Comparative susceptibility of hospital isolates of gram-negative bacteria to antiseptics and disinfectants.

The sensitivity of hospital isolates of Gram-negative bacteria to cationic antiseptics, mercuric chloride and two organomercury compounds has been measured. A comparison was made with laboratory strains of known sensitivity which acted as standards. All strains of Escherichia coli showed a uniformly high sensitivity to chlorhexidine diacetate; other organisms tended to be less sensitive to the biguanide. Quaternary ammonium compounds were less effective than chlorhexidine. Resistance to mercuric chloride was observed frequently, but there was little evidence of organomercurial resistance except in Pseudomonas aeruginosa isolates.