SENSITITRE 18 - 24 HOUR SUSCEPTIBILITY PLATE

K073653 · Trek Diagnostic Systems, Inc. · JWY · Mar 20, 2008 · Microbiology

Device Facts

• Record ID: K073653
• Device Name: SENSITITRE 18 - 24 HOUR SUSCEPTIBILITY PLATE
• Applicant: Trek Diagnostic Systems, Inc.
• Product Code: JWY · Microbiology
• Decision Date: Mar 20, 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.

Device Story

Sensititre system performs antimicrobial susceptibility testing (AST) via micro-broth dilution. Device uses dried antimicrobial agents in microdilution plates; inoculated with patient bacterial isolates; incubated 18–24 hours. Principle of operation: fluorescence-based detection of bacterial growth; fluorogenic substrate added to broth; bacterial surface enzymes cleave substrate to release fluorophore; fluorescence intensity correlates to growth. Output: qualitative/quantitative susceptibility results (MIC or breakpoint). Used in clinical laboratories; operated by technicians. Results read manually (viewer/SensiTouch) or automatically (AutoReader/ARIS). Output informs clinicians of inducible clindamycin resistance in Staphylococcus spp., guiding antibiotic selection.

Clinical Evidence

Performance evaluated using 207 S. aureus and 200 coagulase-negative Staphylococcus isolates across three sites. Compared against CLSI broth dilution reference method. Manual read method showed 100% category agreement (CA) for both groups. Automated read method showed 100% CA for S. aureus and 98.9% CA for coagulase-negative Staphylococcus (2 very major errors). Reproducibility testing performed on 15 isolates with acceptable results. QC performed daily using S. aureus ATCC BAA-976 and BAA-977.

Technological Characteristics

Micro-broth dilution AST system. Fluorescence-based growth detection via fluorogenic substrate cleavage by bacterial surface enzymes. Dried antimicrobial agents in microdilution plates. Incubation 34-36°C for 18-24 hours. Connectivity via Sensititre AutoReader or ARIS instrumentation. Manual reading options include viewer or SensiTouch.

Indications for Use

Indicated for clinical susceptibility testing of gram-positive and gram-negative organisms. Specifically, the Dtest is indicated for Staphylococcus spp. isolates that are erythromycin-resistant (MIC ≥ 8µg/ml) and clindamycin-susceptible or intermediate (MIC < 2µg/ml) to detect inducible clindamycin resistance.

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:
k073653

B. Purpose for Submission:
To add the Dtest to the Sensititre® 18 – 24 hour MIC or Breakpoint (BP) panel for testing *Staphylococcus* spp.

C. Measurand:
Clindamycin 0.5, 1.5 µg/mL
Erythromycin 4, 8 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 &gt;16 hour incubation
LRG Automated readings of AST of &gt;16 hour incubation

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4. Panel:

83 - 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 is indicated for the addition of Dtest (Dtest well 1 contains 4 µg/mL erythromycin and 0.5 µg/mL clindamycin; Dtest well 2 contains 8 µg/mL erythromycin and 1.5 µg/mL clindamycin) for testing Staphylococcus spp. 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):

2

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K033119

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-S18) "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

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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.

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

### 1. Analytical performance:

#### a. Precision/Reproducibility:

Reproducibility testing was performed on ten Staphylococcus aureus, and five Coagulase Negative Staphylococcus isolates using either the automated read method or the manual read method. Acceptable reproducibility was demonstrated with only category agreement (Negative, Positive) since that is all that is detected.

#### 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 BAA-976 and S. aureus ATCC BAA-977 were tested daily with acceptable results with the reference method. Quality control was also performed at all sites using both the manual read method and the Autoread method. The Sensititre® results demonstrated that the system can produce QC results in the recommended range for both the manual method of reading and the automated read method.

### Quality Control Table for DTEST

| ORGANISM | Conc ug/mL (Ery/Cli) | Sensititre® Autoread | Sensititre® manual | Reference |
| --- | --- | --- | --- | --- |
| | | | | |
| S. aureus BAA-976
Expected Range :
Neg | 4/0.5 Neg | 64 | 60 | 63 |
| | 8/1.5 Neg | 64 | 60 | 63 |
| | Pos | | | |
| | | | | |
| S. aureus BAA-977
Expected Range : Pos | 4/0.5 Neg | 1 | 1 | 0 |
| | 8/1.5 Neg | 1 | 1 | 0 |
| | | | | |
| | 4/0.5 Pos | 57 | 58 | 60 |
| | 8/1.5 Pos | 57 | 58 | 60 |
| | | | | |

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

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calibrated each time it was used. Colony counts were also performed at each site to demonstrate that colony counts were in the expected range in most occasions.

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:

The CLSI recommended broth dilution reference panel was prepared according to the CLSI recommendation. Clinical testing was performed on 207 S. aureus and 200 coagulase negative Staphylococcus spp. isolates at three external sites which included fresh and stock clinical isolates, a set of challenge organisms, and CDC study isolates.

Sensititre Dtest uses two wells to detect inducible clindamycin resistance. Growth in either or both wells indicates the presence of inducible clindamycin resistance. These isolates would be reported as clindamycin resistant. No growth in both wells will be reported as negative for inducible resistance.

The comparison resulted in the following performance evaluations as reflected below.

Summary Table for (Manual Read Method)

| | Total | CA | CA% | # Neg | # Pos | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- |
| S. aureus | 207 | 207 | 100 | 92 | 115 | 0 | 0 |
| Coagulase-negative Staphylococcus | 200 | 200 | 200 | 95 | 105 | 0 | 0 |

Summary Table for (Auto Read Method)

| | Total | CA | CA% | # Neg | # Pos | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- |
| S. aureus | 207 | 207 | 100 | 92 | 115 | 0 | 0 |
| Coagulase-negative Staphylococcus | 197 | 195 | 98.9 | 91 | 106 | 0 | 2 |

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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 species – Growth (inducible clindamycin resistance)
No growth (no inducible clindamycin resistance)

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

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