Medium for the specific detection of resistant microorganisms

Abstract

A method for distinguishing among a first group of microorganisms belonging to a first taxon of Gram negative bacteria, the first group of bacteria exhibiting a mechanism of resistance to a treatment; a second group of microorganisms belonging to a second taxon of Gram negative bacteria, the second taxon of bacteria being different than said first taxon, and exhibiting a mechanism of resistance to a treatment identical to the mechanism of the first group; and a third group of Gram negative bacteria that is not resistant to the treatment.

What is claimed is: 
     
         1 . A method for distinguishing among at least three groups of microorganisms that may be present in a biological sample, the at least three groups comprising:
 a first group of microorganisms, belonging to a first taxon of bacteria that is vancomycin resistant;   a second group of microorganisms, belonging to a second taxon of vancomycin resistant bacteria that is different than said first taxon; and   a third group of microorganisms that is not resistant or has a natural resistance to vancomycin, the method comprising:   inoculating a culture medium with the biological sample, the culture medium comprising:
 a first substrate for detecting a first enzymatic activity of said first group of microorganisms; 
 a marker for differentiating the first group of microorganisms and the second group of microorganisms, said marker being a substrate for detecting an enzymatic activity of said second group of microorganisms; and 
 an antimicrobial that is active on the third group of microorganisms, and 
   distinguishing among any members of the three groups of microorganisms that are present on the culture medium to determine of which group of microorganisms they are members on the basis of their interactions with the first substrate, the marker, and the antimicrobial.   
     
     
         2 . The method of  claim 1 , wherein:
 the first group of microorganisms is enterococcal bacteria that have an acquired resistance to vancomycin;   the second group of microorganisms is enterococcal bacteria that have a natural resistance to vancomycin; and   the third group of microorganisms is enterococcal bacteria that is not resistant to vancomycin.   
     
     
         3 . The method of  claim 1 , wherein:
 the first group of vancomycin-resistant microorganisms comprises  Enterococcus faecalis  and  Enterococcus faecium;      the second group of vancomycin-resistant microorganisms comprises  Enterococcus casseliflavus  and  Enterococcus gallinarum ; and   the third group of microorganisms is not resistant to vancomycin.   
     
     
         4 . The method of  claim 1 , wherein:
 the first group of vancomycin-resistant microorganisms comprises  Enterococcus faecium;      the second group of vancomycin-resistant microorganisms comprises  Enterococcus faecalis; and      the third group of microorganisms is enterococcal bacteria that is not resistant to vancomycin or that have a natural resistance to vancomycin.   
     
     
         5 . The method of  claim 1 , wherein:
 the first group of vancomycin-resistant microorganisms comprises  Enterococcus faecalis  and  Enterococcus faecium;      the second group of vancomycin-resistant microorganisms comprises  Staphylococcus aureus  that is intermediary resistant or resistant to vancomycin; and   the third group of microorganisms is not resistant to vancomycin.   
     
     
         6 . The method of  claim 1 , wherein:
 the first substrate is an enzymatic substrate for detecting alpha-glucosidase activity;   the marker is a second substrate for detecting a second activity different than alpha-glucosidase activity; and   the antimicrobial is vancomycin.   
     
     
         7 . The method of  claim 6 , wherein the second substrate detects beta-glucosidase or beta-galactosidase activity. 
     
     
         8 . The method of  claim 6 , wherein:
 the first substrate is 5-bromo-4-chloro-3-indolyl-N-methyl-α-D-glucoside or 5-bromo-4-chloro-3-indolyl-α-D-glucoside, and   the second substrate is 6-chloro-3-indolyl-β-D-glucoside, alizarine-β-D-galactoside, 5-bromo-6-chloro-3-indolyl-β-D-glucoside, 5-bromo-6-chloro-3-indolyl-β-D-galactoside or 6-chloro-3-indolyl-β-D-galactoside.   
     
     
         9 . The method of  claim 6 , wherein:
 the first substrate is 5-bromo-4-chloro-3-indolyl-N-methyl-α-D-glucoside or 5-bromo-4-chloro-3-indolyl-α-D-glucoside, and   the second substrate is 6-chloro-3-indolyl-β-D-glucoside or 5-bromo-6-chloro-3-indolyl-β-D-glucoside.   
     
     
         10 . The method of  claim 1 , wherein:
 the first group of vancomycin-resistant microorganisms comprises  Enterococcus faecalis  and  Enterococcus faecium;      the second group of vancomycin-resistant microorganisms comprises  Enterococcus casseliflavus  and  Enterococcus gallinarum;      the third group of microorganisms is not resistant to vancomycin;
 the first substrate is an enzymatic substrate for detecting alpha-glucosidase activity; 
   the marker is a second substrate for detecting a second activity different than alpha-glucosidase activity; and   the antimicrobial is vancomycin.   
     
     
         11 . The method of  claim 1 , wherein:
 the first group of vancomycin-resistant microorganisms comprises  Enterococcus faecium;      the second group of vancomycin-resistant microorganisms comprises  Enterococcus faecalis;      the third group of microorganisms is enterococcal bacteria that is not resistant to vancomycin or that have a natural resistance to vancomycin;
 the first substrate is an enzymatic substrate for detecting alpha-glucosidase activity; 
   the marker is a second substrate for detecting a second activity different than alpha-glucosidase activity; and   the antimicrobial is vancomycin.   
     
     
         12 . The method of  claim 1 , wherein:
 the first group of vancomycin-resistant microorganisms comprises  Enterococcus faecalis  and  Enterococcus faecium;      the second group of vancomycin-resistant microorganisms comprises  Staphylococcus aureus  that is intermediary resistant or resistant to vancomycin;   the third group of microorganisms are not resistant to vancomycin;   the first substrate is an enzymatic substrate for detecting alpha-glucosidase activity;   the marker is a second substrate for detecting a second activity different than alpha-glucosidase activity; and   the antimicrobial is vancomycin.   
     
     
         13 . The method of  claim 1 , wherein:
 the first group of vancomycin-resistant microorganisms comprises  Enterococcus faecalis  and  Enterococcus faecium;      the second group of vancomycin-resistant microorganisms comprises  Enterococcus casseliflavus  and  Enterococcus gallinarum;      the third group of microorganisms is not resistant to vancomycin;   the first substrate is an enzymatic substrate for detecting alpha-glucosidase activity;   the marker is a second substrate for detecting beta-glucosidase or beta-galactosidase activity; and   the antimicrobial is vancomycin.   
     
     
         14 . The method of  claim 1 , wherein:
 the first group of vancomycin-resistant microorganisms comprises  Enterococcus faecium;      the second group of vancomycin-resistant microorganisms comprises  Enterococcus faecalis;      the third group of microorganisms is enterococcal bacteria that is not resistant to vancomycin or that have a natural resistance to vancomycin;   the first substrate is 5-bromo-4-chloro-3-indolyl-N-methyl-a-D-glucoside or 5-bromo-4-chloro-3-indolyl-a-D-glucoside;   the marker is 6-chloro-3-indolyl-β-D-glucoside, alizarine-β-D-galactoside, 5-bromo-6-chloro-3-indolyl-β-D-glucoside, 5-bromo-6-chloro-3-indolyl-β-D-galactoside or 6-chloro-3-indolyl-β-D-galactoside; and   the antimicrobial is vancomycin.   
     
     
         15 . The method of  claim 1 , wherein:
 the first group of vancomycin-resistant microorganisms comprises  Enterococcus faecalis  and  Enterococcus faecium;      the second group of vancomycin-resistant microorganisms comprises  Staphylococcus aureus  that is intermediary resistant or resistant to vancomycin;   the third group of microorganisms is not resistant to vancomycin;   the first substrate is 5-bromo-4-chloro-3-indolyl-N-methyl-a-D-glucoside or 5-bromo-4-chloro-3-indolyl-a-D-glucoside;   the marker is 6-chloro-3-indolyl-β-D-glucoside or 5-bromo-6-chloro-3-indolyl-β-D-glucoside; and   the antimicrobial is vancomycin.   
     
     
         16 . A method of detecting and distinguishing between any extended-spectrum β-lactamase-producing  E. coli  bacteria (ESBL  E. coli  bacteria) and any extended-spectrum β-lactamase-producing KESC bacteria (ESBL KESC bacteria) that are present on a culture medium, the method comprising:
 inoculating a culture medium with a biological sample, wherein the culture medium comprises:
 a first substrate for detecting beta-galactosidase activity; 
 a second substrate for detecting beta-glucuronidase activity; 
 a third substrate for detecting desaminase activity; and 
 a combination of antimicrobials throughout the entire culture medium, the combination comprising a cephalosporinase inhibitor and a third-generation cephalosporin; and 
 
 simultaneously detecting and distinguishing between any ESBL  E. coli  bacteria and ESBL KESC bacteria that are present on the culture medium. 
 
     
     
         17 . A method of detecting and distinguishing between any extended-spectrum β-lactamase-producing  E. coli  bacteria (ESBL  E. coli  bacteria) and any extended-spectrum β-lactamase-producing KESC bacteria (ESBL KESC bacteria) that are present on a culture medium, the method comprising:
 inoculating a culture medium with a biological sample, wherein the culture medium comprises:
 a first substrate for detecting beta-galactosidase activity; 
 a second substrate for detecting beta-glucosidase activity; and 
 a combination of antimicrobials throughout the entire culture medium, the combination comprising a cephalosporinase inhibitor and a third-generation cephalosporin.