This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Adair, F. W. Articles by Gelzer, J. Search for Related Content PubMed Articles by Adair, F. W. Articles by Gelzer, J. Agricola Articles by Adair, F. W. Articles by Gelzer, J.

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1971 June; 21(6): 1058-1063
Copyright © 1971 American Society for Microbiology. All Rights Reserved.

Resistance of Pseudomonas to Quaternary Ammonium Compounds

II. Cross-Resistance Characteristics of a Mutant of Pseudomonas aeruginosa

Research Department, Ciba Pharmaceutical Company, Summit, New Jersey 07901

ABSTRACT

Tube dilution experiments showed that benzalkonium chloride (BC)-resistant mutants of Pseudomonas aeruginosa grown in the presence of 1,000 µg of BC per ml were at least 20 times more sensitive to polymyxin B and colistin sulfate than the BC-sensitive (BCS) parent strain. BCS cells selected for resistance to 500 µg of polymyxin B per ml remained sensitive to BC. There was little difference in the amount of carbenicillin, gentamicin sulfate, or rifampin needed to prevent growth of either the BCS or BC-resistant (BCR) strains. Growth of BCR cells was inhibited by ethylenediaminetetraacetate at a concentration of 400 µg/ml or less, whereas the BCS strain grew at ethylenediaminetetraacetate levels of 10,000 µg/ml. Phenylmercuric acetate and thimerosal inhibited growth of BCR and BCS cells at concentrations of 10 µg/ml or less. BCR cells were cross-resistant to >1,000 µg/ml concentrations of five other quaternary ammonium compounds, including three with C₁₆ alkyls and two with alkyl groups of shorter length. The BCS strain was also resistant to >1,000 µg/ml concentrations of the three quaternary ammonium compounds with C₁₆ alkyl groups but, in addition to BC, was inhibited by 200 µg/ml levels or less of the two quaternary ammonium compounds containing alkyl groups of less than 16 carbon atoms.