Drug resistance studies with topical antiseptics

Area of Science:

• Microbiology
• Antimicrobial Resistance

Background:

• Chlorhexidine is a widely used antiseptic.
• Emerging bacterial resistance to disinfectants is a growing concern.
• Understanding resistance mechanisms is crucial for infection control.

Purpose of the Study:

• To investigate the development of in vitro resistance to chlorhexidine in specific bacterial species.
• To determine if cross-resistance to other disinfectants occurs.
• To assess the stability of acquired chlorhexidine resistance.

Main Methods:

• Exposure of Proteus, Serratia, and Pseudomonas species to sub-inhibitory concentrations of chlorhexidine.
• Serial in vitro transfers (5-8 passages) to induce resistance.
• Testing for cross-resistance to benzalkonium chloride and povidone-iodine.
• Evaluating resistance stability through drug-free transfers.

Main Results:

• Proteus, Serratia, and Pseudomonas species acquired resistance to chlorhexidine after 5-8 in vitro transfers.
• Cross-resistance to benzalkonium chloride was observed in resistant strains.
• No resistance was developed against povidone-iodine.
• Chlorhexidine resistance was stable in Serratia and Pseudomonas but transitory in Proteus.

Conclusions:

• Repeated exposure to chlorhexidine can induce resistance in clinically relevant bacteria.
• Cross-resistance to other quaternary ammonium compounds like benzalkonium chloride is a potential issue.
• Povidone-iodine appears to be a more robust antiseptic against the tested strains.
• The stability of chlorhexidine resistance varies, necessitating further investigation into underlying mechanisms.