Interaction of chlorhexidine with trisEDTA or miconazole <i>in vitro</i> against canine meticillin-resistant and -susceptible <i>Staphylococcus pseudintermedius</i> isolates from two UK regions

Clark, Sian-Marie, Loeffler, Anette, Schmidt, Vanessa M ORCID: 0000-0001-5460-6217, Chang, Yu-Mei, Wilson, Alison, Timofte, Dorina ORCID: 0000-0002-7261-738X and Bond, Ross (2016) Interaction of chlorhexidine with trisEDTA or miconazole <i>in vitro</i> against canine meticillin-resistant and -susceptible <i>Staphylococcus pseudintermedius</i> isolates from two UK regions. VETERINARY DERMATOLOGY, 27 (5). 340-+.

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Abstract

<h4>Background</h4>Topical therapy is an important alternative to systemic antibacterial therapy for treatment of canine superficial pyoderma in light of the emergence of multidrug-resistant staphylococci. Chlorhexidine is widely used in shampoo products alone or in combination with miconazole or tromethamine-ethylenediaminetetraacetic acid (trisEDTA). Comparisons of these combinations have not been made.<h4>Hypothesis/objectives</h4>To determine minimum inhibitory concentrations (MICs) of combinations of chlorhexidine/miconazole and chlorhexidine/trisEDTA in vitro in a collection of Staphylococcus pseudintermedius (SP) from northern (NUK) and southeastern (SEUK) United Kingdom (UK) sources.<h4>Methods</h4>MICs of chlorhexidine, miconazole, trisEDTA and combinations of chlorhexidine/miconazole (1:1) or chlorhexidine/trisEDTA (80:16:1 and 80:5:1) were determined for 196 canine SP isolates from NUK [49 meticillin-resistant (MRSP), 50 meticillin-susceptible (MSSP)] and fom SEUK (48 MRSP, 49 MSSP) using agar dilution.<h4>Results</h4>TrisEDTA alone did not inhibit growth. Chlorhexidine/miconazole MICs (median = 0.5 mg/L) were lower than those of either drug alone (P < 0.05) and lower than chlorhexidine/trisEDTA MICs (median = 1 mg/L; P < 0.0005) in each bacterial type and from both regions, except for miconazole in NUK MSSP. An additive interaction was noted between chlorhexidine and miconazole or trisEDTA (80:16:1 ratio) in 79 and 43 isolates, respectively, whereas antagonism between chlorhexidine and trisEDTA was noted for three isolates. NUK isolates were more susceptible than SEUK isolates (P < 0.05), except MRSP exposed to chlorhexidine and the chlorhexidine/trisEDTA (80:16:1) combination.<h4>Conclusions and clinical importance</h4>These low MICs are likely to be exceeded by topical therapy. Evaluation of the mechanisms by which chlorhexidine combinations interact to reduce MICs is warranted, in view of increasing concerns of biocide tolerance in staphylococci.

Item Type:	Article
Uncontrolled Keywords:	Animals, Dogs, Staphylococcus, Staphylococcal Skin Infections, Dog Diseases, Tromethamine, Methicillin, Chlorhexidine, Edetic Acid, Miconazole, Microbial Sensitivity Tests, Methicillin Resistance, Drug Interactions, United Kingdom
Depositing User:	Symplectic Admin
Date Deposited:	22 Aug 2018 05:53
Last Modified:	12 Oct 2023 09:49
DOI:	10.1111/vde.12357
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3025345