Methods for detecting bacterial infections

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.