Determination of the antibacterial efficacy of several antiseptics tested on skin by an ‘ex-vivo’ test

Abstract

There are many skin antiseptics commercially available. Although their antibacterial activity has often been well studied [1], their potential effectiveness on skin remains poorly documented. To date, in-vivo protocols designed for the testing of the antimicrobial ef®cacy of antiseptics cannot use, for ethical reasons, pathogenic bacteria or new formulations whose toxicity in human subjects is unknown. An`ex-vivo' test was recently developed to overcome these problems. Freshly excised human skin from abdominal or breast reduction was placed in a diffusion cell containing a maintenance medium in the recipient compartment. A bacterial inoculum was then applied to the stratum corneum and, after a drying step, antiseptic formulations were evaluated for their antimicrobial activity. Several micro-organisms were investigated: ± Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Enterococcus faecalis, vancomycinresistant Ent. faecium (VRE), S. epidermidis, Pseudomonas aeruginosa and Escherichia coli ± with several biocides ± para-chloro-meta-xylenol (PCMX, active compound of Dettol), povidone iodine, triclosan (in isopropanol) and chlorhexidine. Results from the ex-vivo test were compared with results obtained in suspension and glass-carrier tests. The bactericidal activity of the biocides depended upon the test performed and results were generally signi®cantly different from one method to the other. All biocides tested in the suspension test achieved >4 log 10 reduction in viable bacterial concentrations, apart from povidone iodine tested against Ent. faecalis and VRE. The antibacterial activity of biocides tested in the glass-carrier test was signi®cantly lower than in the suspension test, with the exception of triclosan in isopropanol, which was as effective in both suspension and glass-carrier test. In the ex-vivo test, triclosan in isopropanol achieved a log 10 reduction in viable bacterial concentration of 1.105±1.771 (with the exception of P. aeruginosa with 0.758 log 10 reduction). PCMX, povidone iodine and chlorhexidine achieved log 10 reductions in viable bacterial concentration of 0.303±0.901. Chlorhexidine tested against P. aeruginosa produced a 1.94 log 10 reduction in concentration. These results con®rm previous observations about the need for testing the antimicrobial activity of antiseptics on skin surface to determine their in-situ ef®cacy and encourage further the use of the ex-vivo protocol.

Comparison of two in vivo and two ex vivo tests to assess the antibacterial activity of several antiseptics

“…Previous experiments validated the efficacy of these neutralizers to quench the activity of their respective antiseptics, and showed that they had no toxic effects on the test strain of Escherichia coli. 11 The in vivo tests were carried out with 12 female and three male volunteers (aged 18 -25 years). Participants had short fingernails and intact skin and were instructed not to apply antibacterial toiletries onto their forearms for 24 h before testing.…”

“…This ex vivo protocol was based on the method of Messager et al 11 Fresh samples of skin were obtained with patients' informed consent after plastic surgery (breast and abdominal reduction) and were cut to fit in diffusion cells (JB and DW Jones, Loughborough, UK) especially designed for that experiment with a donor compartment of 36 mm diameter. 11 The receptor compartment was filled with Earle's balanced salt solution (EBSS, Sigma, Poole, UK).…”

“…11 The receptor compartment was filled with Earle's balanced salt solution (EBSS, Sigma, Poole, UK). A 20 mL aliquot of a E. coli K12 (NCTC 10538) inoculum containing approx.…”

Effectiveness of hand-cleansing formulations containing tea tree oil assessed ex vivo on human skin and in vivo with volunteers using European standard EN 1499

“…Therefore, the efficacy of a hygienic skin wash (HSW) and an alcoholic hygienic skin wash (AHSW) that both contained 5% TTO, as well as 5% TTO in Tween 80, was investigated in vivo according to the European handwashing test. 23 An ex-vivo test, which has been shown to be a reproducible potential substitute for in-vivo testing, [24][25][26] was adapted to imitate the handwashing technique and also used to assess the activity of TTO. Ex-vivo and in vivo data were compared.…”

Vectorization of Harungana madagascariensis Lam. ex Poir. (Hypericaceae) ethanolic leaf extract by using PLG‐nanoparticles: antibacterial activity assessment

“…The ex vivo antibacterial activity test was performed as previously described [Messager et al, 2001;Lboutounne et al, 2002]. Skin fragments were excised from abdominoplasties of female subjects obtained by surgical intervention.…”