A comparison of the antibacterial efficacy and cytotoxicity to cultured human skin cells of 7 commercial hand rubs and Xgel, a new copper-based biocidal hand rub

Rhamnolipid Nano-Micelles versus Alcohol-Based Hand Sanitizer: A Comparative Study for Antibacterial Activity against Hospital-Acquired Infections and Toxicity Concerns

Hospital-acquired infections (HAIs) are considered to be a major global healthcare challenge, in large part because of the development of microbial resistance to currently approved antimicrobial drugs. HAIs are frequently preventable through infection prevention and control measures, with hand hygiene as a key activity. Improving hand hygiene was reported to reduce the transmission of healthcare-associated pathogens and HAIs. Alcohol-based hand sanitizers are commonly used due to their rapid action and broad spectrum of microbicidal activity, offering protection against bacteria and viruses. However, their frequent administration has been reported to be associated with many side effects, such as skin sensitivity, skin drying, and cracks, which promote further skin infections. Thus, there is an essential need to find alternative approaches to hand sanitation. Rhamnolipids are glycolipids produced by Pseudomonas aeruginosa, and were shown to have broad antimicrobial activity as biosurfactants. We have previously demonstrated the antimicrobial activity of rhamnolipid nano-micelles against selected drug-resistant Gram-negative (Salmonella Montevideo and Salmonella Typhimurium) and Gram-positive bacteria (Staphylococcus aureus, Streptococcus pneumoniae). To the best of our knowledge, the antimicrobial activity of rhamnolipid nano-micelles in comparison to alcohol-based hand sanitizers against microorganisms commonly causing HAIs in Egypt—such as Acinetobacter baumannii and Staphylococcus aureus—has not yet been studied. In the present work, a comparative study of the antibacterial activity of rhamnolipid nano-micelles versus alcohol-based hand sanitizers was performed, and their safety profiles were also assessed. It was demonstrated that rhamnolipid nano-micelles had a comparable antibacterial activity to alcohol-based hand sanitizer, with a better safety profile, i.e., rhamnolipid nano-micelles are unlikely to cause any harmful effects on the skin. Thus, rhamnolipid nano-micelles could be recommended to replace alcohol-based hand sanitizers; however, they must still be tested by healthcare workers in healthcare settings to ascertain their antimicrobial activity and safety.

GermiX: A skin friendly hand sanitizer with prolonged effectivity against pathogenic bacteria

COVID-19 pandemic has almost made hand sanitization a ritual resulting in a steep increase in the frequency of hand sanitization and an unprecedented surge in demand for hand sanitizers. In fact, several governments had to ration hand sanitizers in the retail outlets and over the counter chemist shops. Additionally, Indian government has put a cap on the prices of hand sanitizers. Currently, large sections of global and Indian population are grappling under financial crises. Therefore, mandatory hand sanitization has made an unwelcoming, yet unavoidable addition to the already-hard-to-maintain-grocery-list. Here, we have compared the anti-microbial efficacy of Patanjali Hand Sanitizer (PHS), developed and marketed by Patanjali Ayurved Ltd. (an India-based food and herbal medicine company) with one of the topmost hand sanitizers currently used under clinical set-ups. PHS has anti-microbial efficacy comparable to that of the standard hand sanitizer. Besides, disc diffusion and time-dependent thumb print assays showed that PHS has longer retentivity on the applied surfaces, suggesting lesser consumption of the sanitizer and concomitant relaxation on the monthly grocery budget. Observed anti-bacterial potency of PHS is attributed to the disruption of bacterial cell membrane, as employed by alcohol-based hand sanitizers. A rough estimation revealed that PHS is ~ 4.3 times cost effective than the standard hand sanitizer used as the positive control in this study. Taken together, PHS is a suitable alternative for existing hand sanitizers available in the market that can relax the demand–supply strain and soften significantly the burden of monthly expenditure on hand sanitizers.

The Use of Copper as an Antimicrobial Agent in Health Care, Including Obstetrics and Gynecology

Health care-associated infections (HAIs) are a global problem associated with significant morbidity and mortality. Controlling the spread of antimicrobial-resistant bacteria is a major public health challenge, and antimicrobial resistance has become one of the most important global problems in current times. The antimicrobial effect of copper has been known for centuries, and ongoing research is being conducted on the use of copper-coated hard and soft surfaces for reduction of microbial contamination and, subsequently, reduction of HAIs. This review provides an overview of the historical and current evidence of the antimicrobial and wound-healing properties of copper and explores its possible utility in obstetrics and gynecology.

Antibacterial Metallic Touch Surfaces

Our aim is to present a comprehensive review of the development of modern antibacterial metallic materials as touch surfaces in healthcare settings. Initially we compare Japanese, European and US standards for the assessment of antimicrobial activity. The variations in methodologies defined in these standards are highlighted. Our review will also cover the most relevant factors that define the antimicrobial performance of metals, namely, the effect of humidity, material geometry, chemistry, physical properties and oxidation of the material. The state of the art in contact-killing materials will be described. Finally, the effect of cleaning products, including disinfectants, on the antimicrobial performance, either by direct contact or by altering the touch surface chemistry on which the microbes attach, will be discussed. We offer our outlook, identifying research areas that require further development and an overview of potential future directions of this exciting field.

Essential oils and metal ions as alternative antimicrobial agents: a focus on tea tree oil and silver

The increasing occurrence of hospital-acquired infections and the emerging problems posed by antibiotic-resistant microbial strains have both contributed to the escalating cost of treatment. The presence of infection at the wound site can potentially stall the healing process at the inflammatory stage, leading to the development of a chronic wound. Traditional wound treatment regimes can no longer cope with the complications posed by antibiotic-resistant strains; hence, there is a need to explore the use of alternative antimicrobial agents. Pre-antibiotic compounds, including heavy metal ions and essential oils, have been re-investigated for their potential use as effective antimicrobial agents. Essential oils have potent antimicrobial, antifungal, antiviral, anti-inflammatory, antioxidant and other beneficial therapeutic properties. Similarly, heavy metal ions have also been used as disinfecting agents because of their broad spectrum activities. Both of these alternative antimicrobials interact with many different intracellular components, thereby resulting in the disruption of vital cell functions and eventually cell death. This review will discuss the application of essential oils and heavy metal ions, particularly tea tree oil and silver ions, as alternative antimicrobial agents for the treatment of chronic, infected wounds.

Ex vivo porcine vaginal mucosal model of infection for determining effectiveness and toxicity of antiseptics

AIMS

To develop a semi-high-throughput ex vivo mucosal model for determining efficacy and toxicity of antiseptics.

METHODS AND RESULTS

Explants (5 mm) from freshly excised, porcine vaginal mucosa were infected with methicillin-sensitive Staphylococcus aureus (1 × 10(6)  CFU) at the epithelial surface for 2 h. Haematoxylin and eosin staining revealed healthy uninfected tissue and only minor disruptions in tissue infected with methicillin susceptible Staph. aureus (MSSA), which remained in outer epithelial cell layers. After 2 h infection, 10 μl of chlorhexidine digluconate (CHG, 3%), povidone-iodine (PI, 7·5%), octenidine dihydrochloride (OCT, 0·1%) or polyhexamethylene biguanide (PHMB, 0·1%) was applied. Antiseptics significantly reduced MSSA (1-4 log10  CFU/explants) after 0·25 h to 4 h. CHG, PHMB and OCT exhibited persistence at 24 h. In broth culture, CHG 0·012% and PI 0·625% achieved >6 log10 reductions at 2 h. PI-based formulations were more efficacious than unformulated PI. PI-based formulations exhibited no significant cytotoxicity on explants using an MTT assay.

CONCLUSIONS

All antiseptics tested in the mucosal MSSA infection model reduced MSSA. CHG and PI were more potent in broth culture.

SIGNIFICANCE AND IMPACT OF THE STUDY

We developed a semi-high-throughput mucosal model that can identify compounds or formulations with promising antimicrobial and limited cytotoxic properties.

The Effects of Two Novel Copper-Based Formulations on Helicobacter pylori

We investigated the effects of two novel copper-based inorganic formulations for their activity against 60 isolates of Helicobacter pylori (Hp). The two copper-based formulations were tested against three NCTC Helicobacter pylori isolates and 57 clinical strains isolated from the UK and Italy in time-kill assays. Both copper-based formulations were bio-cidal against all Helicobacter pylori strains tested reducing the viable count by 4-5 log within 2 h. These two copper-based anti-microbial agents deserve further study in relation to the treatment of H. pylori-related gastric disease.

Fighting nosocomial infections with biocidal non-intrusive hard and soft surfaces

Approximately 7 million people worldwide acquire a healthcare associated infection each year. Despite aggressive monitoring, hand washing campaigns and other infection control measures, nosocomial infections (NI) rates, especially those caused by antibiotic resistant pathogens, are unacceptably high worldwide. Additional ways to fight these infections need to be developed. A potential overlooked and neglected source of nosocomial pathogens are those found in non-intrusive soft and hard surfaces located in clinical settings. Soft surfaces, such as patient pyjamas and beddings, can be an excellent substrate for bacterial and fungal growth under appropriate temperature and humidity conditions as those present between patients and the bed. Bed making in hospitals releases large quantities of microorganisms into the air, which contaminate the immediate and non-immediate surroundings. Microbes can survive on hard surfaces, such as metal trays, bed rails and door knobs, for very prolonged periods of time. Thus soft and hard surfaces that are in direct or indirect contact with the patients can serve as a source of nosocomial pathogens. Recently it has been demonstrated that copper surfaces and copper oxide containing textiles have potent intrinsic biocidal properties. This manuscript reviews the recent laboratory and clinical studies, which demonstrate that biocidal surfaces made of copper or containing copper can reduce the microbiological burden and the NI rates.

Metal ion acquisition in Staphylococcus aureus: overcoming nutritional immunity

Transition metals are essential nutrients to virtually all forms of life, including bacterial pathogens. In Staphylococcus aureus, metal ions participate in diverse biochemical processes such as metabolism, DNA synthesis, regulation of virulence factors, and defense against oxidative stress. As an innate immune response to bacterial infection, vertebrate hosts sequester transition metals in a process that has been termed "nutritional immunity." To successfully infect vertebrates, S. aureus must overcome host sequestration of these critical nutrients. The objective of this review is to outline the current knowledge of staphylococcal metal ion acquisition systems, as well as to define the host mechanisms of nutritional immunity during staphylococcal infection.

A UK district general hospital cleaning study: a comparison of the performance of ultramicrofibre technology with or without addition of a novel copper-based biocide with standard hypochlorite-based cleaning

We compared the performance of an ultramicrofibre (UMF)-based system with or without a novel copper-based biocide (CuWB50) with standard cleaning using Actichlor Plus in four hospital wards in a crossover study design, and analysed our results using univariate and multivariate statistics. We measured total viable counts (TVCs) and ATP levels in 10 near-patient sites three times weekly, one hour before and after cleaning. Standard cleaning reduced TVCs further than UMF cleaning with water, but UMF cleaning with CuWB50 produced equivalent TVC reduction. Furthermore we identified a ‘residual effect’ with UMF + CuWB50, conferring TVC suppression for up to a week after application. ATP results did not correlate with TVCs. We conclude that UMF-based cleaning with CuWB50 results in TVC reductions equivalent to hypochlorite-based standard cleaning, with the added advantages of a residual effect that keeps TVCs lower between cleaning rounds.

Effect of the dried residues of two hand gels on the survival of meticillin-resistant Staphylococcus aureus and Acinetobacter calcoaceticus-baumannii

We assessed the ability of the residues of an alcohol-based hand gel (hand gel A) and an Aloe vera-based CuAL42 copper biocide-containing hand gel (hand gel B), to support the survival of meticillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter calcoaceticus-baumannii (ACCB). One-millilitre samples of hand gels A and B were spread over marked 20 cm2 areas and dried overnight. MRSA or ACCB (1 × 104 CFU) were spread onto the dried residue and contact plated at various times. MRSA and ACCB survived for 8 hours on hand gel A residue, whilst MRSA did not survive on hand gel B residue and ACCB survived less than 30 min. Low concentrations of hand gel A facilitate the growth of ACCB, but this is not the case for hand gel B. Hand gel A is extensively used in UK hospitals and its residue left on high-touch surfaces may support the survival of bacteria that cause healthcare-acquired infections.

Susceptibility of 169 USA300 methicillin-resistant Staphylococcus aureus isolates to two copper-based biocides, CuAL42 and CuWB50

OBJECTIVES

To test the activity of two copper-based biocides, CuAL42 and CuWB50, and benzalkonium chloride against 169 isolates of methicillin-resistant Staphylococcus aureus (MRSA) pulsotype USA300, a virulent, multiply resistant, widespread clone in the USA.

METHODS

Tests including MIC, MBC and time-kill studies were performed multiple times.

RESULTS

The MIC range, MIC(50) and MIC(90) (0.59-18.75, 4.69 and 4.69 ppm, respectively) and the MBC range, MBC(50) and MBC(90) (1.17-18.75, 4.69 and 9.38 ppm, respectively) for CuAL42 were identical with those obtained with CuWB50, except that the MBC range for CuWB50 was wider (0.59-37.5 ppm). In time-kill studies, a 6 log(10) reduction of cfu was achieved within 1 h (150 ppm) and 0.5 h (300 ppm) for CuAL42, and 1.5 h (150 ppm) and 0.75 h (300 ppm) for CuWB50.

CONCLUSIONS

Both copper-based biocides can effectively kill USA300 MRSA and may facilitate the eradication of the organism from healthcare settings.

Decontamination of laundry at low temperature with CuWB50, a novel copper-based biocidal compound

BACKGROUND

Traditional laundry decontamination relies on thermal disinfection that degrades textiles. We investigated the ability of a novel copper-based biocidal compound, CuWB50, to assist in the decontamination of swatches purposely contaminated with Staphylococcus aureus and Acinetobacter during "real-life" low-temperature machine washing with and without 2 commercial detergents.

METHODS

Contaminated and noncontaminated swatches were attached to ballast sheets and washed in cold water for 15 minutes in an industrial Electrolux machine. We assessed colony-forming units (cfu) on the swatches and in the postwash water.

RESULTS

Low-temperature machine washing produced only partial reductions in viable methicillin-resistant Staphylococcus aureus and Acinetobacter calcoaceticus baumannii counts on swatches and resulted in cross contamination of other swatches in the same wash. Washing with CuWB50 alone at high concentration (100 mg/L), however, resulted in superior decontamination compared with water alone, whereas washing with a combination of detergent and CuWB50 at low concentration (5 mg/L) yielded synergistic and complete decontamination of swatches and postwash water.

CONCLUSION

Our results show highly effective laundry decontamination using CuWB50 with detergent at low temperature and are timely both in terms of rising energy costs and textile degradation issues.