In vitro evaluation of the antimicrobial activity of chlorhexidine alone or in combination with ketoconazole or miconazole against clinical isolates of Malassezia pachydermatis and multidrug-resistant Staphylococcus pseudintermedius

Background. Staphylococcus pseudintermedius (SP) and Malassezia pachydermatis (MP) are common causes of canine skin infections associated with increasing antimicrobial resistance. Topical products containing chlorhexidine and azoles have been utilized to treat these infections. However, a limited number of studies have assessed the interactions between chlorhexidine and azoles against SP and MP.Hypothesis/Objectives. To assess efficacy and potential additivity/synergy between chlorhexidine and azoles against clinical isolates of MP and multidrug-resistant SP (MDR-SP).Materials and Methods. A total of 30 MDR-SP and 30 MP isolates were tested using a modified broth microdilution method. Six twofold dilutions of 2% chlorhexidine gluconate, 1% miconazole nitrate and 0.15% ketoconazole were tested alone and in combination. Minimum inhibitory (MIC) and bactericidal/fungicidal (MBC/MFC) concentrations were recorded, and synergy, additivity or antagonism was calculated.Result. For MDR-SP, the combinations of chlorhexidine/miconazole (P=0.003) and chlorhexidine/ketoconazole (P<0.0001) resulted in lower MICs than chlorhexidine alone. Only the chlorhexidine/ketoconazole combination had lower MBCs (P=0.0071) than chlorhexidine alone. For MP, only the chlorhexidine/ketoconazole combination had lower MICs (P<0.0001) than chlorhexidine alone. Both combinations of chlorhexidine/miconazole (P=0.0028) and chlorhexidine/ketoconazole (P<0.0001) resulted in lower MFCs than chlorhexidine alone. Chlorhexidine/miconazole combination showed synergy in three MDR-SP isolates, but in none of the MP isolates. Chlorhexidine/ketoconazole showed synergy for 1 out of 30 MDR-SP and 19 out of 30 MP isolates.Conclusions and Clinical Relevance. These results suggest that chlorhexidine/azole combinations are an effective topical treatment for MDR-SP and MP infections. Further studies should assess the efficacy of commercial products containing these compounds and their efficacy in vivo.

Authors: G. Goldman and D. Santoro Title: In vitro evaluation of the antimicrobial activity of chlorhexidine alone or in combination with ketoconazole or miconazole against clinical isolates of Malassezia pachydermatis and multidrug-resistant Staphylococcus pseudintermedius Full source: Microbiology (Reading), 2026,Vol 172, Iss 4, Author keywords 172
Résumé, analyse et commentaires
Aucun.
Photo
Aucune.
Analysis
None.
Abstract	Source
Background. Staphylococcus pseudintermedius (SP) and Malassezia pachydermatis (MP) are common causes of canine skin infections associated with increasing antimicrobial resistance. Topical products containing chlorhexidine and azoles have been utilized to treat these infections. However, a limited number of studies have assessed the interactions between chlorhexidine and azoles against SP and MP.Hypothesis/Objectives. To assess efficacy and potential additivity/synergy between chlorhexidine and azoles against clinical isolates of MP and multidrug-resistant SP (MDR-SP).Materials and Methods. A total of 30 MDR-SP and 30 MP isolates were tested using a modified broth microdilution method. Six twofold dilutions of 2% chlorhexidine gluconate, 1% miconazole nitrate and 0.15% ketoconazole were tested alone and in combination. Minimum inhibitory (MIC) and bactericidal/fungicidal (MBC/MFC) concentrations were recorded, and synergy, additivity or antagonism was calculated.Result. For MDR-SP, the combinations of chlorhexidine/miconazole (P=0.003) and chlorhexidine/ketoconazole (P<0.0001) resulted in lower MICs than chlorhexidine alone. Only the chlorhexidine/ketoconazole combination had lower MBCs (P=0.0071) than chlorhexidine alone. For MP, only the chlorhexidine/ketoconazole combination had lower MICs (P<0.0001) than chlorhexidine alone. Both combinations of chlorhexidine/miconazole (P=0.0028) and chlorhexidine/ketoconazole (P<0.0001) resulted in lower MFCs than chlorhexidine alone. Chlorhexidine/miconazole combination showed synergy in three MDR-SP isolates, but in none of the MP isolates. Chlorhexidine/ketoconazole showed synergy for 1 out of 30 MDR-SP and 19 out of 30 MP isolates.Conclusions and Clinical Relevance. These results suggest that chlorhexidine/azole combinations are an effective topical treatment for MDR-SP and MP infections. Further studies should assess the efficacy of commercial products containing these compounds and their efficacy in vivo.