SYNERGISM IN VITRO OF CERTAIN ANTIMICROBIAL AGENTS ß 537 Table III Escherichia coli 1 1 •o tribromosalicylanilide emulsion q- 1 •o tribromosalicylanilide emulsion q-1 •o Phenoxetol q- 1 •o tribromosalicylanilide emulsion q.0.3 •o p-chlorophenoxetol I •o Phenoxetol 2 • Phenoxetol q- 0.3 •o p-chlorophenoxetol Control q- q- strong growth (+) slight growth -- no growth 2 Time + (+) (++) in minutes --- -- •-0 - + : ¾ - (?) 15 30 q- q- These bacteriological results give a clear indication of the value to be attached to combinations of this type for the purpose of combating in- fection by both gram-positive and gram-negative organisms. Repeated evaluations confirmed the results detailed in Tables IV-VII. Tables IV-VII show the bactericidal properties of (a) a commercially available 3% hexachlorophane emulsion, (b) a commercially available 1% tribromosalicylanilide emulsion, (c) aqueous solutions of various concentrations of Phenoxetol and p-chloro- phenoxetol, (d) hexachlorophane emulsions into which Phenoxetol has been incor- porated, and (e) tribromosalicylanilide emulsions into which Phenoxetol or p-chloro- phenoxetol has been incorporated. Table IV Test organism--Staphylococcus aureus (a gram-positive organism) Material A B (2 •o Pheno•etol) D q- 1 •o Phenoxetol Time in minutes

538 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table V Test organism--Pseudomonas pyocyanea (a gram negative organism) Time in minutes 1 2 3 5 10 i 15 30 A + ] + + + + + + B + i + + + + I + -- C (2 % Phenoxetol) -- , .... , __ __ C (1.5•o Phenoxetol) + + + + (+) -- -- C (1.0•o Phenoxetol) + , + + + + + __ C (0.5 •o p-chlorophenoxetol) -- I C (0.8•op-chlorophenoxetol) + I + + + (+) i __ __ D (+ 1• Phenoxetol) + ] + (+) E (+ 1 •o Phenoxetol) + i + E (+ 0.$ •o p-chlorophenoxetol) + i + Table VI Test organism--Escherichia colt (a gram-negative organism) A B C (2 •o Phenoxetol) C (1.5 •o Phenoxetol) C (0.5 •o p-chlorophenoxetol) C (0.3 •o p-chlorophenoxetol) D (+ 1 •o Phenoxetol) E (+ 1 •o Phenoxetot) E (+ 0.$ •o p-chlorophenoxetol) Time in minutes 1 2 3 5 10 15 30 ++ ++ + + + + + + + + + + + + + + -- __ + + + + (+) -- _ + + (+) .... + + (+) .... + I + (+) .... Table VII Test organism--Proteus vulgaris (a gram-negative organism) Time in minutes 1 2 3 5 lO 15 30 , A + + + + + + + B + + + + + + + C (2 •o Phenoxetol) + -- -- I C (1.5 •o Phenoxetol) + + + + + + __ C (0.5 •o p-chlorophenoxetol) + C (0.3•o p-chlorophenoxetol) + + + ! + + (+) __ D (+ 1•o Phcnoxetol) + + -- [ E (+ 1 •o Phenoxetol) + + -- I E (+ 0.3 •o p-chlorophenoxetol) + + -- i -- -- -- + strong growth (+) weak growth -- no growth