In this retrospective study evaluating patients diagnosed with contact allergy to Chlorhexidine digluconate  in a Danish tertiary dermatology clinic, we found that 1.0% of all patients patch tested from 2003 to 2013 had a positive patch test reaction to chlorhexidine. This finding is in line with the prevalence found in studies from other European countries, but is lower than the prevalence in previous studies from Denmark in the 1980s. Most of the reactions were weakly positive, which is in line with a recent study from Finland, but is in contrast to an older study from our clinic, where most of the reactions were strongly/extremely positive. Notably, in our centre, there was a marked decrease in the prevalence, from 1.7% in 2003 to 0.3% in 2013. This is probably because we lowered the test concentration from 1.0 to 0.5% in 2008. Currently, the optimal test concentration remains unknown, and different centres use different concentrations: The European Network for Drug Allergy recently suggested a test concentration of 1% , but some centres use 0.5%. In this study, we found that 0.5% chlorhexidine diacetate and 0.5% chlorhexidine digluconate caused fewer irritant reactions than 1.0% chlorhexidine diacetate and 1.0% chlorhexidine digluconate. These findings are in line with an older study from our clinic, which also found that, especially, 1.0% chlorhexidine diacetate is a strong irritant. Additionally, two older studies found that it was difficult to reproduce the test results when patch testing. Taken together, these findings suggest that 1.0% is too high as a test concentration. Nonetheless, no studies have investigated whether testing with 0.5% is reproducible or whether it causes false-negative results. Therefore, future studies should focus on finding the optimal concentration for patch testing with chlorhexidine; such studies could, for instance, include use testing or patch testing with titrated concentrations, and repeated open applications of solutions of chlorhexidine.
In our questionnaire study, 40% of respondents reported a potential cause of their allergy – products used in the healthcare setting were mainly reported, but some reported cosmetic products. The remaining patients (60%) did not report a known cause of their allergy, and there could be several reasons for this. First, a positive patch test reaction to Chlorhexidine digluconate  indicates sensitization, but this may not lead to allergic symptoms in all patients. Second, some patients may not remember an exposure a long time ago. Third, some patients may have been using a product causing the symptoms without knowing this. Indeed, the last of these could very well be the case in some patients, because 62% of the patients in the questionnaire were unaware of the use of chlorhexidine as a preservative in cosmetic products, and 17% were unaware of the use in the healthcare setting. Exposure assessment is an important part of allergy investigation, but the data saved in the database from the time of the original investigation were incomplete, and could therefore not be included as a supplement in this study.
Evaluation of Chlorhexidine digluconate alcohol skin disinfectant to kill multi-drug resistant bacteria for clinical rational use of disinfectants to provide evidence. In the control group; methicillin-resistant Staphylococcus aureus, and Escherichia coli producing ESBLs PDRPA three kinds of multi-drug resistant bacteria:: the experimental group Methods Suspension quantitative germicidal method, provided the experimental group corresponding to Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa three kinds of non-resistant; compare chlorhexidine gluconate alcohol skin disinfectant to kill drug-resistant and non-resistant bacteria. Results 2% chlorhexidine gluconate alcohol skin disinfectant liquid effect 30s, 1,3min the test and control groups were killing logarithm of 5.0. Conclusion 2% chlorhexidine gluconate alcohol skin disinfectant killing effect on multi-drug resistant and non-resistant equally quick and efficient.