Miniature microwave powered steam sterilization chamber

Atwater, James E.; Dahl, Roger W.; Garmon, Frank C.; Lunsford, Teddie D.; Michalek, William F.; Wheeler, Richard R.; Sauer, Richard L.

doi:10.1063/1.1148059

Cited by 9 publications

(5 citation statements)

References 1 publication

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“…Sodium hypochlorite disinfection has been well (7,13,22,(25)(26)(27)(28)38). Steam treatment is also a well-known method for inactivating viruses on surfaces (6,14,16,26,31). However, typical steam sterilization requires the use of an autoclave which utilizes pressurized steam at 121°C, which was shown previously to have a deleterious effect on FFR performance (36).…”

Section: Discussionmentioning

confidence: 99%

Development of a Test System To Apply Virus-Containing Particles to Filtering Facepiece Respirators for the Evaluation of Decontamination Procedures

Fisher

Rengasamy

Viscusi

et al. 2009

Appl Environ Microbiol

132

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A chamber to apply aerosolized virus-containing particles to air-permeable substrates (coupons) was constructed and validated as part of a method to assess the virucidal efficacy of decontamination procedures for filtering facepiece respirators. Coliphage MS2 was used as a surrogate for pathogenic viruses for confirmation of the efficacy of the bioaerosol respirator test system. The distribution of virus applied onto and within the coupons was characterized, and the repeatability of applying a targeted virus load was examined. The average viable virus loaded onto 90 coupons over the course of 5 days was found to be 5.09 ؎ 0.19 log 10 PFU/coupon (relative standard deviation, 4%). To determine the ability to differentiate the effectiveness of disinfecting procedures with different levels of performance, sodium hypochlorite and steam treatments were tested in experiments by varying the dose and time, respectively. The role of protective factors was assessed by aerosolizing the virus with various concentrations of the aerosol-generating medium. A sodium hypochlorite (bleach) concentration of 0.6% and steam treatments of 45 s and longer resulted in log reductions (>4 logs) which reached the detection limits for both levels of protective factors. Organic matter (ATCC medium 271) as a protective factor afforded some protection to the virus in the sodium hypochlorite experiments but was not a factor in the steam experiments. The evaluation of the bioaerosol respirator test system demonstrated a repeatable method for applying a targeted viral load onto respirator coupons and provided insight into the properties of aerosols that are of importance to the development of disinfection assays for air-permeable materials.

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Section: Discussionmentioning

confidence: 99%

Development of a Test System To Apply Virus-Containing Particles to Filtering Facepiece Respirators for the Evaluation of Decontamination Procedures

Fisher

Rengasamy

Viscusi

et al. 2009

Appl Environ Microbiol

132

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“…The use of microwave radiation for bacterial killing is particularly appealing for sterilization of hospital waste (Pellerin 1994; Tata and Beone 1995; Atwater et al. 1997; Sasaki et al.…”

Section: Introductionmentioning

confidence: 99%

Effect of microwave radiation on Bacillus subtilis spores

Celandroni¹,

Longo

Tosoratti

et al. 2004

J Appl Microbiol

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Aims:To compare the killing efficacy and the effects exerted by microwaves and conventional heating on structural and molecular components of Bacillus subtilis spores. Methods and Results: A microwave waveguide applicator was developed to generate a uniform and measurable distribution of the microwave electric-field amplitude. The applicator enabled the killing efficacy exerted by microwaves on B. subtilis spores to be evaluated in comparison with conventional heating at the same temperature value. The two treatments produced a similar kinetics of spore survival, while remarkably different effects on spore structures were seen. The cortex layer of the spores subjected to conductive heating was 10 times wider than that of the untreated spores; in contrast, the cortex of irradiated spores did not change. In addition, the heated spores were found to release appreciable amounts of dipicolinic acid (DPA) upon treatment, while extracellular DPA was completely undetectable in supernatants of the irradiated spores. These observations suggest that microwave radiation may promote the formation of stable complexes between DPA and other spore components (i.e. calcium ions); thus, making any release of DPA from irradiated spores undetectable. Indeed, while a decrease in measurable DPA concentrations was not produced by microwave radiation on pure DPA solutions, a significant lowering in DPA concentration was detected when this molecule was exposed to microwaves in the presence of either calcium ions or spore suspensions. Conclusions: Microwaves are as effective as conductive heating in killing B. subtilis spores, but the microwave E-field induces changes in the structural and/or molecular components of spores that differ from those attributable only to heat. Significance and Impact of the Study: This study provides information on the effect of microwaves on B. subtilis spore components.

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“…To confirm the efficacy of sterilization under these conditions, a variety of microbial challenges was conducted. Prior to integration of the sterilization chamber into the MSAP device a series of tests was performed using PTFE coupons mounted directly inside the chamber (6). The coupons were contaminated with ∼10 6 colony forming units (CFU) of B. stearothermophilus.…”

Section: Resultsmentioning

confidence: 99%

“…ln τ ≈ 33.90 -0.2535T (6) within a microbially vulnerable system, a closed sterile recirculating loop containing 20 mL of SYE broth was attached to the MSAP. The recirculating loop was prepared using a 25 mm × 150 mm glass culture tube connected to MSAP inlet and outlet ports via 0.32 cm i.d.…”

Section: Resultsmentioning

confidence: 99%

“…Power is transferred to the sterilization chamber via shielded coaxial cable. The design of the sterilization chamber has been described in a previous publication (6). It consists of a small hollow aluminum block with an internal volume containing a SiC ceramic monolith in which the antenna is mounted.…”

Section: Microwave-sterilizable Access Port (Msap) Design and Operationmentioning

confidence: 99%

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A Microwave-Powered Sterilizable Interface for Aseptic Access to Bioreactors That Are Vulnerable to Microbial Contamination

et al. 2001

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Novel methods and apparatus that employ the rapid heating characteristics of microwave irradiation to facilitate the aseptic transfer of nutrients, products, and other materials between microbially sensitive systems and the external environment are described. The microwave-sterilizable access port (MSAP) consists of a 600-W magnetron emitting at a frequency of 2.45 GHz, a sterilization chamber with inlet and outlet flow lines, and a specimen transfer interface. Energy is routed to the sterilization chamber via a coaxial transmission line where small quantities of water couple strongly with the incident radiation to produce a superheated vapor phase. The efficiency of energy transfer is enhanced through the use of microwave susceptors within the sterilization chamber. Mating surfaces are thermally sterilized through direct contact with the hot gas. Efficacy has been demonstrated using the thermophile Bacillus stearothermophilus.

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Miniature microwave powered steam sterilization chamber

Cited by 9 publications

References 1 publication

Development of a Test System To Apply Virus-Containing Particles to Filtering Facepiece Respirators for the Evaluation of Decontamination Procedures

Development of a Test System To Apply Virus-Containing Particles to Filtering Facepiece Respirators for the Evaluation of Decontamination Procedures

Effect of microwave radiation on Bacillus subtilis spores

A Microwave-Powered Sterilizable Interface for Aseptic Access to Bioreactors That Are Vulnerable to Microbial Contamination

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