BD PHOENIX AUTOMATED MICROBIOLOGY SYSTEM - CEFTAZIDIME - GRAM NEGATIVE

K041384 · Becton, Dickinson & CO · LON · Aug 3, 2004 · Microbiology

Device Facts

• Record ID: K041384
• Device Name: BD PHOENIX AUTOMATED MICROBIOLOGY SYSTEM - CEFTAZIDIME - GRAM NEGATIVE
• Applicant: Becton, Dickinson & CO
• Product Code: LON · Microbiology
• Decision Date: Aug 3, 2004
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.1645
• Device Class: Class 2

Intended Use

The BD Phoenix™ Automated Microbiology System is intended for the rapid identification and in vitro antimicrobial susceptibility testing of isolates from pure culture of most aerobic and facultative anaerobic gram-negative and gram-positive bacteria of human origin.

Device Story

The BD Phoenix System is an automated microbiology platform for antimicrobial susceptibility testing (AST) of bacterial isolates. The system uses molded polystyrene panels containing dried antimicrobial agents and growth indicators. Input consists of a pure bacterial culture inoculum (0.5 McFarland standard) prepared in Phoenix broth. The instrument continuously incubates panels and performs optical measurements every 20 minutes using a redox indicator to detect bacterial growth via turbidity changes. The system interprets these measurements to determine the Minimum Inhibitory Concentration (MIC) and categorical results (S, I, or R). Used in clinical microbiology laboratories by trained technicians. The output provides clinicians with susceptibility data to guide antibiotic therapy, potentially improving patient outcomes by enabling targeted treatment.

Clinical Evidence

Performance evaluated via method comparison against NCCLS broth dilution reference panels. Study included 1,707 clinical isolates and 130 challenge isolates (total 1,837). Combined results showed 96.5% Essential Agreement (EA) and 94.3% Category Agreement (CA). Very major discrepancy rate was 9/410 (2.2%). Reproducibility testing across three sites demonstrated >95% reproducibility. Quality control testing using ATCC strains (E. coli 25922, P. aeruginosa 27853, P. aeruginosa 35032) confirmed system performance within recommended ranges.

Technological Characteristics

Automated colorimetric oxidation-reduction growth-based system. Uses 136-well molded polystyrene trays with dried reagents. AST broth is cation-adjusted Mueller-Hinton with 0.01% Tween 80 and redox indicator. Incubation at 35°C. Connectivity: automated instrument with barcode scanning. Software: rule-based 'EXPERT' system using NCCLS standards. Dimensions/form factor: micro-well tray format.

Indications for Use

Indicated for in vitro rapid identification and quantitative antimicrobial susceptibility testing (MIC) of gram-negative aerobic and facultative anaerobic bacteria, including Pseudomonas aeruginosa, in the family Enterobacteriaceae and non-Enterobacteriaceae. Prescription use only. Results for Citrobacter freundii and Stenotrophomonas maltophilia are excluded.

Regulatory Classification

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® System (PMA No. N50510)
• BD Phoenix™ Automated Microbiology System with Gatifloxacin (K020321)
• BD Phoenix™ Automated Microbiology System with Ofloxacin (K020323)
• BD Phoenix™ Automated Microbiology System with Levofloxacin (K020322)
• BD Phoenix™ Automated Microbiology System with Ceftazidime (K033560)

Submission Summary (Full Text)

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

A. 510(k) Number: k041384

B. Purpose for Submission:
To remove a limitation for the testing of ceftazidime with *Pseudomonas aeruginosa*

C. Analyte:
Ceftazidime at 0.5 – 64 ug/mL

D. Type of Test:
Antimicrobial Susceptibility Test (Quantitative) colorimetric oxidation-reduction, growth-based

E. Applicant:
Becton, Dickinson & Company

F. Proprietary and Established Names:
BD Phoenix™ Automated Microbiology System – Ceftazidime Gram Negative

G. Regulatory Information:
1. Regulation section:
21 CFR 866.1645 Fully Automated Short-Term Incubation Cycle
Antimicrobial
2. Classification:
Class II
3. Product Code:
LON
4. Panel:
83 Microbiology

H. Intended Use:
1. Intended use(s):
BD Phoenix™ Automated Microbiology System:
The BD Phoenix™ Automated Microbiology System is intended for
*in vitro* quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration of gram-negative aerobic and facultative anaerobic bacteria belonging to the family *Enterobacteriaceae* and
non – *Enterobacteriaceae* and gram-positive bacteria belonging to the genera *Staphylococcus* and *Enterococcus*.

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The BD Phoenix™ GN Panel: The BD Phoenix™ Automated Microbiology System is intended for the in vitro rapid identification (ID) and quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of gram-negative aerobic and facultative anaerobic bacteria belonging to the family Enterobacteriaceae and non-Enterobacteriaceae.

2. Indication(s) for use:
This submission is for the addition of the antibiotic ceftazidime at concentrations of 0.5 – 64 µg/mL to the gram negative susceptibility panel to include the testing of Pseudomonas aeruginosa.

3. Special condition for use statement(s):
Prescription Use Only
Results for Citrobacter freundii and Stenotrophomonas maltophilia have been excluded in the BD Phoenix™ therefore no results will be reported. An alternate method should be performed with these combinations.

4. Special instrument Requirements:
Not Applicable

I. Device Description:
The BD Phoenix™ Automated Microbiology System includes instrumentation and software, sealed and self-inoculating molded polystyrene trays with 136 micro-wells containing dried reagents, and specific inoculum broth formulations for ID and AST Indicator. The organism to be tested must be a pure culture and be preliminarily identified as gram positive or gram negative. Colonies are then suspended in broth, and equated to a 0.5 McFarland with the recommendation to use the BD CrystalSpec™ Nephelometer. A further dilution is made into an AST broth, which contains an AST indicator, prior to inoculating the panel. The AST broth is a cation-adjusted formulation of Mueller-Hinton broth containing 0.01% Tween 80. After adding the indicator solution to the AST inoculum the color is blue and after inoculation and incubation goes to pink to colorless as reduction in the panel well proceeds. Inoculated panels are barcode scanned and loaded into the BD Phoenix™ Automated Microbiology System instrument where the panels are continuously incubated at 35°C. The AST has a final inoculum of 5 × 10⁵ CFU/ml. The instrument incubates, reads and records the results of the biochemical substrates and antimicrobial agents and interprets the reactions to give an ID of the isolate and MIC value and category interpretation of the antimicrobial agents. Organisms growing in the presence of a given antimicrobic agent reduce the indicator, signaling organism growth and resistance to the antimicrobic agent. Organisms killed or inhibited by a given antimicrobic do not cause reduction of the indicator and therefore do not produce a color change. Additional interpretation is done using software driven "EXPERT" System using rules derived from the NCCLS standards.

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Readings are taken every 20 minutes with an ID result available between 2-12 hours and an AST result available between 4-16 hours. This is only an autoread result; there are no manual readings possible.

## J. Substantial Equivalence Information:

1. Predicate device name(s): VITEK® System
2. Predicate K number(s): N50510
3. Comparison with predicate:

| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Intended use | Intended for the in vitro rapid identification (ID) and quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of gram-negative aerobic and facultative anaerobic bacteria. | same |
| Isolates | Isolated colonies from culture used | Isolated colonies from culture used |
| Results | Report results as minimum inhibitory concentration (MIC) and categorical interpretation (SIR) | Report results as minimum inhibitory concentration (MIC) and categorical interpretation (SIR) |
| Incubation conditions | <16 hours | <16 hours |
| Differences | | |
| Item | Device | Predicate |
| Inoculum preparation | Inoculum density equated to 0.5 McFarland standard | Inoculum density equated to 1.0 McFarland standard |
| Reading algorithm | Results are determined from serial twofold dilutions of antimicrobial agents | Results are determined from extrapolation of doubling dilutions |
| Technology | Automated growth based enhanced by use of a redox indicator (colorimetric oxidation-reduction) to detect organism growth. | Automated growth based with detection using an attenuation of light measured by an optical scanner. |

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

"Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA"; NCCLS M7 (M100-S14)

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"Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard."

L. Test Principle:
The system employs conventional, colorimetric, fluorogenic and chromogenic substrates to identify the genus and species of the isolate. The AST portion of the BD Phoenix™ Automated Microbiology System is a broth based microdilution method that utilizes a redox indicator (colorimetric oxidation-reduction) to enhance detection of organism growth. The MIC is determined by comparing growth in wells containing serial two-fold dilutions of an antibiotic to the growth in "growth control wells" which contain no antibiotic.

M. Performance Characteristics (if/when applicable):

1. Analytical performance:
a. Precision/Reproducibility:
Thirteen isolates were evaluated for site to site and inter site reproducibility demonstrating &gt;95% reproducibility. The ten isolate study described in the guidance document was used (10 organisms tested 3 times on 3 days at 3 sites).
b. Linearity/assay reportable range:
Not applicable
c. Traceability, Stability, Expected values (controls, calibrators, or method):
NCCLS recommended Quality Control strains were tested (see table below). The Phoenix results demonstrate that the system can produce QC results in the recommended range.

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| Organism | Concentration | Reference results | Phoenix™ results |
| --- | --- | --- | --- |
| | | | |
| *E. coli*
ATCC 25922
(range ≤ 0.5 ug/ml ) | ≤ 0.5 | 206 | 196 |
| | 1 | 4 | |
| | 2 | | |
| | 4 | | |
| | | | |
| *P aeruginosa*
ATCC 27853
range 1-4 ug/mL | 1 | 127 | 11 |
| | 2 | 77 | 195 |
| | 4 | 6 | 2 |
| | 8 | 1 | |
| | 16 | | |
| | | | |
| | | | |
| *P. aeruginosa*
ATCC 35032
range 1- 4 ug/mL | ≤ 0.5 | | 1 |
| | 1 | 1 | |
| | 2 | 187 | 203 |
| | 4 | 3 | 4 |
| | 8 | | 1 |
| | 16 | | 5 |

Inoculum density control: The organism suspension density of the ID broth was equivalent to a 0.5 McFarland standard using the BBL™ CrystalSpec™ Nephelometer which was verified each day of testing. Internal data was used to demonstrate that the use of the BBL™ CrystalSpec™ Nephelometer would produce reproducible results. Five different instruments were used.

**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 NCCLS recommended broth dilution reference panel was prepared according to the NCCLS recommendation and used to compare with the Phoenix™ results. Clinical testing was performed at four sites. The testing included both fresh clinical isolates and

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stock isolates along with a challenge set with known results. An additional challenge set was added to supplement the test results for *P. aeruginosa* which included 41 additional isolates of which 38 were resistant. A comparison was provided to the reference method with the following agreement.

| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA N | CA % | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Clinical | 1707 | 1647 | 96.5% | 486 | 436 | 89.7 | 1608 | 94.2 | 348 | 80 | 11 | 8 |
| Challenge | 130 | 126 | 96.9 | 50 | 47 | 94.0% | 125 | 96.2 | 62 | 4 | 0 | 1 |
| Combined | 1837 | 1773 | 96.5% | 536 | 483 | 90.1% | 1733 | 94.3 | 410 | 84 | 11 | 9 |

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 BD Phoenix™ panels agree with the reference test panel results exactly or within one doubling dilution of the reference method. Category agreement (CA) is when the BD Phoenix™ panel result interpretation agrees exactly with the reference panel result interpretation.

The test device had a growth rate of 99.1%.

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:
Enterobacteriaceae and Non-Enterobacteriaceae ≤8 (S), 16(I), ≥32 (R)
The expected value range, interpretative criteria and QC are the same as recommended by NCCLS. All values will be included in the package insert.

N. Conclusion:

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