MICROSCAN DRIED GRAM-NEGATIVE MIC/COMBO PANELS-AMOXICILLIN/CLAVULANATE POTASSIUM (AUGMENTIN)

K033940 · Dade Behring, Inc. · LTT · Feb 25, 2004 · Microbiology

Device Facts

• Record ID: K033940
• Device Name: MICROSCAN DRIED GRAM-NEGATIVE MIC/COMBO PANELS-AMOXICILLIN/CLAVULANATE POTASSIUM (AUGMENTIN)
• Applicant: Dade Behring, Inc.
• Product Code: LTT · Microbiology
• Decision Date: Feb 25, 2004
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.1640
• Device Class: Class 2

Intended Use

The MicroScan® Dried Gram-Negative MIC/Combo Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultative anaerobic gram-negative bacilli. After inoculation, panels are incubated for 16 - 20 hours at 35°C +/- 1°C in a non-CO2 incubator, and read either visually or with MicroScan instrumentation, according to the Package Insert. This particular submission is for the addition of the antimicrobial amoxicillin/ K. clavulanate at concentrations of 0.25/0.12 to 128/64 mcg/ml to the test panel. The gram-negative organisms which may be used for amoxicillin/K. clavulanate susceptibility testing in this panel are: Enterobacter species Escherichia coli Klebsiella species Proteus mirabilis

Device Story

MicroScan® Dried Gram-Negative MIC/Combo Panels contain dehydrated Mueller Hinton Broth and antimicrobial agents. Panels are rehydrated and inoculated with bacterial suspensions prepared via turbidity or Prompt™ methods. After 16-20 hours incubation at 35°C, growth is assessed to determine Minimum Inhibitory Concentration (MIC) and categorical interpretation (SIR). Reading performed manually (touchSCAN® SR) or automatically (autoSCAN® 4 or WalkAway® instrument). Automated systems use optics and growth algorithms to measure inhibition. Results assist clinicians in selecting appropriate antimicrobial therapy for gram-negative bacilli infections.

Clinical Evidence

Performance evaluated via clinical and challenge studies (n=377 combined). Comparison against NCCLS M7-A6 reference method. Essential Agreement (EA) was 99.7% for turbidity/manual method. Category Agreement (CA) was 96.3% (combined). Challenge set (n=75) tested across multiple inoculation (turbidity, Prompt™) and reading (manual, autoSCAN® 4, WalkAway®) methods; EA ranged 98.7-100%, CA ranged 93.3-94.7%. Reproducibility demonstrated across 3 sites/3 days; overall reproducibility >97%.

Technological Characteristics

Miniaturized broth dilution panel; dried antimicrobial agents. Dimensions/form factor: multi-well panel. Connectivity: compatible with autoSCAN-4 and WalkAway instrumentation. Inoculation methods: Turbidity or Prompt. Incubation: 16-20 hours at 35°C +/- 1°C in non-CO2 incubator. Analysis: visual or automated optical reading.

Indications for Use

Indicated for testing Amoxicillin/Clavulanate Potassium (0.25/0.12-128/64ug/mL) against Enterobacteriaceae group organisms.

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.

Predicate Devices

• MicroScan® Dried Gram-Negative and Gram-Positive MIC/Combo Panels (K862140)

Submission Summary (Full Text)

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510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION
DECISION SUMMARY
DEVICE ONLY TEMPLATE

A. 510(k) Number:
k033940

B. Analyte:
Amoxicillin/Clavulanate Potassium at 0.25/0.12-128/64ug/mL AST

C. Type of Test:
Quantitative growth based detection algorithm using optics light detection

D. Applicant:
Dade Behring Inc.
Dade MicroScan Inc.

E. Proprietary and Established Names:
Dried Gram-Negative MIC/Combo panels

F. Regulatory Information:
1. Regulation section:
866.1640 Antimicrobial Susceptibility Test Powder
2. Classification:
II
3. Product Code:
LRG-Instrument for Auto Reader & Interpretation of Overnight Antimicrobial Susceptibility Systems
JWY - Manual Antimicrobial Susceptibility Test Systems
LTT – Panels, Test, Susceptibility, Antimicrobial
LTW – Susceptibility Test Cards, Antimicrobial
4. Panel:
83 Microbiology

G. Intended Use:
1. Intended use(s):
For use with MicroScan® Dried Gram Negative MIC/Combo Panels and Dried Gram Negative Breakpoint Combo Panels.
MicroScan® panels are designed for use in determining antimicrobial agent susceptibility and/or identification to the species level of aerobic and facultatively anaerobic gram-negative bacilli.
The MicroScan® Dried Gram-Negative MIC/Combo Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of

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colonies grown on solid media of rapidly growing aerobic and facultative anaerobic gram-negative bacilli.

2. **Indication(s) for use:**
This will include the antibiotic Amoxicillin/Clavulanate Potassium at 0.25/0.12-128/64ug/mL for testing the appropriate organism in the Enterobacteriaceae group.

3. **Special condition for use statement(s):**
The Prompt™ method of inoculation is an alternate method of inoculum preparation that is supported in the product insert along with the turbidity method. The stationary and log inoculum methods should not be used with this antibiotic.

4. **Special instrument Requirements:**
These panels can be read at ≥ 16 hours of incubation either manually, automatically on the autoSCAN® 4, or with the WalkAway® instrument systems.

## H. Device Description:

The MicroScan® Dried Gram-Negative MIC/Combo Panel contains microdilutions of each antimicrobial agent in various concentrations with Mueller Hinton Broth and various nutrients which are dehydrated and dried in panels. Each panel contains two control wells: a no-growth control well (contains water only/no nutrients or broth), and a growth control well (contains test medium without antibiotic). The panel is rehydrated and inoculated at the same time with 0.1 ml of suspension prepared by the turbidity method (inoculum prepared in water, then 0.1ml transferred to 25ml of inoculum water containing pluronic-D/F-a wetting solution). The Prompt™ method of inoculation is also recommended as an alternate means of preparing the inoculum. The panels are incubated at 35°C in a non-CO₂ incubator for 16-20 hours and read by visual observation for growth. Panels may also be read automatically with the WalkAway® or the AutoSCAN®4.

## I. Substantial Equivalence Information:

1. **Predicate device name(s):**
MicroScan® Dried Gram-Negative and Gram-Positive MIC/Combo Panels

2. **Predicate K number(s):**
K862140

3. **Comparison with predicate:**

| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Intended Use | For use with MicroScan® Dried Gram Negative MIC/Combo Panels and Dried Gram Negative Breakpoint Combo Panels. MicroScan® panels are designed for use in determining antimicrobial agent susceptibility and/or identification to the species level of aerobic and facultatively | Same |

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| | anaerobic gram-negative bacilli. | | |
| --- | --- | --- | --- |
| Test Panel | Dried | | same |
| Instrument/manual | Both manual and instrument reading available. | | same |
| Technology | Growth based after 16 hours incubation | | same |
| Results | Report results as minimum inhibitory concentration (MIC) and categorical interpretation (SIR). | | Same |
| Differences | | | |
| Item | Device | Predicate | |
| Reading algorithm | Unique for Amoxicillin/Clavulanate Potassium | Unique for each antibiotic | |
| Test organism | Enterobacteriaceae | Gram positive and gram negative organisms | |
| Inoculum preparation from colonies | Turbidity and Prompt™ | All methods recommended in the package insert. | |

J. Standard/Guidance Document Referenced (if applicable):
Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA”; NCCLS M7 (M100-S13) “Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard”.

K. Test Principle:
After incubation in a non-CO₂ incubator for 16-20 hours, the minimum inhibitory concentration (MIC) for the test organisms are read by determining the lowest antimicrobial concentration showing inhibition of growth. The panels are read either manually using a touchSCAN® SR, or with the autoSCAN 4® or the WalkAway® instrument, which uses an optics systems with growth algorithms to directly measure organism growth.

L. Performance Characteristics (if/when applicable):
1. Analytical performance:
a. Precision/Reproducibility:
Reproducibility was demonstrated using 10 isolates tested at 3 sites on 3 separate days in triplicate. All ten isolates had a mode that was on scale. The study included the testing of the following inoculum and reading variables; turbidity inoculum method and Prompt™ method of inoculation with reading performed manually using a touchSCAN® SR, or by instrumentation using the autoSCAN 4® or the WalkAway® instrument. The following table provides the overall reproducibility results for all combinations of these variables:

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| Difference in the number of dilutions between the mode of the MicroScan result and the actual result with each different variable for overall reproducibility | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Inoculation method | Read method | ≥ Minus 2 dilutions | Minus 1 dilution | Exact | Plus 1 dilution | ≥ Plus 2 dilutions | % reproducible |
| Turbidity | Manual(touchSCAN®) | | 16 | 209 | 38 | 6 | 97.8 |
| Turbidity | WalkAway® | | 4 | 221 | 38 | 7 | 97.4 |
| Turbidity | autoSCAN® 4 | | 14 | 208 | 41 | 7 | 97.4 |
| Prompt™ | Manual(touchSCAN®) | | 31 | 225 | 12 | 2 | 99.3 |
| Prompt™ | WalkAway® | | 22 | 234 | 12 | 2 | 99.3 |
| Prompt™ | autoSCAN® 4 | | 11 | 226 | 31 | 2 | 99.3 |

This demonstrates good reproducibility overall but the Turbidity method also had one site that was reproducible at <95% (within site reproducibility) for all read methods.

The reproducibility strains were also evaluated for inoculum density for the Prompt™ method with colony counts ranging from 1 x 10⁵ to 13 x 10⁵ with the same variability that was noticed in the Quality Control inoculum density studies. Also more of the averages tended to be closer to 1 x 10⁶ than those that were closer to 5 x 10⁵.

b. Linearity/assay reportable range:
Not applicable

c. Traceability (controls, calibrators, or method):

Quality Control was performed daily with the turbidity method and with the Prompt™ selectively with the following results.

| ORGANISM | | | | | | RESULTS | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | ug/mL | ref | Turbidity inoculation | | | Prompt™ inoculation | | |
| | | | Manual | autoSCAN® | Walk-Away® | Manual | autoSCAN® | Walk-Away® |
| E. coli ATCC 25922
Expected range 2/1 – 8/4 ug/mL | 1/0.5 | | | | | | | |
| | 2/1 | 2 | | | 9 | | | 4 |
| | 4/2 | 84 | 99 | 81 | 72 | 92 | 73 | 70 |
| | 8/4 | 26 | 13 | 1 | 1 | 19 | 7 | 6 |
| | 16/8 | | | | | | | |
| | | | | | | 1 | 2 | 2 |
| | | | | | | | | |
| E. coli ATCC 35218
Expected range 4/2 – 16/8 ug/mL | 2/1 | 2 | 4 | 2 | 2 | 4 | 1 | 1 |
| | 4/2 | 5 | 32 | 29 | 29 | 26 | 23 | 22 |
| | 8/4 | 83 | 60 | 37 | 37 | 68 | 45 | 46 |
| | 16/8 | 9 | 3 | 1 | 1 | 1 | | |
| | 32/16 | | | | | | | |

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Quality control results demonstrated the ability of all variables of the procedure (reading and inoculation) to produce acceptable results. There does not appear to be much of a trend in any of the methods, but the Prompt™ results were less reproducible than the turbidity method of inoculation for the *E. coli* STCC 25922.

Inoculum density control: A turbidity meter was used for the turbidity inoculation method. The Prompt™ method of inoculation had colony counts performed periodically throughout the study to determine the average inoculum density since there is no visual check of the inoculum using this device. Colony counts were also performed using the turbidity method when inoculating both the dried MicroScan® panels and the frozen reference panels. The turbidity method of inoculation for the reference test and all QC strains tested (n = 83) had an average inoculum that was in the range of 3 X 10⁵ to 4.6 X 10⁵, while the Prompt™ method of inoculation had far more variability with average inoculum ranges from 5.4 to 14 X 10⁵. The inoculum of the Prompt™ method of inoculation generally provides a higher number of CFU with more variability than a method using a turbidity meter. The chart below shows this comparison.

| organism | Method of inoculation | Lowest CC x 10⁵ | Highest CC x 10⁵ | Average CC x 10⁵ |
| --- | --- | --- | --- | --- |
| | | | | |
| *E. coli* ATCC 25922 | Prompt™ | 1.8 | 92 | 10.4 |
| | Reference | 1.1 | 4.9 | 3.8 |
| | | | | |
| E. coli ATCC 35218 | Prompt™ | 3.2 | 36 | 9.6 |
| | Reference | 2.3 | 6.8 | 3.7 |

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:
Clinical testing was performed at three sites using mainly fresh isolates supplemented with stock isolates of *Enterobacteriaceae*. A comparison of the MicroScan® Dried Gram-Negative test panel results was made to the reference method conducted as recommended in the NCCLS standard M7-A6. Testing of the reference method and the MicroScan panels was performed at the same time. A challenge set was also tested

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at one site and compared to the reference broth dilution result mode that was determined by previous testing of each isolate multiple times in the recommended reference panel.

Turbidity inoculum with manual readings.

| | total | EA | %EA | Total evaluable | EA of evaluable | %EA | CA | %CA | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Clinical | 302 | 301 | 99.7 | 300 | 299 | 99.7 | 292 | 96.7 | 102 | 10 | 0 | 0 |
| Challenge | 75 | 75 | 100 | 73 | 73 | 100 | 71 | 94.7 | 30 | 4 | 0 | 0 |
| Combined | 377 | 376 | 99.7 | 373 | 372 | 99.7 | 363 | 96.3 | 132 | 14 | 0 | 0 |

EA-Essential Agreement

CA-Category Agreement

R-resistant isolates

maj-major discrepancies

vmj-very major discrepancies

min-minor discrepancies

Evaluable results are those that fall within the test range of the reference method and could also be on-scale with the new device if within the plus/minus one well variability. EA is when there is agreement between the reference method and the MicroScan® within plus or minus one serial two-fold dilution of antibiotic. CA is when the interpretation of the reference method agrees exactly with the interpretation of the MicroScan® result.

The challenge set of organisms was also tested using the Prompt™ method of inoculation with all reading methods and the turbidity method of inoculation with the WalkAway® and the autoSCAN®4. This included seventy five challenge isolates that were tested at one site. The inoculum was prepared by the turbidity or Prompt™ method and incubated in the WalkAway® instrument. All panels had additional readings performed after the WalkAway® reading was completed using the autoSCAN®-4 and then manually on the touchSCAN®-SR.

The following table demonstrates the performance based on essential agreement and category agreement for the challenge set and the different inoculation and reading methods.

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| | total | EA | %EA | Total evaluable | EA of evaluable | %EA | CA | %CA | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Turbidity/manual | 75 | 75 | 100 | 73 | 73 | 100 | 71 | 94.7 | 30 | 4 | 0 | 0 |
| Turbidity/WalkAway® | 75 | 75 | 100 | 73 | 73 | 100 | 70 | 93.3 | 30 | 5 | 0 | 0 |
| Turbidity/autoSCAN® | 75 | 75 | 100 | 73 | 73 | 100 | 70 | 93.3 | 30 | 5 | 0 | 0 |
| Prompt™/manual | 75 | 74 | 98.7 | 73 | 73 | 100 | 71 | 94.7 | 30 | 4 | 0 | 0 |
| Prompt™/WalkAway® | 75 | 74 | 98.7 | 73 | 73 | 100 | 70 | 93.3 | 30 | 4 | 0 | 1 |
| Prompt™/autoSCAN® | 75 | 74 | 98.7 | 73 | 73 | 100 | 70 | 93.3 | 30 | 4 | 0 | 1 |

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: Not applicable

5. Expected values/Reference range: $\leq 8 / 4$ (S), $16 / 8$ (I), $\geq 32 / 16$ (R) The interpretative criteria and QC are the same as recommended in NCCLS. All values will be included in the package insert.

# M. Conclusion:

The reproducibility, quality control results and overall performance is acceptable as described in the "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA" which was used in the design and evaluation of the study. The appropriate control organisms are included in the labeling and are the same as those recommended in the NCCLS M7-(M100-S13) document. This performance as compared to a standard method demonstrates substantial equivalency to the predicate.