Possible link between bacterial resistance and use of antibiotics and biocides

• Published in: Antimicrobial agents and chemotherapy Vol. 42; no. 8; p. 2151
• Main Authors: Russell, A D, Tattawasart, U, Maillard, J Y, Furr, J R
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01-08-1998
• Subjects: Anti-Bacterial Agents; Anti-Bacterial Agents - pharmacology; Anti-Infective Agents, Local; Anti-Infective Agents, Local - pharmacology; Chlorhexidine - pharmacology; Commented On; Drug Resistance, Microbial; Letters to the Editor; Pseudomonas stutzeri; Staphylococcus aureus; Staphylococcus epidermidis
• ISSN: 0066-4804; 1098-6596
• DOI: 10.1128/aac.42.8.2151

Low-level plasmid-mediated resistance to cationic biocides such as chlorhexidine (CHX), quaternary ammonium compounds (QACs), amidines, and acridines has been observed in antibiotic-resistant strains of Staphylococcus aureus and Staphylococcus epidermidis, and it has been postulated that strains in which qac genes are present might have enhanced survival in the clinical environment. Extensive use of cationic biocides could lead to the selection of staphylococcal strains showing resistance to both antibiotics and biocides, but the clinical relevance of this possibility remains contentious. We have developed stable CHX resistance in some strains of Pseudomonas stutzeri by exposure to increasing concentrations of the bisbiguanide. MICs of CHX for parent strains were 2.5 to 5 mu g/ml and MICs for resistant strains were 10 to 100 mu g/ml. The CHX-resistant strains showed a variable increase in resistance to QACs (benzalkonium chloride and cetylpyridinium chloride) and to triclosan (increases in MICs of the phenolic of 25- to 250-fold). Additionally, these CHX-resistant strains also demonstrated a variable increase in resistance to polymyxin B, gentamicin, nalidixic acid, erythromycin, and ampicillin. Resistant cells took up less CHX from solution than susceptible cells and cell envelope changes were observed microscopically, implicating the outer membrane as being involved in this reduced susceptibility.