Infrared measurement for the rapid enumeration of microbial concentrations
Inventors
Rising, Peter E. • Rutledge, Brian H. • Robinson, James L.
Assignees
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Publication Number
US-8679775-B2
Publication Date
2014-03-25
Expiration Date
Abstract
A method for testing for presence of a microbe in a sample includes measuring an instantaneous transmission rate of two or more wavelengths through the sample (1403), providing predetermined transmission rates corresponding to positive or negative samples for the presence of the microbe for each of the two or more wavelengths, and determining a probability of the presence of the microbe based on the instantaneous transmission rate for each of the two or more wavelengths through the sample by comparing the instantaneous transmission rate to the predetermined transmission rates (1404).
Core Innovation
The invention relates to a method for testing for presence of a microbe in a sample by measuring, simultaneously, transmissions of two or more wavelengths of light through the sample over time, and using the sample as its own standard with no control used. The method determines an elapsed-time for a biological population in the sample to grow from a first concentration to a second concentration, where the first and second concentrations are measured using a first of the two or more wavelength transmissions. The biological mass is measured during the elapsed-time using a second of the two or more wavelength transmissions.
The invention determines the presence of the microbe based on a combination of the first and second concentrations and the biological mass given the elapsed-time. It reduces false positives from chemical indicators by relying on time-dependent biological growth measurements rather than chemical indicators alone. It is implemented by using simultaneous multiwavelength transmission over time to characterize biological population growth and biological mass.
In additional aspects, the invention uses time-dependent transmission-rate changes at the wavelengths, compares the changes to predetermined transmission-rate values or a catalog of spectral change, and determines probability of microbe presence. It can match monitored wavelength slope changes and their relative loci across wavelengths to predetermined slope-change patterns to identify microbial species, and can classify lag phase growth versus log phase growth based on how the comparison changes over time up to when the predetermined concentration is measured.
Claims Coverage
The document includes two independent claims (clm-00001 and clm-00005) that each define a multiband, time-resolved transmission approach for determining the presence of a microbe. Together, they introduce a concentration-to-predetermined-concentration elapsed-time concept combined with biological mass measurement, and a probability determination based on instantaneous transmission rates compared to predetermined positive/negative values, with probability combination across wavelengths.
Simultaneous multiwavelength transmissions with sample as its own standard
Measuring, simultaneously, transmissions of two or more wavelengths of light through the sample over time, wherein the sample functions as its own standard, no control is used.
Elapsed-time to a predetermined concentration and coupled mass measurement
Determining an elapsed-time for a biological population in the sample to grow from a first concentration to a second concentration, where the first and second concentrations are measured using a first of the two or more wavelength transmissions and the second concentration is a predetermined concentration; measuring a biological mass of the sample during the elapsed-time using a second of the two or more wavelength transmissions.
Presence of microbe from combined concentration, mass, and elapsed-time
Determining the presence of the microbe based on a combination of the first and second concentrations and the biological mass given the elapsed-time.
Instantaneous transmission-rate probability model using positive/negative predetermined rates
Measuring an instantaneous transmission rate of two or more wavelengths through the sample, a first wavelength corresponding to a concentration measurement of the microbe and a second wavelength corresponding to a mass measurement of the microbe; providing predetermined transmission rates corresponding to positive or negative samples for the presence of the microbe for each of the two or more wavelengths; and determining a probability of the presence of the microbe based on the instantaneous transmission rate for each of the two or more wavelengths through the sample up to the predetermined concentration by comparing the instantaneous transmission rates to the predetermined transmission rates and an elapsed time to achieve the predetermined concentration.
Multiplication of per-wavelength probabilities across wavelengths
Wherein the probability is a result of a multiplication of two or more probabilities corresponding to two or more wavelengths, respectively.
Overall, the claim coverage centers on simultaneous time-resolved multiwavelength transmission with the sample as its own standard and microbe determination from concentration and biological mass using elapsed-time, and a probability-of-presence computation using instantaneous transmission rates compared to predetermined positive/negative transmission rates, combined by multiplication of per-wavelength probabilities up to a predetermined concentration.
Stated Advantages
Reduces false positives from chemical indicators by using time-to-concentration growth measurement and/or simultaneous time-resolved multiwavelength transmission rates.
Provides improved speed versus plate methods, with completion in about 2–3 hours [as described in the provided content].
Documented Applications
Testing for microbe presence in samples including urine testing [as described in the provided content].
Testing for microbe presence in cooling tower water [as described in the provided content].
Microbiological test context that addresses false positives from chemical indicators such as TTC/ORP chemical indicators [as described in the provided content].
Interested in licensing this patent?