SciCombinator

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Concept: Disinfectants

303

Experts agree that careful cleaning and disinfection of environmental surfaces are essential elements of effective infection prevention programs. However, traditional manual cleaning and disinfection practices in hospitals are often suboptimal. This is often due in part to a variety of personnel issues that many Environmental Services departments encounter. Failure to follow manufacturer’s recommendations for disinfectant use and lack of antimicrobial activity of some disinfectants against healthcare-associated pathogens may also affect the efficacy of disinfection practices. Improved hydrogen peroxide-based liquid surface disinfectants and a combination product containing peracetic acid and hydrogen peroxide are effective alternatives to disinfectants currently in widespread use, and electrolyzed water (hypochlorous acid) and cold atmospheric pressure plasma show potential for use in hospitals. Creating “self-disinfecting” surfaces by coating medical equipment with metals such as copper or silver, or applying liquid compounds that have persistent antimicrobial activity surfaces are additional strategies that require further investigation. Newer “no-touch” (automated) decontamination technologies include aerosol and vaporized hydrogen peroxide, mobile devices that emit continuous ultraviolet (UV-C) light, a pulsed-xenon UV light system, and use of high-intensity narrow-spectrum (405 nm) light. These “no-touch” technologies have been shown to reduce bacterial contamination of surfaces. A micro-condensation hydrogen peroxide system has been associated in multiple studies with reductions in healthcare-associated colonization or infection, while there is more limited evidence of infection reduction by the pulsed-xenon system. A recently completed prospective, randomized controlled trial of continuous UV-C light should help determine the extent to which this technology can reduce healthcare-associated colonization and infections. In conclusion, continued efforts to improve traditional manual disinfection of surfaces are needed. In addition, Environmental Services departments should consider the use of newer disinfectants and no-touch decontamination technologies to improve disinfection of surfaces in healthcare.

Concepts: Oxygen, Ultraviolet, Hydrogen peroxide, Antiseptic, Chlorine, Disinfectant, Sodium hypochlorite, Disinfectants

150

There is still an important interest in controlling bacterial endospores. The use of chemical disinfectants and notably oxidising agents to sterilize medical devices is increasing. With this in mind hydrogen peroxide (H2O2) and peracetic acid (PAA) have been used in combination but until now there has been no explanation for the observed increased in sporicidal activity. This study provides information on the mechanism of synergistic interaction of PAA and H2O2 against bacterial spores. The investigations of the efficacy of different combinations, including pre-treatments with the two oxidisers were performed against wild-type and a range of spore mutants deficient in their spore coat or small acid-soluble spore proteins. The concentrations of the two biocides were also measured in the reaction vessels enabling the assessment of any shift from H2O2 to PAA formation. This study confirmed the synergistic activity of H2O2 and PAA combination. However, we observed that the sporicidal activity of the combination is largely due to PAA and not H2O2. Furthermore, we observed that the synergistic combination was based on H2O2 compromising the spore coat, which was the main spore resistance factor, likely allowing better penetration of PAA, resulting in the increased sporicidal activity.

Concepts: Oxygen, Hydrogen peroxide, Chlorine, Disinfectant, Peroxide, Disinfectants, Peracetic acid, Peroxy acid

95

Hand sanitizers are effective and inexpensive products that can reduce microorganisms on the skin, but ingestion or improper use can be associated with health risks. Many hand sanitizers contain up to 60%-95% ethanol or isopropyl alcohol by volume, and are often combined with scents that might be appealing to young children. Recent reports have identified serious consequences, including apnea, acidosis, and coma in young children who swallowed alcohol-based (alcohol) hand sanitizer (1-3). Poison control centers collect data on intentional and unintentional exposures to hand sanitizer solutions resulting from various routes of exposure, including ingestion, inhalation, and dermal and ocular exposures. To characterize exposures of children aged ≤12 years to alcohol hand sanitizers, CDC analyzed data reported to the National Poison Data System (NPDS).* The major route of exposure to both alcohol and nonalcohol-based (nonalcohol) hand sanitizers was ingestion. The majority of intentional exposures to alcohol hand sanitizers occurred in children aged 6-12 years. Alcohol hand sanitizer exposures were associated with worse outcomes than were nonalcohol hand sanitizer exposures. Caregivers and health care providers should be aware of the potential dangers associated with hand sanitizer ingestion. Children using alcohol hand sanitizers should be supervised and these products should be kept out of reach from children when not in use.

Concepts: Health care, Ethanol, Skin, Poison, Poison control center, Isopropyl alcohol, Hand sanitizer, Disinfectants

56

Bisphenol A (BPA) is an endocrine disrupting environmental contaminant used in a wide variety of products, and BPA metabolites are found in almost everyone’s urine, suggesting widespread exposure from multiple sources. Regulatory agencies estimate that virtually all BPA exposure is from food and beverage packaging. However, free BPA is applied to the outer layer of thermal receipt paper present in very high (∼20 mg BPA/g paper) quantities as a print developer. Not taken into account when considering thermal paper as a source of BPA exposure is that some commonly used hand sanitizers, as well as other skin care products, contain mixtures of dermal penetration enhancing chemicals that can increase by up to 100 fold the dermal absorption of lipophilic compounds such as BPA. We found that when men and women held thermal receipt paper immediately after using a hand sanitizer with penetration enhancing chemicals, significant free BPA was transferred to their hands and then to French fries that were eaten, and the combination of dermal and oral BPA absorption led to a rapid and dramatic average maximum increase (Cmax) in unconjugated (bioactive) BPA of ∼7 ng/mL in serum and ∼20 µg total BPA/g creatinine in urine within 90 min. The default method used by regulatory agencies to test for hazards posed by chemicals is intra-gastric gavage. For BPA this approach results in less than 1% of the administered dose being bioavailable in blood. It also ignores dermal absorption as well as sublingual absorption in the mouth that both bypass first-pass liver metabolism. The elevated levels of BPA that we observed due to holding thermal paper after using a product containing dermal penetration enhancing chemicals have been related to an increased risk for a wide range of developmental abnormalities as well as diseases in adults.

Concepts: Metabolism, Liver, Bisphenol A, Skin, Disinfectant, Endocrine disruptor, Hand sanitizer, Disinfectants

30

The use of alcohol-based hand sanitizers has recently become widespread. To the authors' knowledge, no previous study has examined whether application of ethanol-based hand sanitizers by the person operating a common breathalyzer machine will affect the accuracy of the readings. This was a prospective study investigating whether the use of hand sanitizer applied according to manufacturer’s recommendations (Group I), applied improperly at standard doses (Group II), or applied improperly at high doses (Group III) had an effect on breathalyzer readings of individuals who had not ingested alcohol.

Concepts: Alcohol, Ethanol, Antiseptic, Disinfectant, Intoxication, Breathalyzer, Hand sanitizer, Disinfectants

27

The study of the dose-response relationship of disinfectants is of great importance in treating infection, the objective being to use concentrations above the minimal bactericidal concentration (MBC). Below these concentrations, the bacteriostatic or bactericidal effect may be insufficient. Moreover, at low concentrations, a hormetic effect may be observed, producing a stimulation of growth instead of inhibitory action. Hormesis is not well known in the context of antimicrobial substances. This study investigates the possible existence of a hormetic effect in three commonly used antiseptics-chlorhexidine digluconate, povidone iodine and benzalkonium chloride-on strains of reference of Staphylococcus aureus and Pseudomonas aeruginosa. Growth curves were determined for different concentrations of the disinfectants. The variables studied-concentration of disinfectant, instantaneous growth rate and number of generations-were analysed using linear, quadratic and cubic models to adjust for the variables. The three disinfectants tested show a significant hormetic effect with P. aeruginosa and a less significant effect with S. aureus. These findings point to a dose-response effect that is not linear at low concentrations, while hormetic effects observed at some low concentrations result in greater bacterial growth. In infected wounds, materials or surfaces where microorganisms may occupy zones of difficult access for a disinfectant, the hormetic effect may have important consequences.

Concepts: Bacteria, Staphylococcus aureus, Infection, Antibiotic resistance, Pseudomonas aeruginosa, Chlorine, Disinfectants, Benzalkonium chloride

25

A variety of disinfectants have been widely used in veterinary hygiene, food industries and environments, which could induce the development of bacterial resistance to disinfectants. The methods used to investigate antimicrobial effects of disinfectant vary considerably among studies, making comparisons difficult. In this study, agar dilution and broth microdilution methods were used to compare the antimicrobial activities of four quaternary ammonium compounds (QACs) against foodborne and zoonotic pathogens. The potential relationship between the presence of QACs resistance genes and phenotypic resistance to QACs was also investigated. Our results indicated that the minimum inhibitory concentrations (MICs) determined by two methods might be different depended upon different QACs and bacteria applied. Regardless of the testing methods, Klebsiella pneumoniae was more tolerant among Gram-negative strains to four QACs, followed by Salmonella and Escherichia coli. The agreement between MICs obtained by the two methods was good, for benzalkonium chloride (78.15%), didecyldimethylammonium chloride (DDAC) (82.35%), cetylpyridinium chloride (CTPC) (97.48%) and cetyltrimethylammonium bromide (CTAB) (99.16%), respectively. Among all Gram-negative bacteria, 94.55% (n=52) of qacEΔ1-positive strains showed higher MICs (512 mg l(-1)) to CTAB. The qacEΔ1 gene was highly associated (P<0.05) with the high MICs of QACs (⩾512 mg l(-1)). In addition, DDAC remained as the most effective disinfectant against both Gram-positive and Gram-negative bacteria. This is the first study that compared the agar dilution and broth microdilution methods to assess the antimicrobial activity of QACs. The study demonstrated the need to standardize method that would be used in evaluating QACs antimicrobial properties in the future.The Journal of Antibiotics advance online publication, 6 May 2015; doi:10.1038/ja.2015.51.

Concepts: Bacteria, Microbiology, Antibiotic resistance, Escherichia coli, Enterobacteriaceae, Antiseptic, Disinfectants, Quaternary ammonium compounds

25

We investigated the contamination levels of dental goggles to assess the infection risk in a stomatology hospital and compared the effectiveness of 3 disinfectants, including Swashes (Swashes Enterprise, Co. Ltd., Shenzhen, China), medical ethanol (75%), and chlorine-containing disinfectant (500 mg/L). The results showed that 87.41% of goggles had bacterial contamination. In total, 54% of cultures included gram-positive cocci, making them the major microbial group contaminating the goggles. All 3 disinfectants showed excellent performance in disinfection, and there were no significant differences among the eligibility rates of the 3 disinfectants (97.2% vs 100.0% vs 100.0%, respectively). The study highlights the fact that dental goggles are potential reservoirs of nosocomial pathogens. Disinfection of goggles could be an effective and practical infection control method for dental practice.

Concepts: Bacteria, Microbiology, Mycobacterium tuberculosis, Antiseptic, Disinfectant, Dentistry, Disinfectants

12

In March 2014, a new disinfection product, consisting of hydrogen peroxide, peroxyacetic acid, and acetic acid, was introduced at a Pennsylvania hospital to aid in the control of health care-associated infections. The product is an Environmental Protection Agency-registered non-bleach sporicide advertised as a one-step cleaner, disinfectant, and deodorizer. According to the manufacturer’s safety data sheet, the product requires no personal protective equipment when it is diluted with water by an automated dispenser before use. On January 30, 2015, CDC’s National Institute for Occupational Health (NIOSH) received a confidential employee request to conduct a health hazard evaluation at the hospital. The request cited concerns about exposure of hospital environmental services staff members to the product and reported symptoms among persons who had used the product that included eye and nasal problems, asthma-like symptoms, shortness of breath, skin problems, wheeze, chest tightness, and cough.

Concepts: Oxygen, Hydrogen peroxide, Personal protective equipment, Protection, Chlorine, Occupational safety and health, Disinfectants, Health Hazard Evaluation Program

11

The recently emerged chytrid fungus Batrachochytrium salamandrivorans (Bsal) causes European salamander declines. Proper hygiene protocols including disinfection procedures are crucial to prevent disease transmission. Here, the efficacy of chemical disinfectants in killing Bsal was evaluated. At all tested conditions, Biocidal®, Chloramine-T®, Dettol medical®, Disolol®, ethanol, F10®, Hibiscrub®, potassium permanganate, Safe4®, sodium hypochlorite, and Virkon S®, were effective at killing Bsal. Concentrations of 5% sodium chloride or lower, 0.01% peracetic acid and 0.001-1% copper sulphate were inactive against Bsal. None of the conditions tested for hydrogen peroxide affected Bsal viability, while it did kill Batrachochytrium dendrobatidis (Bd). For Bsal, enzymatic breakdown of hydrogen peroxide by catalases and specific morphological features (clustering of sporangia, development of new sporangia within the original sporangium), were identified as fungal factors altering susceptibility to several of the disinfectants tested. Based on the in vitro results we recommend 1% Virkon S®, 4% sodium hypochlorite and 70% ethanol for disinfecting equipment in the field, lab or captive setting, with a minimal contact time of 5 minutes for 1% Virkon S® and 1 minute for the latter disinfectants. These conditions not only efficiently target Bsal, but also Bd and Ranavirus.

Concepts: Fungus, Hydrogen peroxide, Antiseptic, Chlorine, Disinfectant, Disinfectants, Chytridiomycota, Batrachochytrium dendrobatidis