Commercial Systems Available: PallCheck (Pall Life Sciences), Milliflex (Millipore Corporation), Rapiscreen (Celsis), and novaLUM (Charm). Hygiena also
has a small hand-held luminometer.
Other: The majority of ATP-based systems are quantitative. The capability of these instruments can be enhanced by using the microbiology
application of most probable number techniques.
Adenylate Kinase
Type of Technology: Growth-based.
Premise of Technology: Adenylate kinase is a cellular component that allows for microbial detection. The adenylate kinase released from cells reacts
with ADP to form ATP. The ATP is detected using an ATP bioluminescence method. Using these technologies significantly lowers
the level of detection for the system. The assay has a detection level of about 34 cells. The detection level can be further
reduced (to about four cells) by extending the incubation for ATP generation time.8
Commercial Systems Available:
Celsis has given presentations on a new system that uses this technology.
Arrays, Microarrays, Microchips
See Lab-on-a-Chip
Biochemical Assays and Physiological Reactions
Type of Technology: Cell-component-based.
Premise of Technology: Pure culture suspensions are tested with a series of biochemical substrates or subjected to analysis to generate a spectrum.
The microorganisms have specific reactions to these test conditions. The results are compared to a database of expected results.
These comparisons allow the user to identify the microorganism. Systems vary from manual to highly automated.
Commercial Systems Available:
API Systems (bioMerieux), BIOLOG Systems (Biolog), and VITEK and VITEK2 (bioMerieux).
Other:
Many of these systems require performance of a Gram stain prior to further evaluation. The accuracy of the Gram stain
can significantly influence results.
Biosensors and Immunosensors
Type of Technology:
Various, depending on the sensor technology used.
Premise of Technology: Immunological reagents are combined with varying sensor detection systems to produce an immunosensor. Typically, these systems
are used for pathogens (including bioterrorism organisms).8
Commercial Systems Available:
Test kits and sensors are specific to the type of application being monitored.
Changes in Headspace Pressure
Type of Technology:
Growth-based.
Premise of Technology: Electronic transducers measure positive or negative pressure changes in the head space of each culture bottle. These changes
are caused by microbial growth. If the growth causes significant production or consumption of gas, the samples are flagged
as positive. Large quantities of samples can be placed in these instruments for testing with frequent monitoring of the head-space
pressure. These systems are based on non-invasive, continuous, automated monitoring of microbial cultures.
Commercial Systems Available:
BacT/Alert (bioMerieux) and ESP Microbial Detection System (AccuMed).
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