S. AUREUS/CNS PNA FISH, MODEL KT005

K092166 · Advandx, Inc. · NXX · Nov 23, 2009 · Microbiology

Device Facts

• Record ID: K092166
• Device Name: S. AUREUS/CNS PNA FISH, MODEL KT005
• Applicant: Advandx, Inc.
• Product Code: NXX · Microbiology
• Decision Date: Nov 23, 2009
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.3700
• Device Class: Class 1

Indications for Use

S. aureus/CNS PNA FISH is a multicolor, qualitative nucleic acid hybridization assay intended for the identification of Staphylococcus aureus and/or selected other Staphylococcus species on smears made from positive blood cultures containing Grampositive cocci in clusters observed on Gram stain. Subculturing of positive blood cultures is necessary for susceptibility testing and/or differentiation of mixed growth. S. aureus/CNS PNA FISH is intended as an aid in the diagnosis of S. aureus bacteremia.

Device Story

In vitro diagnostic assay; utilizes PNA FISH (Peptide Nucleic Acid Fluorescence In Situ Hybridization) technology. Input: smears prepared from positive blood culture bottles containing Gram-positive cocci in clusters. Process: fluorescently labeled PNA probes hybridize to specific ribosomal RNA sequences within the bacteria; hybridization visualized via fluorescence microscopy. Output: qualitative identification of S. aureus and/or other Staphylococcus species. Used in clinical microbiology laboratories by trained laboratory personnel. Results assist clinicians in rapid identification of S. aureus bacteremia, facilitating targeted antimicrobial therapy and improved patient management. Subculturing remains required for susceptibility testing.

Clinical Evidence

No clinical data provided in the summary document; substantial equivalence is based on bench testing and performance validation of the PNA FISH assay methodology.

Technological Characteristics

Qualitative nucleic acid hybridization assay using PNA probes. Employs fluorescence in situ hybridization (FISH) principle. Requires fluorescence microscopy for visualization. Standalone diagnostic kit format. No software or electronic components.

Indications for Use

Indicated for identification of S. aureus and/or selected coagulase-negative Staphylococcus (CNS) species in patients with positive blood cultures containing Gram-positive cocci in clusters observed on Gram stain.

Regulatory Classification

Identification

Staphylococcus aureus serological reagents are devices that consist of antigens and antisera used in serological tests to identify enterotoxin (toxin affecting the intestine) producing staphylococci from cultured isolates. The identification aids in the diagnosis of disease caused by this bacterium belonging to the genus Staphylococcus and provides epidemiological information on these diseases. Certain strains of Staphylococcus aureus produce an enterotoxin while growing in meat, dairy, or bakery products. After ingestion, this enterotoxin is absorbed in the gut and causes destruction of the intestinal lining (gastroenteritis).

Predicate Devices

• S. aureus PNA FISH Culture Identification Kit (K061336)

Submission Summary (Full Text)

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

A. 510(k) Number:
K092166

B. Purpose for Submission:
To determine substantial equivalence of the device for the identification of S. aureus and/or selected other coagulase negative Staphylococcus species on smears from positive blood cultures containing Gram positive cocci in clusters.

C. Measurand:
S. aureus specific ribosomal RNA sequences

D. Type of Test:
Fluorescence In Situ Hybridization (FISH) using protein nucleic acid (PNA) probes

E. Applicant:
AdvanDx, Inc

F. Proprietary and Established Names:
AdvanDx S. aureus/CNS PNA FISH Culture Identification Kit

G. Regulatory Information:
1. Regulation section:
866.3700
2. Classification:
Class I
3. Product code:
NXX
4. Panel:

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83 Microbiology

## H. Intended Use:

1. Intended use:

S. aureus/CNS PNA FISH is a multicolor, qualitative nucleic acid hybridization assay intended for the identification of S. aureus and/or selected other Staphylococcus species on smears made from positive blood cultures containing Gram-positive cocci in clusters observed on Gram stain. Subculturing of positive blood cultures is necessary for susceptibility testing and/or differentiation of mixed growth.

S. aureus/CNS PNA FISH is intended as an aid in the diagnosis of S. aureus bacteremia.

2. Indications for use:

S. aureus/CNS PNA FISH is a qualitative nucleic acid hybridization assay intended for the identification of S. aureus and/or selected other Staphylococcus species on smears made from positive blood cultures containing Gram-positive cocci in clusters observed on Gram stain. Subculturing of positive blood cultures is necessary for susceptibility testing and/or differentiation of mixed growth.

S. aureus/CNS PNA FISH is intended as an aid in the diagnosis of S. aureus bacteremia.

3. Special conditions for use statement(s):

Prescription use only

4. Special instrument requirements:

Dual Band Filter (Cat. No. AC003)

Microscope Slides (Cat. No. AC001)

## I. Device Description:

A mixture of fluorescein-labeled, S. aureus specific PNA probe and a Texas Red labeled PNA targeting other Staphylococci (CNS) is added to a smear prepared from a positive blood culture. PNA FISH is performed directly on smears fixed onto microscope slides. The fluorescein-labeled PNA probes are added to a smear prepared from a positive blood culture. Hybridization is performed at 55°C for 30 minutes. The hybridization is followed by a post-hybridization wash at 55°C for 30 minutes with a stringent Wash Solution to remove unbound PNA probe. Finally, the smear is mounted with Mounting Medium and examined by fluorescence microscopy.

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J. Substantial Equivalence Information:

1. Predicate device name(s):
S. aureus PNA FISH

2. Predicate 510(k) number(s):
K060099
K091827

3. Comparison with predicate:
| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Technology | Fluorescence In Situ Hybridization (FISH) using protein nucleic acid (PNA) probe | Same |
| Sample | Positive blood culture | Same |
| Interpretation of Results | Qualitative Fluorescence microscope | Same |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| PNA Probes | Fluorescein-labeled S. aureus specific PNA probe and Texas Red labeled PNA targeting other Staphylococci (CNS) | Fluorescein-labeled S. aureus specific PNA probe |
| Time to result | 1.5 hrs. | 2.5 hrs. |

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

L. Test Principle:
A mixture of fluorescein-labeled, S. aureus specific PNA probe and a Texas Red labeled PNA targeting other Staphylococci (CNS) is added to a smear prepared from a positive blood culture. Hybridization is performed at 55°C for 30 minutes. The hybridization is followed by a post-hybridization wash at 55°C for 30 minutes with a stringent Wash Solution to remove unbound PNA probe. Finally, the smear is mounted with Mounting Medium and examined by fluorescence microscopy. While maintaining the morphology of the cells, S. aureus and selected other Staphylococcus

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species (CNS) cells become fluorescent by specific binding of the fluorophore-labeled PNA probes.

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

### 1. Analytical performance:

a. Precision/Reproducibility:

A reproducibility study for *S. aureus*/CNS PNA FISH assay, using new procedure, was performed by using ten reference Gram positive cocci, in triplicates with positive and negative controls, over a period of three days at three different sites, by at least two different operators at each site. Results showed 100% precision and reproducibility between and within sites.

b. Linearity/assay reportable range:

Not applicable

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

Positive and negative control slides were performed at each testing site on each day of testing. Results were as expected for this type device.

d. Detection limit:

The detection limit was determined to be approximately 10⁵ CFU/mL by serial dilutions of *S. aureus* and *S. epidermidis* cultures. The average number of colonies per mL (CFU/mL) was calculated from three plates. The data sets showed a minimum of 10⁵ CFU/mL to produce a positive result for the *S. aureus*/CNS PNA FISH™ assay.

e. Analytical specificity:

The new assay procedure was tested and compared to the original assay procedure. All 43 *S. aureus* showed positive-green results, 39 CNS showed positive-red results. Additionally, results indicated that *S. aureus*/CNS PNA FISH is negative (no positive-red) for *S. felis*, *S. simulans*, *Macrococcus casseolyticus* (formerly *Staph cohnii* subspp. *cohnii*), and *Macrococcus equipericus* (formerly *Staph equipericus*).

Thirty-three Gram negative organisms, 25 Gram positive organisms and six yeast isolates were tested with the new procedure, with *Candida krusei* demonstrated weak green fluorescence, and the other 63 non-*Staphylococcus* organisms were negative.

f. Assay cut-off:

Not applicable

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2. Comparison studies:

a. Method comparison of device to conventional methods, as the reference method:

Not applicable

b. Matrix comparison:

Not applicable

3. Clinical studies:

A total of 402 (Gram positive cocci in clusters) positive blood culture bottles at four sites were included in the studies, and showed 99.5% (400/402) overall agreement between S. aureus/CNS PNA FISH and conventional routine methods. The performance data are shown at the table below.

a. Clinical Sensitivity:

| Study | S. aureus | CNS | Other | Blood Culture System |
| --- | --- | --- | --- | --- |
| A | 100% (32/32) | 100% (67/67) | 100% (1/1) | BACTEC |
| | 95% CI (91.1-100) | 95% CI (95.6-100) | 95% CI (1.0-100) | |
| B | 100% (17/17) | 100% (82/82) | 100% (4/4) | BacT/ALERT |
| | 95% CI (83.8-100) | 95% CI (96.4-100) | 95% CI (47.3-100) | |
| C | 100% (32/32) | 100% (65/65) | 100% (4/4) | BACTEC |
| | 95% CI (91.1-100) | 95% CI (95.5-100) | 95% CI (47.3-100) | |
| D | 96.9% (32/32) | 98.4% (64/64) | 0% (0/2)* | VersaTREK |
| | 95% CI (84.2-99.9) | 95% CI (81.7-99.9) | 95% CI (0-52.7) | |
| Total | Sensitivity | Sensitivity | Specificity | |
| | 100 % (113/113) | 100 % (278/278) | 81.8 % (9/11) | |
| | 95% CI (97.4-100) | 95% CI (98.9-100) | 95% CI (48.2-97.7) | |

* Two false positive-red were Micrococcus spp.

b. Clinical specificity:

See Table above.

c. Other clinical supportive data (when a. and b. are not applicable):

Not applicable

4. Clinical cut-off:

Not applicable

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5. Expected values/Reference range:

S. aureus cells: multiple bright green fluorescent clusters of cocci in multiple fields

CNS cells: multiple bright red fluorescent clusters of cocci in multiple fields

The expected S. aureus and CNS positive result rate from Gram positive cocci positive blood culture bottles is approximately 21% and 55%, respectively, but may vary depending on institution and patient population.

N. Proposed Labeling:

The labeling is sufficient and it 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.