Analysis of Expedient Field Decontamination Methods for the XMX/2L-MIL High-Volume Aerosol Sampler

The XMX/2L-MIL is a high volume air sampler used by the Air Force Bioenvironmental Engineering community to collect biological aerosols. Without a verified decontamination technique, however, the XMX cannot be used effectively. The objective of this study was to evaluate several proposed methods for expedient field decontamination of the XMX. This study centered on the inactivation of Bacillus atrophaeus spores and vegetative Erwinia herbicola organisms from the XMX inner canister. The goals in this investigation were twofold: 1) to verify the antimicrobial efficacy of a 10% bleach solution and 2) to determine if wiping the components with a bleach-soaked paper towel or submerging the components directly in the bleach solution represents the optimal decontamination procedure. Data was gathered at the Dycor Technologies facility located in Edmonton, Alberta, Canada. Their Aerosol Test Chamber was used to disseminate the surrogate agents and then sample the aerosol using three XMX devices. Counts of the microbial population were calculated at each stage of the procedure to assess the efficacy of the two proposed methods. It was observed that 10% bleach solutions resulted in approximately 102-fold decreases in aggregate microbial contamination on XMX components. Of the methods tested, the submersion in a 10% bleach solution plus a 15-minute air purge showed the most efficiency. Contamination levels were consistent between all three devices during the trial and were measured at or below background levels after decontamination

Inactivation of Airborne Bacteria by Direct Interaction with Non-Thermal Dielectric Barrier Discharge Plasma: The Involvement of Reactive Oxygen Species

The present study examined the effect of Dielectric Barrier Discharge (DBD) plasma on bioaerosol particles. Different DBD plasma devices were designed and tested for their efficacy in inactivation of airborne bacteria. Bacterial aerosols were injected in / through the plasma stream and the treated bioaerosols were analyzed. The results indicated a complete inactivation of bioaerosol upon a very short exposure in the range of milliseconds to plasma discharge. A large system was designed to evaluate its efficacy to inactivate bacterial spores. After preliminary studies, to study the underlying mechanisms of inactivation, a single filament DBD plasma generating probe was developed and used for subsequent studies. In parallel, a near uniform aerosol generator (nebulizer) was optimized, and aerosol particle size characterized. The kinetics of bacterial inactivation produced by this system was investigated, and sub-lethal dose determined. We hypothesized that the prototype bacteria, Escherichia coli when present in aerosols and exposed to single filament DBD plasma system, activates intracellular reactive oxygen species (ROS). The predetermined sub-lethal dose of DBD plasma was used to study the cellular responses of Escherichia coli during its inactivation. Cell membrane is more vulnerable when bacteria are present in aerosols, and hence the changes in features, such as cellular respiration and growth, permeation, and depolarization were investigated following exposure to single filament DBD plasma system. During studies, the catalase mediated defense system was found to be involved predominantly in the management of intracellular ROS pool. Through the use of E. coli derivatives of specific gene mutation, we analyzed the involvement of heat stress-responsive genes. Although the plasma is considered non-thermal, localized heating and the generated interactive stress is likely involved in the inactivation of E. coli bioaerosol. These findings provide a new dimension in underlying mechanisms of E. coli inactivation during DBD plasma exposure.Ph.D., Biomedical Engineering -- Drexel University, 201

Medical Microbiology, Virology & Immunology

УЧЕБНЫЕ ПОСОБИЯМИКРОБИОЛОГИЯВИРУСОЛОГИЯИММУНОЛОГИЯАЛЛЕРГОЛОГИЯ И ИММУНОЛОГИЯВ пособие включены разделы по общей микробиологии и медицинской иммунологии

Decontamination of bioaerosols within engineering tolerances of aircraft materials

2012 Fall.Includes bibliographical references.To view the abstract, please see the full text of the document

Inside or Out: Characterizing petrobactin use by Bacillus anthracis

Bacillus anthracis is a Gram-positive, spore-forming bacillus and causes the disease anthrax. Anthrax is a deadly infection that begins with phagocytosis of a B. anthracis spore by an antigen presenting cell and ends when bacilli-laden blood from the carcass is exposed to oxygen, which initiates sporulation. Each step in the infection process requires access to nutrients, including iron. Iron is required as a protein co-factor for many different cellular processes but is also tightly regulated within organisms, including both the mammalian host and the bacterium. To gather iron during infection, B. anthracis employs a heme acquisition system as well as two siderophores, petrobactin and bacillibactin. Of these three systems, only petrobactin is required for growth in iron-deplete medium, macrophages, and to cause disease in mouse models of infection. Chapter one describes what is understood about petrobactin including biosynthesis by the asb operon, regulation of biosynthesis, how the ferric-petrobactin complex is imported, and relevance to disease. I also highlight remaining questions such as how petrobactin is exported from the cell and its role in spore biology. In chapter two, I describe my work identifying the petrobactin exporter ApeX. Using a bioinformatics-based protocol to identify putative targets for petrobactin export, I generated single deletion mutants. Laser ablation electrospray ionization mass spectroscopy (LAESI-MS) was adapted to screen for deletion mutants that failed to export petrobactin, enabling identification of ApeX as a petrobactin exporter. An apeX deletion mutant unable to export petrobactin, instead accumulated the molecule within the cell pellet and exported components. These petrobactin components are still able to transport iron and cause disease in a mouse model of inhalational anthrax. I also used LAESI-MS in chapter three to detect petrobactin within B. anthracis spores and explore the role of petrobactin in spore biology. Petrobactin is not required for germination from the spore, but is required for rapid sporulation in the iron-rich ModG sporulation medium. Fluorescent reporters show induction of the asb operon during late stage growth and early sporulation. This phenotype is likely relevant to disease transmission since experiments in defibrinated bovine blood demonstrate that petrobactin is the preferred iron acquisition system during growth in blood and is required for sporulation in aerated blood. Chapter four offers hypotheses and suggestions for how to answer remaining questions not addressed by the research done in this work. I also make hypotheses regarding alternative, non-iron-scavenging functions for petrobactin and discuss the future potential for LAESI-MS as a research tool.PHDMicrobiology & ImmunologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/144141/1/akhagan_1.pd

Disinfection of Viruses

Each of the chapters in Disinfection of Viruses touches on virucidal efficacy for SARS-CoV-2, the causative agent for the COVID-19 disease, or enveloped viral surrogates. SARS-CoV-2 is an enveloped virus of the Coronaviridae family and therefore is expected to be susceptible to all classes of microbicides. The book is divided into three sections. Section 1: “Microbicides for Viral Inactivation,” includes chapters on the efficacy of chemical virucides, Section 2: “Physical Inactivation Approaches,” includes a chapter on the efficacy of gamma irradiation, ultraviolet light, and heat for inactivating coronaviruses, and Section 3: “Viral Persistence and Disinfection,” includes data on viral persistence for SARS-CoV-2, as these data inform the need for and the approaches that might be used for disinfection

Clinical Laboratory Biosafety Gaps: Lessons Learned from Past Outbreaks Reveal a Path to a Safer Future

Review articleBiosafety gaps found during the 2014 Ebola Outbreak202134105993PMC82628061151

The use of dioxy MP 14 (stabilized aqueous chlorine dioxide) to control environmental airborne microorganisms

Magister Pharmaceuticae - MPharmDioxy MP 14 is a locally developed form of stabilized chlorine dioxide in an aqueous medium. It has all the sanitizing properties of chlorine dioxide gas, a neutral compound of chlorine in the +IV oxidation state, which has been used extensively as a non-toxic sterilizing agent with various applications. In this study, Dioxy MP14 was tested in a commercial chicken pen to determine its effectiveness as an environmental sanitizing agent. Control of environmental microbes in a chicken pen is important to ensure healthy birds and optimum egg production. The biocide was introduced via an overhead misting system with a variable dosing pump at various daily frequencies.The effectiveness of environmental microorganism control was determined with air settle plates. The health and performance of the chickens were evaluated and compared to chickens in a control pen.The results show a decrease in airborne microbial load in the treated pen. Better egg production and lower mortality of the chickens in the treated pen compared to the control pen, indicate effective environmental microbial control was achieved with a residual 7.46 ppm Dioxy MP 14 at a daily dose given for 5 minutes every 2 hours.This study was a pilot study, with encouraging results, for an extended study to investigate the feasibility of introducing Dioxy MP 14 through a misting system in a clinical environment (clinics and hospitals) to control airborne pathogens like Mycobacterium tuberculosis thereby reducing the infection risks for clinical workers and medical staff

Advances in Sterilization and Decontamination: a Survey

Recent technical advances made in the field of sterilization and decontamination and their applicability to private and commercial interests are discussed. Government-sponsored programs by NASA produced the bulk of material presented in this survey. The summary of past and current research discussed is detailed to enhance an effective transfer of technology from NASA to potential users

Guideline for disinfection and sterilization in healthcare facilities, 2008. Update: May 2019

The Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008, presents evidencebased recommendations on the preferred methods for cleaning, disinfection and sterilization of patientcare medical devices and for cleaning and disinfecting the healthcare environment. This document supercedes the relevant sections contained in the 1985 Centers for Disease Control (CDC) Guideline for Handwashing and Environmental Control. Because maximum effectiveness from disinfection and sterilization results from first cleaning and removing organic and inorganic materials, this document also reviews cleaning methods. The chemical disinfectants discussed for patient-care equipment include alcohols, glutaraldehyde, formaldehyde, hydrogen peroxide, iodophors, ortho-phthalaldehyde, peracetic acid, phenolics, quaternary ammonium compounds, and chlorine. The choice of disinfectant, concentration, and exposure time is based on the risk for infection associated with use of the equipment and other factors discussed in this guideline. The sterilization methods discussed include steam sterilization, ethylene oxide (ETO), hydrogen peroxide gas plasma, and liquid peracetic acid. When properly used, these cleaning, disinfection, and sterilization processes can reduce the risk for infection associated with use of invasive and noninvasive medical and surgical devices. However, for these processes to be effective, health-care workers should adhere strictly to the cleaning, disinfection, and sterilization recommendations in this document and to instructions on product labels.In addition to updated recommendations, new topics addressed in this guideline include1. inactivation of antibiotic-resistant bacteria, bioterrorist agents, emerging pathogens, and bloodborne pathogens;2. toxicologic, environmental, and occupational concerns associated with disinfection andsterilization practices;3. disinfection of patient-care equipment used in ambulatory settings and home care;4. new sterilization processes, such as hydrogen peroxide gas plasma and liquid peracetic acid; and5. disinfection of complex medical instruments (e.g., endoscopes).This guideline discusses use of products by healthcare personnel in healthcare settings such as hospitals, ambulatory care and home care; the recommendations are not intended for consumer use of the products discussed.disinfection-guidelines-H.pd