# US 9,518,972 B2 · Methods for detecting bacterial infections > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,972 B2 - Document ID: US9518972B2 - Status: Granted - Kind: B2 - Application number: 14/045,856 - Filed: 2013-10-04 - Published: 2014-04-24 - Granted: 2016-12-13 - Earliest claimed: 2012-10-19 - Assignees: Avisa Pharma Inc.; Southwest Sciences Incorporated - Applicants: Avisa Pharma Inc.; Southwest Sciences, Inc. - Inventors: David S. Joseph; Steven M. Massick; Kristen A. Peterson; Anthony L. Gomez; Joel A. Silver - Web page: https://patentgrep.com/patent/US9518972B2 ## CPC - G01N 33/0055: {Radionuclides} - A61B 5/082: {Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath (A61B5/083, A61B5/091 take precedence)} - A61B 5/097: Devices for facilitating collection of breath or for directing breath into or through measuring devices - A61B 5/42: {Detecting, measuring or recording for evaluating the gastrointestinal, the endocrine or the exocrine systems (A61B1/00, A61B5/4857, A61B5/486, A61B5/4866, A61B5/4869 take precedence)} - A61K 51/1206: {Administration of radioactive gases, aerosols or breath tests} - C12Q 1/02: involving viable microorganisms - G01N 33/497: of gaseous biological material, e.g. breath - G01N 33/569: for microorganisms, e.g. protozoa, bacteria, viruses - G01N 2458/15: Non-radioactive isotope labels, e.g. for detection by mass spectrometry - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D) - C12Q: MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS (immunoassay G01N33/53); COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES ## Abstract The invention is directed to methods of detecting lung, gastrointestinal tract, and systemic infections by measuring 13CO2/12CO2 isotopic ratios of gaseous carbon dioxide in exhaled breath samples of a subject after administration of a 13C-isotopically-labeled compound. ## Claims ### Claim 1 A method for determining the presence or absence of a bacterial lung infection in a subject comprising: administering to the subject, a 13C-isotopically-labeled compound that produces 13CO2 upon bacterial metabolism; collecting at least one sample of exhaled breath from the subject; conducting the sample to a sample chamber of a detection apparatus; actuating a laser light source of the detection apparatus to emit one or more of the wavelength pairs 2054.37 and 2052.42; 2054.96 and 2051.67; or 2760.53 and 2760.08 nanometers; directing the laser light thus actuated through the sample in the sample chamber to impinge upon a detector for such wavelengths; and ascertaining the isotopic ratio of 13CO2 to 12CO2 present in the sample to determine the presence or absence of a bacterial lung infection in the subject. ### Claim 2 (depends on 1) The method of claim 1 further comprising comparing the isotopic ratio of the sample with the isotopic ratio of a control sample to effect said determination. ### Claim 3 (depends on 2) The method of claim 2, wherein the control sample comprises at least one sample of exhaled breath from the subject prior to administration of the 13C-isotopically-labeled compound. ### Claim 4 (depends on 2) The method of claim 2, wherein the control sample includes the isotopic ratio of 13CO2 to 12CO2 present in exhaled breath of a population that has not been administered the 13C-isotopically-labeled compound. ### Claim 5 (depends on 1) The method of claim 1, wherein the compound is isotopically labeled urea, isotopically labeled glycine, isotopically labeled citrulline, or mixture thereof. ### Claim 6 (depends on 1) The method of claim 1, wherein the 13C-isotopically-labeled compound is tyrosine, p-hydroxyphenylacetic acid, or a mixture thereof. ### Claim 7 (depends on 1) The method of claim 1, wherein the 13C-isotopically-labeled compound is administered by inhalation. ### Claim 8 (depends on 1) The method of claim 1, wherein the 13C-isotopically-labeled compound is administered by ingestion. ### Claim 9 (depends on 1) The method of claim 1, wherein the 13C-isotopically-labeled compound is administered by injection. ### Claim 10 (depends on 1) The method of claim 1, wherein the lungs are infected by Pseudomonas aeruginosa, Staphylococcus aureus, Mycobacterium tuberculosis, Acenitobacter baumannii, Klebsiella pneumonia, Francisella tularenis, Proteus mirabilis, Aspergillus species, or Clostridium difficile. ### Claim 11 (depends on 1) The method of claim 1, wherein the infection is a result of an infection from a bacteria having citrulline ureidase. ### Claim 12 (depends on 1) The method of claim 1, wherein the apparatus further comprises a processor for interpreting or presenting the signals received by the detector. ### Claim 13 (depends on 1) The method of claim 1, wherein the apparatus further comprises one or more of power supply, gas pump, pressure gauge, signal processor, and reference gas chamber. ### Claim 14 (depends on 1) The method of claim 1, wherein the laser light source of the apparatus scans the pair of wavelengths using wavelength modulation spectroscopy. ### Claim 15 (depends on 1) The method of claim 1, wherein the wavelength pair is 2054.37 and 2052.42 nanometers. ### Claim 16 (depends on 1) The method of claim 1, wherein the wavelength pair is 2051.67 and 2054.96 nanometers. ### Claim 17 (depends on 1) The method of claim 1, wherein the wavelength pair is 2760.53 and 2760.08 nanometers. ### Claim 18 (depends on 1) The method of claim 1, wherein the laser light source of the apparatus comprises a pair of laser emitters. ### Claim 19 (depends on 1) The method of claim 1, wherein the laser light source of the apparatus is a vertical cavity surface emitting laser. ### Claim 20 (depends on 1) The method of claim 1 wherein the isotopically labeled compound is 13C-labeled urea. ### Claim 21 (depends on 1) The method of claim 1 wherein the isotopically labeled compound is a mixture of 13C-labeled urea and 13C-labeled glycine. ### Claim 22 (depends on 1) The method of claim 1 wherein the bacterial lung infection is Pseudomonas aeruginosa. ### Claim 23 (depends on 1) The method of claim 1 further comprising comparing the isotopic ratio of 13CO2 to 12CO2 in the exhaled breath samples obtained after administration of the 13C-isotopically labeled compound to the isotopic ratio of 13CO2 to 12CO2 in an exhaled breath sample obtained from the subject prior to the administration of the 13C-isotopically labeled compound. ### Claim 24 (depends on 23) The method of claim 23, wherein an increase in the ratio of 13CO2 to 12CO2 in the exhaled breath samples obtained after inhalation of the 13C-isotopically labeled compound to the isotopic ratio of 13CO2 to 12CO2 in the exhaled breath sample obtained from the subject prior to the inhalation of the 13C-isotopically labeled compound indicates the presence of a bacterial lung infection.