to inhibit growth of unwanted organisms that normally give positive results in tests for p aeruginosa application_number US 68265376 A description the detection broth of the present invention contains from 2 7 to 3 3 by weight nutrients which are trypticase soy broth from bbl about 0 029 to about 0 031 cetyl trimethylammonium bromide which operates as a biological inhibitor to inhibit the growth of gram negative organisms and about 0 45 to about 0 55 by weight sodium nitrate which operates to stimulate growth of p aeruginosa organism in a reduced oxygen environment the nutrient portion of the medium contains from about 27 gm to about 33 gm trypticase soy broth per liter of broth medium trypticase soy broth is a mixture of peptones and contains per liter of distilled water 17 grams of peptone derived from casein by pancreatic digestion 3 grams of a papaic digest of soya meal high in vitamins especially thiamine 5 grams nacl 2 5 grams dipotassium phosphate and 2 5 grams dextrose it has a ph of about 7 3 suitable substitutes for trypticase soy broth are protease peptone 3 from difco and thiotone from bbl any peptone containing sufficient vitamins will operate in this invention the purpose of the soy broth is to promote growth of p aeruginosa organism a suitable base or acid is used to adjust the ph of the medium to 6 7 to 6 9 an important aspect of this invention lies in the action of the chemical inhibitor cetyl trimethylammonium bromide this inhibitor acts to inhibit the growth of gram.