Irritative potency of selected wound antiseptics in the hen's egg test on chorioallantoic membrane to predict their compatibility to wounds.

Antiseptics are being used for prevention of infections in acute wounds and for treatment of infections in acute and chronic wounds. However, some antiseptics' high tissue toxicity might delay the healing process. The aim of this study was to investigate the tissue toxicity of preferentially used wound antiseptics and the influence of antiphlogistic additives via the hen's egg test on the chorioallantoic membrane (HET-CAM). The HET-CAM is a semi-in-vivo method testing the tissue tolerability of wound antiseptics by evaluating the blood vessel reaction of the chorioallantoic membrane in terms of hemorrhage, vessel lysis, and coagulation. For each test day, selected test substances were applied on the membranes of two to three eggs according to the test protocol. The overall irritation was then evaluated by referring to a calculated score. Normal distribution of the resulting scores was confirmed by D'Agostino-Pearson omnibus K2 test. Significant differences between the antiseptics were calculated by Tukey's multiple comparisons test. Severe CAM reactions were observed after short-term application of octenidine based wound gel (0.05%) and chlorhexidine digluconate (0.5% solution), moderate reactions for octenidine (0.05%) in aqueous solution combined with dexpanthenol (1.34%) and allantoin (0.2%) or for hydrogen peroxide (1.5% and 0.5%) in aqueous solution, slight reactions were observed for hydrogen peroxide (1.5%) in aqueous solution in combination with sodium thiocyanate (0.698%) and for the combination of NaOCl/HOCl (each 0.004%). Polyhexanide (0.04%) in Ringer solution and polyhexanide (0.05%) in Lipofundin, the hemoglobin spray (10%), dexpanthenol, and allantoin showed no irritation. The HET-CAM qualifies as a primary screening test for tissue tolerance of wound antiseptics. Regarding local tolerability, polyhexanide and hypochlorite are superior to other antiseptics.

Proposed phase 2/ step 2 in-vitro test on basis of EN 14561 for standardised testing of the wound antiseptics PVP-iodine, chlorhexidine digluconate, polihexanide and octenidine dihydrochloride.

BACKGROUND: Currently, there is no agreed standard for exploring the antimicrobial activity of wound antiseptics in a phase 2/ step 2 test protocol. In the present study, a standardised in-vitro test is proposed, which allows to test potential antiseptics in a more realistically simulation of conditions found in wounds as in a suspension test. Furthermore, factors potentially influencing test results such as type of materials used as test carrier or various compositions of organic soil challenge were investigated in detail. METHODS: This proposed phase 2/ step 2 test method was modified on basis of the EN 14561 by drying the microbial test suspension on a metal carrier for 1 h, overlaying the test wound antiseptic, washing-off, neutralization, and dispersion at serial dilutions at the end of the required exposure time yielded reproducible, consistent test results. RESULTS: The difference between the rapid onset of the antiseptic effect of PVP-I and the delayed onset especially of polihexanide was apparent. Among surface-active antimicrobial compounds, octenidine was more effective than chlorhexidine digluconate and polihexanide, with some differences depending on the test organisms. However, octenidine and PVP-I were approximately equivalent in efficiency and microbial spectrum, while polihexanide required longer exposure times or higher concentrations for a comparable antimicrobial efficacy. CONCLUSION: Overall, this method allowed testing and comparing differ liquid and gel based antimicrobial compounds in a standardised setting.

New strategies for preoperative skin antisepsis.

During the past decades, encouraging progress has been made in the prevention of surgical site infections (SSI). However, as SSI still occur today, strategic prevention measures such as standardized skin antisepsis must be implemented and rigorously promoted. Recent discoveries in skin physiology necessitate the development of novel antiseptic agents and procedures in order to ameliorate their efficacy. In particular, alternate target structures in the skin need to be taken into consideration for the development of the next generation of antiseptics. Recent investigations have shown that a high number of microorganisms are located within and in the close vicinity of the hair follicles. This suggests that these structures are an important reservoir of bacterial growth and activity in human skin. To date, it has not been fully elucidated to what extent conventional liquid antiseptics sufficiently target the hair follicle-related microbial population. Modern technologies such as tissue-tolerable plasma (TTP) have been tested for their potential antiseptic efficiency by reducing the bacterial load in the skin and in the hair follicles. First experiments using liposomes to deliver antiseptics into the hair follicles have been evaluated for their potential clinical application. The present review evaluates these two innovative methods for their efficacy and applicability in preoperative skin antiseptics.

Shortening the Application Time of Alcohol-Based Hand Rubs to 15 Seconds May Improve the Frequency of Hand Antisepsis Actions in a Neonatal Intensive Care Unit.

BACKGROUND For alcohol-based hand rubs, the currently recommended application time of 30 seconds is longer than the actual time spent in clinical practice. We investigated whether a shorter application time of 15 seconds is microbiologically safe in neonatal intensive care and may positively influence compliance with the frequency of hand antisepsis actions. METHODS We conducted in vitro experiments to determine the antimicrobial efficacy of hand rubs within 15 seconds, followed by clinical observations to assess the effect of a shortened hand antisepsis procedure under clinical conditions in a neonatal intensive care unit (NICU). An independent observer monitored the frequency of hand antisepsis actions during shifts. RESULTS All tested hand rubs fulfilled the requirement of equal or even significantly higher efficacy within 15 seconds when compared to a reference alcohol propan-2-ol 60% (v/v) within 30 seconds. Microbiologically, reducing the application time to 15 seconds had a similar effect when compared to 30-second hand rubbing, but it resulted in significantly increased frequency of hand antisepsis actions (7.9±4.3 per hour vs 5.8±2.9 per hour; P=.05). CONCLUSION Time pressure and workload are recognized barriers to compliance. Therefore, reducing the recommended time for hand antisepsis actions, using tested and well-evaluated hand rub formulations, may improve hand hygiene compliance in clinical practice. Infect Control Hosp Epidemiol 2017;38:1430-1434.

Consensus statement: patient safety, healthcare-associated infections and hospital environmental surfaces.

Healthcare-associated infections have serious implications for both patients and hospitals. Environmental surface contamination is the key to transmission of nosocomial pathogens. Routine manual cleaning and disinfection eliminates visible soil and reduces environmental bioburden and risk of transmission, but may not address some surface contamination. Automated area decontamination technologies achieve more consistent and pervasive disinfection than manual methods, but it is challenging to demonstrate their efficacy within a randomized trial of the multiple interventions required to reduce healthcare-associated infection rates. Until data from multicenter observational studies are available, automated area decontamination technologies should be an adjunct to manual cleaning and disinfection within a total, multi-layered system and risk-based approach designed to control environmental pathogens and promote patient safety.

Influence of preoperative skin sealing with cyanoacrylate on microbial contamination of surgical wounds following trauma surgery: a prospective, blinded, controlled observational study.

OBJECTIVE: Intraoperative bacterial contamination is a risk factor for surgical site infections (SSIs). This prospective, randomized, blinded, controlled trial (Reg. No. BB08/12) investigated the effect of a cyanoacrylate-based skin sealant (InteguSeal) on intraoperative wound contamination during trauma surgery. METHODS: A total of 128 patients undergoing trauma surgery were assigned randomly to an intervention (n=62) or a control group (n=66). Surgical sites were investigated at three locations: maximum incision depth (base), wound margin prior to wound closure (margin), and the surgical sutures (suture). Colony-forming units (CFU) were counted after 48h of incubation. RESULTS: Overall, significantly lower CFU counts were obtained for samples from the intervention group at all three sample sites compared to the control group. The difference, however, was only significant for the suture site (p=0.040). CONCLUSIONS: Preoperative sealing reduced microbial contamination on sutures during surgery, while the overall wound contamination remained unchanged. Hence, prevention of the clinically more relevant deep SSIs may not be expected. However, this study was not designed to detect differences in the rate of SSI. The role of the reduction in suture contamination with regard to the prevention of SSI remains to be evaluated.

Interaction of polyhexamethylene biguanide hydrochloride (PHMB) with phosphatidylcholine containing o/w emulsion and consequences for microbicidal efficacy and cytotoxicity.

Oil-in-water (o/w) emulsions containing egg yolk phosphatidylcholine (EPC) were combined with aqueous polyhexamethylene biguanide hydrochloride (PHMB). The PHMB concentration in the aqueous phase was estimated by filtration centrifugation experiments. In parallel, PHMB concentration was assessed utilizing cytotoxicity assays (neutral red) on cultured murine fibroblasts (L929 cells) and tests of bactericidal efficacy on either Pseudomonas aeruginosa or Staphylococcus aureus. Biological tests were performed in cell culture medium. Filtration centrifugation experiments demonstrated much higher aqueous PHMB concentrations than did the assays for biologically effective PHMB. Therefore, biological test systems should preferably be used to verify effective PHMB concentrations. Tests of microbicidal efficacy in which the same 0.05% PHMB o/w emulsion was re-used 8 times revealed a drug delivery system activated by the presence of test bacteria.

Evaluation of the PotoClean(®) decontamination technology for reprocessing of water supply lines in dental units during routine work.

BACKGROUND: A frequent problem in dental units is the microbial contamination of water and biofilm formation in the water supply lines. After random identification of a bacterial contaminated dental unit (310 cfu/ml) in a practise with 3 dental units we implemented the present study to evaluate the efficacy of the PotoClean(®) technology, based on anodic oxidation. METHOD: The efficacy of a regular low concentrated permanent decontamination (1 mg Cl/L) with an additional intensive decontamination by PotoClean(®) (three times 20 mg Cl/ml for 2 h) on three dental units was tested over 7 months. Microbial contamination, total chlorine concentration and redox potential have been analyzed. Dental unit A and B was 15 years old, unit C 5 years. RESULTS: After 3 intensive decontaminations, in dental unit A and B the number of bacteria and moulds could be reduced less than 7 d. Thereafter the bacteria counts increased again during the subsequent 7 month period and the amount of moulds was with some exceptions 300 cfu/ml, although PotoClean(®) was constantly added in the system (1 mg Cl/L). After further 7.5 month only with low concentrated permanent disinfection (1 mg Cl/L) both units were successful decontaminated. Dental unit C represented an object which was easier to decontaminate because of the advanced construction (prevention of water stagnation) and the shorter useful life. At the beginning of the decontamination it was no bacterial contamination, but moulds were contained (300 cfu/ml). Already after the first intensive decontamination, no further bacteria and moulds could be detected. DISCUSSION: An important factor for the efficacy of PotoClean(®) was the age of the units and their construction. For a new generation of dental units PotoClean(®) was effective during the whole period of monitoring. For two old types of dental unit with massive biofilm development the successful decontamination needed more than 7 month. CONCLUSION: The PotoClean(®) technology has resulted in even old-type turbines with intensive biofilm formation to complete decontamination. In a recent turbine design already after the first intensive decontamination with PotoClean(®) and its continuous use (1 mg Cl/L) no more contamination by bacteria and moulds were detectable.

Decontamination of room air and adjoining wall surfaces by nebulizing hydrogen peroxide.

AIM: In 2010, the ASP GLOSAIR(TM) 400 was introduced in Germany for nebulizing hydrogen peroxide (H(2)O(2)). Since there were no results of practical experience, the new method was to be checked under practical conditions for its effectiveness in decontaminating air in rooms, infested with mold after water damage and, at the same time, under experimentally controlled conditions, test surfaces, contaminated with Aspergillus brasiliensis. METHOD: After the nebulizer was used in two rooms with a massive mold infestation, the air colony count was determined (MAS-100(®) Zinsser Analytik) and, at the same time, the mold infestation in samples of wall plaster.As part of this controlled study, test surfaces contaminated with Aspergillus brasiliensis were positioned vertically and horizontally in a test room. The effectiveness of the nebulization (5-6% H(2)O(2) for 2 hours) was tested on these surfaces according to EN 13697. RESULTS: In a massive mold infestation resulting from water damage (worst case), an approximately 9-fold decrease in the mold content and an approximately 13-fold decrease in the number of colony-forming units (sum of the bacteria + fungi) could be detected in the room air immediately after the nebulizing was finished. Even in samples of wall and joint plaster, the molds were reduced, although to a distinctly lesser extent. By indoor nebulization of 5-6% H(2)O(2), A. brasiliensis was reduced >4 log on vertical and horizontal surfaces. DISCUSSION: In rooms with a massive mold infestation, the ASP GLOSAIR(TM) 400 system is suitable for attaining a clear reduction in the fungal and bacterial room air load, lasting for a week. On vertical and horizontal surfaces, contaminated experimentally with A. brasiliensis, a reduction of >4 lg is achieved. As a load of 10(4) to 10(5) fungal spores is unlikely to occur on pre-cleaned surfaces, the GLOSAIR(TM) 400 can be considered a suitable complementary process for the substantial reduction of fungal contamination.

Reduced cytotoxicity of polyhexamethylene biguanide hydrochloride (PHMB) by egg phosphatidylcholine while maintaining antimicrobial efficacy.

Liposomes or oil-in-water emulsions containing egg yolk phosphatidylcholine (EPC) were combined with aqueous polyhexamethylene biguanide hydrochloride (PHMB). The bactericidal activity of these preparations against Pseudomonas aeruginosa and Staphylococcus aureus as well as their cytotoxicity on cultured murine fibroblasts (L929 cells) was then assayed for either 30 min or 60 min in the presence of cell culture medium containing 10% fetal bovine serum as surrogate for wound fluid. We used two assay designs: in the first bactericidal activity and cytotoxicity were determined in separate experiments; in the second both were determined in one experiment. Combining PHMB and EPC containing o/w emulsions or liposomes protects mammalian cells without neutralizing the antiseptic effect. From all tested combinations the o/w emulsions containing 0.05% PHMB proved to be superior in this respect to the aqueous preparation.

Minimum inhibitory (MIC) and minimum microbicidal concentration (MMC) of polihexanide and triclosan against antibiotic sensitive and resistant Staphylococcus aureus and Escherichia coli strains.

BACKGROUND: An in-vitro study was conducted investigating the antimicrobial efficacy of polihexanide and triclosan against clinical isolates and reference laboratory strains of Staphylococcus aureus and Escherichia coli. METHODS: The minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC) were determined following DIN 58940-81 using a micro-dilution assay and a quantitative suspension test following EN 1040. Polihexanide was tested in polyethylene glycol 4000, triclosan in aqueous solutions. RESULTS: Against all tested strains the MIC of polihexanide ranged between 1-2 µg/mL. For triclosan the MICs varied depending on strains ranging between 0.5 µg/mL for the reference strains and 64 µg/mL for two clinical isolates. A logRF >5 without and logRF >3 with 0.2% albumin burden was achieved at 0.6 µg/mL triclosan. One exception was S. aureus strain H-5-24, where a triclosan concentration of 0.6 µg/mL required 1 minute without and 10 minutes with albumin burden to achieve the same logRFs. Polihexanide achieved a logRF >5 without and logRF >3 with albumin burden at a concentration of 0.6 µg/mL within 30 sec. The exception was the North-German epidemic MRSA strain, were an application time of 5 minutes was required. CONCLUSION: The clinical isolates of E. coli generally showed higher MICs against triclosan, both in the micro-dilution assay as well in the quantitative suspension test than comparable reference laboratory strains. For polihexanide and triclosan strain dependant susceptibility was shown. However, both antimicrobial compounds are effective when used in concentrations common in practice.

Results of a field study on the influence of HygienicWood mattress toppers on the number of mites in bed dust and the state of health of people with house dust mite allergies.

OBJECTIVES: So far, there has been no practical or toxicologically non-hazardous way to decimate mites - without interrupting use of beds - in their main reservoir on bed mattresses to such an extent that the allergic condtion of people suffering from house dust mite allergies is reduced or even remedied. As so-called HygienicWood was effective against mites under simulated conditions, the influence of a mattress topper filled with HygienicWood chips on the content of mite antigen Der p1 was to be investigated and the influence on the state of health of the persons concerned analysed at the same time. PROCEDURE: 32 test persons suffering from dust mite allergy were randomly selected. During the course of 5 months, the influence of a HygienicWood mattress topper on the content of the mite antigen Der p1 as well as the number of bacteria, dermatophytes and yeasts in the bed dust were determined and compared with the values obtained during the 5 weeks prior to the application of HygienicWood mattress toppers. The samples were taken from between the HygienicWood mattress topper and the sheet below. At the same time, changes in well-being, state of health, typical allergy symptoms and frequency of taking antihistamines and glucocorticoids were recorded as self-assessments in the form of questionnaires. FINDINGS: The most striking finding was the significant decrease (p=0.000) of the house dust mite antigen Der p1 during usage of the HygienicWood mattress toppers. The effect started immediately after applying the toppers and continued with little fluctuation until the end of the observation period without lessening. At the end of the study, 43% of the test persons stated a slight improvement in their well-being. 13% of the test persons felt no change, and 6% of the test persons stated a slight deterioration. The situation was similar with regard to allergy symptoms: 43% reported a significant reduction, 38% a slight reduction, and 19% did not notice any change. The improvement in symptomatology could not be ascribed to an increased intake of antihistamines or glucocorticoids.The dermatophytes, too, showed a slight, albeit statistically not significant decrease after application of HygienicWood mattress toppers. In contrast, the pollution of bed dust with yeasts rose significantly (p=0.002), whereas there was only a tendency towards an increase in the number of bacteria, which, if one considers the slight increase, is without hygienic relevance. CONCLUSION: HygienicWood mattress toppers are able to reduce the house dust mite allergen load. This leads to a distinct reduction in the allergy symptomatology, and the well-being of the persons concerned increased significantly.

Genome-wide mRNA profiling in glucose starved Bacillus subtilis cells.

In this study global changes in gene expression were monitored in Bacillus subtilis cells entering stationary growth phase owing to starvation for glucose. Gene expression was analysed in growing and starving cells at different time points by full-genome mRNA profiling using DNA macroarrays. During the transition to stationary phase we observed extensive reprogramming of gene expression, with approximately 1,000 genes being strongly repressed and approximately 900 strongly up-regulated in a time-dependent manner. The genes involved in the response to glucose starvation can be assigned to two main classes: (i) general stress/starvation genes which respond to various stress or starvation stimuli, and (ii) genes that respond specifically to starvation for glucose. The first class includes members of the sigma(B)-dependent general stress regulon, as well as 90 vegetative genes, which are strongly down regulated in the course of the stringent response. Among the genes in the second class, we observed a decrease in the expression of genes encoding proteins required for glucose uptake, glycolysis and the tricarboxylic acid cycle. Conversely, many carbohydrate utilisation systems that depend on phosphotransferase systems (PTS) or ABC transporters were activated. The expression of genes required for utilisation or generation of acetate indicates that acetate constitutes an important energy source for B. subtilis during periods of glucose starvation. Finally, genome wide mRNA profiling data can be used to predict new metabolic pathways in B. subtilis. Thus, our data suggest that glucose-starved cells are able to degrade branched-chain fatty acids to pyruvate and succinate via propionyl-CoA using the methylcitrate pathway. This pathway appears to link lipid degradation to gluconeogenesis in glucose-starved cells.