← Product Code [LON](/submissions/MI/subpart-b%E2%80%94diagnostic-devices/LON) · K050976

# VITEK 2 GRAM POSITIVE TRIMETHOPRIM/SULFAMETHOXAZOLE (K050976)

_bioMerieux, Inc. · LON · May 23, 2005 · Microbiology · SESE_

**Canonical URL:** https://fda.innolitics.com/submissions/MI/subpart-b%E2%80%94diagnostic-devices/LON/K050976

## Device Facts

- **Applicant:** bioMerieux, Inc.
- **Product Code:** [LON](/submissions/MI/subpart-b%E2%80%94diagnostic-devices/LON.md)
- **Decision Date:** May 23, 2005
- **Decision:** SESE
- **Submission Type:** Traditional
- **Regulation:** 21 CFR 866.1645
- **Device Class:** Class 2
- **Review Panel:** Microbiology
- **Attributes:** AI/ML

## Indications for Use

The VITEK® 2 Antimicrobial Susceptibility Test (AST) is intended to be used with the VITEK® 2 and VITEK® 2 Compact Systems for the automated quantitative or qualitative susceptibility testing of isolated colonies of clinically significant aerobic gram-positive bacteria, including Staphylococcus spp., Enterococcus spp., Streptococcus agalactiae, and S. pneumoniae. VITEK® 2 Gram Positive Trimethoprim/sulfamethoxazole is designed for susceptibility testing of Staphylococcus aureus. VITEK 2 Gram Positive Trimethoprim/sulfamethoxazole is a qualitative test. It 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.

## Device Story

VITEK® 2 Gram Positive Trimethoprim/sulfamethoxazole card is an in vitro diagnostic test for antimicrobial susceptibility. Input: pure culture organism suspension standardized to McFarland 0.5. Operation: card contains 64 microwells with premeasured antibiotic and culture medium; system automatically fills/seals (or manual for Compact) and incubates at 35.5°C. Optical scanning monitors growth via light transmittance every 15 minutes for up to 18 hours. Output: MIC value and interpretive category result. Used in clinical laboratories by technicians/lab staff. Results assist healthcare providers in determining appropriate antimicrobial therapy for Staphylococcus aureus infections.

## Clinical Evidence

Bench testing only. Performance evaluated using fresh and stock clinical isolates and challenge strains. Compared against NCCLS reference macrobroth dilution method. Results demonstrated 99.6% overall Category Agreement. Reproducibility and Quality Control testing yielded acceptable results.

## Technological Characteristics

Microdilution-based AST card with 64 microwells. Uses optical transmittance to measure organism growth. Automated incubation at 35.5°C. Compatible with VITEK® 2 and VITEK® 2 Compact systems. Software-based discriminant analysis algorithm for MIC calculation.

## Regulatory 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 Gram Positive AST Panel for sparfloxacin (N50510/S141)

## Submission Summary (Full Text)

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

A. 510(k) Number:
k050976

B. Purpose for Submission:
To include Trimethoprim/sulfamethoxazole on the VITEK® 2 gram positive AST panel for testing appropriate gram positive isolates.

C. Measurand:
Trimethoprim/sulfamethoxazole at ≤0.5/9.5 - ≥16/304μg/ml

D. Type of Test:
Qualitative growth based detection algorithm using optics light detection

E. Applicant:
bioMerieux, Inc.

F. Proprietary and Established Names:
VITEK® 2 Gram Positive Trimethoprim/sulfamethoxazole

G. Regulatory Information:
1. Regulation section:
866.1645 Short-Term Antimicrobial Susceptibility Test System
2. Classification:
II
3. Product Code:
LON System, Test, Automated, Antimicrobial Susceptibility, Short Incubation
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 agalactiae, and S. pneumoniae.

The VITEK® 2 Gram Positive susceptibility Card is intended for use with the VITEK® 2 System and the VITEK® 2 Compact System in clinical laboratories as an in vitro test to determine the susceptibility of Staphylococcus spp., Enterococcus spp., and Streptococcus agalactiae to antimicrobial agents when used as instructed in the Online Product Information.

2. Indication(s) for use:
This submission is for the addition of the antibiotic Trimethoprim/sulfamethoxazole at concentrations at 2, 8, and 16 ug/mL for a calling range of ≤0.5/9.5-≥16/304ug/mL to the VITEK® 2 gram positive susceptibility CARD for the testing of Staphylococcus aureus.

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It 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.

3. Special condition for use statement(s): Prescription Use only.
4. Special instrument Requirements: Not applicable

# I. Device Description:

Each VITEK® 2 test card contains 64 microwells. A control well, that contains only microbiological culture medium is resident on all cards, with the remaining wells containing premeasured amounts of a specific antibiotic combined with culture medium. A suspension of organism is made in  $0.45\%$  sterile saline from a pure culture and standardized to a McFarland 0.5 standard using the DensiChek. The VITEK® 2 automatically fills, seals and places the card into the incubator/reader. The VITEK® 2 Compact has a manual filling and sealing operation. Each card is manually transferred from the cassette to a card loader to a place into a slot on a carousel where it remains throughout its incubation. The VITEK® 2 systems monitor growth by optical scanning of each well in the card over a defined period of time (up to 18 hours) of incubation at  $35.5^{\circ}\mathrm{C}$ . Minimum Inhibitory Concentration (MIC) readings are performed every 15 minutes. 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 contained on the card.

# J. Substantial Equivalence Information:

1. Predicate device name(s): VITEK® 2 Gram Positive AST Panel for sparfloxacin
2. Predicate K number(s): N50510/S141
3. Comparison with predicate:

|  Similarities  |   |   |
| --- | --- | --- |
|  Item | Device | Predicate  |
|  Intended Use | AST testing of gram positive isolates | Same  |
|  Test organism | Colonies of Staphylococcus spp. | Same  |
|  Test Card | VITEK® 2 card format with base broth | Same  |
|  Instrument | VITEK® 2 System and the VITEK® 2 Compact System | Same  |
|  Performance | Categorical interpretation | Categorical interpretation  |
|  Differences  |   |   |
|  Item | Device | Predicate  |
|  Antibiotic | Trimethoprim/sulfamethoxazole | Sparfloxacin  |
|  Reading algorithm | Unique for Trimethoprim/sulfamethoxazole | Unique for Sparfloxacin  |

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K. Standard/Guidance Document Referenced (if applicable):
Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA”; Clinical and Laboratory Standards Institute (CLSI) M7 (M100-S15) “Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard”.

L. Test Principle:
Optics systems use visible light to directly measure organism growth. These 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. An interpretive call is made between 4 and 16 hours for an early reading of results with an option to incubate up to 18 hours if necessary. The VITEK® 2 Susceptibility Card test is based on the microdilution minimum inhibitory concentration technique with concentrations equivalent to standard method concentrations. Several parameters based on the growth characteristics observed are used to provide appropriate input for the MIC calculations. Discriminate analysis is used to develop the algorithm that determines the susceptibility result for all antimicrobials on the VITEK® 2 systems. The MIC result must be linked to an organism identification in order to determine a category interpretation. A category interpretation will be reported.

M. Performance Characteristics (if/when applicable):
1. Analytical performance:
a. Precision/Reproducibility:
Ten on-scale S. aureus isolates were tested in triplicate at each of three sites for three days for an overall inter and intra site reproducibility of >95%. This testing was performed using both the manual dilution of the inoculum and also the automatic dilution method.
b. Linearity/assay reportable range:
Not applicable
c. Traceability (controls, calibrators, or method):
Quality Control was performed during the studies using both the auto-dilution and the manual method of diluting the organisms. This included one recommended QC organism with the following results.

|  ORGANISM | VITEK® Conc. | Auto-dilution | Manual dilution | Reference conc. | Reference  |
| --- | --- | --- | --- | --- | --- |
|  S. aureus ATCC 29213
Range ≤0.5/9.5 ug/mL | ≤10 | 79 | 77 | ≤10 | 79  |
|   |  20 |  |  | 20 |   |
|   |  40 |  |  | 40 |   |
|   |  80 |  |  | 80 |   |
|   |  160 |  |  | 160 |   |
|   |  ≥320 |  |  | 320 |   |
|   |   |  |  | 640 |   |
|   |   |  |  | ≥1280 |   |

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Inoculum density control: Internal verification of the DensiChek was performed using 2 ATCC organisms and five instruments with 50 results available for each organism. The clinical sites also performed weekly standardization of the DensiChek used at that site. All recorded calibrated values were within acceptable parameters.

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:

A comparison of the clinical data was performed to the broth macrodilution as the reference method as described in the CLSI M7. All of the test organisms that provided results did so in  $< 16$  hours. Testing was performed using the automatic dilution feature. In the Clinical testing both oxacillin susceptible and oxacillin resistant Staphylococcus aureus were tested at three sites that included both clinical and challenge isolates. A total of 405 clinical isolates were tested. Due to insufficient concentrations tested,  $(< 5)$  a CA only can be determined. The data in the table below reflects the testing performed using broth macrodilution as the reference method for the evaluation criteria:

|   | total | CA | %CA | #R | min | maj | vmj  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  Clinical | 405 | 403 | 99.5 | 38 | 0 | 2 | 0  |
|  Challenge | 75 | 75 | 100 | 4 | 0 | 0 | 0  |
|  Combined | 480 | 478 | 99.6 | 42 | 0 | 0 | 0  |

CA-Category agreement

min-minor discrepancies

vmj-very major discrepancies

maj-major discrepancies

CA is when the interpretation of the VITEK  $^{10}$  2 results agrees exactly with the interpretation of the reference method. The CA is acceptable when compared to the reference method as described in the FDA guidance document, "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA".

The challenge set of organisms was also tested at one site using the manual and auto-dilution methods of inoculation with the following performance that demonstrated that there was little or no difference between the two inoculation methods. The table below contains the data from the two dilution methods of testing Staphylococcus aureus using broth macrodilution as the reference method:

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Manual testing:
|   | total | #R | CA | %CA | Min | Maj | vmj  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  Challenge | 75 | 4 | 75 | 100 | 0 | 0 | 0  |

Autodilution testing:
|   | total | #R | CA | %CA | Min | Maj | vmj  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  Challenge | 75 | 4 | 75 | 100 | 0 | 0 | 0  |

The test device had a growth rate of >95%.

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:
Staphylococcus spp. ≤2/38 (S), ≥4/76 (R)

The expected value range and the interpretive criteria are the same as recommended in CLSI.

Staphylococcus spp. ≤0.5/9.5 (S)

QC is the same as recommended in CLSI.

N. Proposed Labeling
The labeling is sufficient and it satisfies the requirement of 21 CFR Part 809.10

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

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**Source:** [https://fda.innolitics.com/submissions/MI/subpart-b%E2%80%94diagnostic-devices/LON/K050976](https://fda.innolitics.com/submissions/MI/subpart-b%E2%80%94diagnostic-devices/LON/K050976)

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