Resistance and cross-resistance in Staphylococcus spp. strains following prolonged exposure to different antiseptics

Abstract

Objectives: This aim of this study was to evaluate the potential of staphylococci to develop resistance and cross-resistance to antibiotics following exposure to antiseptics. Methods: The antibiotic susceptibility profile as well as the antiseptic minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBC) were determined for Staphylococcus epidermidis and Staphylococcus aureus clinical isolates and reference strains (methicillin resistant or not) before and after prolonged exposure to low concentrations of two antiseptics, namely chlorhexidine digluconate (CHG) and octenidine dihydrochloride (OCT). Results: Resistance was observed to both tested antiseptics following exposure. CHG exposure led to increased MICs in five of the six tested strains of S. epidermidis and S. aureus and also led to clinically decreased susceptibility to gentamicin in S. aureus ATCC 43300 (MRSA) and to penicillin and tetracycline in S. aureus ATCC 25923 (MSSA). OCT exposure led to an increased MIC only in S. epidermidis ATCC 12228 (MSSE) and also led to a clinically decreased susceptibility to penicillin in S. aureus clinical strain SAL. One strain (MSSE) showed a four-fold increase in the MIC against CHG. Several strains showed a two-fold increase in the MIC against CHG and only one strain (MSSE) against OCT. Conclusion: These results support the urgent need to apply the same administration rules currently accepted for antibiotics to antiseptics in order to preserve the benefits both of antiseptics and antibiotics.

Keywords

• Antibiotic
• Antiseptic
• Chlorhexidine digluconate
• Octenidine dihydrochloride
• Resistance
• Staphylococcus spp.