Patent Publication Number: US-2006019331-A1

Title: Method and system for generating a telephone alert indicating the presence of an analyte

Description:
CROSS REFERENCE  
      This application is based upon and claims the benefit of priority from U.S. Provisional Application No. 60/589,499 to Gideon Eden filed on Jul. 20, 2004, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD  
      This disclosure relates generally to detecting an analyte and, more particularly, to detecting the presence or amount of an analyte in a sample.  
     BACKGROUND  
      Microbial contamination may occur in various substances, such as food, pharmaceuticals, cosmetics, and water. Detection and analysis of such contamination may require estimations of total numbers of bacteria, yeasts, and molds, as well as concentrations of specific groups of organisms.  
      U.S. Pat. No. 5,366,873 issued on Nov. 22, 1994 to Eden et al. (the &#39;873 patent) discloses a device for rapidly detecting microorganisms in a sample using semi-liquid material and electronic detection devices. Although this device is highly effective in many applications, it is desirable to efficiently communicate the detection of an alarm condition.  
      Methods and systems consistent with the present invention address one or more of the issues set forth above.  
     SUMMARY  
      One aspect of the present invention includes a system for detecting a presence or amount of an analyte in a sample. The system may include a detection device detecting a characteristic of a fluid in communication with the sample to generate an electrical signal corresponding to the characteristic of the fluid and a processor coupled to the detection device and determining at least one property relating to the analyte, based on the electrical signal. The system may also include a telephone interface device. The telephone interface device may be coupled to the processor and responsive to the processor to transmit an alarm message indicating the property of the analyte to at least one telephone communication device.  
      Another aspect of the present invention includes a microbiological alert system for detecting contamination in a sample. The system may include a detection device detecting light from a fluid in communication with the sample to generate an electrical signal corresponding to the light from the fluid. The system may also include a processor coupled to the detection device and determining at least one parameter relating to a presence of microorganisms in the test sample based on the electrical signal and a telephone interface device. The telephone interface device may be coupled to the processor, and responsive to the processor to transmit an alarm message indicating the presence of microorganisms. Further, the presence of microorganisms may be determined. by the processor based upon the at least one parameter and a predetermined alarm criterion.  
      Another aspect of the present invention includes a microbiological alert system. The system may include detection means for generating data corresponding to at least one parameter relating to a property of an analyte in a test sample and processor means for receiving the data from the detection means. The system may also include means for storing processor instructions to be executed to determine an alarm state based upon at least the parameter and a specified alarm criterion and telephone interface means for transmitting an alarm message indicating the alarm state to an external telephone device under the control of the processor means.  
      Another aspect of the present invention includes a method for detecting and alerting a presence or amount of an analyte in a test sample. The method may include generating an electrical signal corresponding to a characteristic related to the analyte in the test sample and determining at least one parameter relating to the characteristic based on the electrical signal. The method may also include determining an alert condition indicating the presence of the analyte based upon the at least one parameter and a predetermined alarm criterion and communicating the alert condition to an external telephone device via a telephone communication channel.  
      It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an illustration of an exemplary system for detecting the presence or amount of an analyte in a sample consistent with the present invention;  
       FIG. 2  illustrates a block diagram of a processor consistent with the present invention;  
       FIG. 3  illustrates a flowchart of an exemplary microbiological detection and alert process performed by a processor consistent with the present invention; and  
       FIG. 4  is an exemplary graph of microbiological detection.  
    
    
     DETAILED DESCRIPTION  
      Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
       FIG. 1  shows an exemplary system  100  for detecting the presence of an analyte, for example, a containment. As shown in  FIG. 1 , system  100  may include a container such as a vial  102 , a liquid media  104 , a barrier layer, or region,  106 , a test sample  108 , a light source  110 , and a light source controller  112 . System  100  may also include a detection device  114 , a processor  116 , and a telephone interface device  118 . Telephone interface device  118  may communicate with devices such as a land-line telephone  120  and/or a cellular telephone  122 . It is understood that the devices and components listed are exemplary only, the number of the devices and components may be changed, and that other components may also be included.  
      Vial  102  may comprise any appropriate type of container made of transparent material (e.g., glass, transparent plastics, etc.) to hold test materials, such as liquid media  104 , barrier region  106 , test sample  108 , etc. Liquid media  104  may comprise any appropriate type of fluid for cultivating microorganisms contained in test sample  108 , such as plate count broth (Difco), etc. Liquid media  104  may also contain one or more indicator substances which are capable of undergoing certain types of transformation in the presence of microorganism growth. In some embodiments, the indicator substances may be capable of undergoing transformation in the presence of, or at a certain level of concentration of, an analyte, such as a microorganism, in test sample  108 .  
      The transformation may be observed based on a certain characteristic of the fluid. For example, the color hue or intensity of the fluid may be changing. Alternatively, the way how light is reflected by the fluid and/or travels through the fluid may be changing. Other detectable characteristics may also be used.  
      Barrier region  106  may be disposed in vial  102  and may be a semi-fluid substance with a fluid portion and a non-fluid portion. The fluid portion of barrier region  106  may include a composition similar to or the same as liquid media  104 , such that liquid media  104  and the fluid portion of barrier region  106  are in equilibrium. The non-fluid portion of barrier region  106  may include a gelling agent such as an appropriate type of agar (e.g., Muller Hinton Agar by Difco, Detroit, Mich.). Barrier region  106  may be positioned in vial  102  to facilitate measurement of changes in test sample  108 .  
      Prior to introduction of test sample  108 , both liquid media  104  and barrier region  106  may be sterilized, and liquid media  104  may be poured on the top of barrier region  106 . After introduction of sample  108 , microorganisms may be present in liquid media  106 . However, both test sample  108  and microorganisms contained in test sample  108  are usually too large molecularly to penetrate the non-fluid portion of barrier region  106 . Thus, barrier region  106  may be free of large molecules (e.g., test sample  108 , microorganisms) and more suitable for providing accurate testing and detection results.  
      Initially, test sample  108 , potentially containing microorganisms to be detected, may be placed in liquid media  104  of vial  102 . Vial  102  may then be placed in an incubating device, at an appropriate temperature, to promote growth of any microorganisms of interest. The incubating device may include components such as an air incubator, heating and cooling blocks, or a heat exchanger. If microorganisms are indeed present in sample  108 , the promoted growth of such microorganisms may result in changes in the composition of the liquid throughout vial  102 , both the liquid in barrier region  106  and liquid media  104 , because the liquid in barrier region  106  is in equilibrium with the remainder of the liquid in liquid media  104 .  
      As explained above, the change in the composition of the liquid may be detected and measured in barrier region  106 , which is in communication with test sample  108  but is free of test sample  108  and free of microorganisms. Thus, barrier region  106  provides a zone within which changes in the liquid, brought on by microorganism growth, can be readily detected and measured without any interference from the test sample.  
      As noted above, liquid media  104  may contain one or more indicator substances. In certain embodiments, the indicator substances may include a non-toxic indicator dye that changes in color hue or color intensity in the presence of microorganism growth. Examples of such indicator substances include pH indicators such as Bromcresol Purple, Phenol Red, Bromcresol Green, Bromphenol Blue, and Bromthymol Blue, and Redox indicators such as resazurin, methylene Blue, tetrazolium, and thionine. In operation, the indicator substance may be added to the liquid of both liquid media  104  and barrier region  106 .  
      Further, the indicator substance may also include a luminescent substance that emits light as a result of microbial growth and metabolism such as ATP with luciferin/luciferase enzyme, or a chemiluminescent material such as luminal. Fluorescent materials, such as umbeliferons and coumarins may also be utilized.  
      The change in color hue or intensity of the indicator substances may be detected, monitored, and/or measured by measuring a parameter, such as light from light source  110  transmitted through barrier region  106 . Light source  110  may be positioned at the bottom part of vial  102  such that light transmitted from light source  110  may be directed through transparent walls of vial  102  and through barrier region  106 . Light source  110  may include any appropriate type of light source, such as incandescent lamps, gas-charged lamps, lasers, and light emitting diodes (LED&#39;s). In certain embodiments, a specific LED color, such as yellow, orange, green, and blue LED&#39;s, may be selected based upon spectral characteristics of barrier region  106 . In applications using a luminescent material, light source  110  may not be required.  
      Light source  110  may be controlled by light source controller  112 . Light source controller  112  may include any appropriate type of light source control system to provide electrical energy such that light from light source  110  is spatially and temporally uniform and stable.  
      Light transmitted from light source  110  may be detected by detection device  114  after passing through barrier region  106 . The optical transmissive properties of barrier region  106  may be detected and monitored continuously and/or periodically. Additionally, other optical changes in barrier region  106 , such as reflectance or fluorescence, may also be measured and analyzed. Further, multiple samples, each in a separate vial, may be used in system  100 , with each vial  102  having a separate light source and detection device  114  to eliminate complex mechanical indexing devices utilized in optical readers. Other configurations, however, may also be used.  
      Detection device  114  may include any appropriate type of light detecting and signal processing device. Detection device  114  may include one or more light sensors (not shown) to convert dynamic changes in transmitted or reflected light, which may be indicators of bacterial activity, into electrical signals. The light sensors may include any appropriate types of sensors, such as photo voltaic sensors, photodiodes, phototransistors, photo multipliers, charged coupled devices (CCD), and/or multi-channel devices using low cost solid state sensors, etc.  
      Detection device  114  may also include other electronic components and/or devices, such as analog-to-digital (A/D) converters, to process electrical signals from the light sensors into corresponding output signals. The output signals may then be transmitted to processor  116  for further processing.  
       FIG. 2  shows an exemplary block diagram of processor 116 . As shown in  FIG. 2 , processor  116  may include a central processing unit (CPU)  202 , a random access memory (RAM)  204 , a read-only memory (ROM)  206 , a control console  208 , an I/O interface  210 , and mass storage  212 . It is understood that the type and number of listed devices are exemplary only and not intended to be limiting. The number of listed devices may be changed and other devices may be added.  
      CPU  202  may comprise any appropriate type of general purpose microprocessor, digital signal processor, or microcontroller, such as, for example, a Pentium IV. CPU  202  may execute sequences of computer program instructions to perform various processes. The computer program instructions may be loaded into RAM  204  for execution by CPU  202  from a read-only memory (ROM), or from mass storage  212 . Mass storage  212  may include any appropriate type of mass storage device to store information that CPU  202  may need to perform the desired processes. For example, mass storage  212  may include one or more hard disk devices, optical disk devices, or other storage devices.  
      Control console  208  may provide a graphic user interface (GUI) to display information to operators and users of system  100 . Control console  208  may include any appropriate type of computer display devices or computer monitors. Further, I/O interface  210  may be provided for CPU  202  to communicate with peripheral devices including detection device  114  and telephone interface  118 .  
      Returning to  FIG. 1 , telephone interface  118  may be provided to permit system  100 , especially processor  116 , to communicate with various telephone devices, such as land-line telephone  120  and cellular telephone  122 . Telephone interface  118  may include any appropriate type of telephone modem, such as a land-line telephone modem, a wireless/cellular telephone modem, a facsimile modem, etc.  
      In operation, system  100  may perform a microbiological detection and alert process to accurately detect and report a property such as the presence and/or concentration level of an analyte, such as a microorganism, microorganism growth, and/or presence of a certain substance, etc. Multiple analytes, or substances, under analysis, may also be processed.  FIG. 3  shows a flow chart diagram of an exemplary microbiological detection and alert process.  
      As shown in  FIG. 3 , at the beginning of the process, processor  116  may calibrate light source  110  and detection device  114  (step  302 ). Calibration may be performed without vial  102  to self-calibrate electronic components (e.g., light source  110 , detection device  114 , etc.). Other calibration methods may also be used.  
      Returning to  FIG. 3 , after completing calibration, processor  116  may select an alarm criterion (step  304 ). The alarm criterion may be used to determine whether an alarm state has been reached. The alarm criterion may be selected based on a desired detection property of the microorganisms, such as contamination level, contamination time, etc. The alarm criterion may also be selected based on results of known test samples. For example, the selected alarm criterion may be an increase in growth rate occurring within a shorter time period than the rate indicated in  FIG. 4 . Other alarm criteria, however, may also be used.  
      Processor  116  may then start microbiological detection (step  306 ). As explained above, test sample  108  may be placed in vial  102  together with liquid media  104 , barrier region  106 , and indicator dye, such as Brom Crysol Purple, and incubated. The indicator dye may change its color from purple to yellow when the PH of liquid media  104  drops below 5.5. As liquid media  104  and barrier region  106  are in direct contact, small molecules (e.g., dye, H + , and/or other ions) may diffuse back and forth between liquid media  104  and barrier region  106 , while barrier region  106  prevents microorganisms or other large molecules from entering. When vial  102  with test sample  108  is incubated, the microorganisms initially present in test sample  108  may grow and metabolize, thereby changing the PH of liquid media  104 . At some point in time, the PH indicator may change color in liquid media  104 , as well as in barrier region  106 . The color change may then be detected by using light source  110   1 ight source controller  112 , and detection device  114 .  
      After digital signals corresponding to the color change are obtained by processor  116  from detection device  114 , processor  116  may determine optical readings or detection parameters based on the signals (step  308 ). Processor  116  may obtain optical readings at specific time intervals (e.g. 6 minutes apart) and store these readings in memory. Processor  116  may analyze these stored readings to determine the presence of an alarm condition. The alarm condition may refer to a property, such as a presence of a microorganism, a particular growth rate of the microorganism, and/or a concentration level of the microorganism in sample  108 . The alarm condition may also refer to a presence or a concentration of a particular substance in test sample  108 . When determining the alarm condition, processor  116  may record certain time parameters. For example, the time period after which a significant increase in rate of change of a detection parameter occurs may indicate the presence or absence of an alarm condition. This may be indicated by a detection time, that is, the point in time when substantial color change occurs.  
      Referring to  FIG. 4 , there is shown a graph of the output signal of detection device  114  vs. time. The units of the horizontal axis are hours and the units of the vertical axis are arbitrary units indicating the amount of light detected by the detection device  114 , representative of color change.  FIG. 4  indicates a detection time of about three hours, at which time a color change is detected. The detection time may be an indication of a presence of microorganisms in test sample  108  and a level of concentration of the microorganisms. Faster detection time may indicate a higher contamination of test sample  108 . For example, a sample generating a 2 hour detection time may be more contaminated than a sample generating a 3 hour detection time.  
      Processor  116  may further determine a critical detection time (step  310 ). The critical time may be associated with a critical contamination level. In certain embodiments, processor  116  may predetermine a critical detection time or a critical contamination level. Processor  116  may also calculate the acceleration rate of microorganism growth or growth rate by analyzing readings in consecutive time intervals or time intervals in a certain sequence. The growth rate may be used to determine the presence and level of microorganisms in the original sample  108 .  
      Further, processor  116  may determine whether an alert condition exists (step  312 ). If processor  116  determines a detection time faster than the predetermined critical detection time, or, alternatively, an acceleration rate larger than a predetermined growth rate, processor  116  may decide that an alert condition exists (step  312 ; YES). Otherwise, processor  116  may decide that an alert condition does not exist (step  312 ; NO). If there is no alert condition (step  312 ; NO), processor  116  may go back to step  308  to continue reading detection parameters.  
      On the other hand, if processor  116  decides that an alert condition exists (step  312 ; YES), processor  116  may generate an alarm message or messages to warn users of a detected contamination (step  314 ). Processor  116  may present the alarm message either audibly and/or visibly on control console  208 . Processor  116  may also transmit an alarm message over telephone interface  118  to devices such as land-line telephone  120  and cellular telephone  122 .  
      Processor  116  may connect via telephone interface  118  to a commercial telephone communication device to send an alarm message (step  316 ). For example, processor  116  may activate a dial-up telephone modem included in telephone interface  118  and dial a preprogrammed telephone number that receives the alert. Processor  116  may also generate a relevant voice message describing the nature of the alarm after dialing. Alternatively or in addition, processor  116  may generate alarm messages in the form of digital text messages that may be transmitted over specific telephone systems. For example, processor  116  may activate a wireless/cellular modem to use short message service (SMS) to transmit an alarm message to certain cellular telephones via an external SMS server in place of, or in addition to, transmitting a relevant voice message. In other embodiments, processor  116  may activate a facsimile modem to transmit an alarm message to one or more facsimile machines to provide a detailed printed alarm message. After sending out alarm messages, the microbiological detection and alert process may be completed.  
      Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.