The BD Phoenix™ Automated Microbiology System is intended for in vitro quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of most Gram-negative aerobic and facultative anaerobic bacteria isolates from pure culture for Enterobacteriaceae and Non-Enterobacteriaceae and most Gram-positive bacteria isolates from pure culture belonging to the genera Staphylococcus, Enterococcus and Streptococcus. Imipenem has been shown to be active in vitro against most strains of microorganisms listed below, as described in the FDA-approved package insert for this antimicrobial agent. Active In Vitro and in Clinical Infections Against: Acinetobacter spp. Citrobacter spp. Enterobacter cloacae Escherichia coli Klebsiella spp. Pseudomonas aeruginosa Serratia marcescens
Device Story
System performs automated antimicrobial susceptibility testing (AST) on pure bacterial cultures. Input: bacterial colonies suspended in broth, inoculated into 136-well polystyrene trays containing dried reagents and redox indicator. Instrument incubates at 35°C; continuously monitors color change (oxidation-reduction) and turbidity via optical scanning. Growth in presence of antibiotic prevents color change; inhibition allows reduction. Software-driven 'EXPERT' system interprets results based on CLSI rules. Output: MIC values and categorical interpretations (SIR). Used in clinical microbiology labs; operated by trained technicians. Benefits: rapid, automated determination of antibiotic susceptibility to guide clinical treatment decisions.
Clinical Evidence
Performance evaluated using clinical and challenge isolates across multiple US sites. Comparison against CLSI reference broth microdilution method. For Imipenem (0.0625-32 µg/mL), study reported 94.6% Essential Agreement (n=1348) and 95.3% Category Agreement (n=1348). Reproducibility study across three sites showed >95% agreement (+/- 1 dilution).
Technological Characteristics
System uses broth microdilution in 136-well molded polystyrene panels. Sensing principle: redox indicator and turbidity measurement. Energy source: electrical (instrument). Connectivity: standalone instrument with integrated software. Incubation: 35°C ± 1°C. Software: automated interpretation of growth kinetics.
Indications for Use
Indicated for in vitro quantitative determination of antimicrobial susceptibility (MIC) of Gram-negative aerobic/facultative anaerobic bacteria (Enterobacteriaceae, Non-Enterobacteriaceae) and Gram-positive bacteria (Staphylococcus, Enterococcus, Streptococcus) from pure culture. Active against Acinetobacter spp., Citratebacter spp., Enterobacter cloacae, Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, and Serratia marcescens.
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)
Submission Summary (Full Text)
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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY ONLY TEMPLATE
A. 510(k) Number:
k123404
B. Purpose for Submission:
The addition of imipenem
C. Measurand:
Imipenem 0.0625-32μg/mL
D. Type of Test:
Antimicrobial Susceptibility Test (AST) colorimetric oxidation-reduction, growth-based
E. Applicant:
Becton, Dickinson & Company
F. Proprietary and Established Names:
BD Phoenix™ Automated Microbiology System- Imipenem 0.0625-32μg/mL
G. Regulatory Information:
1. Regulation section:
21 CFR 866.1645 - Fully Automated Short-Term Incubation Cycle Antimicrobial Susceptibility System
2. Classification:
II
3. Product code:
LON
4. Panel:
83 Microbiology
H. Intended Use:
1. Intended use(s):
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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:
The BD Phoenix™ Automated Microbiology System is intended for in vitro quantitative determination of antimicrobial susceptibility by minimal inhibitory concentration (MIC) of most Gram-negative aerobic and facultative anaerobic bacteria isolates from pure culture for Enterobacteriaceae and Non-Enterobacteriaceae and most Gram-positive bacteria isolates from pure culture belonging to the genera Staphylococcus, Enterococcus and Streptococcus.
Imipenem has been shown to be active in vitro against most strains of microorganisms listed below, as described in the FDA-approved package insert for this antimicrobial agent.
Active In Vitro and in Clinical Infections Against:
- Acinetobacter spp.
- Citrobacter spp.
- Enterobacter cloacae
- Escherichia coli
- Klebsiella spp.
- Pseudomonas aeruginosa
- Serratia marcescens
3. Special conditions for use statement(s):
For prescription use only
4. Special instrument requirements:
For use with BD Phoenix™ Automated Microbiology System
I. Device Description:
This submission is for the AST Panel only. The ID system was not reviewed.
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 BD nephelometer devices. A further dilution is made into an AST broth, which turns to blue after AST broth indicator is added prior to inoculating the panel. The AST broth is a cation-adjusted formulation of Mueller-Hinton broth containing 0.01%
2
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Tween 80, and has a final inoculum of approximately $5 \times 10^{5} \mathrm{CFU/mL}$. After inoculation and incubation, the color changes to pink then 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 incubated at $35^{\circ} \mathrm{C}$ and continuously measured of changes to the indicator as well as bacterial turbidity to determine the bacterial growth in the presence of an antimicrobial agent. Organisms growing in the presence of a given antimicrobial agent reduce the indicator, signaling organism growth and resistance to the antimicrobial agent. Organisms killed or inhibited by a given antimicrobial 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 CLSI documentation.
Readings are taken every 20 minutes with an AST result available between 4-16 hours. This is only an autoread result; no manual readings are possible with this system.
## J. Substantial Equivalence Information:
1. Predicate device name(s):
VITEK® System
2. Predicate 510(k) number(s):
N50510
3. Comparison with predicate:
| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| 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. | The VITEK System is intended for the determination of in vitro susceptibility to antimicrobial agents for rapidly growing, aerobic and/or facultative anaerobic Gram-negative and Gram-positive bacteria. |
| Sample | Isolated colonies from culture | Same |
| Result reported | Minimum inhibitory concentration (MIC) and categorical interpretation (SIR) | Same |
| Incubation Time | <16 hours | <16 hours |
| Type of Test | Automated | Same |
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| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Results achieved (MIC) | Serial twofold dilutions of antimicrobial | Computer-assisted 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 Systems; Guidance for Industry and FDA”
CLSI M7-A8, “Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically”
CLSI M100, S22 “Performance Standards for Antimicrobial Susceptibility Testing”
L. Test Principle:
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 contains no antibiotic.
M. Performance Characteristics (if/when applicable):
1. Analytical performance:
a. Precision/Reproducibility:
Eighteen organisms were evaluated at three sites (one internal and two external) in triplicate on three separate days using inoculum prepared manually or by the automated BD Phoenix AP. Inter-site and Intra-site testing demonstrated reproducibility of $\geq 95\%$.
b. Linearity/assay reportable range:
Not applicable
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c. Traceability, Stability, Expected values (controls, calibrators, or methods):
The FDA and CLSI recommended QC isolates, E. coli ATCC 25922 and P. aeruginosa ATCC 27853 were used with the reference method and the BD Phoenix™ Automated Microbiology System. Inoculum density was standardized by manual (CrystalSpec or BD PhoenixSpec) or automated (BD Phoenix AP) methods. The BD Phoenix™ was tested sufficient number of times to demonstrate that the system can produce acceptable range results >95% of the time by both inoculum preparation methods.
Imipenem QC Table
| ORGANISM | conc. (μg/mL) | Manual (CrystalSpec/ PhoenixSpec) | | BD Phoenix™ AP | |
| --- | --- | --- | --- | --- | --- |
| | | Ref | Phoenix | Ref | Phoenix |
| E. coli ATCC 25922
Expected Range: ≤0.0625- 0.25μg/mL | ≤0.0625 | | | | |
| | 0.125 | 40 | 30 | 40 | 24 |
| | 0.25 | 35 | 67 | 35 | 128 |
| | 0.5 | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| P. aeruginosa
ATCC 27853
Expected Range: 1-4 μg/mL | 0.25 | | | | |
| | 0.5 | 1 | | 1 | |
| | 1 | 20 | | 20 | |
| | 2 | 51 | 93 | 51 | 82 |
| | 4 | 3 | 5 | 3 | 12 |
| | NC | 1 | | | |
Inoculum density control: The organism suspension density of the ID broth was standardized using BD nephelometer device which was verified each day of testing. Internal validation data was used to demonstrate that the use of BD nephelometer devices would produce reproducible results.
d. Detection limit:
Not applicable
e. Analytical specificity:
Not applicable
f. Assay cut-off:
Not applicable
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2. Comparison studies:
a. Method comparison with predicate device:
The broth dilution reference panel was prepared according to CLSI recommendation and was used to compare with the BD Phoenix™ results. Clinical testing was performed at three sites. The testing included both fresh clinical isolates and stock isolates along with a challenge set with known results. The test device had a growth rate of >95%. A comparison was provided to the reference method with the following agreement.
GP Accuracy Summary Clinical and Challenge
| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA Tot | CA N | CA % | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Clinical | 1177 | 1104 | 93.8 | 1123 | 1051 | 93.6 | 1177 | 1117 | 94.9 | 110 | 56 | 3 | 1 |
| Challenge | 171 | 171 | 100 | 146 | 146 | 100 | 171 | 167 | 97.7 | 63 | 4 | 0 | 0 |
| Combined | 1348 | 1275 | 94.6 | 1269 | 1197 | 94.3 | 1348 | 1284 | 95.3 | 173 | 60 | 3 | 1 |
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. Evaluable EA is when the MIC result is on scale for both the BD Phoenix™ and the reference and have on-scale EA.
The overall performance was acceptable. There was one very major discrepancy with P. aeruginosa resulting in an acceptable category agreement of 91.2% when analyzing separately. Of the three major discrepancies, two were from Enterobacter cloacae (maj discrepancy rate 2.1%) and one from E. coli (maj discrepancy rate 0.2%). The overall vmj rate and maj rate were 0.6% and 0.3% respectively; they were acceptable. In the clinical studies, the trend was more resistant (1 dilution higher) when comparing to the reference for these organisms: E. coli, K. oxytoca, K. pneumoniae and P. aeruginosa.
The performance of the BD Phoenix AP was also evaluated in the challenge study with acceptable results:
Comparison challenge Data- Manual and automated Phoenix AP
| | EA Tot | EA N | EA % | Eval EA Tot | Eval EA N | Eval EA % | CA Tot | CA N | CA % | #R | min | maj | vmj |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Manual | 171 | 171 | 100 | 146 | 146 | 100 | 171 | 167 | 97.7 | 63 | 4 | 0 | 0 |
| Phoenix AP | 173 | 171 | 98.8 | 148 | 146 | 98.6 | 173 | 168 | 97.1 | 65 | 5 | 0 | 0 |
b. Matrix comparison:
Not applicable
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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 ≤1, 2, ≥4
Pseudomonas aeruginosa ≤2, 4, ≥8
Acinetobacter spp. ≤4, 8, ≥16
N. Proposed Labeling:
The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.
O. Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
