The BACcelr8r™

Summary Points

• The BACcelr8r™ is a product in development at Accelr8. It integrates Accelr8's proprietary technology into an analytical platform.
• Its purpose is to rapidly identify bacterial pathogen species and strains, including strain identification by means of major antibiotic resistance categories.
• The commercializable system will include an automated instrument that performs analyses in single-use, disposable cassettes. Each instrument will have the capacity to concurrently manage multiple cassettes.
• We are designing the system to operate automatically, without human intervention, after brief manual sample preparation and sample introduction into a disposable cassette.
• The BACcelr8r eliminates culturing and strain isolation by analyzing the responses of each individual bacterial cell extracted from a patient's specimen.
• Testing indicates that by eliminating bacterial culturing and strain isolation, the BACcelr8r's methods appear able to deliver pathogen identification in less than two hours, and complete antibiotic resistance analysis in less than eight hours after starting specimen preparation.

A System for Rapid Bacterial Analysis

The BACcelr8r™ is a product in development. It will be an automated system for rapid bacterial identification and antibiotic resistance testing. We intend to commercialize the system for research and clinical applications. We are designing it to complement standard equipment and methods. Instead of identifying a large number of species as in general microbiology practice, the BACcelr8r will identify a relatively small number of species that account for the large majority of specific high-risk diagnoses (typically 5-15 species cover at least 85% of cases).

Diagnostic examples include hospital-acquired pneumonia, bacterial meningitis, blood-borne neonatal infections, surgical infections, etc.. The system will provide a different type of dedicated cassette for each such diagnostic category.

The BACcelr8r's technical advantages include speed and the ability to analyze tens of thousands of individual bacterial cells concurrently. It eliminates the need for prior culturing and strain isolation, instead using bacteria extracted directly from the patient specimen or laboratory sample.

We intend the BACcelr8r to address urgent medical applications, such as hospital acquired infection (HAI) in the ICU. In these applications today's methods are far too slow to be useful in selecting effective therapy. A rapid and accurate alternative could significantly improve medical outcomes for critically ill patients.

The BACcelr8r will also offer significant advantages in certain microbiology research applications. The complex research methods now used to accurately characterize antibiotics and new drug candidates are highly labor-intensive and slow. By eliminating the numerous, time-consuming culturing steps the BACcelr8r might offer a substantial improvement in throughput and accuracy. The BACcelr8r's unique methods for single-cell microbiology promise great sensitivity and precision.

With adaptations, we believe that the system can also apply to molecular analyses. Our technology originated with microarray applications, for example. By adapting assays to molecular targets instead of bacteria, the automated imaging system could provide readily-analyzed data. Such a system should succeed with genetic probes, micro-immunoassays, and protein interaction assays. Please see the Partnering page for more information.

Product Architecture

BACcelr8r™ Concept Rendering

The BACcelr8r™ will be an integrated system, with an automated instrument and single-use, disposable analytical cassettes. The instrument will automatically process a number of cassettes. Each cassette will contain one sample taken from one patient.

The instrument will house all of the fixed equipment and large-volume liquid reservoirs. An automated cassette handler will move cassette between the stage of an automated microscope and a storage “hotel” between readings. A computer will control the microscope to allow rapid scanning across all flowcells in each cassette. A digital camera will acquire images for each set of observations, and image analysis software will derive analytical data from the image files.

Automated fluidic pumps and controls will manage programmed reagent and nutrient flow through the cassette. The system will perform various assays by delivering the required media at specified times.

8-Channel Cassette Prototype

Each cassette contains a number of individual flowcells. A flowcell is a small, specialized region within a fluid passageway that has particular dimensions and materials to enable assay performance. BACcelr8r flowcells have the bacterial capture agent on one surface. They have transparent electrodes on two surfaces to create the electrokinetic field. The automated microscope focuses on the flowcell capture surface.

The cassette also has upstream reservoirs that feed a common distribution passageway. The distributor passage branches and delivers balanced, equal flow through all flowcells at the same time. Upstream reservoirs hold the sample and different assay reagents (stains and antibodies).

Each flowcell also has its own separate reservoir immediately upstream. In an antibiotic test, for example, each flowcell uses a different antibiotic. In this case the individual reservoirs each contain the antibiotics.

Cassette fluidic channel (courtesy of Edge Embossing LLC)

Research versions of the cassette also permit the operator to load different bacterial samples for each flowcell. This enables experiments that run multiple samples on one cassette – as long as all samples (flowcells) receive the same reagents and drugs.

The cassette carries on-board reagents because most of the materials become unstable in solution. Some are costly as well, so it is not practical to use a large common source in the instrument. On-board reagents assure that the system uses fresh reagents for each sample.

A control program for an experiment (or diagnostic analysis) consists of a sequence of sample capture followed by a timed flow and valve sequence to deliver different reagents at the protocol requirements.

The program also controls the microscope. It controls stage motion to scan across the cassette's individual flowcells for image acquisition. For each flowcell stop, it controls image acquisition: exposure, illumination modes (light scattering, fluorescence, fluorescent wavelengths, etc.

A full analysis (described in the single-cell microbiology and Quantum Microbiology™ pages) typically requires measurements on approximately 3-4 million individual clone images.

Accelr8's Enabling Technology

The BACcelr8r cassette design uses OptiChem® surface chemistry for two purposes. Passivated OptiChem prevents bacteria from adhering to fluid passageway walls. Small, precisely defined regions of activated OptiChem bind to a proprietary bacterial capture agent. This design prevents loss of sample bacteria upstream of the flowcell region. The capture agent occupies a precisely defined pattern on one surface inside the microscope's field of view in each flowcell. OptiChem's unique anti-fouling and high ligand capacity greatly simplify the flowcell design, also maximizing overall sensitivity and accuracy.

The flowcell uses Accelr8's proprietary electrokinetic technology to rapidly concentrate bacteria to the flowcell capture surface. This step replaces culturing and strain isolation, reducing an overnight (or longer) process to 5 minutes or less.

We have applied for patents on key aspects of Quantum Microbiology methodology. QM provides the BACcelr8r's foundation. These applications include certain aspects of Accelr8's detection technology as well as practical single-cell microbiological principles.

Dual Cassette Lab Prototype (on Microscope Stage)

Development Status

We have developed a number of fixtures and prototypes for various system components since originating the analytical concept (QM) early in 2004. We now have lab research prototype instruments that combine commercially available lab components with custom-engineered components and software.

Current prototypes use 8-channel cassettes. This means that each cassette has eight separate flowcells. One research prototype instrument carries two cassettes. The instruments have highly automated operation, and offer flexible support for challenging research protocols.

Research cassettes require manual reagent solution preparation and injection into the cassette reservoirs. This provides great flexibility for research.

We use these systems for internal research to develop and characterize the novel biological phenomena made possible by QM. This research is proving quite fruitful. We have begun to publish results of this research in leading international scientific and clinical meetings and peer-reviewed professional journals.

At present, we plan for a commercial diagnostic version to use 64 flowcells per cassette, and multiple cassettes. The specification allows the user to insert cassettes at will (batch operation not required). In addition, a commercial diagnostic product requires dried reagents and drugs to provide long shelf life and ease of operation.