Rapid detection of viable bacteria system and method

Abstract

An improved system and method is provided for detecting viable bacteria in a suspension sample. A sample of a suspension in which bacterial presence is suspected is collected from a source and a portion of the sample transferred to a microfluidic unit. A series of analysis signals at different frequencies are applied to the sample portion. An impedance is measured via a signal analyzer for the sample portion for each of the analysis signals to define an impedance data set. An initial bulk capacitance value is determined for a model circuit based on the impedance dataset. After a predetermined time period, a new bulk capacitance value is determined for another portion of the sample. The difference between the new bulk capacitance and the initial bulk capacitance value is compared to a threshold value to determine if viable bacterial is present in the sample.

What is claimed is: 
     
         1 . A non-transitory computer-readable medium encoded with a bacteria detection instructions stored thereon that, when executed by a computing device cause the computing device to perform operations for detecting viable bacteria in a sample of a suspension, the operations comprising:
 activating a signal generator to generate a series of analysis signals to apply to a portion of a particular sample in response to an initial analysis request received from a user interface; each of the series of analysis signals being generated at a different frequency;   activating a signal analyzer to generate an initial impedance data set for the particular sample by determining an impedance of the particular sample during application of each of the series of analysis signals;   activating the signal generator to generate another series of analysis signals to apply to another portion of the particular sample, each of the other series of analysis signals being generated at the different frequency; and   activating the signal analyzer to generate a new impedance data set for the particular sample by determining the impedance of the particular sample during application of each of the other series of analysis signals;   determining at least one initial parametric value of a model circuit based on the initial impedance data set, the at least one initial parametric value comprising an initial impedance parameter value and an initial confidence interval value; and   determining at least one new parametric value of the model circuit based on the new impedance data set, the at least one initial parametric value comprising an new impedance parameter value and a new confidence interval value;   determining if the initial confidence interval value and the new confidence interval value overlap; and   generating a positive result to indicate that viable bacteria is present when the initial confidence interval value and the new confidence interval value do not overlap; and   generating the positive result for display.   
     
     
         2 . The non-transitory computer-readable medium of  claim 1  further comprising:
 retrieving pre-determined time interval data for the particular sample from a data source, the pre-determined time interval data comprising a corresponding pre-determined time interval comprising at least one member selected from a group consisting of a minimum doubling time of an expected bacteria type in the suspension and a finite period of time defined by a user; and 
 initiate generation of another analysis request after expiration of the corresponding pre-determined time interval; and 
 generating a negative result to indicate that viable bacteria is not present when the initial confidence interval value and the new confidence interval value overlap. 
 
     
     
         3 . The non-transitory computer-readable medium of  claim 1  wherein the operations further include initiating the generation of the other analysis request by generating a notification request to notify a user to generate the other analysis request at the user interface after expiration of the corresponding pre-determined time interval. 
     
     
         4 . The non-transitory computer-readable medium of  claim 1  wherein the operations further include initiating the generation of the other analysis request by automatically generating the other analysis request after expiration of the pre-determined time interval. 
     
     
         5 . The non-transitory computer-readable medium of  claim 2  wherein the data source further comprises a maximum processing time defining a maximum amount of time for attempting to detect viable bacteria in the particular sample. 
     
     
         6 . The non-transitory computer-readable medium of  claim 5  wherein the operations further comprise:
 automatically generating a second other analysis request in response to the negative result after expiration of the corresponding pre-determined time interval if the maximum processing time has not expired; and 
 generating the negative result for display if the maximum processing time has expired. 
 
     
     
         7 . The non-transitory computer-readable medium of  claim 5  wherein the operations further comprise:
 generating another notification to notify the user to generate a second other analysis request at the user interface in response to the negative result after expiration of the corresponding pre-determined time interval if the maximum processing time has not expired; and 
 generating the negative result for display if the maximum processing time has expired. 
 
     
     
         8 . The non-transitory computer-readable medium of  claim 1  wherein:
 the at least one initial parametric value of the model circuit comprises an initial magnitude of a Constant Phase Element; and 
 the at least one new parametric value of the model circuit comprises a new magnitude of the Constant Phase Element. 
 
     
     
         9 . The non-transitory computer-readable medium of  claim 1  wherein the series of analysis signals comprises at least one member selected from a group consisting of voltage signals and current signals. 
     
     
         10 . The non-transitory computer-readable medium of  claim 1  wherein the plurality of suspension types comprises at least one member selected from a group consisting of a bodily suspension, a food product suspension, and a non-food product suspension. 
     
     
         11 . A method for detecting viable bacteria in a sample of a suspension, the method comprising:
 generating a series of analysis signals at a signal generator to apply to a portion of a particular sample in response to an initial analysis request received from a user interface; each of the series of analysis signals being generated at a different frequency;   generating an initial impedance data set at a signal analyzer for the particular sample by determining an impedance of the particular sample during application of each of the series of analysis signals;   generating another series of analysis signals at the signal generator to apply to another portion of the particular sample, each of the other series of analysis signals being generated at the different frequency; and   generating a new impedance data set at the signal analyzer for the particular sample by determining the impedance of the particular sample during application of each of the other series of analysis signals;   determining at least one initial parametric value of a model circuit at a processor based on the initial impedance data set, the at least one initial parametric value comprising an initial impedance parameter value and an initial confidence interval value; and   determining at least one new parametric value of the model circuit at the processor based on the new impedance data set, the at least one initial parametric value comprising a new impedance parameter value and a new confidence interval value;   determining if the initial confidence interval value and the new confidence interval value overlap at the processor; and   displaying a positive result indicating that viable bacteria are present when the initial confidence interval value and the new confidence interval value do not overlap.   
     
     
         12 . The method of  claim 11  further comprising:
 retrieving pre-determined time interval data for the particular sample from a data source, the pre-determined time interval data comprising a corresponding pre-determined time interval comprising at least one member selected from a group consisting of a minimum doubling time of an expected bacteria type in the suspension and a finite period of time defined by a user; and 
 initiating generation of another analysis request after expiration of the corresponding pre-determined time interval. 
 
     
     
         13 . The method of  claim 12  further comprising initiating the generation of the other analysis request by generating a notification request to notify a user to generate the other analysis request at the user interface after expiration of the corresponding pre-determined time interval. 
     
     
         14 . The method of  claim 12  further comprising initiating the generation of the other analysis request by automatically generating the other analysis request after expiration of the pre-determined time interval. 
     
     
         15 . The method of  claim 12  further comprising;
 retrieving a maximum processing time from the data source, the maximum processing time defining a maximum amount of time for attempting to detect viable bacteria in the particular sample; and 
 generating a negative result to indicate that viable bacteria are not present when the initial confidence interval value and the new confidence interval value overlap and the maximum processing time has not expired. 
 
     
     
         16 . The method of  claim 15  further comprising:
 generating another notification to notify the user to generate a second other analysis request at the user interface in response to the negative result after expiration of the corresponding pre-determined time interval if the maximum processing time has not expired; and 
 displaying the negative result if the maximum processing time has expired. 
 
     
     
         17 . The method of  claim 15  further comprising:
 automatically generating a second other analysis request in response to the negative result after expiration of the corresponding pre-determined time interval if the maximum processing time has not expired; and 
 displaying the negative result if the maximum processing time has expired. 
 
     
     
         18 . The method of  claim 11  wherein:
 the at least one initial parametric value of the model circuit comprises an initial magnitude of a Constant Phase Element; and 
 the at least one new parametric value of the model circuit comprises a new magnitude of the Constant Phase Element. 
 
     
     
         19 . The method of  claim 11  wherein the series of analysis signals comprises at least one member selected from a group consisting of voltage signals and current signals. 
     
     
         20 . The method of  claim 11  wherein the plurality of suspension types comprises at least one member selected from a group consisting of a bodily suspension, a food product suspension, and a non-food product suspension.