A case study on decontamination of a biosafety level-3 laboratory and associated ductwork within an operational building using gaseous chlorine dioxide

Best practices of highly infectious decedent management: Consensus recommendations from an international expert workshop

With the increasing number of highly infectious disease incidents, outbreaks, and pandemics in our society (e.g., Ebola virus disease, Lassa fever, coronavirus diseases), the need for consensus and best practices on highly infectious decedent management is critical. In January 2020, a workshop of subject matter experts from across the world convened to discuss highly infectious live patient transport and highly infectious decedent management best practices. This commentary focuses on the highly infectious decedent management component of the workshop. The absence of guidance or disparate guidance on highly infectious decedent management can increase occupational safety and health risks for death care sector workers. To address this issue, the authorship presents these consensus recommendations on best practices in highly infectious decedent management, including discussion of what is considered a highly infectious decedent; scalability and storage for casualty events; integration of key stakeholders; infection control and facility considerations; transport; care and autopsy; psychological, ethical, and cultural considerations as well as multi-national care perspectives. These consensus recommendations are not intended to be exhaustive but rather to underscore this overlooked area and serve as a starting point for much-needed conversations.

Low-cost, Small-scale Decontamination of Laboratory Equipment by Using Chlorine Dioxide Gas

A significant concern in laboratory animal medicine is contamination due to pathogen outbreaks and how to adequately decontaminate small equipment. Many factors play a role in the selection of the decontamination method including cost, efficacy, personnel time and safety. Chlorine dioxide (ClO₂) gas is an effective method, but decontamination often requires a ClO₂ gas generator with a specialized air-tight exposure chamber. Although this method works well for large-scale decon- tamination, the use of a gas generator may be impractical and too costly for smaller-scale decontamination. The goal of this study was to create and validate an effective, small-scale decontamination method that uses ClO₂ gas and which is an affordable, efficient, safe, and reproducible. First, we identified a product that generates ClO₂ gas after the combination of 2 dry reagents. To find an affordable exposure chamber, we evaluated the ability of 4 household totes with gasket-seal lid systems to retain ClO₂ gas and relative humidity (RH). The efficacy of decontamination was validated by concurrently using 2 different biologic indicators (BI), Bacillus atrophaeus (B.a.) and Geobacillus stearothermophilus (G.s.). All household totes evaluated held sufficient gas and RH for a 15-h cycle, providing adequate contact time to inactivate both BI evaluated. Our results suggest that a total exposure dose of 71 ± 42 ppm-h of ClO₂ gas over 15 h at 90% or greater RH is adequate to inactivate both B.a. and G.s. There was no statistical significance between the 2 BI as indicators for decontamination; 65 of 230 (28.3%) B.a. and 75 of 230 (32.6%) G.s spore strips were positive for growth (P = 0.36). In conclusion, we successfully combined a variety of low-cost materials to establish an effective, small-scale method to decontaminate laboratory equipment. Depending on the size of the tote and whether BI are used, the cost of our method is roughly 1% that of large-scale ClO₂ gas generators used with specialized air-tight exposure chambers.

Evaluation of an Environmental Monitoring Program for the Microbial Safety of Air and Surfaces in a Dairy Plant Environment

Microbiological hazards can occur when foodstuffs come into contact with contaminated surfaces or infectious agents dispersed by air currents in the manufacturing environment. An environmental monitoring program (EMP) is a critical aspect of sustainable and safe food manufacturing used to evaluate the effectiveness of the microbial controls in place. An effective EMP should be based on risk analysis, taking into account previous sampling history to determine the selection of the sampling points, the scope of the test, and the frequency of analysis. This study involved evaluation of the environmental monitoring regime and microbiological status of a medium-sized dairy plant manufacturing food ingredients, e.g., proteins, milk powders, and dairy fats. The data specific to microbial tests ( n = 3,468), recorded across 124 fixed sampling locations over a 2-year period (2014 to 2015) from air ( n = 1,787) and surfaces ( n = 1,681) were analyzed. The aim of this study was to highlight the strengths and weaknesses of the EMP in a select dairy processing plant. The results of this study outline the selection of sampling locations, the scope of the test, and the frequency of analysis. An analysis of variance revealed subsections of the manufacturing areas with high risk factors, especially the packaging subsection specified for bulk packaging, the atomizer, and the fluidized bed. The temporal and spatial analysis showed the potential to reduce or relocate the monitoring effort, most notably related to total coliforms and Staphylococcus aureus, across the dairy plant due to homogeneity across the sampling subsections with little or no deviations. The results suggest a need to reevaluate the current EMP and the corrective action plan, especially with regard to detection of pathogens. Recommendations for optimization of the EMP are presented to assist the dairy industry with reviewing and revising the control measures and hazard assessment with regard to existing contamination issues.

Kinetics of Inactivation of Bacillus subtilis subsp. niger Spores and Staphylococcus albus on Paper by Chlorine Dioxide Gas in an Enclosed Space

Bacillus subtilis subsp. niger spore and Staphylococcus albus are typical biological indicators for the inactivation of airborne pathogens. The present study characterized and compared the behaviors of B. subtilis subsp. niger spores and S. albus in regard to inactivation by chlorine dioxide (ClO2) gas under different gas concentrations and relative humidity (RH) conditions. The inactivation kinetics under different ClO2 gas concentrations (1 to 5 mg/liter) were determined by first-order and Weibull models. A new model (the Weibull-H model) was established to reveal the inactivation tendency and kinetics for ClO2 gas under different RH conditions (30 to 90%). The results showed that both the gas concentration and RH were significantly (P < 0.05) and positively correlated with the inactivation of the two chosen indicators. There was a rapid improvement in the inactivation efficiency under high RH (>70%). Compared with the first-order model, the Weibull and Weibull-H models demonstrated a better fit for the experimental data, indicating nonlinear inactivation behaviors of the vegetative bacteria and spores following exposure to ClO2 gas. The times to achieve a six-log reduction of B. subtilis subsp. niger spore and S. albus were calculated based on the established models. Clarifying the kinetics of inactivation of B. subtilis subsp. niger spores and S. albus by ClO2 gas will allow the development of ClO2 gas treatments that provide an effective disinfection method.

IMPORTANCE

Chlorine dioxide (ClO2) gas is a novel and effective fumigation agent with strong oxidization ability and a broad biocidal spectrum. The antimicrobial efficacy of ClO2 gas has been evaluated in many previous studies. However, there are presently no published models that can be used to describe the kinetics of inactivation of airborne pathogens by ClO2 gas under different gas concentrations and RH conditions. The first-order and Weibull (Weibull-H) models established in this study can characterize and compare the behaviors of Bacillus subtilis subsp. niger spores and Staphylococcus albus in regard to inactivation by ClO2 gas, determine the kinetics of inactivation of two chosen strains under different conditions of gas concentration and RH, and provide the calculated time to achieve a six-log reduction. These results will be useful to determine effective conditions for ClO2 gas to inactivate airborne pathogens in contaminated air and other environments and thus prevent outbreaks of airborne illness.

Response surface modeling for the inactivation of Bacillus subtilis subsp. niger spores by chlorine dioxide gas in an enclosed space

Bacillus subtilis subsp. niger spores are a commonly used biological indicator to evaluate the disinfection of an enclosed space. In the present study, chlorine dioxide (ClO2) gas was applied to inactivate B. subtilis subsp. niger spores in an enclosed space. The effects of the ClO2 gas concentration (1-3 mg/l), relative humidity (RH, 30-70%) and exposure time (30-90 min) were investigated using a response surface methodology (RSM). A three-factor Box-Behnken experimental design was used. The obtained data were adequately fitted to a second-order polynomial model with an R2adj of 0.992. The ClO2 gas concentration, RH and exposure time all significantly (P<0.05) and positively correlated with the inactivation of B. subtilis subsp. niger spores. The interaction between the ClO2 gas concentration and RH as well as that between the exposure time and RH indicated significant and synergistic effects (P<0.05). The predictive model was validated by additional eight experiments and proven to be with good accuracy. Overall, this model established by the RSM could show the trend of the inactivation of spores, indicate the interactions between important factors, and provide a reference to determine effective conditions for the disinfection in different enclosed spaces by ClO2 gas.

IMPLICATIONS

The inactivation of indoor biological contaminants plays an important role in preventing the transmission of pathogens and ensuring human safety. The predictive model using response surface methodology indicates the influence and interaction of the main factors on the inactivation of Bacillus subtilis subsp. niger spores by ClO2 gas, and can predict a ClO2 gas treatment condition to achieve an effective sterilization of enclosed spaces. The results in this paper will provide a reference for the application of ClO2 gas treatments for indoor disinfection.

Decontamination of a hospital room using gaseous chlorine dioxide: Bacillus anthracis, Francisella tularensis, and Yersinia pestis

This study assessed the efficacy of gaseous chlorine dioxide for inactivation of Bacillus anthracis, Francisella tularensis, and Yersinia pestis in a hospital patient care suite. Spore and vegetative cells of Bacillus anthracis Sterne 34F2, spores of Bacillus atrophaeus ATCC 9372 and vegetative cells of both Francisella tularensis ATCC 6223 and Yersinia pestis A1122 were exposed to gaseous chlorine dioxide in a patient care suite. Organism inactivation was then assessed by log reduction in viable organisms postexposure to chlorine dioxide gas compared to non-exposed control organism. Hospital room decontamination protocols utilizing chlorine dioxide gas concentrations of 377 to 385 ppm maintained to exposures of 767 ppm-hours with 65% relative humidity consistently achieved complete inactivation of B. anthracis and B. atrophaeus spores, as well as vegetative cells of B. anthracis, F. tularensis, and Y. pestis. Decrease in exposure (ppm-hours) and relative humidity (<65%) or restricting airflow reduced inactivation but achieved >8 log reductions in organisms. Up to 10-log reductions were achieved in a hospital room with limited impact on adjacent areas, indicating chlorine dioxide concentrations needed for decontamination of highly concentrated (>6 logs) organisms can be achieved throughout a hospital room. This study translates laboratory chlorine dioxide fumigation studies applied in a complex clinical environment.

Challenges and Practices in Building and Implementing Biosafety and Biosecurity Programs to Enable Basic and Translational Research with Select Agents

Select agent research in the United States must meet federally-mandated biological surety guidelines and rules which are comprised of two main components: biosecurity and biosafety. Biosecurity is the process employed for ensuring biological agents are properly safeguarded against theft, loss, diversion, unauthorized access or use/release. Biosafety is those processes that ensure that operations with such agents are conducted in a safe, secure and reliable manner. As such, a biological surety program is generally concerned with biological agents that present high risk for adverse medical and/or agricultural consequences upon release outside of proper containment. The U.S. Regional and National Biocontainment Laboratories (RBL, NBL) represent expertise in this type of research, and are actively engaged in the development of programs to address these critical needs and federal requirements. While this comprises an ongoing activity for the RBLs, NBLs and other facilities that handle select agents as new guidelines and regulations are implemented, the present article is written with the goal of presenting a simplified yet comprehensive review of these requirements. Herein, we discuss the requirements and the various activities that the RBL/NBL programs have implemented to achieve these metrics set forth by various agencies within the U.S. Federal government.