Penetration of chlorhexidine into human skin

This study evaluated a model of skin permeation to determine the depth of delivery of chlorhexidine into full-thickness excised human skin following topical application of 2% (wt/vol) aqueous chlorhexidine digluconate. Skin permeation studies were performed on full-thickness human skin using Franz diffusion cells with exposure to chlorhexidine for 2 min, 30 min, and 24 h. The concentration of chlorhexidine extracted from skin sections was determined to a depth of 1,500 µm following serial sectioning of the skin using a microtome and analysis by high-performance liquid chromatography. Poor penetration of chlorhexidine into skin following 2-min and 30-min exposures to chlorhexidine was observed (0.157 ± 0.047 and 0.077 ± 0.015 µg/mg tissue within the top 100 µm), and levels of chlorhexidine were minimal at deeper skin depths (less than 0.002 µg/mg tissue below 300 µm). After 24 h of exposure, there was more chlorhexidine within the upper 100-µm sections (7.88 ± 1.37 µg/mg tissue); however, the levels remained low (less than 1 µg/mg tissue) at depths below 300 µm. There was no detectable penetration through the full-thickness skin. The model presented in this study can be used to assess the permeation of antiseptic agents through various layers of skin in vitro. Aqueous chlorhexidine demonstrated poor permeation into the deeper layers of the skin, which may restrict the efficacy of skin antisepsis with this agent. This study lays the foundation for further research in adopting alternative strategies for enhanced skin antisepsis in clinical practice.

Enhanced chlorhexidine skin penetration with eucalyptus oil

Background Chlorhexidine digluconate (CHG) is a widely used skin antiseptic, however it poorly penetrates the skin, limiting its efficacy against microorganisms residing beneath the surface layers of skin. The aim of the current study was to improve the delivery of chlorhexidine digluconate (CHG) when used as a skin antiseptic. Method Chlorhexidine was applied to the surface of donor skin and its penetration and retention under different conditions was evaluated. Skin penetration studies were performed on full-thickness donor human skin using a Franz diffusion cell system. Skin was exposed to 2% (w/v) CHG in various concentrations of eucalyptus oil (EO) and 70% (v/v) isopropyl alcohol (IPA). The concentration of CHG (µg/mg of skin) was determined to a skin depth of 1500 µm by high performance liquid chromatography (HPLC). Results The 2% (w/v) CHG penetration into the lower layers of skin was significantly enhanced in the presence of EO. Ten percent (v/v) EO in combination with 2% (w/v) CHG in 70% (v/v) IPA significantly increased the amount of CHG which penetrated into the skin within 2 min. Conclusion The delivery of CHG into the epidermis and dermis can be enhanced by combination with EO, which in turn may improve biocide.

Does nuclear tissue infected with bacteria following disc herniations lead to Modic changes in the adjacent vertebrae?

Purpose To investigate the prevalence of infected herniated nucleus material in lumbar disc herniations and to determine if patients with an anaerobic infected disc are more likely to develop Modic change (MC) (bone oedema) in the adjacent vertebrae after the disc herniation. MCs (bone oedema) in vertebrae are observed in 6 % of the general population and in 35-40 % of people with low back pain. These changes are strongly associated with low back pain. There are probably a mechanical cause and an infective cause that causes MC. Several studies on nuclear tissue from herniated discs have demonstrated the presence of low virulent anaerobic microorganisms, predominantly Propionibacterium acnes, in 7-53 % of patients. At the time of a herniation these low virulent anaerobic bacteria may enter the disc and give rise to an insidious infection. Local inflammation in the adjacent bone may be a secondary effect due to cytokine and propionic acid production. Methods Patients undergoing primary surgery at a single spinal level for lumbar disc herniation with an MRI-confirmed lumbar disc herniation, where the annular fibres were penetrated by visible nuclear tissue, had the nucleus material removed. Stringent antiseptic sterile protocols were followed. Results Sixty-one patients were included, mean age 46.4 years (SD 9.7), 27 % female. All patients were immunocompetent. No patient had received a previous epidural steroid injection or undergone previous back surgery. In total, microbiological cultures were positive in 28 (46 %) patients. Anaerobic cultures were positive in 26 (43 %) patients, and of these 4 (7 %) had dual microbial infections, containing both one aerobic and one anaerobic culture. No tissue specimens had more than two types of bacteria identified. Two (3 %) cultures only had aerobic bacteria isolated. In the discs with a nucleus with anaerobic bacteria, 80 % developed new MC in the vertebrae adjacent to the previous disc herniation. In contrast, none of those with aerobic bacteria and only 44 % of patients with negative cultures developed new MC. The association between an anaerobic culture and new MCs is highly statistically significant (P = 0.0038), with an odds ratio of 5.60 (95 % CI 1.51-21.95). Conclusion These findings support the theory that the occurrence of MCs Type 1 in the vertebrae adjacent to a previously herniated disc may be due to oedema surrounding an infected disc. The discs infected with anaerobic bacteria were more likely (P<0.0038) to develop MCs in the adjacent vertebrae than those in which no bacteria were found or those in which aerobic bacteria were found. © Springer-Verlag Berlin Heidelberg 2013.

Antimicrobial efficacy of chlorhexidine digluconate alone and in combination with eucalyptus oil, tea tree oil and thymol against planktonic and biofilm cultures of Staphylococcus epidermidis

Objectives Effective skin antisepsis and disinfection of medical devices are key factors in preventing many healthcare-acquired infections associated with skin microorganisms, particularly Staphylococcus epidermidis. The aim of this study was to investigate the antimicrobial efficacy of chlorhexidine digluconate (CHG), a widely used antiseptic in clinical practice, alone and in combination with tea tree oil (TTO), eucalyptus oil (EO) and thymol against planktonic and biofilm cultures of S. epidermidis. Methods Antimicrobial susceptibility assays against S. epidermidis in a suspension and in a biofilm mode of growth were performed with broth microdilution and ATP bioluminescence methods, respectively. Synergy of antimicrobial agents was evaluated with the chequerboard method. Results CHG exhibited antimicrobial activity against S. epidermidis in both suspension and biofilm (MIC 2–8 mg/L). Of the essential oils thymol exhibited the greatest antimicrobial efficacy (0.5–4 g/L) against S. epidermidis in suspension and biofilm followed by TTO (2–16 g/L) and EO (4–64 g/L). MICs of CHG and EO were reduced against S. epidermidis biofilm when in combination (MIC of 8 reduced to 0.25–1 mg/L and MIC of 32–64 reduced to 4 g/L for CHG and EO, respectively). Furthermore, the combination of EO with CHG demonstrated synergistic activity against S. epidermidis biofilm with a fractional inhibitory concentration index of <0.5. Conclusions The results from this study suggest that there may be a role for essential oils, in particular EO, for improved skin antisepsis when combined with CHG.

Chlorhexidine and the prevention of surgical site infection

Surgical site infections (SSI) are a prevalent health care-associated infection (HAl). Prior to the mid-19th century, surgical sites commonly developed postoperative wound complications. It was in the 1860's, after Joseph Lister introduced carbolic acid and the principles of antisepsis that postoperative wound infection significantly decreased. Today, patient preoperative skin preparation with an antiseptic agent prior to surgery is a standard of practice. Povidone-iodine and chlorhexidine gluconate are currently the most commonly used antimicrobial agents used to prep the patient's skin. In this current study, the epidemiology, diagnosis, surveillance and prevention of SSI with chlorhexidine were investigated. The antimicrobial activity of chlorhexidine was assessed. In in-vitro and in-vivo studies the antimicrobial efficacy of 2% (w/v) chlorhexidine gluconate (CHG) in 70% isopropyl alcohol (IPA) and 10% povidoneiodine (PVP-I) in the presence of 0.9% normal saline or blood were examined. The 2% CHG in 70% IPA solutions antimicrobial activity was not diminished in the presence of 0.9% normal saline or blood. In comparison, the traditional patient preoperative skin preparation, 10% PVP-I antimicrobial activity was not diminished in the presence of 0.9% normal saline, but was diminished in the presence of blood. In an in-vivo human volunteer study the potential for reduction of the antimicrobial efficacy of aqueous patient preoperative skin preparations compromised by mechanical removal of wet product from the application site (blot) was assessed. In this evaluation, 2% CHG and 10% povidone-iodine (PVP-I) were blotted from the patient's skin after application to the test site. The blotting, or mechanical removal, of the wet antiseptic from the application site did not produce a significant difference in product efficacy. In a clinical trial to compare 2% CHG in 70% IPA and PVP-! scrub and paint patient preoperative skin preparation for the prevention of SSI, there were 849 patients randomly assigned to the study groups (409 in the chlorhexidine-alcohol and 440 in the povidone-iodine group) in the intention-to-treat analysis. The overall surgical site infection was significantly lower in the 2% CHG in 70% IPA group than in the PVP-I group (9.5% versus 16.1 %, p=0.004; relative risk, 0.59 with 95% confidence interval of 0.41 to 0.85). Preoperative cleansing of the patient's skin with chlorhexidine-alcohol is superior to povidone-iodine in preventing surgical site infection after clean-contaminated surgery.