536 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS destroyed the same organism within 5 min. When using 0.3% p-chloro- phenoxetol together with 1% tribromosalicylanilide this organism was destroyed within 2 min (Table II). Table I Pseudomonas pyocyanea 3 % Ilexachlorophane emulsion alone 3 % Ilexachlorophane emulsion plus 1% phenoxetol 2 •o Phenoxetol alone 1% Phenoxetol alone Control q- strong growth (+) slight growth -- no growth Time in minutes 1 3 5 + + + __ __ (++) 10 15 30 + + + -- -- __ -- -- __ + Table II Pseudomonas pyocyanea Time in minutes 1 2 3 5 10 15 30 1% emulsion of tribromo- salicylanilide q- q- q- q- q- q- -- 1% emulsion of tribromo- salicylanilide + 1 • Phenoxetol + + (+) .... 1% emulsion of tribromo salicylanilide +0.3 % p-chloro-phenoxetol q- ...... 1% Phenoxetol + + + + + q- -- 0.3 % p-chloro-phenoxetol q- q- q- .... Control + + + + + + + q- strong growth (+) slight growth -- no growth It should be noted that both the 3% hexachlorophane and 1% tri- bromosalicylanilide emulsions, when used alone, were very effective in destroying Staphylococcus, kills being obtained within 60 s. In comparison 2% Phenoxetol does not destroy these organisms in 60 min. Against Escherichia coli a combination of tribromosalicylanilide and Phenoxetol or p-chlorophenoxetol exhibited similar results (Table III).

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