Coliform detection process and kit for use therein

Abstract

A process comprises (a) providing (1) at least one sample suspected of comprising at least one coliform strain, (2) at least one culture device comprising at least one culture medium that is hydrated or hydratable, and (3) at least one particulate concentration agent that is substantially optically transparent when in contact with the culture medium in the culture device when the culture medium is hydrated; (b) placing the particulate concentration agent in contact with the sample such that at least a portion of the coliform strain is bound to the particulate concentration agent to form coliform-bound particulate concentration agent; (c) placing the coliform-bound particulate concentration agent in contact with the culture medium; (d) incubating the culture device comprising the coliform-bound particulate concentration agent in contact with the culture medium, the culture medium being hydrated; and (e) optically detecting the presence of the coliform strain without separating the coliform strain from the particulate concentration agent.

We claim: 
     
         1 . A process comprising
 (a) providing at least one sample suspected of comprising at least one coliform strain;   (b) providing at least one culture device comprising at least one culture medium that is hydrated or hydratable;   (c) providing at least one particulate concentration agent that is substantially optically transparent when in contact with said culture medium in said culture device when said culture medium is hydrated, wherein said at least one particulate concentration agent can concentrate a variety of coliform strains, wherein said particulate concentration agent comprises inorganic microparticles selected from metal silicates; silica; metal carbonates; metal phosphates; metal oxide-, gold-, or platinum-modified diatomaceous earth; and combinations thereof;   (d) placing said particulate concentration agent in contact with said sample such that at least a portion of said coliform strain is bound to or captured by said particulate concentration agent to form coliform-bound particulate concentration agent;   (e) placing said coliform-bound particulate concentration agent in contact with said culture medium of said culture device;   (f) incubating said culture device comprising said coliform-bound particulate concentration agent in contact with said culture medium, said culture medium being hydrated; and   (g) optically detecting the presence of said coliform strain without separating said coliform strain from said particulate concentration agent.   
     
     
         2 . The process of  claim 1 , wherein said sample is in the form of a fluid. 
     
     
         3 . The process of  claim 1 , wherein said sample is a water sample. 
     
     
         4 . The process of  claim 1 , wherein said coliform strain is a gas-producing coliform strain. 
     
     
         5 . The process of  claim 1 , wherein said coliform strain is  Escherichia coli.    
     
     
         6 . The process of  claim 1 , wherein said culture medium comprises at least one fermentable nutrient. 
     
     
         7 . The process of  claim 1 , wherein said culture device is a flat film culture device comprising culture medium that comprises at least one fermentable nutrient. 
     
     
         8 . The process of  claim 1 , wherein said particulate concentration agent captures or binds at least about 60 percent of the microorganisms present in said sample, relative to a corresponding control sample without said particulate concentration agent. 
     
     
         9 . The process of  claim 1 , wherein said placing in contact with said sample is carried out by mixing said particulate concentration agent and said sample. 
     
     
         10 . The process of  claim 1 , wherein said process further comprises segregating said coliform-bound particulate concentration agent and/or separating the resulting segregated particulate concentration agent from said sample. 
     
     
         11 . The process of  claim 1 , wherein said process further comprises identifying and/or enumerating said coliform strain. 
     
     
         12 . The process of  claim 1 , wherein said optically detecting comprises detecting at least one color change. 
     
     
         13 . The process of  claim 1 , wherein said optically detecting is effected by an automated optical detection system. 
     
     
         14 . A process comprising
 (a) providing at least one water sample suspected of comprising  Escherichia coli;      (b) providing at least one flat film culture device comprising at least one culture medium that is hydrated or hydratable and that comprises at least one fermentable nutrient;   (c) providing at least one particulate concentration agent that is substantially optically transparent when in contact with said culture medium in said flat film culture device when said culture medium is hydrated, wherein said at least one particulate concentration agent can concentrate a variety of coliform strains, said particulate concentration agent comprising inorganic microparticles selected from calcium carbonate; silica; hydroxyapatite; titanium dioxide-modified diatomaceous earth; and combinations thereof;   (d) placing said particulate concentration agent in contact with said water sample such that at least a portion of said  Escherichia coli  is bound to or captured by said particulate concentration agent to form  Escherichia coli -bound particulate concentration agent;   (e) placing said  Escherichia coli -bound particulate concentration agent in contact with said culture medium of said flat film culture device;   (f) incubating said flat film culture device comprising said  Escherichia coli -bound particulate concentration agent in contact with said culture medium, said culture medium being hydrated; and   (g) optically detecting the presence of said  Escherichia coli  without separating said  Escherichia coli  from said particulate concentration agent, said optically detecting comprising detecting at least one color change and the presence of at least one gas bubble proximate at least one  Escherichia coli  colony by digital optical imaging using an automated optical detection system comprising at least one scanner.   
     
     
         15 . A diagnostic kit for use in carrying out the process of  claim 1  comprising
 (a) at least one culture device comprising at least one culture medium that is hydrated or hydratable; and 
 (b) at least one particulate concentration agent that is substantially optically transparent when in contact with said culture medium and can concentrate a variety of coliform strains in said culture device when said culture medium is hydrated.