Detector arrangement for blood culture bottles with colorimetric sensors

• US 9,739,788 B2
• Filed: 07/19/2011
• Issued: 08/22/2017
• Est. Priority Date: 07/20/2010
• Status: Active Grant

• Current Assignee: Biomerieux Incorporated (Compagnie Merieux Alliance SAS)
• Original Assignee: Biomerieux Incorporated (Compagnie Merieux Alliance SAS)
• Inventors: Clay, Bradford G.
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): Fisher, Brittany
• Application Number:
  US13/185,898
• Publication Number:
  US 20120021455A1
• Time in Patent Office: 2,226 Days
• Field of Search: 422 8205
• CPC Class Codes: C12M 41/26 of pH
• CPC Class Codes: C12M 41/34 of gas
• CPC Class Codes: C12M 41/36 of biomass, e.g. colony counters or by turbidity measurements electrooptical investigation of individual particles G01N15/14, flow cytometers G01N15/1404
• CPC Class Codes: G01N 2021/3181 using LEDs
• CPC Class Codes: G01N 21/3151 using two sources of radiation of different wavelengths G01N21/33 - G01N21/39 take precedence
• CPC Class Codes: G01N 21/78 producing a change of colour
• CPC Class Codes: G01N 21/783 for analysing gases
• CPC Class Codes: G01N 21/80 Indicating pH value
• CPC Class Codes: G01N 2201/127 Calibration; base line adjustment; drift compensation
• CPC Class Codes: G01N 33/84 involving inorganic compounds or pH

Abstract

A detector arrangement for a blood culture bottle incorporating a colorimetric sensor which is subject to change of color due to change in pH or CO₂ of a sample medium within the blood culture bottle. The detector arrangement includes a sensor LED illuminating the colorimetric sensor, a reference LED illuminating the colorimetric sensor, a control circuit for selectively and alternately activating the sensor LED and the reference LED, and a photodetector. The photodetector measures reflectance from the colorimetric sensor during the selective and alternating illumination of the colorimetric sensor with the sensor LED and the reference LED and generates intensity signals. The reference LED is selected to have a peak wavelength of illumination such that the intensity signals of the photodetector from illumination by the reference LED are not substantially affected by changes in the color of the colorimetric sensor.

Claims

1. A detection system comprising:

a blood culture bottle comprising a sample medium;

a colorimetric sensor positioned in the blood culture bottle and subject to change of color due to change in pH or CO₂ of the sample medium;

a sensor LED illuminating the colorimetric sensor;

a reference LED illuminating the colorimetric sensor;

a control circuit configured to selectively and alternately activating the sensor LED and the reference LED; and

a photodetector, the photodetector configured to measure reflectance from the colorimetric sensor during the selective and alternating illumination of the colorimetric sensor with the sensor LED and the reference LED and configured to generate intensity signals;

a computer receiving the intensity signals, the computer including a memory storing a calibration relationship between intensity signals for the reference LED as a function of distance of the bottle from a home position in relation to the detection arrangement;

wherein the reference LED has a peak wavelength of illumination between 750 and 900 nm.

2. The detection arrangement of claim 1, wherein the memory further stores a calibration relationship between intensity signals for the sensor LED as a function of distance of the bottle from the home position and wherein the computer comprises computer executable instructions configured to compensate for a drop in intensity signals from the sensor LED due to the bottle being positioned a distance away from the home position in accordance with calibration relationships for the sensor LED and the reference LED.

3. A method comprising the steps of:

providing a blood culture bottle comprising a sample medium and a colorimetric sensor positioned in the blood culture bottle, the colorimetric sensor subject to change of color due to change in pH or CO₂ of the sample medium;

alternately and repeatedly illuminating the colorimetric sensor with a sensor LED and a reference LED;

measuring reflectance from the colorimetric sensor due to the illumination of the colorimetric sensor by the sensor LED and reference LED with a photodetector, the photodetector responsively generating intensity signals;

receiving the intensity signals at a computer, the computer including a memory storing a calibration relationship between intensity signals for the reference LED as a function of distance of the bottle from a home position in relation to the detection arrangement;

wherein the reference LED has a peak wavelength of illumination of between 750 and 900 nm.

4. The method of claim 3, further comprising the step of storing in computer memory a calibration relationship between intensity signals for the reference LED as a function of distance of the bottle from a home position in relation to the sensor LED, reference LED and photodetector.

5. The method of claim 3, further comprising the step of storing in computer memory a calibration relationship between intensity signals for the sensor LED as a function of distance of the bottle from a home position in relation to the sensor LED, reference LED and photodetector.

6. The method of claim 5, further comprising the step of compensating for a drop in intensity signals from the sensor LED due to the bottle being positioned a distance away from the home position in accordance with calibration relationships for the sensor LED and the reference LED.

7. The method of claim 6, wherein the step of compensating comprises the step of determining a displacement value for the bottle using the calibration relationship for the reference LED and using the calibration relationship for the sensor LED to adjust the intensity signal from the photodetector to correct for the displacement of the bottle by the displacement value.

8. The method of claim 6, further comprising determining bacterial growth in the bottle based at least in part on the reflectance from the colorimetric sensor due to the illumination of the colorimetric sensor by the sensor LED after compensating for the drop in the intensity signals.

9. The method of claim 3, further comprising determining bacterial growth in the bottle based at least in part on the reflectance from the colorimetric sensor due to the illumination of the colorimetric sensor by the sensor LED.

10. The method of claim 3, further comprising determining a calibration relationship between intensity signals for the reference LED as a function of distance of the bottle from a home position in relation to the sensor LED, reference LED, and photodetector.