Assay for the comprehensive identification of antibiotic sensitivity

Abstract

Disclosed herein are methods determining susceptibility of bacteria in a sample from a subject suspected of having an infection to a plurality of antibiotics simultaneously, wherein the sample is tested without first isolating the bacteria from the sample.

What is claimed is: 
     
         1 . A method for simultaneously determining susceptibility of a mixed population of bacteria in a sample to a plurality of antibiotics, the method comprising:
 applying a quantity of the sample simultaneously to a plurality of antibiotic-containing medium, wherein the sample is from a subject suspected of having an infection;   culturing the sample on the medium for a period of time;   suspending bacteria present in the medium with a solution and recovering the suspension;   measuring an OD 600  of the suspension, wherein an adjusted OD 600  of a suspension indicates the susceptibility or resistance of bacteria in the sample to an individual antibiotic; and   providing the susceptibility information to a medical professional to determine antibiotic therapy for the subject.   
     
     
         2 . The method according to  claim 1 , wherein the plurality of antibiotic-containing medium comprises a multi-well assay plate having disposed in a plurality of wells antibiotic-containing bacterial growth medium. 
     
     
         3 . The method according to  claim 2 , wherein the bacterial growth medium is an agar-containing medium. 
     
     
         4 . The method according to  claim 3 , wherein each of the plurality of wells contains a single antibiotic or a combination of antibiotics. 
     
     
         5 . The method according to  claim 4 , wherein the plurality of antibiotics comprises at least two antibiotics, at least three antibiotics, at least four antibiotics, at least five antibiotics, at least six antibiotics, at least seven antibiotics, at least eight antibiotics, at least nine antibiotics, or at least ten antibiotics. 
     
     
         6 . The method according to  claim 1 , wherein each antibiotic, or combination of antibiotics, is present in the wells at two or more concentrations. 
     
     
         7 . The method according to  claim 1 , wherein the adjusted OD 600  comprises the mean OD 600  of a plurality of measurements less a background control. 
     
     
         8 . The method according to  claim 1 , wherein the bacteria in the sample are susceptible to an antibiotic, or combination of antibiotics, if the adjusted OD 600  is less than 0.025. 
     
     
         9 . The method according to  claim 1 , wherein the bacteria in the sample are resistant to an antibiotic, or combination of antibiotics, if the adjusted OD 600  is greater than or equal to 0.025. 
     
     
         10 . The method according to  claim 1 , wherein the sample is a biological fluid or a biopsy sample. 
     
     
         11 . The method according to  claim 10 , wherein the biological fluid is urine, blood, saliva, sputum, pulmonary lavage, vaginal secretions, biopsy tissue, or cerebrospinal fluid. 
     
     
         12 . A method for simultaneously determining susceptibility of a mixed population of bacteria in a sample to a plurality of antibiotics, the method comprising:
 mixing a quantity of a sample with growth medium and incubating for a period of time;   applying the sample simultaneously to a plurality of antibiotic-containing medium, wherein the sample is from a subject suspected of having an infection;   culturing the sample in the antibiotic-containing medium for a period of time;   measuring bacterial growth in the medium by OD 600  measurement, wherein an adjusted OD 600  measurement of the sample indicates the susceptibility or resistance of the bacteria in the sample to an individual antibiotic; and   providing the susceptibility information to a medical professional to determine antibiotic therapy for the subject.   
     
     
         13 . The method according to  claim 12 , wherein the plurality of antibiotic-containing medium comprises a multi-well assay plate having disposed in a plurality of wells antibiotic-containing bacterial growth medium. 
     
     
         14 . The method according to  claim 12 , wherein the medium is a liquid broth medium. 
     
     
         15 . The method according to  claim 13 , wherein each of the plurality of wells contains a single antibiotic or a combination of antibiotics. 
     
     
         16 . The method according to  claim 15 , wherein the plurality of antibiotics comprises at least two antibiotics, at least three antibiotics, at least four antibiotics, at least five antibiotics, at least six antibiotics, at least seven antibiotics, at least eight antibiotics, at least nine antibiotics, or at least ten antibiotics. 
     
     
         17 . The method according to  claim 12 , wherein each antibiotic, or combination of antibiotics, is present in the wells at two or more concentrations. 
     
     
         18 . The method according to  claim 12 , wherein the adjusted OD 600  comprises a single OD 600  measurement, or a mean OD 600  of a plurality of measurements, less a background control. 
     
     
         19 . The method according to  claim 12 , wherein the bacteria in the sample are susceptible to an antibiotic, or combination of antibiotics, if the adjusted OD 600  is less than 0.065. 
     
     
         20 . The method according to  claim 12 , wherein the bacteria in the sample are resistant to an antibiotic, or combination of antibiotics, if the adjusted OD 600  is greater than or equal to 0.065. 
     
     
         21 . The method according to  claim 12 , wherein the sample is a biological fluid or a biopsy sample. 
     
     
         22 . The method according to  claim 21 , wherein the biological fluid is urine, blood, saliva, sputum, pulmonary lavage, vaginal secretions, biopsy tissue, or cerebrospinal fluid.