Persistence analysis of poliovirus on three different types of fomites

A comprehensive approach for evaluating the virucidal performance of domestic laundry detergents under practical conditions

AIMS

We aimed to develop a method to assess the virucidal performance of domestic laundry in a lab-scale washing machine (Rotawash) based on EN 17658.

METHODS AND RESULTS

For method development, virus recovery was investigated after drying on cotton carriers for three test viruses murine norovirus (MNV), modified vaccinia virus Ankara (MVA), and bovine coronavirus (BCoV), followed by washing simulations in flasks and Rotawash. MNV and MVA demonstrated sufficient recovery from carriers after drying and washing (up to 40°C and 60 min). BCoV exhibited lower recovery, indicating less relevance as a test virus. Rotawash efficacy tests conducted with MNV, a resistant, non-enveloped virus, showed limited efficacy of a bleach-free detergent, aligning with results from a domestic washing machine. Rotawash washes achieved higher reductions in infectious virus titers than suspension tests, indicating the role of washing mechanics in virus removal.

CONCLUSIONS

This study established a practical method to test the virucidal efficacy of laundry detergents in Rotawash, simulating domestic washing.

Viability of Moniliophthora roreri on Cocoa Beans Under Microfermentation and Long-Term Survival on Carrier Materials

The viability of Moniliophthora roreri inoculum was evaluated during the microfermentation process of diseased and healthy pulp-seed masses and on a range of carrier materials: aluminum, cloth, glass, paper, plastic, raffia, and rubber tire. Fungal survival was assessed before the microfermentation (0 h) and every 24 to 96 h by the growth of colonies in potato-dextrose-agar (PDA) and sporulation in seed shells. Colonies of M. roreri and sporulation on seed shells were observed from seeds not submitted to microfermentation. No growth was recovered from diseased cocoa beans after 48 h under the microfermentation. The viability of M. roreri spores recovered from carrier materials was evaluated at 7, 15, 30, 45, and 100 days after inoculation (DAI) by collecting spores and plating them on Sabouraud dextrose yeast extract agar amended with chloramphenicol (50 mg l1). The viability was determined by counting germinated and ungerminated spores under a light microscope (40×) after incubating in a moist chamber at 26 ± 2°C for 72 h. Spores maintained long-term viability on all tested carrier materials toward the end of the experiment (overall 26%) with significant differences (<0.05) among them. Maximum spore viability occurred at 7 and 15 DAI, with cloth and plastic carrier materials considered at high risk of acting as vehicles for the fungal spread. Mathematical models of spore viability over time were fit to the data using the Bayesian information criterion. Findings confirmed the importance of the fermentation process to hamper M. roreri growth and the potential of carrier materials for fungal dispersal.

A New Synergistic Strategy for Virus and Bacteria Eradication: Towards Universal Disinfectants

In response to the COVID-19 and monkeypox outbreaks, we present the development of a universal disinfectant to avoid the spread of infectious viral diseases through contact with contaminated surfaces. The sanitizer, based on didecyldimethylammonium chloride (DDAC), N,N-bis(3-aminopropyl)dodecylamine (APDA) and γ-cyclodextrin (γ-CD), shows synergistic effects against non-enveloped viruses (poliovirus type 1 and murine norovirus) according to the EN 14476 standard (≥99.99% reduction of virus titer). When a disinfectant product is effective against them, it can be considered that it will be effective against all types of viruses, including enveloped viruses. Consequently, "general virucidal activity" can be claimed. Moreover, we have extended this synergistic action to bacteria (P. aeruginosa, EN 13727). Based on physicochemical investigations, we have proposed two independent mechanisms of action against bacteria and non-enveloped viruses, operating at sub- and super-micellar concentrations, respectively. This synergistic mixture could then be highly helpful as a universal disinfectant to avoid the spread of infectious viral or bacterial diseases in community settings, including COVID-19 and monkeypox (caused by enveloped viruses).

Meta-Analysis Addressing the Implications of Model Uncertainty in Understanding the Persistence of Indicators and Pathogens in Natural Surface Waters

This study evaluates the impact persistence model selection has on the prediction of persistence values of interest and the identification of influential water quality and environmental factors for microorganisms in natural surface waters. Five persistence models representing first-order decay and nonlinear decay profiles were fit to a comprehensive database of 629 data sets for fecal indicator bacteria (FIB), bacteriophages, bacteria, viruses, and protozoa mined from the literature. Initial periods of minimal decay and decay rates tapering off over time were often observed, and a two-parameter model, based on the logistic probability distribution, provided the best fit to the data most frequently. First-order decay kinetics provided the best fit to less than 20% of the analyzed data. Using the best fitting models in this analysis, T90 and T99 metrics were calculated for each data set and used as the dependent variable in a variety of exploratory factor analyses. Random forest methods identified temperature and predation as some of the most important water quality factors influencing persistence, and the protozoa target type differed the most from FIB. This analysis further confirmed the interactions between temperature and predation and suggests that pH and turbidity be more frequently documented in persistence studies to further elucidate their impact on target persistence. The findings from this analysis and the calculated persistence metrics can be used to better inform quantitative microbial risk assessments and may lead to improved predictions of human health risks and water management decisions.

Microbial Air Quality in Healthcare Facilities

There is increasing evidence that indoor air quality and contaminated surfaces provide an important potential source for transmission of pathogens in hospitals. Airborne hospital microorganisms are apparently harmless to healthy people. Nevertheless, healthcare settings are characterized by different environmental critical conditions and high infective risk, mainly due to the compromised immunologic conditions of the patients that make them more vulnerable to infections. Thus, spread, survival and persistence of microbial communities are important factors in hospital environments affecting health of inpatients as well as of medical and nursing staff. In this paper, airborne and aerosolized microorganisms and their presence in hospital environments are taken into consideration, and the factors that collectively contribute to defining the infection risk in these facilities are illustrated.

Persistence of Pathogens on Inanimate Surfaces: A Narrative Review

For the prevention of infectious diseases, knowledge about transmission routes is essential. In addition to respiratory, fecal-oral, and sexual transmission, the transfer of pathogens via surfaces plays a vital role for human pathogenic infections-especially nosocomial pathogens. Therefore, information about the survival of pathogens on surfaces can have direct implications on clinical measures, including hygiene guidelines and disinfection strategies. In this review, we reviewed the existing literature regarding viral, bacterial, and fungal persistence on inanimate surfaces. In particular, the current knowledge of the survival time and conditions of clinically relevant pathogens is summarized. While many pathogens persist only for hours, common nosocomial pathogens can survive for days to weeks under laboratory conditions and thereby potentially form a continuous source of transmission if no adequate inactivation procedures are performed.

Energy Requirements for Loss of Viral Infectivity

Outside the host, viruses will eventually lose their ability to infect cells due to conformational changes that occur to proteins on the viral capsid. In order to undergo a conformational change, these proteins require energy to activate the chemical reaction that leads to the conformational change. In this study, data from the literature is used to calculate the energy required for viral inactivation for a variety of different viruses by means of the Arrhenius equation. We find that some viruses (rhinovirus, poliovirus, human immunodeficiency virus, Alkhumra hemorrhagic fever virus, and hepatitis A virus) have high inactivation energies, indicative of breaking of a chemical double bond. We also find that several viruses (respiratory syncytial virus, poliovirus, and norovirus) have nonlinear Arrhenius plots, suggesting that there is more than a single pathway for inactivation of these viruses.

How long can nosocomial pathogens survive on textiles? A systematic review

Aims: Healthcare-associated infections linked to contaminated textiles are rare but underline their potential role as a source for transmission. The aim of the review was to summarize the experimental evidence on the survival and persistence of the different types of nosocomial pathogens on textiles.

Methods: A literature search was performed on MedLine. Original data on the survival of bacteria, mycobacteria, and fungi and persistence of viruses on textiles were evaluated.

Results: The survival of bacteria at room temperature was the longest on polyester (up to 206 days), whereas it was up to 90 days for some species on cotton and mixed fibers. Only low inocula of 100 CFU were found on all types of textiles with a short survival time of ≤3 days. Most bacterial species survived better at elevated air humidity. The infectivity of viruses on textiles is lost much faster at room temperature, typically within 2–4 weeks.

Conclusions: Contaminated textiles or fabrics may be a source of transmission for weeks. The presence of pathogens on the coats of healthcare workers is associated with the presence of pathogens on their hands, demonstrating the relevance of textile contamination in patient care.