Search Results

The PBC Separator with Selux AST System is an automated inoculum preparation system that uses lysis, centrifugation and sequential optical density measurements to generate a McFarland-equivalent suspension from positive blood culture samples that can be used for quantitative in vitro antimicrobial susceptibility testing by the Selux AST System. Samples are processed directly from blood culture samples identified as positive by a continuous monitoring blood culture system. Samples should be confirmed as monomicrobial, gram negative rods or gram positive cocci by Gram stain. Organism identification is required for AST result interpretation and reporting, per the Selux AST System Instructions for Use.

Inoculum preparation by the PBC Separator was evaluated for use with the Selux AST System and the Selux AST Gram Negative Panel. Performance was demonstrated for the antimicrobial agents and organisms identified below:

• Amikacin: Acinetobacter baumannii complex, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa

· Amoxicillin-Clavulanate: Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae), Proteus mirabilis, Proteus vulgaris

· Ampicillin: Escherichia coli, Proteus mirabilis

· Ampicillin-Sulbactam: Acinetobacter baumannii complex, Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis

• Cefazolin: Escherichia coli, Klebsiella pneumoniae

· Cefepime: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa

• Ceftazidime: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa

· Ceftazidime-Avibactam: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa

· Ceftriaxone: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli,

Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Serratia marcescens

• Ciprofloxacin: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa

• Ertapenem: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens

• Gentamicin: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa

· Imipenem: Acinetobacter baumannii complex, Escherichia coli, Klebsiella pneumoniae

· Meropenem: Acinetobacter baumannii complex, Citrobacter koser, Enterobacter cloacae complex, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa

· Minocycline: Acinetobacter baumannii complex, Escherichia coli, Klebsiella pneumoniae

• Piperacillin-Tazobactam: Acinetobacter baumannii complex, Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Morganella morganii, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa

• Tobramycin: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa

Inoculum preparation by the PBC Separator was evaluated for use with the Selux AST System and the Selux AST Gram Positive Panel. Performance was demonstrated for the antimicrobial agents and organisms identified below:

• Ampicillin: Enterococcus faecalis, Enterococcus faecium
• Ceftaroline: Staphylococcus aureus
• Daptomycin: Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus
• · Linezolid: Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus
• Oxacillin: Staphylococcus aureus
• Vancomycin: Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus

The PBC Separator with Selux AST System Gram Positive Panel is a qualitative test for the following antimicrobial agents with the specific target organisms identified below:

• · Cefoxitin Screen to predict mecA-mediated oxacillin resistance: Staphylococcus aureus
  Susceptibility test results are intended to be used in conjunction with other clinical and laboratory findings. Standard laboratory protocols for processing positive blood cultures should be followed to ensure availability of isolates for supplemental testing as needed. Additionally, subculture of positive is necessary for the susceptibility testing of organisms present in polymicrobial samples, for testing antimicrobial agents and species not indicated for testing with the device, for epidemiologic testing, and for recovery of organisms present in microbial samples.

The Positive Blood Culture (PBC) Separator with Selux AST System is an automated sample preparation instrument with associated consumables that uses lysis, centrifugation, and sequential optical density measurements to prepare a tuned McFarland-equivalent inoculum from positive blood culture bottles that have rung positive on a continuous monitoring blood culture system. Inoculums containing monomicrobial, gram negative or gram positive bacteria are used for Antimicrobial Susceptibility Testing (AST) processing with the Selux AST System. The Selux AST System includes a sample prep station (i.e., AST Workbench), an Inoculator, an Analyzer, Workbench Computer, and the reagents and consumables required to perform AST testing. The PBC Separator and all Selux AST System components are connected to a site workstation, which coordinates sample processing on all instruments. The PBC Separator contains embedded software and a graphical user interface that guides users through the PBC Separator workflow. Once processing of the PBC sample is complete, the user transfers the tuned McFarland inoculum to the Selux AST System for further AST processing.

The PBC Separator with Selux AST System can only provide AST results for monomicrobial samples. Since the PBC Separator with Selux AST System does not perform identification (ID), the monomicrobial nature of the sample under test must be confirmed by an FDA-cleared directfrom-positive blood culture ID system.

While PBC Separator processing can be performed without species-level ID, this information is required for the Selux AST System to interpret and report susceptibility results. Species ID can be performed by any appropriate method and this information can be either manually input to the Selux AST System or automatically downloaded from the laboratory information system (LIS) at any time, once the sample ID is entered into the LIS.

The PBC Separator with the Selux AST System utilizes a 384-well panel, either the Selux Gram-Negative Panel or Selux Gram-Positive Panel, that provides parallel results for the antimicrobials indicated for each sample type. The Selux AST System software masks non-indicated results. The average time-to-result for positive blood culture processed with the PBC Separator and Selux AST System is under 7 hours.

Principle of Operation

The PBC Separator automatically prepares a tuned bacterial inoculum directly from a blood culture bottle sample that "rang" positive on an FDA-cleared continuous monitoring blood culture system, including the Becton Dickinson BACTEC, the bioMerieux BacT/Alert 3D, and the bioMerieux Virtuo. The PBC Separator removes contaminants through repeated centrifugation-wash cycles and specific chemical lysis of mammalian cells and cell fragments. The PBC Separator utilizes an on-board spectrometer to tune the inoculum for the right cell density to perform AST.

Tuned inoculums are used with the Selux AST System. The Selux AST System performs AST similarly to the reference broth microdilution method by first incubating samples, then quantifying microbial growth in each well of an antimicrobial dilution series after a growth period, and finally determining the minimum inhibitory concentration (MIC) by comparing growth data in each well,

AST testing of PBC samples requires that the Gram type (classification) of the organism be known prior to testing on the Selux AST System as the information is necessary to select the proper AST panel to use. Organism identification (ID) is not needed to initiate testing with the Selux AST System. However, the organism ID is necessary for a result to be interpreted and reported because the MIC-determining algorithm is species-specific as is the interpretative Susceptible (S), Susceptible Dose Dependent (SDD), Intermediate (I), or Resistant (R) determination. Any FDAcleared method may be used to provide an ID including biochemical techniques, matrix-assisted laser desorption/ionization mass spectrometry, and multiplex genetic assays.

Here's an analysis of the acceptance criteria and the study proving device performance, based on the provided FDA 510(k) summary for the PBC Separator with Selux AST System:

Acceptance Criteria and Device Performance Study

The document outlines analytical and clinical studies to demonstrate the performance of the PBC Separator with Selux AST System, particularly for gram-positive organisms, compared to a reference method (broth microdilution).

1. Table of Acceptance Criteria and Reported Device Performance

The document presents performance in terms of Essential Agreement (EA), Category Agreement (CA), Very Major Errors (VMJ), Major Errors (MAJ), and Minor Errors (MIN). While explicit "acceptance criteria" are not listed as a single table, the overall performance metrics, particularly the high percentages for EA and CA, and low error rates, indicate the expected and achieved levels of performance. For reproducibility, quantitative acceptance criteria were explicitly stated.

Reproducibility Acceptance Criteria:

• Best-case reproducibility: ≥95%
• Worst-case reproducibility: ≥89% (for inter- and intra-site)

Essential Agreement (EA) Acceptance Criteria (Implicit from "meets performance criteria"):
The overall impression from the "Blood Culture Bottle Compatibility Study" and "Interfering Substances Testing" sections is that EA should be >89.9%.
For the "Clinical Studies" section, while not explicitly stated as a numerical threshold, FDA typically expects high EA and CA (e.g., >90-95%) and very low VMJ/MAJ errors (94% (Range: 94.8% - 100%) |
| Cefoxitin Screen | Inter-site (modal) | N/A (matched modal result) | 99.3% |
| | Intra-site (modal) | N/A (matched modal result) | 100% |
| Bottle Compatibility| Essential Agreement (EA) | >89.9% | Aerobic bottles: 99.4% EA (range ≥96.7%); Anaerobic bottles: 99.3% EA (range ≥96.7%) |
| | Cefoxitin Screen | 100% agreement expected | 100% agreement, except one instance demonstrating 66.7% (2/3) out-of-agreement in BD BACTEC Aerobic Plus bottles. |
| Interfering Substances| Essential Agreement (EA) | >89.9% | All endogenous interferents: 83.3% - 100% EA. All exogenous interferents: 66.7% - 100% EA. |
| | Cefoxitin Screen | No interference (100% agreement) | 100% agreement. |
| Clinical Performance| Essential Agreement (EA) | High (e.g., >90-95%) | Range: 94% - 100% (Individual combos: 75% for Ampicillin Enterococci Eval, 0% for Daptomycin E. faecalis Eval, 47.6% for Vancomycin Enterococci Eval) |
| | Category Agreement (CA) | High (e.g., >90-95%) | Range: 94.6% - 100% |
| | Very Major Errors (VMJ) | Low (e.g.,

Ask a specific question about this device

The PBC Separator with Selux AST System is an automated inoculum preparation system that uses lysis, centrifugation and sequential optical density measurements to generate a McFarland-equivalent suspension from positive blood culture samples that can be used for quantitative in vitro antimicrobial susceptibility testing by the Selux AST System. Samples are processed directly from blood culture samples identified as positive by a continuous monitoring blood culture system. Samples should be confirmed as monomicrobial, gram negative rods by Gram stain. Organism identification is required for AST result interpretation and reporting, per the Selux AST System instructions for use.

Inoculum preparation by the PBC Separator was evaluated for use with the Selux AST System and the Selux Gram Negative Panel. Performance was demonstrated for the antimicrobial agents and organisms identified below:

Amikacin: Acinetobacter baumannii complex, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa

Amoxicillin-Clavulanate: Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae), Proteus mirabilis, Proteus vulgaris

Ampicillin: Escherichia coli, Proteus mirabilis

Ampicillin-Sulbactam: Acinetobacter baumannii complex, Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis

Cefazolin: Escherichia coli, Klebsiella pneumoniae

Cefepime: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa Ceftazidime: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa

Ceftazidime-Avibactam: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa

Ceftriaxone: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Proteus mirabilis, Serratia marcescens

Ciprofloxacin: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa

Ertapenem: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens

Gentamicin: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa Imipenem: Acinetobacter baumannii complex, Escherichia coli, Klebsiella pneumoniae

Meropenem: Acinetobacter baumannii complex, Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii. Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa Minocycline: Acinetobacter baumannii complex, Escherichia coli, Klebsiella pneumoniae

Piperacillin-Tazobactam: Acinetobacter baumannii complex, Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, Pseudomonas aeruginosa

Tobramycin: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa

Susceptibility test results are intended to be used in conjunction with other clinical and laboratory findings. Standard laboratory protocols for processing positive blood cultures should be followed to ensure availability of isolates for supplemental testing as needed. Additionally, subculture of positive blood culture is necessary for the susceptibility testing of organisms present in polymicrobial samples, for testing antimicrobial agents and species not indicated for testing with the device, for epidemiologic testing, and for recovery of organisms present in microbial samples.

The Positive Blood Culture (PBC) Separator with Selux AST System is an automated sample preparation instrument with associated consumables that uses lysis, centrifugation, and sequential optical density measurements to prepare a tuned McFarland-equivalent inoculum from positive blood culture bottles that have rung positive on a continuous monitoring blood culture system. Inoculums containing monomicrobial, gram negative bacteria are used for AST processing with the Selux AST System. The Selux AST System includes a sample prep station (i.e., AST Workbench), an Inoculator, an Analyzer, Workbench Computer, and the reagents and consumables required to perform AST testing. The PBC Separator and all Selux AST System components are connected to a site workstation, which coordinates sample processing on all instruments. The PBC Separator contains embedded software and a graphical user interface that guides users through the PBC Separator workflow. Once processing of the PBC sample is complete, the user transfers the tuned McFarland inoculum to the Selux AST System for further AST processing.

The PBC Separator with Selux AST System can only provide AST results for monomicrobial samples. Since the PBC Separator with Selux AST System do not perform identification (ID), the monomicrobial nature of the sample under test must be confirmed by an FDA-cleared direct-frompositive blood culture ID system.

While PBC Separator processing can be performed without species-level ID, this information is required for the Selux AST System to interpret and report susceptibility results. Species ID can be performed by any appropriate method and this information can be either manually input to the Selux AST System or automatically downloaded from the laboratory information system (LIS) at any time, once the sample ID is entered into the LIS.

The PBC Separator with the Selux AST System utilizes the Selux Gram Negative Panel, a 384well panel that provides parallel results for the antimicrobials indicated for each sample type. The Selux AST System software masks non-indicated results. The average time-to-result for positive blood culture processed with the PBC Separator and Selux AST System is under 7 hours.

Here's a breakdown of the acceptance criteria and study details for the PBC Separator with Selux AST System, based on the provided FDA 510(k) summary:

Acceptance Criteria and Device Performance

The core performance criteria for the PBC Separator with Selux AST System relate to its ability to accurately determine antimicrobial susceptibility. The primary metric used is Essential Agreement (EA), which measures how closely the MIC results from the device match the reference method, and Category Agreement (CA), which assesses agreement in susceptibility interpretations (Susceptible, Intermediate, Resistant - SIR).

Overall Acceptance Criterion: The device must meet performance criteria for each indication, generally interpreted as high percentages of Essential Agreement (EA) and Category Agreement (CA) (typically >90% as seen in the tables for acceptable overall performance, though individual instances below 90% might be deemed acceptable based on the totality of data).

1. Table of Acceptance Criteria and the Reported Device Performance

Study Details

The document primarily describes analytical and clinical studies for the performance evaluation of the PBC Separator with Selux AST System.

2. Sample Size Used for the Test Set and Data Provenance

• Reproducibility:
  • Intra-site: Minimum of 45 results per antimicrobial (5 samples * 3 triplicates * 3 days).
  • Inter-site: Minimum of 135 results per antimicrobial (5 samples * 3 triplicates * 3 days * 3 sites).
  • Data Provenance: Not explicitly stated as retrospective or prospective, but involves seeding isolates into fresh human blood and processing, suggesting a controlled laboratory setting. The "3 sites (2 external, 1 internal)" suggests internal and possibly US/international external sites.
• Post-Positivity Sample Stability: 265 results comparing 16-hour processing to 0-hour processing.
  • Data Provenance: Fresh human blood from a healthy donor.
• Blood Culture Bottle Compatibility:
  • Aerobic: 1640 results across 11 bottle types.
  • Anaerobic: 979 results across 11 bottle types.
  • Data Provenance: Seeded bacterial samples at clinically relevant concentrations into blood culture bottles with manufacturer-recommended volumes of healthy donor human blood.
• Interfering Substances Testing:
  • Each interferent tested involved "at least one species for each reporting group for each antimicrobial."
  • Data Provenance: Healthy donor blood used to seed interferents and bacteria.
• Carry-Over/Cross-Contamination Study: 5 E. coli and 5 K. pneumoniae positive blood culture samples; 5 AST panels for each organism.
  • Data Provenance: Seeded isolates.
• Clinical Studies:
  • Total Isolates: 469 clinical (162 fresh and 307 seeded) and 87 challenge isolates.
  • Organisms: 12 Enterobacterales species, Acinetobacter baumannii complex, and Pseudomonas aeruginosa.
  • Antimicrobials: 17.
  • Total Data Points: Varied from 38 to 469 per antimicrobial-organism combination.
  • Data Provenance:
    • Fresh clinical samples: "left over from routine clinical care" from two clinical sites in New York City. This indicates retrospective use of fresh samples collected in a clinical setting.
    • Seeded samples: "banked frozen isolates seeded... into blood culture bottles together with approximately 10 mL of fresh human blood from a healthy donor." These seeded samples were chosen "to represent geographic diversity across the continental U.S." This component is laboratory-based but designed to represent real-world diversity.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and their Qualifications

The document does not explicitly state the number of experts or their qualifications for establishing ground truth. However, it indicates that triplicate broth microdilution results performed at an independent reference laboratory were used as the reference method. This implies that the ground truth was established by laboratory personnel in a CLIA-certified or equivalent reference lab, following a recognized standard for AST.

4. Adjudication Method for the Test Set

The document does not describe an explicit adjudication method (e.g., 2+1, 3+1) for the interpretation of test results or discrepancies. The comparison is made directly between the device's results and the reference broth microdilution results. Any discrepancies would be evaluated against established acceptance criteria, but no formal expert adjudication process is detailed.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. The device is for antimicrobial susceptibility testing, which does not involve human readers interpreting images or data alongside AI. The device provides a direct microbiological result (MIC and SIR category).

6. If a Standalone Performance Study (algorithm only without human-in-the-loop performance) was done

Yes, the studies described are primarily standalone performance studies for the device. The "PBC Separator with Selux AST System" directly processes samples and generates MICs and SIR interpretations. While requiring inputs like Gram stain and organism identification before result interpretation, the AST process itself (lysis, centrifugation, optical density measurements, and MIC determination) is automated by the device without real-time human intervention in the result generation. The performance is compared to a reference standard (broth microdilution), reflecting the algorithm's output.

7. The Type of Ground Truth Used

The ground truth used for all performance evaluations (reproducibility, stability, compatibility, interferents, clinical performance) was broth microdilution (BMD), which is the gold standard reference method for antimicrobial susceptibility testing. For the clinical studies, it specifies "triplicate broth microdilution results performed at an independent reference laboratory."

8. The Sample Size for the Training Set

The document does not specify the sample size for the training set. The provided information focuses entirely on the validation and testing of the device's performance, not its development or training data.

9. How the Ground Truth for the Training Set Was Established

Since the document does not mention a training set or its size, it also does not describe how the ground truth for a training set was established.

Ask a specific question about this device

Intended Use:
The Selux AST System is intended to be used for the automated quantitative susceptibility testing for most clinically significant aerobic microorganisms. The Selux AST System does not provide organism identification.

Indications for Use:
The Selux Gram-Negative Panel is intended for use with the Selux AST System as an in vitro test to determine the susceptibility of isolated colonies of specific gram-negative bacilli to specific antimicrobial agents when used as instructed.

The Selux Gram-Negative Panel is a quantitative test for the following antimicrobial agents with the specific organisms identified below:

• Amikacin: Pseudomonas aeruginosa
• Amoxicillin-Clavulanate: Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae), Proteus mirabilis
• Ampicillin: Escherichia coli, Proteus mirabilis
• Ampicillin-Sulbactam: Acinetobacter baumannii complex, Escherichia species (including K. oxytoca, K. pneumoniae), Proteus mirabilis, Proteus vulgaris
• Aztreonam: Escherichia coli
• Cefazolin: Escherichia coli, Klebsiella pneumoniae
• Cefepime: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
• Cefoxitin: Escherichia coli, Klebsiella species (including K. oxytoca, K. pneumoniae), Morganii
• Ceftazidime: Citrobacter species (including C. freundii complex, C. koseri), Enterobacter cloacae complex, Escherichia coli, Klebsiella species (including K. aerogenes, K. pneumoniae), Proteus mirabilis, Proteus vulgaris, Serratia marcescens
• Ceftazidime-Avibactam: Citrobacter freundii complex, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens
• Ceftriaxone: Citrobacter freundii complex, Citrobacter koseri, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis
• Ciprofloxacin: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa
• Eravacycline: Citrobacter freundii complex, Enterobacter cloacae complex, Escherichia oxytoca
• Ertapenem: Citrobacter freundii complex, Citrobacter koseri, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
• Gentamicin: Citrobacter species (including C. freundii complex, C. koseri), Enterobacter cloacae complex, Escherichia coli, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae), Proteus species (including P. mirabilis, P. vulgaris), Pseudomonas aeruginosa, Serratia marcescens
• Imipenem-Relebactam: Citrobacter freundii complex, Citrobacter koseri, Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa
• Levofloxacin: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris, Serratia marcescens
• Meropenem: Citrohacter freundii complex. Citrobacter cloacae complex. Escherichia coli. Klebsiella oxvtoca, Klebsiella pneumoniae, Morganella morganii. Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens
• Meropenem-Vaborbactam: Citrobacter freundii complex, Citrobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, Serratia marcescens
• Minocycline: Escherichia coli, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae)
• Piperacillin-Tazobactam: Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Morganii, Proteus mirabilis, Proteus vulgaris
• Tobramycin: Pseudomonas aeruginosa
• Trimethoprim-Sulfamethoxazole: Enterobacter cloacae complex, Klebsiella species (including K. aerogenes, K. oxytoca, K. pneumoniae)

The Selux AST System for antimicrobial susceptibility testing (AST) consists of a Sample Prep Station, an Inoculator, an Analyzer, a computer workstation, and the reagents and consumables required to perform AST testing. The system is operated via software that guides users through the manual sample preparation process and operates the automated Inoculator and Analyzer. The software includes an algorithm that enables the system to determine the susceptibilities of an organism to the variety of antimicrobials under test.

The system is designed so that only Gram stain information is required to initiate testing (to select the proper antimicrobial panel, gram-negative or gram-positive). While complete system testing can be performed without species-level identification (ID), this information is required for the system to report susceptibility results. Species ID can be performed by any appropriate method and this information can be either manually input to the Selux system or automatically downloaded from the laboratory information system (LIS) at any time, once the sample ID is entered into the system.

The system utilizes 384-well panels to provide parallel results for a large number of antimicrobials. Its average time-to-result is under 6 hours, as demonstrated in various studies.

Principle of Operation
The Selux platform performs AST similarly to the reference broth microdilution method by first incubating samples, then quantifying microbial growth in each well of an antimicrobial dilution series after a growth period, and finally determining the MIC by comparing growth data in each well. The Selux AST test requires that the Gram type (Classification) of the organism be known prior to testing as the information is necessary to select the proper AST panel to use. The organism identification (ID) need not be known for Selux AST processing to be performed. However, the organism ID is necessary for a result to be obtained because the MIC-determining algorithm is species-specific as is the interpretative Susceptible, Intermediate, or Resistant (SIR) determination. Any FDA-cleared method may be used to provide an ID including biochemical techniques, matrixassisted laser desorption/isotherm mass spectrometry, and multiplex genetic assays.

To ensure accurate results, the Selux method initiates antimicrobial susceptibility assays only after sufficient microorganism replication has occurred. Following determination of sufficient growth, two complementary metabolic assays are performed that quantify microbial growth, namely an indicator assay to estimate the number of bacteria present and a surface binding assay. These data are input to an MIC-determining algorithm that provides results when organism IDs are available. The sufficient growth assay ensures that the metabolic reagents used for the high-sensitivity organism quantification assays are not added until after sufficient microbial growth has occurred. To get an accurate reading of microbial replication, the sufficient growth assay monitors growth in dedicated AST panel wells that contain organisms and cation-adjusted Mueller-Hinton Broth but no antimicrobials or probes. Sufficient growth assay wells are monitored by fluorescence to those wells which the standard viability assay pair resazurin/methylene blue have been added and/or by optical absorbance.

Two probe-based assays, a viability assay and a surface area assay, commence across all wells in the panel after the sufficient growth threshold has been met. Both of these assays are performed in each AST panel well, providing two complementary datasets for each well.

Here's a summary of the acceptance criteria and study details for the Selux AST System, based on the provided FDA 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for the Selux AST System are based on the comparison of its results with triplicate broth microdilution results from an independent reference laboratory. The specific performance metrics are "Essential Agreement" (EA) and "Category Agreement" (CA), along with an analysis of Very Major Errors (VMJ), Major Errors (MAJ), and Minor Errors (MIN). While the exact numerical acceptance criteria are not explicitly stated as "X% EA and Y% CA," the table below presents the reported performance, which implicitly met the FDA's requirements for substantial equivalence. The document states that the "Selux AST System meets performance criteria for each indication."

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size:
  • A total of 1401 clinical isolates (426 contemporary and 975 stock) and 222 challenge isolates were used.
  • This totals 1623 isolates across 12 Enterobacterales species, Acinetobacter baumannii complex, and Pseudomonas aeruginosa.
  • The number of data points for various antimicrobial-organism combinations ranged from 165 to 977, depending on the specific combination.
• Data Provenance: Clinical isolates were from "diverse geographic locations across the US." The study included both contemporary and frozen clinical isolates, as well as banked challenge isolates (selected for resistance profiles). This indicates a prospective and retrospective collection for clinical isolates and potentially retrospective for banked challenge isolates.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

The document does not specify the number or qualifications of experts. However, it states that the ground truth was established by "triplicate broth microdilution results performed at an independent reference laboratory." This implies that the standard reference method for antimicrobial susceptibility testing was used, which is typically conducted by trained microbiologists.

4. Adjudication Method for the Test Set

The document does not explicitly describe an adjudication method for discrepancies between the device and the reference method. The comparison methodology is directly stated as: "Selux AST System performance was determined by comparing Selux AST System results with triplicate broth microdilution results performed at an independent reference laboratory." This suggests a direct comparison rather than an adjudication process by additional experts for discordant results.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No, an MRMC comparative effectiveness study involving human readers with and without AI assistance was not done. This device is an automated antimicrobial susceptibility testing system, not an imaging or diagnostic device that typically involves human interpretation of outputs aided by AI. Its performance is compared directly to a reference laboratory method for accuracy.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Yes, the study described is a standalone performance evaluation of the Selux AST System. The system "determines the susceptibilities of an organism to the variety of antimicrobials under test" using its integrated software and algorithm. While human input is required for initial sample preparation and entry of organism identification (which can be manual or LIS-automated), the core susceptibility determination by the system is automated ("algorithm only"). The results are then compared to the reference method (broth microdilution).

7. The Type of Ground Truth Used

The ground truth used was broth microdilution results, specifically "triplicate broth microdilution results performed at an independent reference laboratory." Broth microdilution is considered a gold standard reference method for antimicrobial susceptibility testing.

8. The Sample Size for the Training Set

The document does not explicitly state the sample size for the training set. The provided details focus on the validation/test set used for clinical performance evaluation.

9. How the Ground Truth for the Training Set Was Established

Since the training set size and details are not provided, information on how its ground truth was established is also not available in this document.

Ask a specific question about this device

Intended Use:
The Selux AST System is intended to be used for the automated quantitative susceptibility testing for most clinically significant aerobic microorganisms. The Selux AST System does not provide organism identification.

Indications for Use:
The Selux Gram-Positive Panel is intended for use with the Selux AST System as an in vitro test to determine the susceptibility of isolated colonies of specific Staphylococcus species to species to specific antimicrobial agents when used as instructed.

The Selux Gram-Positive Panel is a quantitative test for the following antimicrobial agents with the specific organisms identified below:

• Ampicillin: Enterococcus faecium, Enterococcus faecalis
• Clindamycin: Staphylococcus aureus, Staphylococcus epidermidis
• Ceftaroline: Staphylococcus aureus
• Daptomycin: Staphylococcus aureus, Enterococcus faecalis
• Delafloxacin: Staphylococcus aureus, Staphylococcus haemolyticus, Enterococcus faecalis
• Eravacycline: Staphylococcus aureus, Enterococcus faecalis
• Erythromycin: Staphylococcus aureus
• Linezolid: Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus haemolyticus, Enterococcus faecium, Enterococcus faecalis
• Levofloxacin: Enterococcus faccium, Enterococcus faecalis, methicillin-susceptible Staphylococcus aureus
• Minocycline: Staphylococcus aureus
• Oxacillin: Staphylococcus aureus, Staphylococcus lugdunensis
• Penicillin: Enterococcus faecium, Enterococcus faecalis, Staphylococcus aureus
• Trimethoprim: Staphylococcus aureus, Coagulase-Negative Staphylococci (including S. capitus, S. haemolyticus, S. saprophyticus, S. simulans)
• Vancomycin: Staphylococcus aureus, Coagulase-Negative Staphylococci (CoNS) (including S. capitus, S. cohnii, S. epidermidis, S. haemolyticus, S. internedius group, S. lugdunensis, S. saprophyticus, S. schleiferi, S. simulans) Enterococcus faecium, Enterococcus faecalis

The Selux Gram-Positive Panel is a qualitative test for the following antimicrobial agents with the specific target organisms identified below:

• Cefoxitin Screen to predict mecA-mediated oxacillin resistance: Staphylococcus aureus, Staphylococcus lugdunensis

The Selux AST System for antimicrobial susceptibility testing (AST) consists of a Sample Prep Station, an Inoculator, an Analyzer, a computer workstation, and the reagents and consumables required to perform AST testing. The system is operated via software that guides users through the manual sample preparation process and operates the automated Inoculator and Analyzer. The software includes an algorithm that enables the system to determine the susceptibilities of an organism to the variety of antimicrobials under test.

The system is designed so that only Gram stain information is required to initiate testing (to select the proper antimicrobial panel, gram-negative or gram-positive). While complete system testing can be performed without species-level identification (ID), this information is required for the system to report susceptibility results. Species ID can be performed by any appropriate method and this information can be either manually input to the Selux system or automatically downloaded from the laboratory information system (LIS) at any time, once the sample ID is entered into the LIS.

The system utilizes 384-well panels to provide parallel results for a large number of antimicrobials. Its average time-to-result is under 6 hours, as demonstrated in various studies.

Here's a breakdown of the acceptance criteria and study information for the Selux AST System, based on the provided FDA 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for each antimicrobial-organism combination are not explicitly stated as numerical targets (e.g., "EA must be >90%"). Instead, the document presents the observed performance and notes where EA (Essential Agreement) falls below 90%, implying that 90% is a general benchmark for acceptable performance, with specific justifications or labeling changes for values below this. The table below summarizes the reported performance.

*¹ EA performance (

Ask a specific question about this device