Method for detecting escherichia coli

Abstract

Described herein are methods of detecting an infection and for detecting the presence or absence of microorganisms, for example, wound pathogens in a sample, by contacting a sample with an enzyme produced and/or secreted by the bacteria, and detecting modification or the absence of modification of the substrate, as an indicator of the presence or absence of the enzyme in the sample. The present invention also features a biosensor for detecting the presence or absence of bacteria in a sample.

1 . A method for detecting the presence or absence of  Escherichia coli  in a sample, comprising the steps of: 
 a) contacting the sample with a detectably labeled substrate for an enzyme produced and/or secreted by  Escherichia coli , under conditions that result in modification of said substrate by said enzyme; and    b) detecting the modification or the absence of the modification of said substrate,    wherein modification of said substrate indicates the presence of  Escherichia coli  in said sample, and wherein the absence of modification of said substrate indicates the absence of  Escherichia coli  in said sample.    
     
     
         2 . The method of  claim 1 , wherein said enzyme is a protease.  
     
     
         3 . The method of  claim 1 , wherein said sample is selected from the group consisting of a wound surface on a subject and a body fluid.  
     
     
         4 . The method of  claim 1 , wherein said substrate is on a solid support.  
     
     
         5 . The method of  claim 4 , wherein said solid support comprises a material required to be free of microbial contaminants.  
     
     
         6 . The method of  claim 4 , wherein said solid support is a selected from the group consisting of a wound dressing, a container for holding body fluids, a disk, a scope, a filter, a lens, foam, cloth, paper, a suture, a food packaging material, and a swab.  
     
     
         7 . The method of  claim 6 , wherein said container for holding body fluids is selected from the group consisting of a urine collection bag, a blood collection bag, a plasma collection bag, a test tube, a catheter, and a well of a microplate.  
     
     
         8 . A method for detecting the presence or absence of an infection in a subject, comprising the steps of: 
 a) contacting a sample obtained from a subject with a detectably labeled substrate for an enzyme produced and/or secreted by  Escherichia coli , under conditions that result in modification of said substrate by said enzyme; and    b) detecting the modification or the absence of the modification of said substrate,    wherein modification of said substrate indicates the presence of an infection in said subject, and wherein the absence of modification of said substrate indicates the absence of an infection in said subject.    
     
     
         9 . The method of  claim 8 , wherein said enzyme is a protease.  
     
     
         10 . The method of  claim 8 , wherein said sample is a body fluid.  
     
     
         11 . The method of  claim 8 , wherein said substrate is on a solid support.  
     
     
         12 . The method of  claim 11 , wherein said solid support comprises a material required to be free of microbial contaminants.  
     
     
         13 . The method of  claim 12 , wherein said solid support is a selected from the group consisting of a wound dressing, a container for holding body fluids, a disk, a scope, a filter, a lens, foam, cloth, paper, a suture, and a swab.  
     
     
         14 . The method of  claim 13 , wherein said container for holding body fluids is selected from the group consisting of a urine collection bag, a blood collection bag, a plasma collection bag, a test tube, a catheter, and a well of a microplate.  
     
     
         15 . A method for detecting the presence or absence of a wound infection in a subject, comprising the steps of: 
 a) contacting a wound in a subject with a detectably labeled substrate for an enzyme produced and/or secreted by  Escherichia coli , under conditions that result in modification of said substrate by said enzyme; and    b) detecting the modification or the absence of the modification of said substrate,    wherein modification of said substrate indicates the presence of a wound infection in said subject, and wherein the absence of modification of said substrate indicates the absence of a wound infection in said subject.    
     
     
         16 . The method of  claim 15 , wherein said enzyme is a protease.  
     
     
         17 . The method of  claim 15 , wherein said substrate is on a solid support.  
     
     
         18 . The method of  claim 17 , wherein said solid support is a wound dressing.  
     
     
         19 . A biosensor for detecting the presence or absence of  Escherichia coli  in a sample, said biosensor comprising a solid support and a detectably labeled substrate specific for an enzyme produced and/or secreted by said microorganism, said substrate attached to said solid support.  
     
     
         20 . The biosensor of  claim 19 , wherein the solid support comprises a material required to be free of microbial contaminants.  
     
     
         21 . The biosensor of  claim 19 , wherein said solid support is a selected from the group consisting of a wound dressing, a container for holding body fluids, a disk, a scope, a filter, a lens, foam, cloth, paper, a suture, a food packaging material, and a swab.  
     
     
         22 . The biosensor of  claim 21 , wherein said container for holding body fluids is selected from the group consisting of a urine collection bag, a blood collection bag, a plasma collection bag, a test tube, a catheter, and a well of a microplate.  
     
     
         23 . The biosensor of  claim 19 , wherein said biosensor directly contacts said wound.  
     
     
         24 . A kit for detecting an infection, comprising a biosensor according to  claim 19 , and one or more reagents for detecting the enzyme produced and/or secreted by  Escherichia coli  causing said infection.