Chlorquinaldol, a topical agent for skin and wound infections: anti-biofilm activity and biofilm-related antimicrobial cross-resistance
Received 3 April 2019
Accepted for publication 14 June 2019
Published 19 July 2019 Volume 2019:12 Pages 2177—2189
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Melinda Thomas
Peer reviewer comments 2
Editor who approved publication: Dr Eric Nulens
Alessandro Bidossi,1 Marta Bottagisio,1 Roberta De Grandi,1 Lorenzo Drago,2 Elena De Vecchi1
1Laboratory of Clinical Chemistry and Microbiology, IRCCS Orthopedic Institute Galeazzi, Milan, Italy; 2Laboratory of Clinical Microbiology, Department of Biomedical Science for Health, University of Milan, Milan, Italy
Purpose: Persistence of skin and wound infections is nowadays accepted being linked to bacterial biofilms, which are highly recalcitrant to treatments and contribute to maintain a constant inflammation state and prevent a correct healing. Topical antimicrobials are the most common first-line self-medications; however, treatment failure is not uncommon and emerging resistance to antibiotics is alarming. Chlorquinaldol is an antimicrobial with a wide spectrum of activity and desirable characteristics for topical application. Aim of this study was to evaluate the efficacy of chlorquinaldol to prevent or eradicate S. aureus and P. aeruginosa biofilms, in comparison to classic topical antibiotics like gentamicin and fusidic acid.
Methods: Minimum inhibitory concentrations (MIC) were assessed for each strain and subinhibitory concentrations (½ and ¼ MIC) were used in the biofilm assay. Antimicrobial assays were performed during biofilm formation or were applied on mature biofilms and were evaluated by means of crystal violet assay and confocal laser scan microscopy.
Results: Chlorquinaldol and gentamicin were the most effective antimicrobials in both eradicating and preventing pathogens biofilm; however, resistance to methicillin and impermeability to carbapenems impaired chlorquinaldol effect. In addition, similarly to other hydroxyquinolines, aspecific metal chelation is here proposed as chlorquinaldol mode of action.
Conclusion: Relying on an acceptable antibiofilm and a wide spectrum of activity, an aspecific mode of action and consequent absence of resistance development, chlorquinaldol proved to be a good antimicrobial for topical use.
Keywords: chlorquinaldol, biofilm, skin and wound tissue infection, Staphylococcus aureus, Pseudomonas aeruginosa
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