Process and system for identifying the gram type of a bacterium

Patent metadata

Field	Value
Publication number	US-2019323948-A1
Application number	US-201716310487-A
Country	US
Kind code	A1
Filing date	Jun 13, 2017
Priority date	Jun 16, 2016
Publication date	Oct 24, 2019
Grant date	—

Abstract

A detection of the Gram type of a bacterial strain includes: illumination, in the wavelength range 415 nm-440 nm, of at least one bacterium of said strain having a natural electromagnetic response in said range; acquisition, in the range 415 nm-440 nm, of a light intensity reflected by, or transmitted through, said illuminated bacterium; and determination of the Gram type of the bacterial strain as a function of the light intensity acquired in the range 415 nm-440 nm.

First claim

1 - 16 . (canceled)

17 . A process of determining Gram type of a bacterial strain, comprising:
illuminating at least one bacterium of the bacterial strain with light in a wavelength range of 415 nm-440 nm to which the bacterium has a natural electromagnetic response; acquiring a light intensity from light in the wavelength range of 415 nm-440 nm that is reflected by, or transmitted through, the illuminated bacterium; and determining the Gram type of the bacterial strain as a function of the light intensity acquired in the wavelength range of 415 nm-440 nm.

18 . The process as claimed in claim 17 , wherein:
the bacterium is also illuminated with light in a wavelength range of 750 nm-800 nm to which the bacterium has a natural electromagnetic response; a light intensity is acquired from light in the wavelength range of 750 nm-800 nm that is reflected by, or transmitted through, the illuminated bacterium; and the Gram type of the bacterial strain is determined as a function of the light intensities acquired in the wavelength ranges of 415 nm-440 nm and 750 nm-800 nm.

19 . The process as claimed in claim 17 , wherein determining the Gram type of the bacterial strain comprises:
calculating a reflectance or absorption factor of the illuminated bacterium as a function of the acquired light intensity; and determining the Gram type of the bacterial strain as a function of the calculated reflectance or absorption factor.

20 . The process as claimed in claim 19 , wherein determining the Gram type of the bacterial strain further comprises:
calculating a first derivative in the wavelength of the calculated reflectance or absorption factor; and determining the Gram type of the bacterial strain as a function of the calculated first derivative.

21 . The process as claimed in claim 17 , wherein the Gram type of the bacterial strain is determined as a function of the light intensity acquired from light at a single wavelength in the wavelength range of 415 nm-440 nm.

22 . The process as claimed in claim 21 , wherein the Gram type of the bacterial strain is determined as a function of the light intensity acquired from light at a wavelength of 420 nm in the wavelength range of 415 nm-440 nm.

23 . The process as claimed in claim 22 , wherein determining the Gram type of the bacterial strain comprises:
comparing a value equal to the light intensity acquired from light at the wavelength of 420 nm, or calculated therefrom, to a first predetermined threshold and a second predetermined threshold separating the Gram-positive staining from the Gram-negative staining, the first threshold being greater than the second threshold; and determining that the bacterial strain is Gram-negative if the value is above the first threshold or determining that the bacterial strain is Gram-positive if the value is below the second threshold.

24 . The process as claimed in claim 17 , wherein determining the Gram type of the bacterial strain comprises applying a predetermined linear prediction linking the acquired light intensity, or a value calculated therefrom, to the Gram type, followed by thresholding of the result of the applied linear prediction.

25 . The process as claimed in claim 17 , wherein determining the Gram type of the bacterial strain comprises applying a two-class classification of SVM type to the acquired light intensity, or to a value calculated therefrom.

26 . The process as claimed in claim 17 , wherein the illumination and acquisition are directly performed on a sample that comprises a colony of the bacterial strain and a nutritive medium in which the colony of the bacterial strain has grown.

27 . The process as claimed in claim 26 , wherein the Gram type of the bacterial strain is determined as a function of the nutritive medium.

28 . The process as claimed in claim 26 , wherein the nutritive medium is an opaque substrate at a surface on which the colony of the bacterial strain has grown.

29 . The process as claimed in claim 28 , wherein the opaque substrate has a reflectance p of less than or equal to 10%.

30 . The process as claimed in claim 28 , wherein the opaque substrate has a reflectance p of less than or equal to 5%.

31 . The process as claimed in claim 17 , wherein acquiring the light intensity comprises acquiring a hyperspectral or multispectral image of a colony of the bacterial strain, and determining the light intensity as a function of at least one pixel of the hyperspectral or multispectral image that corresponds to the colony of the bacterial strain.

32 . The process as claimed in claim 31 , wherein the light intensity is equal to mean pixels of the hyperspectral or multispectral image that corresponds to the colony of the bacterial strain.

33 . A system for detecting Gram type of a bacterial strain, comprising:
an illuminator configured to illuminate at least one bacterium of the bacterial strain with light in a wavelength range of 415 nm-440 nm; a sensor configured to acquire a light intensity from light in the wavelength range of 415 nm-440 nm that is reflected by, or transmitted through, the illuminated bacterium; and a computer unit configured to determine the Gram type of the bacterial strain as a function of the light intensity acquired in the wavelength range of 415 nm-440 nm.

34 . The system as claimed in claim 33 , wherein:
the illuminator is further configured to illuminate the bacterium with light in a wavelength range of 750 nm-800 nm; the sensor is further configured to acquire a light intensity from light in the wavelength range of 750 nm-800 nm that is reflected by, or transmitted through, the illuminated bacterium; and the computer unit is configured to determine the Gram type of the bacterial strain as a function of the light intensities acquired in the wavelength ranges of 415 nm-440 nm and 750 nm-800 nm.

35 . The system as claimed in claim 33 , configured to illuminate, and to acquire an image of, a sample that comprises a colony of the bacterial strain and a nutritive medium in which the colony of the bacterial strain has grown.

Assignees

• Biomerieux Sa

Inventors

• Leroux Denis
• Laloum Eric
• Mahe Pierre
• Midahuen Rony
• Barlas Philippine

Classifications

• G01N2021/174

  either absorption-reflection or emission-fluorescence · CPC title

• C12Q1/04 Primary

  Determining presence or kind of microorganism; Use of selective media for testing antibiotics or bacteriocides; Compositions containing a chemical indicator therefor {(C12Q1/6897 takes precedence)} · CPC title

• G01N21/25 Primary

  Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands · CPC title

• G01N21/01

  Arrangements or apparatus for facilitating the optical investigation · CPC title

• G06V20/695

  Preprocessing, e.g. image segmentation · CPC title