Survival of Clostridioides difficile spores in thermal and chemo-thermal laundering processes and influence of the exosporium on their adherence to cotton bed sheets.

Clostridioides difficile spores were previously demonstrated to survive industrial laundering. Understanding interactions between heat, disinfectants and soiling (e.g. bodily fluids) affecting C. difficile spore survival could inform the optimization of healthcare laundry processes. Reducing spore attachment to linen could also enhance laundering efficacy. This study aimed to compare the sensitivity of C. difficile spores to heat and detergent, with and without soiling and to investigate adherence to cotton. Survival of C. difficile spores exposed to industrial laundering temperatures (71-90°C), reference detergent and industrial detergent was quantified with and without soiling. The adherence to cotton after 0 and 24 h air drying was determined with the exosporium of C. difficile spores partially or fully removed. Clostridioides difficile spores were stable at 71°C for 20 min (≤0·37 log10 reduction) while 90°C was sporicidal (3 log10 reduction); soiling exerted a protective effect. Industrial detergent was more effective at 71°C compared to 25°C (2·81 vs 0·84 log10 reductions), however, specifications for sporicidal activity (>3 log10 reduction) were not met. Clostridioides difficile spores increasingly adhered to cotton over time, with 49% adherence after 24 h. Removal of the exosporium increased adherence by 19-23% compared to untreated spores. Further understanding of the role of the exosporium in attachment to cotton could enhance spore removal and aid decontamination of linen.

A novel disinfected Trombe wall for space heating and virus inactivation: Concept and performance investigation.

Trombe wall is a simple and mature passive solar building design while its utilization of solar energy is limited to space heating. Aerosol transmission, as a potential transmission pathway of COVID-19, poses a serious threat to the public health especially in a closed indoor environment. The thermal disinfection of virus, which can be easily integrated into solar systems, seems to be a suitable method for controlling bioaerosols. Therefore, a novel disinfected Trombe wall for virus inactivation and space heating is proposed, providing a potential way to fight the current COVID-19 pandemic. After the proposal of the concept, its performance on space heating and virus inactivation was investigated through experimental and simulation methods. The main results were as follows: (1) The average thermal efficiency was 0.457 and the average indoor temperature was 20.7 ℃, 1.9 ℃ higher than the ambient temperature. (2) The maximum single-pass inactivation ratio was 0.893, 0.591 and 0.893 while the total production of clean air was 112.3, 63.8 and 114.7 m3 for SARS-CoV-1, SARS-CoV-2 and MERS-CoV, respectively. (3) The increase of ambient temperature or solar irradiance may enhance the thermal efficiency while the former has little effect on the thermal disinfection process. (4) Extending the height or narrowing the thickness of the duct by 40% may contribute to an increase in total production of clean air by 510 m3 or 681 m3 per unit area during the heating seasons, but the later may cause a larger decrease (about 8%) in the heat gain of indoor air.

Controlling the hospital aquatic reservoir of multidrug-resistant organisms: a cross-sectional study followed by a nested randomized trial of sink decontamination.

OBJECTIVES: The hospital water environment is an important reservoir of multidrug-resistant organisms (MDROs) and presents a risk for patient safety. We assessed the effectiveness of thermal and chemical interventions on sinks contaminated with MDRO in the hospital setting. METHODS: We conducted a cross-sectional assessment of MDRO contamination of sinks and toilets in 26 clinical wards of a tertiary care hospital. MDRO-contaminated sink traps were then replaced and randomized (1:1:1) to receive chemical (sodium hypochlorite), thermal disinfection (steam), or no intervention. Interventions were repeated weekly for 4 weeks. Sinks were resampled 7 days after the last intervention. The primary outcome was the proportion of decontaminated sinks. MDROs of interest were extended spectrum beta-lactamase (ESBL) producing and carbapenemase-producing Enterobacterales, and non-fermentative Gram-negative bacilli. RESULTS: In the cross-sectional assessment, at least one MDRO was identified in 258 (36%) of the 748 samples and in 91 (47%) of the 192 water sources. In total, 57 (42%) of the 137 sinks and 34 (62%) of the 55 toilets were contaminated with 137 different MDROs. The most common MDRO were ESBL Enterobacterales (69%, 95/137), followed by Verona Integron-Borne Metallo-ß-Lactamase (VIM) carbapenemase producing Pseudomonas aeruginosa (9%, 12/137) and Citrobacter spp. (6%, 5/137). In the nested randomized trial, five of the 16 sinks (31%) in the chemical disinfection group were decontaminated, compared with 8 of 18 (44%) in the control group (OR 0.58; 95% CI, 0.14-2.32) and 9 of 17 (53%) in the thermal disinfection group (OR 1.40; 95% CI, 0.37-5.32). DISCUSSION: Our study failed to demonstrate an added benefit of repeated chemical or thermal disinfection, beyond changing sink traps, in the MDRO decontamination of sinks. Routine chlorine-based disinfection of sinks may need to be reconsidered.

Effective disinfecting of protective devices used in the course of treating SARS-CoV2-positive patients.

BACKGROUND: Powered Air-Purifying Respirator (PAPR) was widely used in Sengkang General Hospital (SKH) during the SARS-CoV-2 outbreak. Ensuring a sustained supply of clean and reusable PAPR masks for frontline medical team is an immediate challenge. The Central Sterile Supplies Unit (CSSU) adopts existing disinfection methods and technology for the reprocessing of reusable personal protective equipment (PPE) such as PAPR masks and goggles. OBJECTIVE: To determine an effective disinfecting method for protective devices used in the course of treating SARS-CoV2-positive patients. METHOD: A comparison on surface disinfection and modified thermal disinfection outcome was conducted on 30 PAPR masks through detecting the presence of adenosine triphosphate (ATP) by swab following both disinfecting methods. RESULTS: The modified thermal cycles emerged as the recommended disinfection method. DISCUSSION: The outcome of this study has enhanced understanding on the risk imposed on frontline healthcare personnel who perform surface disinfecting on masks for reuse during the work shift. Leveraging on the current expertise from existing instrument logistics, CSSU takes charge of the processing and stock management of SKH's PAPR masks. An additional workflow is needed to establish reprocessing methods for other reusable PPEs such as face shields or overalls.

Thermal disinfection at suboptimal temperature of Pseudomonas aeruginosa biofilm on copper pipe and shower hose materials.

BACKGROUND: Hospital-acquired infections caused by Pseudomonas aeruginosa have been linked to contaminated shower systems in health care. Thermal disinfection, whereby colonized outlets are flushed with existing hot water supplies, is a commonly used method to disinfect contaminated systems. Temperatures of 60°C are recommended for inactivation of P. aeruginosa; however, this is often not achievable at outlets. AIM: To investigate whether thermal disinfection at a suboptimal temperature (58°C) can effectively eradicate planktonic P. aeruginosa and biofilm adherent on copper piping and shower hoses. Exposure times of up to 60 min and efficacy of repeated cycles were evaluated. METHODS: A type culture and an environmental strain of P. aeruginosa isolated from a hospital shower were tested. Planktonic bacteria and biofilm adhered to sections of copper pipe and shower hoses were exposed to water at 58°C for up to 60 min. Biofilms were tested with static water, flushing water and repeated cycles of disinfection. Remaining viable bacteria after disinfection were enumerated. FINDINGS: Planktonic P. aeruginosa remained viable after up to 60 min of thermal disinfection. With static water, biofilm was removed from copper piping after 15 min, but remained viable in shower hoses for up to 60 min. With thermal flushing, biofilm was fully eradicated from copper piping after 2 min, but remained viable on shower hoses. Repeated cycles did not shorten thermal disinfection exposure times. CONCLUSION: Thermal disinfection at 58°C was effective at eliminating biofilm on copper; however, biofilm on shower hoses remained viable after 60 min of exposure.

Mycobacterium hassiacum: a thermophilic Mycobacterium species to demonstrate thermal disinfection of medical devices.

OBJECTIVE: Reprocessing reusable medical devices is crucial in the healthcare industry. To ensure patient safety, strict standards are dictated to validate thermal disinfection in automated washer-disinfectors. The United States Food and Drug Administration (FDA) has specific recommendations on the vegetative bacterial challenge but comparatively vague guidance on the use of a thermophilic Mycobacterium strain for thermal disinfection studies. This study aims to compare thermal resistance of Mycobacterium hassiacum and Mycobacterium terrae and determine which strain is suitable for medical device thermal disinfection validation testing in automated washer-disinfectors. RESULTS: Thermal resistance was demonstrated in vitro by calculating D-values for each strain at different exposure temperatures, and correlated with actual in situ processing conditions. M. terrae was completely killed (> 7 log reduction) at temperatures above 68 °C, with D-values between 46.6 and 27.8 s at temperatures between 59.5 and 67.2 °C. M. hassiacum was completely killed (> 8 log reduction) at temperatures above 75 °C, with D-values between 82.1 and 21.7 s at temperatures ranging between 69.2 and 73.6 °C. In vitro results were correlated in a washer-disinfector performance validation setup.

Systematic review and meta-analysis of time-temperature pathogen inactivation.

Heat treatment, or thermal disinfection, is one of the simplest disinfection methods, and is widely used in the water, sanitation, and food sectors, especially in low resource settings. Pathogen reductions achieved during heat treatment are influenced by a combination of temperature and exposure time. The objective of this paper was to construct updated time-temperature pathogen inactivation curves to define "safety zones" for the reduction of four pathogen groups (bacteria, viruses, protozoan (oo)cysts, and helminth eggs) during heat treatment in a variety of matrices. A systematic review and meta-analysis were conducted to determine the times needed to achieve specified levels of pathogen reduction at different temperatures. Web of Science was searched using a Boolean string to target studies of heat treatment and pasteurization systems that exposed pathogens in water, wastewater, biosolids, soil, or food matrices to temperatures between 20 °C and 95 °C. Data were extracted from tables or figures and regression was used to assess the relationship between time and temperature. Our findings indicate that the temperatures and times needed to achieve a 1-log10 reduction of all pathogen groups are likely higher and longer, respectively, than previously reported. The type of microorganism and the matrix significantly impact T90 values reported at different temperatures. At high temperatures, the time-temperature curves are controlled by thermally stable viruses such as hepatitis A virus. Data gaps include the lack of data on protozoa, and the lack of data on all pathogen groups at low temperatures, for long exposure times, and with high log10 reductions. The findings from this study can be used by engineers, food safety specialists for the planning and design of engineered water, sanitation, and food pasteurization and treatment systems.

Viability and infectivity of viable but nonculturable Legionella pneumophila strains induced at high temperatures.

Thermal disinfection is commonly used to prevent the proliferation of culturable Legionella in engineered water systems (EWS). In response to such stress, culturable Legionella populations can switch into a viable but nonculturable (VBNC) state. The importance of such VBNC Legionella cells is currently hotly debated. Here, we investigated the stress response patterns and transitions of the bacteria to the VBNC state at 55 °C, 60 °C and 70 °C on two L. pneumophila strains for >80 days using a combination of cell-based viability indicators. Complete loss of culturability at 55 °C, 60 °C and 70 °C occurred after 3-8 h, 60 min and <2 min, respectively. In contrast, L. pneumophila strains required 9 days at 55 °C, 8 h at 60 °C and 20 min at 70 °C to achieve a 2 log reduction in cells with intact membranes and high esterase activity; a 4 log reduction was achieved only after 150, 8-15 and 1-4 days, respectively. In parallel, the presence of diagnostic outer-membrane epitopes (OMEs) and changes in the infectivity patterns of the two strains towards amoebae and THP-1 cells were assessed. OMEs were more persistent than viability indicators, showing their potential as targets for VBNC Legionella detection. L. pneumophila strains infected amoebae and THP-1 cells for at least 85 days at 55 °C and 60 °C and for up to 8 days at 70 °C. However, they did so with reduced efficiency, requiring prolonged co-incubation times with the hosts and higher Legionella cell numbers in comparison to culturable cells. Consequently, infection of amoebae by thermally induced VBNC L. pneumophila with lowered virulence can be expected in EWS. Although the gold standard method cannot detect VBNC Legionella, it provides important information about the most virulent bacterial subpopulations. Our results indicate that a prolonged thermal regime ≥60 °C at the central parts of warm water systems is not only effective against culturable L. pneumophila but in the long run even against VBNC cells.

Thermal disinfection in hemodialysis using the A0 concept as dispenser. / Desinfección térmica en hemodiálisis usando el concepto A0 como dosificador.

Patients with chronic kidney disease in the hemodialysis program are exposed to large amounts of water, as this constitutes about 96% of the dialysis fluid. It is known that the use of better quality water decreases the state of chronic inflammation in dialysis patients. Disinfection as part of water treatment plays an important role in meeting the established quality standards; currently, heat disinfection is highly recommended, however its dose is not clearly established in the literature. The objective of this review is to know what is available in the literature on the dose of heat disinfection that should be used in hemodialysis and to present our experience with this method at a set dose of 12.000 A0.

The Role of Heat-Tolerant Endotoxin-Retentive Ultrafilters (UFs) for the Remediation of Reverse Osmosis (RO) Plants Employed for Surgical Hand Antisepsis Using Periodic Thermal Disinfection-A Ten Year Longitudinal Experience Study in the Operating Theater.

Recently, the use of filters has come into light for sanitizing water plants. This study investigated the role of heat-tolerant ultrafilters (UFs) for the remediation of reverse osmosis (RO) plants using periodic thermal disinfection. Two completely identical RO plants (RO plants A and B) were installed in 2006 for surgical hand antisepsis in the operating theater. RO water was stored in the 300 L storage tank and recirculated in the 190 meter-long loop delivering water to 12 faucets in each RO plant. Periodic thermal disinfection came into practice periodically when a UF module was retrofitted to the recirculation loop of each RO plant in 2010. Endotoxin was monitored closely before and after thermal disinfection. Before UF modules were retrofitted, endotoxin increased to a maximum of 0.301 EU/mL in RO plant A and 1.446 EU/mL in RO plant B after thermal disinfection, respectively. Since a UF module was retrofitted to each RO plant in 2010, endotoxin has been continuously below 0.025 EU/mL in RO plant A and exceeded this level five times in RO plant B. On one occasion, endotoxin increased in all samples collected simultaneously after solenoid valves were replaced in the recirculation loop near the air conditioner outlet. At this time, the inside of the pipework was exposed to the ventilation airflow. After the valves were replaced again, this time with the workplace isolated using a curing sheet, endotoxin decreased. On the other occasions, endotoxin increased only in one sample and decreased after thermal disinfection. Annually replaced UF modules were examined twice for estimating the amounts of immobilized endotoxin. The estimated amounts decreased in 2013 by the order of 10-3 in comparison with those in 2011 in both RO plants. The present study suggested that UFs acted synergistically with periodic thermal disinfection for the remediation of RO plants.

Legionella Persistence in Manufactured Water Systems: Pasteurization Potentially Selecting for Thermal Tolerance.

Legionella is an opportunistic waterborne pathogen of increasing public health significance. Pasteurization, otherwise known as super-heat and flush (increasing water temperature to above 70°C and flushing all outlets), has been identified as an important mechanism for the disinfection of Legionella in manufactured water systems. However, several studies have reported that this procedure was ineffective at remediating water distribution systems as Legionella was able to maintain long term persistent contamination. Up to 25% of L. pneumophila cells survived heat treatment of 70°C, but all of these were in a viable but non-culturable state. This demonstrates the limitations of the culture method of Legionella detection currently used to evaluate disinfection protocols. In addition, it has been demonstrated that pasteurization and nutrient starvation can select for thermal tolerant strains, where L. pneumophila was consistently identified as having greater thermal tolerance compared to other Legionella species. This review demonstrates that further research is needed to investigate the effectiveness of pasteurization as a disinfection method. In particular, it focuses on the potential for pasteurization to select for thermal tolerant L. pneumophila strains which, as the primary causative agent of Legionnaires disease, have greater public health significance compared to other Legionella species.

Avaliação do desempenho da limpeza e desinfecção das máquinas lavadoras desinfectadoras automáticas em programas com diferentes tempos e temperaturas / Evaluation of cleaning and disinfection processes performed by automatic washing machine in programs presenting different time and temperature

A limpeza é, inegavelmente, o núcleo central de todas as atividades relacionadas ao reprocessamento de artigos médico-hospitalares. A lavadora desinfectadora é uma nova tecnologia, que trouxe grandes vantagens, como padronização dos procedimentos de limpeza, documentação do processo e diminuição do risco ocupacional de ordem biológica. Atualmente, existem equipamentos que disponibilizam programas com diferentes tempo e temperatura. Para subsidiar a escolha de programas, propôs-se nesta pesquisa investigar o desempenho das lavadoras desinfectadoras nos distintos programas (Norma Alemã, BGA 94ºC/10 minutos; Norma da Grã-Bretanha, DHSS/HTM 90ºC/1segundo; Norma da Grã-Bretanha, DHSS/HTM 82ºC/2minutos; Norma da Holanda, RIVM 90ºC/5 minutos; Norma da Suécia, SPRI/SIS 85ºC/1minuto; Norma da Suécia, SPRI/SIS 85ºC/3 minutos; ciclo com temperatura 70ºC e tempo 30 minutos para Pasteurização), avaliando-se o desempenho dos testes de limpeza e termodesinfecção em equipamento validado. Conforme as recomendações das Normas ISO 15883-1/1999 e HTM2030 (NHS States,1997), para avaliação do desempenho da limpeza foram utilizados três testes: Soil Test, Biotrace Pro-tect e Test Kit Proteína. Como resultado dos testes do desempenho da limpeza, constatou-se resíduo de sujidade após avaliação com Soil-Test em 1,3% dos instrumentais, do total de 313 avaliados (cinco instrumentais de complexidade crítica, dois deles não desmontáveis-Kerrison e Goiva). Na avaliação de resíduo de proteína com teste Biotrace Pro-tect constatou-se que, dos 65 instrumentais avaliados, 60 (92%) apresentaram resultado satisfatório. Os cinco instrumentais (8%) que apresentaram resíduo de sujidade com Soil-Test, também apresentaram, após avaliação com teste Biotrace Pro-tect, resíduo de proteína. Na avaliação realizada com o Test Kit Proteína, 141(100%) instrumentais apresentaram ausência de proteína. Para avaliação do desempenho da termodesinfecção, ) os instrumentais escolhidos para experimento foram intencionalmente contaminados com sangue humano e em seguida submetidos aos processos de termodesinfecção em diferentes programas. A contagem de UFC dos microrganismos viáveis foi feita antes e após a termodesinfecção, partindo-se da contaminação inicial de 107 e 108 UFC. Quanto aos resultados destes testes, de modo uniforme, todos os ciclos apresentaram desempenho satisfatório de <102 UFC, resultado esse entendido como ausência de crescimento microbiano, considerando-se a diluição empregada. Nos cálculos dos valores da Letalidade Mínima e DAL - Nível de Segurança de Desinfecção, os protocolos aprovados foram: Norma Alemã, BGA 94ºC/10 minutos; Norma da Grã-Bretanha, DHSS/HTM 90ºC/1 segundo; Norma da Holanda, RIVM 90ºC / 5 minutos; Norma da Suécia, SPRI/SIS 85ºC / 1 minuto; Norma da Suécia, SPRI/SIS 85ºC/ 3 minutos. Os protocolos que não alcançaram os valores preconizados da Letalidade Mínima de 10 minutos e DAL =10-2 após validação foram: Norma da Grã-Bretanha, DHSS/HTM 82ºC / 2 minutos; Temperatura 70ºC e Tempo de 30 minutos para Pasteurização. Como conclusão, a presente pesquisa evidenciou desempenhos satisfatórios das Máquinas Lavadoras Desinfectadoras tanto na limpeza mecânica quanto na desinfecção, em todos os programas testados, com diferentes tempos e temperaturas apesar do DAL e A0 de alguns programas terem sido reprovados. Evidenciou que em instrumentais de conformação complexa, especialmente quando não desmontáveis, a remoção completa dos resíduos não ocorre nas máquinas, sugerindo que a limpeza destes seja manual, utilizando-se artefatos adequados.

Cleaning is undeniably the main focus of all activities related to the reprocessing of medical and hospital supplies. The washer-disinfector machine represents a new technology that has brought great advantages as the standardization of the cleaning procedures, the process registering and the reduction of occupational hazards coming from biological sources. Nowadays, there are equipments with programs presenting different time and temperature. In order to subside the choice of programs, this essay aims to investigate the performance of washer-disinfectors in the following different programs (German Federal Health Authority BGA, 94ºC/10 minutes; British Standard DHSS/HTM, 90º C/1 second; British Standard DHSS/HTM, 82º C/2 minutes; The Netherlands RIVM, 90º C/5 minutes; Swedish Standards Institute SPRI/SIS, 85ºC/1 minute; Swedish Standard Institute SPRI/SIS, 85ºC/3minutes; cycle temperature 70ºC and pasteurization time 30 minutes), evaluating the performance of cleaning and thermo disinfection tests in validated equipment. According to recommendations in ISO 15883-1/1999 and HTM 2030 (NHS States, 1997) for evaluating the cleaning and disinfection processes, three tests were performed: Soil Test, Biotrace Pro-tect and Test Kit Protein. As a result of the cleaning tests performance, soiling was found after evaluation with Soil Test performed in 1,3% of the instruments (5 of them presenting critical complexity, 2 of them not dismountable - Kerrison and Rongeur). In 65 instruments evaluated by Biotrace Pro-tect, 60 instruments (92%) presented good results. Five instruments (8%) presented soiling after evaluation with Soil Test, and after Biotrace Pro-tect evaluation presented protein contamination. After the evaluation performed with Test Kit Protein no instrument presented protein contamination (141 instruments, 100%). To evaluate the thermo disinfection performance the instruments chosen for the test were intentionally contaminated with human blood and after that were under thermo disinfection processes in different programs. The counting of possible present microorganisms was done before and after the thermo disinfection process, starting from an initial contamination of 107 and 108 UFC. Concerning the results of these tests, in general all cycles presented a good performance (<102 UFC), which was understood as the absence of microbiological growth, considering the dilution given. To calculate the Minimal Lethality and DAL - Disinfection Assurance Level, the approved protocols were: German Federal Health Authority BGA, 94ºC/10 minutes; British Standard DHSS/HTM, 90ºC/1 second; The Netherlands RIVM, 90ºC/5 minutes; Swedish Standards Institute SPRI/SIS, 85ºC/1 minute and Swedish Standards Institute SPRI/SIS, 85ºC/3 minutes. The protocols that did not reach the professed values for Minimal Lethality of 10 minutes and DAL = 10 -2 after validation were: British Standard DHSS/HTM, 82ºC/2 minutes; temperature 70ºC and pasteurization time 30 minutes. Concluding, this study evidenced the good performance of the washer-disinfector machines for mechanic cleaning as for disinfection in all tested programs with different time and temperature. It also demonstrated that for instruments with complex shape, specially the not dismountable ones, the complete soiling remove do not occur on the machines and suggests that this cleaning requires handicraft employing adequate material.