzed separately. It was further evaluated by trending as demonstrated in Table 4 below:

Table 4: Trending of On-Scale Clinical and Challenge Isolate Results- P. aeruginosa

| | # of Isolates | Difference in MIC as Compared to the CLSI Reference Method | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | ≥3 dil. lower | 2 dil. lower | 1 dil. Lower | Exact | 1 dil. higher | 2 dil. higher | ≥3 dil higher |
| Clinical | 283 | 3 | 4 | 19 | 118 | 113 | 24 | 2 |
| Challenge | 20 | 0 | 0 | 2 | 7 | 10 | 1 | 0 |
| Combined | 303 | 3 (1.0%) | 4 (1.3%) | 21 (6.9%) | 125 (41.3%) | 123 (40.6%) | 25 (8.3%) | 2 (0.7%) |

The following footnote pertinent to cefepime is added to the VITEK 2 Performance Characteristics for Gram-Negative Antimicrobial Susceptibility Testing Table (Table 127, Product Information Manual):

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The EA for VITEK2 Cefepime with Pseudomonas aeruginosa was 88.4%. The trending of on-scale results demonstrated: 41.3% equivalent, 40.6% one doubling dilution higher, and 6.9% one doubling dilution lower when compared to the CLSI reference broth microdilution.

## Challenge

The challenge set of 80 Enterobacteriaceae and 20 Pseudomonas aeruginosa isolates were evaluated with both automatic dilution and manual dilution methods on the VITEK 2 System and with the manual dilution method on the VITEK2 Compact System. The performance is shown in Table 5.

Table 5: Performance of VITEK 2 and VITEK 2 Compact
| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA N | CA % | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | VITEK 2 | | | | | | | | | | | |
| Auto-dilution | 100 | 96 | 96.0 | 32 | 28 | 87.5 | 99 | 99.0 | 2 | 0 | 0 | 1 |
| Manual Dilution | 100 | 95 | 95.0 | 32 | 27 | 84.4 | 97 | 97.0 | 2 | 2 | 0 | 1 |
| | VITEK 2 Compact | | | | | | | | | | | |
| Manual Dilution | 100 | 96 | 96.0 | 32 | 28 | 87.5 | 97 | 97.0 | 2 | 2 | 0 | 1 |

The performance of the VITEK 2 Compact (manual dilution) was considered acceptable based on the reproducibility (100%), QC (Table 2), and challenge (Table 5) studies.

b. Matrix comparison:

Not Applicable

3. Clinical studies:

a. Clinical Sensitivity:

Not Applicable

b. Clinical specificity:

Not Applicable

c. Other clinical supportive data (when a. and b. are not applicable):

Not Applicable

4. Clinical cut-off:

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Not Applicable

5. Expected values/Reference range:

Table 6: Breakpoints for Cefepime (FDA Approved labeling)

| Organism | Cefepime FDA MIC Breakpoints (μg/mL) | | |
| --- | --- | --- | --- |
| | S | I | R |
| Enterobacteriaceae | ≤2 | 4-8 | ≥16 |
| Pseudomonas aeruginosa | ≤8 | -- | ≥16 |

N. Proposed Labeling:

The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.

O. Conclusion:

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