A Study of the Molecular Diversity of Staphylococcus aureus Plasmids and Their Role in the Characterisation of Methicillin-Resistant Staphylococcus aureus

Two hundred and sixty-four isolates of Staphylococcus aureus were collected; 163 methicillin-sensitive Staph, aureus (MSSA) and 101 methicillin-resistant Staph, aureus (MRSA). MSSA comprised: from Glasgow Royal Infirmary (GRI) 50 blood culture isolates (BC), 63 isolates from routine diagnostic specimens (RD) and fifty strains from nasal swabs of patients attending a general practitioner (GP). The MRSA from GRI comprised: 53 isolates from 1985-86 (MRSA(l)) and 48 isolates from 1986-87 (MRSA(2))

Synergistic efficacy of 405 nm light and chlorinated disinfectants for the enhanced decontamination of Clostridium difficile spores

The ability of Clostridium difficile to form highly resilient spores which can survive in the environment for prolonged periods causes major contamination problems. Antimicrobial 405 nm light is being developed for environmental decontamination within hospitals, however further information relating to its sporicidal efficacy is required. This study aims to establish the efficacy of 405 nm light for inactivation of C. difficile vegetative cells and spores, and to establish whether spore susceptibility can be enhanced by the combined use of 405 nm light with low concentration chlorinated disinfectants. Vegetative cells and spore suspensions were exposed to increasing doses of 405 nm light (at 70–225 mW/cm2) to establish sensitivity. A 99.9% reduction in vegetative cell population was demonstrated with a dose of 252 J/cm2, however spores demonstrated higher resilience, with a 10-fold increase in required dose. Exposures were repeated with spores suspended in the hospital disinfectants sodium hypochlorite, Actichlor and Tristel at non-lethal concentrations (0.1%, 0.001% and 0.0001%, respectively). Enhanced sporicidal activity was achieved when spores were exposed to 405 nm light in the presence of the disinfectants, with a 99.9% reduction achieved following exposure to 33% less light dose than required when exposed to 405 nm light alone. In conclusion, C. difficile vegetative cells and spores can be successfully inactivated using 405 nm light, the sporicidal efficacy can be significantly enhanced when exposed in the presence of low concentration chlorinated disinfectants. Further research may lead to the potential use of 405 nm light decontamination in combination with selected hospital disinfectants to enhance C. difficile cleaning and infection control procedures

Inactivation of C. difficile by 405 nm HINS-light

This poster discusses using 405nm HINS-light to make Clostridium difficile cells and spores inactive

New proof-of-concept in viral inactivation: virucidal efficacy of 405 nm light against feline calicivirus as a model for norovirus decontamination

The requirement for novel decontamination technologies for use in hospitals is ever present. One such system uses 405 nm visible light to inactivate microorganisms via ROS-generated oxidative damage. Although effective for bacterial and fungal inactivation, little is known about the virucidal effects of 405 nm light. Norovirus (NoV) gastroenteritis outbreaks often occur in the clinical setting, and this study was designed to investigate potential inactivation effects of 405 nm light on the NoV surrogate, feline calicivirus (FCV). FCV was exposed to 405 nm light whilst suspended in minimal and organically-rich media to establish the virucidal efficacy and the effect biologically-relevant material may play in viral susceptibility. Antiviral activity was successfully demonstrated with a 4 Log10 (99.99%) reduction in infectivity when suspended in minimal media evident after a dose of 2.8 kJ cm−2. FCV exposed in artificial faeces, artificial saliva, blood plasma and other organically rich media exhibited an equivalent level of inactivation using between 50–85% less dose of the light, indicating enhanced inactivation when the virus is present in organically-rich biologically-relevant media. Further research in this area could aid in the development of 405 nm light technology for effective NoV decontamination within the hospital environment

Clinical studies of the high-intensity narrow-spectrum light environmental decontamination system (HINS-light EDS), for continuous disinfection in the burn unit inpatient and outpatient settings

Infections are the leading cause of morbidity and mortality in burn patients and prevention of contamination from exogenous sources including the hospital environment is becoming increasingly emphasised. The High-Intensity Narrow-Spectrum light Environmental Decontamination System (HINS-light EDS) is bactericidal yet safe for humans, allowing continuous disinfection of the environment surrounding burn patients. Environmental samples were collected from inpatient isolation rooms and the outpatient clinic in the burn unit, and comparisons were then made between the bacterial contamination levels observed with and without use of the HINS-light EDS. Over 1000 samples were taken. Inpatient studies, with sampling carried out at 0800 h, demonstrated a significant reduction in the average number of bacterial colonies following HINS-light EDS use of between 27% and 75%, (p<0.05). There was more variation when samples were taken at times of increased activity in the room. Outpatient studies during clinics demonstrated a 61% efficacy in the reduction of bacterial contamination on surfaces throughout the room during the course of a clinic (p=0.02). The results demonstrate that use of the HINS-light EDS allows efficacious bacterial reductions over and above that achieved by standard cleaning and infection control measures in both inpatient and outpatient settings in the burn unit

Enhanced decontamination of C. difficile spores on surfaces via the synergistic action of 405nm light and disinfectants

The ability of C. difficile to form spores which can survive for prolonged periods causes significant environmental contamination problems. 405nm light has wide antimicrobial activity against vegetative bacteria, and is being developed for environmental decontamination within hospitals. As expected, spores are more resilient to inactivation. This study aims to establish whether spore susceptibility can be enhanced by combining 405nm light with low concentration chlorinated disinfectants: sodium hypochlorite, Actichlor and Tristel. Spore suspensions were seeded onto surfaces including PVC, stainless steel and vinyl flooring. Disinfectant was added to the surface, and the samples were then exposed to 405nm light at irradiances of ~0.2-225 mWcm-2. Control samples were exposed to 405nm light alone, and disinfectants alone, to establish the sporicidal activity of each agent, and to demonstrate the synergistic effect when combined. Results demonstrated increased sporicidal activity of 405nm light and low-concentration sodium hypochlorite and Actichlor against C. difficile seeded on vinyl flooring and PVC surfaces, with approximately 3-log10 reductions achieved with up to 66% lower doses than achieved with light alone. Tristel demonstrated limited synergy on vinyl and PVC, whilst all three disinfectants demonstrated minimal synergy on stainless steel. Results are also reported for lower intensity light, as used in the clinical environment. In conclusion, the sporicidal efficacy of 405nm light is enhanced when used alongside chlorinated disinfectants. Further research could potentially lead to the use of lower strength chlorinated disinfectants in combination with 405nm light to provide enhanced decontamination of C. difficile spores in the clinical environment

The prevalences of Salmonella Genomic Island 1 variants in human and animal Salmonella Typhimurium DT104 are distinguishable using a Bayesian approach

Throughout the 1990s, there was an epidemic of multidrug resistant Salmonella Typhimurium DT104 in both animals and humans in Scotland. The use of antimicrobials in agriculture is often cited as a major source of antimicrobial resistance in pathogenic bacteria of humans, suggesting that DT104 in animals and humans should demonstrate similar prevalences of resistance determinants. Until very recently, only the application of molecular methods would allow such a comparison and our understanding has been hindered by the fact that surveillance data are primarily phenotypic in nature. Here, using large scale surveillance datasets and a novel Bayesian approach, we infer and compare the prevalence of Salmonella Genomic Island 1 (SGI1), SGI1 variants, and resistance determinants independent of SGI1 in animal and human DT104 isolates from such phenotypic data. We demonstrate differences in the prevalences of SGI1, SGI1-B, SGI1-C, absence of SGI1, and tetracycline resistance determinants independent of SGI1 between these human and animal populations, a finding that challenges established tenets that DT104 in domestic animals and humans are from the same well-mixed microbial population

Efficacy of a pentavalent rotavirus vaccine in reducing rotavirus-associated health care utilization across three regions (11 countries)

OBJECTIVE: To evaluate the effect of a human-bovine reassortant pentavalent rotavirus vaccine (PRV) on health care encounters in nearly 70 000 subjects randomized in three regions - Europe, the United States, and Latin America/the Caribbean - in the Rotavirus Efficacy and Safety Trial (REST). METHODS: Healthy 6- to 12-week-old infants received 3 doses of PRV or placebo at 4- to 10-week intervals. The exact binomial method for ratios of Poisson counts was used to evaluate the effect of PRV on the rate of rotavirus-related hospitalizations and emergency department (ED) visits involving rotavirus G-types 1-4 occurring > or =14 days after the third dose of vaccine for up to 2 years. RESULTS: In fully vaccinated infants, reductions in rotavirus-associated hospitalizations and ED visits were 94.7% (95% CI: 90.9, 96.9) in Europe, 94.9% (95% CI: 84.0, 98.9) in the United States, and 90.0% (95% CI: 29.4, 99.8) in the Latin American/Caribbean regions. CONCLUSIONS: PRV reduced hospitalizations and ED visits within each region in REST. Results were consistent across regions and across the overall study cohort

Impact of recurrent Clostridium difficile infection: hospitalization and patient quality of life

Objectives: Data quantifying outcomes of recurrent Clostridium difficile infection (rCDI) are lacking. We sought to determine the UK hospital resource use and health-related quality of life (HrQoL) associated with rCDI hospitalisations. Patients and methods: A non-interventional study in 6 UK acute hospitals collected retrospective clinical and resource use data from medical records of 64 adults hospitalised for rCDI and 64 matched inpatient controls with a first episode only (f)CDI. Patients were observed from the index event (date rCDI/fCDI confirmed) for 28-days (or death, if sooner); UK-specific reference costs were applied. HrQoL was assessed prospectively in a separate cohort of 30 patients hospitalised with CDI, who completed the EQ-5D-3L questionnaire during their illness. Results: The median total management cost (post-index) was £7,539 and £6,294 for rCDI and fCDI, respectively (cost difference, p=0.075); median length of stay (LOS) was 21 days and 15.5 days, respectively (p=0.269). The median cost difference between matched rCDI and fCDI cases was £689 (IQR=£-1,873-£3,954). Subgroup analysis demonstrated the highest median costs (£8,542/patient) in severe rCDI cases. CDI management costs were driven primarily by hospital LOS, which accounted for >85% of costs in both groups. Mean EQ-5D index values were 46% lower in CDI patients compared with UK population values (0.42 and 0.78, respectively); EQ-VAS scores were 38% lower (47.82 and 77.3, respectively). Conclusions: CDI has considerable impact on patients and healthcare resources. This multicentre study provides a contemporaneous estimate of the real-world UK costs associated with rCDI management, which are substantial and comparable to fCDI costs

Joint Healthcare Infection Society (HIS) and Infection Prevention Society (IPS) guidelines for the prevention and control of meticillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities

Meticillin-resistant Staphylococcus aureus (MRSA) infections remain a serious cause of healthcare-associated infection (HCAI) in many countries. MRSA is easily spread by multiple routes and can persist in the environment for long periods. In health and care settings, transmission via staff hands remains the most important route for patient MRSA acquisition. Infection prevention and control (IPC) measures and control of the use of antimicrobials are effective in reducing prevalence of MRSA. There have been many publications related to MRSA since the last guideline was published in 2006 and this update contains further measures that are clinically effective for preventing transmission when used by healthcare workers (Table I). Methods for systematic review were in accordance with National Institute for Health and Care Excellence (NICE) approved methodology and critical appraisal followed Scottish Intercollegiate Guidelines Network (SIGN) and other standard checklists. Articles published between 2004 and February 2021 were included. Questions for review were derived from a stakeholder meeting, which included patient representatives in accordance with the Population Intervention Comparison Outcome(PICO) framework. Recommendations are made in the following areas: screening, management of colonised healthcare staff, environmental screening and cleaning/disinfection, surveillance, IPC precautions (including isolation and movement of patients and equipment), and patient information