SENSITITRE 18-24 SUSCEPTIBILITY PLATE

K073558 · Trek Diagnostic Systems, Inc. · JWY · Mar 13, 2008 · Microbiology

Device Facts

• Record ID: K073558
• Device Name: SENSITITRE 18-24 SUSCEPTIBILITY PLATE
• Applicant: Trek Diagnostic Systems, Inc.
• Product Code: JWY · Microbiology
• Decision Date: Mar 13, 2008
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.1640
• Device Class: Class 2

Indications 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 Gram positive isolates comprising of Staphylococci, Enterococci, and beta hemolytic Streptococci other than S. pneumoniae. This 510k will include cefoxitin screen at a concentration of 6 µg/mL for testing Staphylococcus aureus on the Sensititre® 18 – 24 hour MIC or BP panel.

Device Story

Sensititre® system performs antimicrobial susceptibility testing (AST) on non-fastidious Gram-positive bacteria; utilizes microdilution plates pre-dosed with antimicrobial agents. Inoculum prepared via direct method (0.5 McFarland); plates sealed, incubated 18–24 hours at 34–36°C. Growth detection via fluorescence monitoring of bacterial surface enzyme activity; fluorophore release from non-fluorescent substrate correlates to growth. Results read automatically (AutoReader®/ARIS®) or manually (viewer/SensiTouch®). System provides qualitative/quantitative susceptibility data to clinicians for antibiotic selection; aids in identifying resistant isolates.

Clinical Evidence

Performance evaluated using 207 S. aureus isolates (clinical, stock, challenge, and CDC strains) across three sites. Compared against CLSI broth dilution reference method. Manual read method showed 99.4% category agreement (CA) for clinical/challenge and 100% for CDC isolates; 1 very major discrepancy. Automated read method showed 98.9% CA for clinical/challenge and 100% for CDC isolates; 2 very major discrepancies. Reproducibility testing on 19 isolates demonstrated >95% reproducibility for both read methods. Quality control performed daily using S. aureus ATCC 29213 and BAA-976, meeting expected ranges.

Technological Characteristics

Microdilution plate format; dried antimicrobial agents. Fluorescence-based growth detection via bacterial surface enzyme activity (fluorogenic substrate). Incubation 18–24 hours at 34–36°C. Compatible with automated (AutoReader/ARIS) or manual (viewer/SensiTouch) reading. Inoculum standardized via nephelometer.

Indications for Use

Indicated for clinical susceptibility testing of gram-positive and gram-negative organisms, specifically for the detection of mecA-mediated resistance in Staphylococcus aureus using a Cefoxitin Screen (6µg/ml).

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

A. 510(k) Number:
k073558

B. Purpose for Submission:
To add Cefoxitin screen on the Sensititre® 18 – 24 hour MIC or Breakpoint (BP) panel for testing *Staphylococcus aureus*

C. Measurand:
Cefoxitin 6 µg/mL

D. Type of Test:
Quantitative Antimicrobial Susceptibility Test (AST) growth based fluorescence

E. Applicant:
TREK Diagnostic Systems, Inc.

F. Proprietary and Established Names:
Sensititre® 18 – 24 hour MIC or BP Susceptibility plates

G. Regulatory Information:
1. Regulation section:
866.1640 Antimicrobial Susceptibility Test Powder
2. Classification:
Class II
3. Product code:
JWY-manual readings of AST testing of >16 hour incubation
LRG Automated readings of AST of >16 hour incubation

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4. Panel:
Microbiology

H. Intended Use:

1. Intended use(s):
The Sensititre® 18 – 24 hour MIC or Breakpoint Susceptibility System is an in vitro diagnostic product for clinical susceptibility testing of non-fastidious Gram positive isolates comprising of Staphylococci, Enterococci, and beta hemolytic Streptococci other than S. pneumoniae.

2. Indication(s) for use:
This 510k will include cefoxitin screen at a concentration of 6 µg/mL for testing Staphylococcus aureus on the Sensititre® 18 – 24 hour MIC or BP panel.

3. Special conditions for use statement(s):
Prescription use

4. Special instrument requirements:
Not applicable

I. Device Description:
The Sensititre® MIC or BP Susceptibility system is a microversion of the classic broth dilution methods and can provide both qualitative and quantitative susceptibility results. Each microdilution plate is dosed with antimicrobial agents at appropriate dilutions then dried. After inoculation, plates are sealed with an adhesive seal, incubated at 34 -36°C for 18 – 24 hours and examined for bacterial growth.

AST results may be read automatically using the Sensititre® AutoReader® or Sensititre® ARIS® or manually using the Sensititre manual viewer or SensiTouch®.

J. Substantial Equivalence Information:

1. Predicate device name(s):
Pasco MIC and MIC/ID Panels

2. Predicate K number(s):
K033119

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3. Comparison with predicate:

| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Intended use | an in vitro diagnostic product for clinical susceptibility testing of gram negative and gram positive organisms. | same |
| Inoculum | Prepared from colonies using the direct inoculation method | Prepared from colonies using the direct inoculation method |
| Inoculation method | Direct equated to a 0.5 McFarland | Direct equated to a 0.5 McFarland |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Type panel | Dried antibiotics | 100 μl/well frozen |
| Incubation | 18-24 hours | 16-24 hours |
| Technology | Fluorescence detection of growth | Turbidity detection of growth |
| Reading method | Visual growth and Auto read by instrumentation | Turbidity detection of growth |

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

"Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test Systems; Guidance for Industry and FDA"; CLSI M7 (M100-S17) "Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard."

L. Test Principle:

The Sensititre® Autoread System utilizes fluorescence technology to read 18-24 hour plates. 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 form a non-fluorescent (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 fluorophore is then said to be quenched. The substrate can be added to the inoculum broth and dispensed into the test plates at the same time as the test organism or the plates can be prepared with substrate already added to the plate. Enzymatic action of the bacterial surface enzymes on the specific substrates cleave this bond releasing the fluorophore which is now capable of fluorescing. The amount of fluorescence detected is directly related to the activity of bacterial growth. The MIC is determined by observing the lowest

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dilution of antimicrobial agent that inhibits growth of the organism.

## M. Performance Characteristics (if/when applicable):

### 1. Analytical performance:

#### a. Precision/Reproducibility:

Reproducibility testing was performed on 19 S. aureus isolates. These were tested one time at each of the three sites on each reading method. This demonstrated >95% reproducibility using either the automated read method or the manual read method.

#### b. Linearity/assay reportable range:

Not applicable

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

The CLSI recommended Quality Control (QC) isolates, S. aureus ATCC 29213, and S. aureus ATCC BAA-976 were tested daily with acceptable results as shown in the table below. Quality control was also performed at all sites using both manual and autoread methods. The Sensititre® results demonstrated that the system can produce QC results in the recommended range for both manual and automated read methods.

Quality Control Table

| ORGANISM | Results | Sensititre®
Autoread | Sensititre®
manual | Reference |
| --- | --- | --- | --- | --- |
| | | | | |
| S. aureus | Neg | 60 | 60 | 60 |
| ATCC 29213 | Pos | | | |
| Expected Result : Neg | | | | |
| | | | | |
| S. aureus | Neg | | | |
| BAA-976 | Pos | 60 | 60 | 60 |
| Expected Result: Pos | | | | |
| | | | | |

A nephelometer was used at each site to standardize the inoculum and it was calibrated each time it was used.

#### d. Detection limit:

Not applicable

#### e. Analytical specificity:

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Not applicable

f. Assay cut-off:

Not applicable

## 2. Comparison studies:

a. Method comparison with predicate device:

The CLSI recommended broth dilution reference panel was prepared according to the CLSI recommendation. Clinical testing was performed on 207 S. aureus isolates at three sites which included fresh and stock clinical isolates, a set of challenge organisms, and Centers for Disease Control (CDC) study isolates. Two read methods (manual and automated) were evaluated. The comparison resulted in the following performance evaluations as reflected below.

Summary Table for (Manual Read Method)

| | Total | #S | #R | CA | %CA | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Clinical and Challenge | 177 | 75 | 102 | 176 | 99.4 | 0 | 1 |
| CDC | 30 | 13 | 17 | 30 | 100 | 0 | 0 |

Summary Table for (Auto Read Method)

| | Total | #S | #R | CA | %CA | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Clinical and Challenge | 177 | 74 | 103 | 175 | 98.9 | 0 | 2 |
| CDC | 30 | 13 | 17 | 30 | 100 | 0 | 0 |

CA-Category Agreement

maj-major discrepancies

vmj-very major discrepancies

CA is when the interpretation of the reference method agrees exactly with the interpretation of the VITEK®2 results.

b. Matrix comparison:

Not applicable

## 3. Clinical studies:

a. Clinical Sensitivity:

Not applicable

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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:
S. aureus – growth or no growth

N. Proposed Labeling:
The Interpretative criteria, QC isolates and the expected ranges are the same as recommended by the FDA. All values will be included in the package insert.

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