Discover the most talked about and latest scientific content & concepts.

Concept: Disinfectant


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


Disulfides from Allium stipitatum, commonly known as Persian shallot, were previously reported to possess antibacterial properties. Analogues of these compounds, produced by S-methylthiolation of appropriate thiols using S-methyl methanethiosulfonate, exhibited antimicrobial activity, with one compound inhibiting the growth of Mycobacterium tuberculosis at 17 µM (4 mg L-1) and other compounds inhibiting Escherichia coli and multi-drug-resistant (MDR) Staphylococcus aureus at concentrations ranging between 32-138 µM (8-32 mg L-1). These compounds also displayed moderate inhibitory effects on Klebsiella and Proteus species. Whole-cell phenotypic bioassays such as the spot-culture growth inhibition assay (SPOTi), drug efflux inhibition, biofilm inhibition and cytotoxicity assays were used to evaluate these compounds. Of particular note was their ability to inhibit mycobacterial drug efflux and biofilm formation, while maintaining a high selectivity towards M. tuberculosis H37Rv. These results suggest that methyl disulfides are novel scaffolds which could lead to the development of new drugs against tuberculosis (TB).

Concepts: Microbiology, Antibiotic resistance, Tuberculosis, Mycobacterium, Mycobacterium tuberculosis, Enterobacteriaceae, Inhibitor, Disinfectant


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


Chlorhexidine gluconate (CHX) and benzalkonium chloride (BZK) formulations are frequently used as antiseptics in healthcare and consumer products. Burkholderia cepacia complex (BCC) contamination of pharmaceutical products could be due to the use of contaminated water in the manufacturing process, over-diluted antiseptic solutions in the product, and the use of outdated products, which in turn, reduces the antimicrobial activity of CHX and BZK. To establish a “safe use” period following opening containers of CHX and BZK, we measured the antimicrobial effects of CHX (2 ~ 10 µg/ml) and BZK (10 ~ 50 µg/ml) at sub-lethal concentrations on six strains of Burkholderia cenocepacia using chemical and microbiological assays. CHX (2, 4 and 10 µg/ml) and BZK (10, 20 and 50 µg/ml) stored for 42 days at 23°C showed almost the same concentration and toxicity compared to freshly prepared CHX and BZK on B. cenocepacia strains. When 5 µg/ml CHX and 20 µg/ml BZK were spiked with six B. cenocepacia strains with different inoculum sizes (10⁰ ~ 10⁵CFU/mL), their toxic effects were not changed for 28 days. B. cenocepacia strains in diluted CHX and BZK were detectable at concentration up to 10² CFU/mL after incubation for 28 days at 23°C. Although abiotic and biotic changes in the toxicity of both antiseptics were not observed, our results indicate that B. cenocepacia strains could remain viable in CHX and BZK for 28 days, which in turn, indicates the importance of control measures to monitor BCC contamination in pharmaceutical products.

Concepts: Microbiology, Antiseptic, Toxicity, Disinfectant, Burkholderia, Burkholderiales, Mouthwash, Antiseptics


ClO2, the so-called “ideal biocide”, could also be applied as an antiseptic if it was understood why the solution killing microbes rapidly does not cause any harm to humans or to animals. Our aim was to find the source of that selectivity by studying its reaction-diffusion mechanism both theoretically and experimentally.

Concepts: Microbiology, Oxide, Chlorine, Disinfectant, Antimicrobial, Tea tree oil, Biocide, Chlorine dioxide


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


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


The ability to disinfect and reuse disposable N95 filtering facepiece respirators (FFRs) may be needed during a pandemic of an infectious respiratory disease such as influenza. Ultraviolet germicidal irradiation (UVGI) is one possible method for respirator disinfection. However, UV radiation degrades polymers, which presents the possibility that UVGI exposure could degrade the ability of a disposable respirator to protect the worker. To study this, we exposed both sides of material coupons and respirator straps from four models of N95 FFRs to UVGI doses from 120 to 950 J/cm(2). We then tested the particle penetration, flow resistance and the bursting strengths of the individual respirator coupon layers, and the breaking strength of the respirator straps. We found that UVGI exposure led to a small increase in particle penetration (up to 1.25%) and had little effect on the flow resistance. UVGI exposure had a more pronounced effect on the strengths of the respirator materials. At the higher UVGI doses, the strength of the layers of respirator material was substantially reduced (in some cases, by >90%). The changes in the strengths of the respirator materials varied considerably among the different models of respirators. UVGI had less of an effect on the respirator straps; a dose of 2360 J/cm(2) reduced the breaking strength of the straps by 20% to 51%. Our results suggest that UVGI could be used to effectively disinfect disposable respirators for reuse, but the maximum number of disinfection cycles will be limited by the respirator model and the UVGI dose required to inactivate the pathogen.

Concepts: Ultraviolet, Hydrogen peroxide, Materials science, Disinfectant, Hygiene, Sunburn, Respirator, Ultraviolet germicidal irradiation


Transmission is driving the global TB epidemic, especially in congregate settings. Worldwide, natural ventilation is the most common means of air disinfection, but it is inherently unreliable, and of limited use in cold climates. Upper room germicidal UV air disinfection with air mixing has been shown to be highly effective, but improved evidence-based dosing guidelines are needed.

Concepts: Epidemiology, The Canon of Medicine, Sun, Avicenna, Tuberculosis, Disinfectant, HVAC, Ultraviolet germicidal irradiation


To evaluate the antimicrobial effect of a diode laser irradiation, photo-activated disinfection (PAD), conventional and sonic activated irrigation with 2.5% sodium hypochlorite (NaOCl) on Enterococcus faecalis.

Concepts: Hydrogen peroxide, Laser diode, Chlorine, Disinfectant, Hypochlorous acid, Sodium hypochlorite, Enterococcus faecalis, Bleach