Jonathan D. Sexton

Reduction in the microbial load on high-touch surfaces in hospital rooms by treatment with a portable saturated steam vapor disinfection system

BACKGROUND Recent scientific literature suggests that portable steam vapor systems are capable of rapid, chemical-free surface disinfection in controlled laboratory studies. This study evaluated the efficacy of a portable steam vapor system in a hospital setting. METHODS The study was carried out in 8 occupied rooms of a long-term care wing of a hospital. Six surfaces per room were swabbed before and after steam treatment and analyzed for heterotrophic plate count (HPC), total coliforms, methicillin-intermediate and -resistant Staphylococcus aureus (MISA and MRSA), and Clostridium difficile. RESULTS The steam vapor device consistently reduced total microbial and pathogen loads on hospital surfaces, to below detection in most instances. Treatment reduced the presence of total coliforms on surfaces from 83% (40/48) to 13% (6/48). Treatment reduced presumptive MISA (12/48) and MRSA (3/48) to below detection after cleaning, except for 1 posttreatment isolation of MISA (1/48). A single C difficile colony was isolated from a door push panel before treatment, but no C difficile was detected after treatment. CONCLUSION The steam vapor system reduced bacterial levels by >90% and reduced pathogen levels on most surfaces to below the detection limit. The steam vapor system provides a means to reduce levels of microorganisms on hospital surfaces without the drawbacks associated with chemicals, and may decrease the risk of cross-contamination.

Opto-electrophoretic detection of bio-molecules using conducting chalcogenide glass sensors

Novel telluride glasses with high electrical conductivity, wide infrared transparency and good resistance to crystallization are used to design an opto-electrophoretic sensor for detection and identification of hazardous microorganisms. The sensor is based on an attenuated total reflectance element made of Ge-As-Te glass that serves as both an optical sensing zone and an electrode for driving the migration of bio-molecules within the evanescent wave of the sensor. An electric field is applied between the optical element and a counter electrode in order to induce the migration of bio-molecules carrying surface charges. The effect of concentration and applied voltage is tested and the migration effect is shown to be reversible upon switching the electric field. The collected signal is of high quality and can be used to identify different bacterial genus through statistical spectral analysis. This technique therefore provides the ability to detect hazardous microorganisms with high specificity and high sensitivity in aqueous environments. This has great potential for online monitoring of water quality.

Impact of disinfectant wipes on the risk of Campylobacter jejuni infection during raw chicken preparation in domestic kitchens.

In the present study, we conducted a quantitative microbial risk assessment forecasting the exposure to Campylobacter jejuni contaminated surfaces during preparation of chicken fillets and how using a disinfectant‐wipe intervention to clean a contaminated work area decreases the risk of infection following the preparation of raw chicken fillet in a domestic kitchen.

Modeling Surface Disinfection Needs To Meet Microbial Risk Reduction Targets

It is known that the use of EPA-registered surface disinfectant sprays can reduce infection risk if used according to the manufacturers instructions. However, there are currently no standards for health care environments related to contamination levels on surfaces. The significance of this research is in quantifying needed reductions to meet various risk targets using realistic viral concentrations on surfaces for health care environments. This research informs the design of cleaning protocols by demonstrating that multiple applications may be needed to reduce risk and by highlighting a need for more models exploring the relationship among microbial contamination of surfaces, patient and health care worker behaviors, and infection risks. ABSTRACT Nosocomial viral infections are an important cause of health care-acquired infections where fomites have a role in transmission. Using stochastic modeling to quantify the effects of surface disinfection practices on nosocomial pathogen exposures and infection risk can inform cleaning practices. The purpose of this study was to predict the effect of surface disinfection on viral infection risks and to determine needed viral reductions to achieve risk targets. Rotavirus, rhinovirus, and influenza A virus infection risks for two cases were modeled. Case 1 utilized a single fomite contact approach, while case 2 assumed 6 h of contact activities. A 94.1% viral reduction on surfaces and hands was measured following a single cleaning round using an Environmental Protection Agency (EPA)-registered disinfectant in an urgent care facility. This value was used to model the effect of a surface disinfection intervention on infection risk. Risk reductions for other surface-cleaning efficacies were also simulated. Surface reductions required to achieve risk probability targets were estimated. Under case 1 conditions, a 94.1% reduction in virus surface concentration reduced infection risks by 94.1%. Under case 2 conditions, a 94.1% reduction on surfaces resulted in median viral infection risks being reduced by 92.96 to 94.1% and an influenza A virus infection risk below one in a million. Surface concentration in the equations was highly correlated with dose and infection risk outputs. For rotavirus and rhinovirus, a >99.99% viral surface reduction would be needed to achieve a one-in-a-million risk target. This study quantifies reductions of infection risk relative to surface disinfectant use and demonstrates that risk targets for low-infectious-dose organisms may be more challenging to achieve. IMPORTANCE It is known that the use of EPA-registered surface disinfectant sprays can reduce infection risk if used according to the manufacturers instructions. However, there are currently no standards for health care environments related to contamination levels on surfaces. The significance of this research is in quantifying needed reductions to meet various risk targets using realistic viral concentrations on surfaces for health care environments. This research informs the design of cleaning protocols by demonstrating that multiple applications may be needed to reduce risk and by highlighting a need for more models exploring the relationship among microbial contamination of surfaces, patient and health care worker behaviors, and infection risks.

Microbial transmission in an outpatient clinic and impact of an intervention with an ethanol-based disinfectant

Background: Halting the spread of harmful microbes requires an understanding of their transmission via hands and fomites. Previous studies explored acute and long‐term care environments but not outpatient clinics. Objectives of this study were to track microbial movement throughout an outpatient clinic and evaluate the impact of a disinfectant spray intervention targeting high‐touch point surfaces. Methods: At the start of the clinic day, a harmless viral tracer was placed onto 2 fomites: a patient room door handle and front desk pen. Patient care, cleaning, and hand hygiene practices continued as usual. Facility fomites (n=19), staff hands (n=4), and patient hands (n=3–4) were sampled after 2, 3.5, and 6 hours. Tracer concentrations at baseline (before intervention) were evaluated 6 hours after seeding. For the intervention trials, high‐touch surfaces were cleaned 4 hours after seeding with an ethanol‐based disinfectant and sampled 2 hours after cleaning. Results: At 2, 3.5, and 6 hours after seeding, virus was detected on all surfaces and hands sampled, with examination room door handles and nurses’ station chair arms yielding the highest concentrations. Virus concentrations decreased by 94.1% after the disinfectant spray intervention (P=.001). Conclusions: Microbes spread quickly in an outpatient clinic, reaching maximum contamination levels 2 hours after inoculation, with the highest contamination on examination room door handles and nurses’ station chairs. This study emphasizes the importance of targeted disinfection of high‐touch surfaces.

Recreational water contamination

In this chapter we present an exchange systems approach to evaluate the potential of water markets to provide sustainable and equitable access for all. The approach is sourced from marketing theory, which in turn is constructed on a social exchange and general systems theory platform (Bagozzi, 1978; Layton, 2007). The exchange systems concept offers a systemic view of exchange that allows for the integration of broader economic and social considerations into the design of water markets. We illustrate different types of exchange systems to offer the reader a broader perspective on water markets. Such a perspective can enable new thinking in how water provision systems can contribute to improved human health. We begin with a general introduction to the marketing exchange concept and subsequently trace its evolution to exchange systems.

Detection of bio-molecules using conductive chalcogenide glass sensor

Novel telluride glasses with high electrical conductivity, wide infrared transparency and good resistance to crystallization are used to design an opto-electrophoretic sensor for detection and identification of hazardous microorganisms. The sensor is based on an attenuated total reflectance element made of Ge-As-Te glass that serves as both an optical sensing zone and an electrode for driving the bio-molecules within the evanescent wave of the sensor. An electric field is applied between the optical element and a counter electrode in order to induce the migration of bio-molecules carrying surface charges. The effect of concentration and applied voltage is tested and the migration effect is shown to be reversible upon switching the electric field. The collected signal is of high quality and can be used to identify different bio-molecules through spectral analysis. This technique therefore provides the ability to detect hazardous microorganisms with high specificity and good sensitivity in aqueous environments.