ETEST TIGECYCLINE GRAM POSITIVE AND GRAM NEGATIVE AEROBIC BACTERIA, STREPTOCOCCUS SPP. AND ANAEROBIC BACTERIA

K052366 · Ab Biodisk · JWY · Oct 13, 2005 · Microbiology

Device Facts

• Record ID: K052366
• Device Name: ETEST TIGECYCLINE GRAM POSITIVE AND GRAM NEGATIVE AEROBIC BACTERIA, STREPTOCOCCUS SPP. AND ANAEROBIC BACTERIA
• Applicant: Ab Biodisk
• Product Code: JWY · Microbiology
• Decision Date: Oct 13, 2005
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.1640
• Device Class: Class 2

Indications for Use

Tigecycline at 0.016 – 256 µg/mL for in vitro diagnostic use for MIC determination with Gram positive and Gram negative aerobic bacteria, Streptococcus species other than S. pneumoniae, and anaerobic bacteria.

Device Story

Etest® is a quantitative antimicrobial susceptibility testing system. It consists of a predefined antibiotic gradient on a plastic strip. The strip is applied to an inoculated agar plate. During overnight incubation, the antibiotic diffuses into the agar, creating a concentration gradient. The MIC is determined by observing the point where the bacterial growth inhibition ellipse intersects the strip. Used in clinical microbiology laboratories by trained technicians. Results assist clinicians in selecting appropriate antibiotic therapy for patients with bacterial infections.

Clinical Evidence

Bench testing only. The submission demonstrates the performance of the Etest® for Tigecycline by comparing MIC results to established reference methods for the specified bacterial groups.

Technological Characteristics

Quantitative gradient diffusion method. Consists of a plastic strip with a predefined antibiotic concentration gradient. Designed for use on agar media. Manual application and visual reading of MIC values after overnight incubation.

Indications for Use

Indicated for the determination of antimicrobial susceptibility (MIC) of Tigecycline in Gram-positive, S. pneumoniae, and anaerobic bacteria.

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:
K052366

B. Purpose for Submission:
Addition of the antibiotic Tigecycline at concentrations of 0.016 - 256 µg/mL to the Etest® in the MIC range of 0.016 – 256 µg/mL with Gram positive and Gram negative aerobic bacteria, *Streptococcus* species other than *S. pneumoniae*, and anaerobic bacteria.

C. Measurand:
Tigecycline at 0.016 – 256 µg/mL

D. Type of Test:
Manual Antimicrobial Susceptibility Test System—growth based

E. Applicant:
AB BIODISK

F. Proprietary and Established Names:
Etest® Antimicrobial Susceptibility Test – Tigecycline at 0.016 – 256 µg/mL

G. Regulatory Information:
1. Regulation section:
21 CFR 866.1640 – Antimicrobial susceptibility test powder
2. Classification:
Class II
3. Product Code:
JWY – Manual Antimicrobial Susceptibility Test Systems
4. Panel:
83 Microbiology

H. Intended Use:
1. Intended use(s):
Tigecycline at 0.016 – 256 µg/mL for *in vitro* diagnostic use for MIC determination with Gram positive and Gram negative aerobic bacteria, *Streptococcus* species other than *S. pneumoniae*, and anaerobic bacteria.

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Etest® is a quantitative technique for the determination of antimicrobial susceptibility of both non-fastidious Gram negative and Gram positive aerobic bacteria, such as Enterobacteriaceae, Pseudomonas, Staphylococcus and Enterococcus species and fastidious bacteria, such as anaerobes, N. gonorrhoeae, S. pneumoniae, Streptococcus, and Haemophilus species. The system comprises a predefined antibiotic gradient which is used to determine the Minimum Inhibitory Concentration (MIC) in $\mu \mathrm{g} / \mathrm{mL}$ of different antimicrobial agents against microorganisms as tested on agar media by overnight incubation.

2. Indication(s) for use:

This submission is for the addition of antibiotic Tigecycline to the Etest® for MIC determination in the MIC range of $0.016 - 256\ \mu \mathrm{g/mL}$ with Gram positive and Gram negative aerobic bacteria, Streptococcus species other than S. pneumoniae, and anaerobic bacteria.

3. Special condition for use statement(s):

Prescription Use Only

4. Special instrument Requirements:

Manual readings only

I. Device Description:

The Etest® gradient technology is based on a combination of the concepts of dilution and diffusion test methods for susceptibility testing. Etest® directly quantifies antimicrobial susceptibility in terms of discrete MIC values. When the Etest® strip is applied to an inoculated agar plate, the antibiotic is immediately released from the plastic surface into the agar. A predefined, continuous gradient of antibiotic concentrations is created and maintained directly underneath the strip. After incubation whereby bacterial growth becomes visible, a symmetrical inhibition ellipse centered along the strip will be observed. The MIC value in $\mu \mathrm{g} / \mathrm{mL}$ is read where the ellipse edge intersects the strip. Since Etest® generates MIC values which fall between two-fold dilutions for interpretation; the MIC value read must be recorded to the next higher two-fold dilution.

Etest® consists of a thin, inert and non-porous plastic strip, which is $5\mathrm{mm}$ wide and $60\mathrm{mm}$ long. Strips are supplied in a plastic blister package with 10 units in each of 10 individually sealed compartments. One side of the strip is labeled with the MIC reading scale in $\mu \mathrm{g} / \mathrm{mL}$ and a three-letter code on the handle to designate the identity of the antibiotic. The other side of the strip is impregnated with a predefined, dried and stabilized, exponential gradient of an antibiotic, expressed

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as a minimum and a maximum value. The gradient covers a continuous concentration range across 15 two-fold dilutions.

# J. Substantial Equivalence Information:

1. Predicate device name(s): The E Test®
2. Predicate K number(s): K913459
3. Comparison with predicate:

| Similarities | | | |
| --- | --- | --- | --- |
| Item | Device | | Predicate |
| Intended use | Etest® is a quantitative technique for the determination of antimicrobial susceptibility of both non-fastidious Gram negative and Gram positive aerobic bacteria, such as Enterobacteriaceae, Pseudomonas, Staphylococcus and Enterococcus species and fastidious bacteria, such as anaerobes, Pneumococcus, Streptococcus, Gonococcus and Haemophilus species. The system comprises a predefined antibiotic gradient which is used to determine the Minimum Inhibitory Concentration (MIC) in μg/mL of different antimicrobial agents against microorganisms as tested on agar media by overnight incubation. | | same |
| Isolates | Isolated colonies from culture used | | same |
| Results | Report results as minimum inhibitory concentration (MIC) | | same |
| Type of Test | Manual read only | | same |
| Differences | | | |
| Item | Device | | Predicate |
| Antibiotic | Tigecycline | | Various antibiotics |

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4. Standard/Guidance Document Referenced (if applicable):
“Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA”; CLSI M7 (M100-S15)
“Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard”; CLSI M11-A6, “Methods for Antimicrobial Susceptibility Testing of Anaerobic Bacteria; Approved Standard – Sixth Edition.”

5. Test Principle:
The Etest® gradient technology is based on a combination of the concepts of dilution and diffusion test methods for susceptibility testing. Etest® directly quantifies antimicrobial susceptibility in terms of discrete MIC values. When the Etest® strip is applied to an inoculated agar plate, the antibiotic is immediately released from the plastic surface into the agar. A predefined, continuous gradient of antibiotic concentrations is created and maintained directly underneath the strip. After incubation whereby bacterial growth becomes visible, a symmetrical inhibition ellipse centered along the strip will be observed. The MIC value in $\mu \mathrm{g} / \mathrm{mL}$ is read where the ellipse edge intersects the strip. Since Etest® generates MIC values which fall between two-fold dilutions for interpretation; the MIC value read must be recorded to the next higher two-fold dilution.

6. Performance Characteristics (if/when applicable):

7. Analytical performance:

a. Precision/Reproducibility:
Reproducibility was established using a variety of 26 Gram positive and Gram negative aerobic isolates; 26 Streptococcus species; and 26 anaerobes comprised of a variety of Bacteroides species, which were evaluated three times at each site, for site to site, and inter site studies. All organisms were tested at all three sites, which demonstrated $>95\%$ reproducibility.

b. Linearity/assay reportable range
Not applicable

c. Traceability, Stability, Expected values (controls, calibrators, or method):
FDA recommended Quality Control strains were tested at the concentrations listed (see tables below). The results demonstrated that the device system could produce QC results in the recommended range.

Quality control results demonstrated the ability of the device to produce acceptable results $>95\%$ of the time for all QC organisms.

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Table 7.c.1. - Tigecycline QC results for aerobic bacteria

| Organism | Concentration μg/mL | Reference results | Etest® results |
| --- | --- | --- | --- |
| Gram negative | | | |
| | | | |
| E. coliATCC 259220.03 - 0.25μg/mL | <0.032 | | |
| | 0.032 | | |
| | 0.064 | 7 | |
| | 0.125 | 41 | 55 |
| | 0.25 | 12 | 2 |
| | >0.25 | | |
| Gram positive | | | |
| | | | |
| S. aureusATCC 29213Expected range0.032 - 0.25μg/mL | <0.032 | | |
| | 0.032 | | |
| | 0.064 | 1 | 2 |
| | 0.125 | 23 | 40 |
| | 0.25 | 36 | 18 |
| | 0.5 | | |
| | | | |
| E. faecalisATCC 29212Expected range0.032 - 0.125μg/mL | <0.032 | | |
| | 0.032 | | |
| | 0.064 | 17 | 14 |
| | 0.125 | 43 | 46 |
| | 0.25 | | |
| | 0.5 | | |

Table 7.c.3. Tigecycline QC Data for Streptococcus pneumoniae

| Organism | Concentration μg/mL | Reference results | Etest® results |
| --- | --- | --- | --- |
| Streptococcus. pneumoniae | | | |
| | | | |
| S. pneumoniaeATCC 49619Expected range0.016 – 0.125μg/mL | | | |
| | 0.016 | 2 | 1 |
| | 0.032 | 38 | 36 |
| | 0.064 | 20 | 23 |
| | 0.125 | | |
| | | | |

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Table 7.c.3. - Tigecycline QC results for anaerobic bacteria

| Organism | Concentration μg/mL | Reference results | Etest® results |
| --- | --- | --- | --- |
| Anaerobes | | | |
| | | | |
| Bacteroides fragilisATCC 25285Expected range 0.125 - 1 μg/mL | <0.125 | | |
| | 0.125 | | |
| | 0.25 | 31 | 30 |
| | 0.5 | 29 | 30 |
| | 1 | | |
| | >1 | | |
| | | | |
| B. thetaiotaomicronATCC 29741Expected range 0.5 - 2 μg/mL | <0.25 | | |
| | 0.25 | | |
| | 0.5 | 40 | 42 |
| | 1 | 20 | 17 |
| | 2 | | 1 |
| | >2 | | |
| Eubacterium lentumATCC 43055Expected range 0.064 - 0.5 μg/mL | <0.032 | | |
| | 0.032 | | |
| | 0.064 | 35 | 28 |
| | 0.125 | 25 | 30 |
| | 0.25 | | 2 |
| | 0.5 | | |

A 0.5 McFarland is used to determine the correct inoculum.

Colony counts for the clinical / stock isolates were performed periodically at each site to demonstrate that the inoculum procedure results were in the expected CFU/ml range. All colony count inoculum check mean results were within the acceptable ranges.

# 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 reference panels were prepared and tested as recommended by CLSI, including the addition of $2.5 - 5\%$ lysed horse blood when testing

Streptococcus spp. CLSI recommended broth microdilution and agar dilution

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methods were utilized as the reference methods, and were used to compare with the Etest® results. Broth microdilution testing of aerobic organisms for MIC values was performed in testing media that was fresh (&lt;12 hours old).

Clinical testing was performed at three sites. The testing included fresh/stock, clinical aerobic Gram positive and Gram negative isolates; fresh/stock clinical *Streptococcus* isolates; and fresh/stock clinical isolates of a variety of anaerobic strains. Approximately 60% of the Clinical strains were fresh isolates. The Challenge isolates selected for each testing group of organisms were appropriate for this antibiotic; all Challenge strain testing was performed at the sponsor's site. Low numbers from each organism group were tested, although overall the numbers tested were sufficient.

The study included a variety of Gram positive aerobic Clinical isolates and a variety of Gram positive aerobic Challenge isolates, with the following performance (see table below). The FDA provides breakpoints for tigecycline only for *Staphylococcus aureus* (both methicillin-susceptible and methicillin-resistant isolates), and *Enterococcus faecalis* (vancomycin-susceptible isolates only). Therefore, the table below contains performance data for all Gram positive aerobic species for EA and Eval EA, and *S. aureus* and *E. faecalis* only for CA.

Gram positive aerobic isolates

| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA Tot* | CA N* | CA % | NS |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Clinical | 96 | 95 | 99.0 | 96 | 95 | 99.0 | 78 | 78 | 100.0 | 0 |
| Challenge | 33 | 33 | 100.0 | 33 | 33 | 100.0 | 18 | 18 | 100.0 | 0 |
| Combined | 129 | 128 | 99.2 | 129 | 128 | 99.2 | 96 | 96 | 100.0 | 0 |

* The CA Total and CA N apply to *S. aureus* and *E. faecalis* only

NS-Non Susceptible

EA-Essential Agreement

CA-Category Agreement

R-resistant isolates

maj-major discrepancies

vmj-very major discrepancies

min- minor discrepancies

Essential agreement (EA) is when the Etest® panels agree with the reference test panel results exactly or within one doubling dilution of the reference method. Category agreement (CA) is when the Etest® panel result interpretation agrees exactly with the reference panel result interpretation. Evaluable (Eval) are results that are within the test range and on scale.

There were 206 Clinical and 30 Challenge isolates from a variety of Enterobacteriaceae strains with the following performance.

Enterobacteriaceae isolates

| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA Tot | CA N | CA % | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Clinical | 206 | 205 | 99.5 | 206 | 205 | 99.5 | 206 | 199 | 96.6 | 13 | 7 | 0 | 0 |
| Challenge | 30 | 30 | 100.0 | 30 | 30 | 100.0 | 30 | 30 | 100.0 | 0 | 0 | 0 | 0 |
| Combined | 236 | 235 | 99.6 | 236 | 235 | 99.6 | 236 | 229 | 97.0 | 13 | 7 | 0 | 0 |

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There were 369 Streptococcus species, not S. pneumoniae isolates tested. Of that total, 298 were Clinical isolates and 71 were Challenge isolates with the following performance.

Streptococcus species, not S. pneumoniae

| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA Tot | CA N | CA % | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Clinical | 298 | 298 | 100.0 | 282 | 282 | 100.0 | 282 | 282 | 100.0 | 2 | 0 | 0 | 0 |
| Challenge | 71 | 71 | 100.0 | 71 | 71 | 100.0 | 71 | 71 | 100.0 | 1 | 0 | 0 | 0 |
| Combined | 369 | 369 | 100.0 | 353 | 353 | 100.0 | 353 | 353 | 100.0 | 3 | 0 | 0 | 0 |

A total of 385 anaerobic bacteria from a variety of Bacteroides species, were tested. There were 310 Clinical isolates and 75 Challenge isolates with the following performance.

Anaerobes

| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA Tot | CA N | CA % | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Clinical | 310 | 303 | 97.7 | 310 | 303 | 97.7 | 310 | 300 | 96.8 | 7 | 10 | 0 | 0 |
| Challenge | 75 | 75 | 100.0 | 75 | 75 | 100.0 | 75 | 73 | 97.3 | 4 | 2 | 0 | 0 |
| Combined | 385 | 378 | 98.2 | 385 | 378 | 98.2 | 385 | 373 | 96.7 | 11 | 12 | 0 | 0 |

The test device had a growth rate of $&gt;95\%$ .

i. Matrix comparison:

Not applicable

b. Clinical studies:

i. Clinical sensitivity:

Not applicable

ii. Clinical specificity:

Not applicable

iii. Other clinical supportive data (when a and b are not applicable

Not applicable

c. Clinical cut-off:

Not applicable

d. Expected values/Reference range

| Organism | S | I | R |
| --- | --- | --- | --- |
| Staphylococcus aureus(including methicillin-resistant isolates) | ≤0.5 | * | * |
| Streptococcus spp.other than S. pneumoniae | ≤0.25 | * | * |
| Enterococcus faecalis(vancomycin-susceptible isolates only) | ≤0.25 | * | * |
| Enterobacteriaceae | ≤2 | 4 | ≥8 |
| Anaerobes | ≤4 | 8 | ≥16 |

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*The current absence of resistant isolates precludes defining any results other than Susceptible. Isolates yielding MIC results suggestive of “NonSusceptible” category should be submitted to a reference laboratory for further testing.

**N. Proposed Labeling:**

The expected value range, interpretive criteria and QC are the same as recommended by 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.