- Biological indicators (BIs) are test systems containing spores of heat-resistant bacteria, e.g. Geobacillus stearothermophilus.
- BIs are used to monitor sterilization processes in health care facilities.
- Government guidelines require that a spore test should be used on each sterilizer at least weekly. A spore test should also be used for every load with an implantable device.
- It has become common practice to test sterilizer daily, but there is a trend to use BIs with each load.
- In this respect, an inexpensive BI like the BCR-30 min BI affords testing with each load.
Technological Basis of the BCR-30-min BI
Despite many technological advances, present-day self-contained biological indicators (SCBIs) still have limitations: (1) relatively high cost compared to traditional spore strips; (2) occurrence of “false negatives” caused by air trapped in the indicator― false negatives are particularly significant because they may conceal contaminated surgical supplies in use; and (3) exclusion of extensive sterilization cycles that can damage either the growth medium or the fluorogenic substrate.
The unprecedented features of the BCR-30-min BI derive from a novel technology (patent pending) centered on phenotypically engineered spores (termed F-spores) that function as self-reporters of germination. F-spores have the unique property of being fluorogenic, i.e., they are non-fluorescent when dormant, but produce intense fluorescence a few minutes after the onset of germination (PLoS ONE 5, e9283, 2010). Measuring spore germination (instead of conventional spore outgrowth) enables extremely short readouts without sacrificing sterility assurance.
Features of the BCR-30-min BI
The figures below show the BCR-30-min BI together with a diagram of a self-contained BI (SCBI), currently the most used BI.
The outstanding features of the BCR-30-min BI are:
– Low cost
– 30-minute readout
These features permit every load monitoring, considered the best practice for improving patient safety and preventing costly recalls due to sterilization malfunction.
Also, an attribute unique to the BCR-30-min BI is that it contains only spores (in contrast, SCBIs contain medium and fluorogenic substrate), which allows for extended sterilization, a significant advantage over existing self-contained indicators.”
- F-spores are phenotypically engineered bacterial spores that function as self-reporters of germination (PLoS ONE 5, e9283, 2010). F-spores have a unique property of being fluorogenic, i.e., they are non-fluorescent when dormant, but produce intense fluorescence a few minutes after the onset of germination.
Applications of F-spores
- Biological Indicators – e.g., BCR-30-min BI
Biological indicators (BIs) are test systems used to monitor sterilization processes in health care facilities. BIs contain spores of heat-resistant bacteria, e.g. Geobacillus stearothermophilus.
After sterilization, the number of surviving spores is measured. There are many different commercial BIs with a broad range of performance and cost. The CDC regulates the use of BIs in healthcare facilities.
- LEXSAS (label-free exponential signal-amplification system)
Biosensing system for detecting low levels of bacteria in real-time.
The system exploits the F-spore’s ability to produce fluorescence when sensing a germinant. The LEXSAS has been used for identifying bacterially contaminated platelet concentrates used for transfusion, because the system offers rapid analysis, high sensitivity, and low cost https://www.ncbi.nlm.nih.gov/pubmed/12480543.
Fiber-based Internal Reflection
FiBIR is an unprecedented optical phenomenon poised to revolutionize the growing fluorescence-based assay industry.
Because of its simplicity and low cost, it is expected that FiBIR will lead the development of next generation fluorometers.
BCR’s prototype fluorometer operates using a 6-mm chip designed to hold 12 µl samples. However, FiBIR is amenable to use other physical configurations such as ELISA plates and micro tubes as those used in automated fluorometers using for nanoliter samples.
The prototype FiBIR fluorometer performs at a sensitivity 20-times higher than the best instruments in the same price range. It is projected that a FiBIR fluorometer will retail under $ 600.
The performance of the FiBIR fluorometer prototype is shown below:
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