The bactericidal effect of microwaves on Mycobacterium bovis dried on scalpel blades

Enhancing Staphylococcus aureus sterilization of stainless steel by the synergistic effect of surface structure and physical washing

Staphylococcus aureus infection is common in the clinical environment. It has been shown that the presence of micro/nano structures on material surfaces promote bacterial adhesion resistance. Herein, we assessed the S. aureus adhesion properties on laser micro/nano structured stainless-steel (316 L) surfaces after mechanical rotation and ultrasonic washing. The interaction force between S. aureus and structured surfaces was evaluated. A high concentration S. aureus solution was used to evaluate the bacterial sterilization efficiency after film formation on the stainless-steel surface. After 24 h of incubation, S. aureus films were formed on material surfaces. The comparison of static washing, surface mechanical rotation, and ultrasonic washing showed a decrease of S. aureus adhesion on the polished and laser induced periodic surface structures. However, S. aureus adhesion on the micro/nanoparticle surface after mechanical rotation washing did not display any obvious change compared to the polished one. Additionally, specimens after ultrasonic cleaning showed clear antibacterial adhesion than mechanical rotation. After the ultrasonic sterilization process, the laser induced periodic laser surface sample showed optimal bacterial adhesion inhibition. Finally, in vitro tests showed that the biocompatibility of the laser-induced structured surface did not change significantly from the polished surface one.

Nebuliser hygiene in cystic fibrosis: evidence-based recommendations

Nebulised therapies are extensively used in the daily therapeutic management of cystic fibrosis both for mucociliary clearance and for the management of chronic infections. Extensive developments have been made in relation to nebulised drug delivery mechanisms and drug formulations, and guidelines have been prepared that have addressed the appropriate use of such therapies. However, due to these developments, a plethora of nebuliser devices and drug chambers exist, and frequently, the limited guidance provided in relation to nebuliser hygiene is to follow manufacturers' instructions. Such instructions are inconsistent and at times confusing, translating to an increase in the burden associated with nebuliser maintenance. An evidence-based universal guideline relating to nebuliser care and hygiene is urgently required that is applicable to both at-home use and inpatient use. This article reviews the scientific literature in order to propose an evidence-based approach to nebuliser hygiene to ensure optimum drug delivery, and infection prevention and control.

EDUCATIONAL AIMS

To understand the reasons why nebuliser hygiene is important.To give an overview of the current nebuliser care instructions that have been described by manufacturers, societies and the scientific literature.To outline the current nebuliser hygiene practices used by persons with cystic fibrosis in the home and hospital settings.To highlight areas that need further evaluation to promote optimum nebuliser care.To establish an evidence-based guideline for nebuliser hygiene in relation to cystic fibrosis.

Infection Prevention and Control Guideline for Cystic Fibrosis: 2013 Update

The 2013 Infection Prevention and Control (IP&C) Guideline for Cystic Fibrosis (CF) was commissioned by the CF Foundation as an update of the 2003 Infection Control Guideline for CF. During the past decade, new knowledge and new challenges provided the following rationale to develop updated IP&C strategies for this unique population:

1.The need to integrate relevant recommendations from evidence-based guidelines published since 2003 into IP&C practices for CF. These included guidelines from the Centers for Disease Control and Prevention (CDC)/Healthcare Infection Control Practices Advisory Committee (HICPAC), the World Health Organization (WHO), and key professional societies, including the Infectious Diseases Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA). During the past decade, new evidence has led to a renewed emphasis on source containment of potential pathogens and the role played by the contaminated healthcare environment in the transmission of infectious agents. Furthermore, an increased understanding of the importance of the application of implementation science, monitoring adherence, and feedback principles has been shown to increase the effectiveness of IP&C guideline recommendations.

2.Experience with emerging pathogens in the non-CF population has expanded our understanding of droplet transmission of respiratory pathogens and can inform IP&C strategies for CF. These pathogens include severe acute respiratory syndrome coronavirus and the 2009 influenza A H1N1. Lessons learned about preventing transmission of methicillin-resistantStaphylococcus aureus(MRSA) and multidrug-resistant gram-negative pathogens in non-CF patient populations also can inform IP&C strategies for CF.

Thermal and nonthermal effects of discontinuous microwave exposure (2.45 gigahertz) on the cell membrane of Escherichia coli

The aim of this study was to investigate the effects on the cell membranes of Escherichia coli of 2.45-GHz microwave (MW) treatment under various conditions with an average temperature of the cell suspension maintained at 37°C in order to examine the possible thermal versus nonthermal effects of short-duration MW exposure. To this purpose, microwave irradiation of bacteria was performed under carefully defined and controlled parameters, resulting in a discontinuous MW exposure in order to maintain the average temperature of the bacterial cell suspensions at 37°C. Escherichia coli cells were exposed to 200- to 2,000-W discontinuous microwave (DW) treatments for different periods of time. For each experiment, conventional heating (CH) in a water bath at 37°C was performed as a control. The effects of DW exposure on cell membranes was investigated using flow cytometry (FCM), after propidium iodide (PI) staining of cells, in addition to the assessment of intracellular protein release in bacterial suspensions. No effect was detected when bacteria were exposed to conventional heating or 200 W, whereas cell membrane integrity was slightly altered when cell suspensions were subjected to powers ranging from 400 to 2,000 W. Thermal characterization suggested that the temperature reached by the microwave-exposed samples for the contact time studied was not high enough to explain the measured modifications of cell membrane integrity. Because the results indicated that the cell response is power dependent, the hypothesis of a specific electromagnetic threshold effect, probably related to the temperature increase, can be advanced.

Microwave or autoclave treatments destroy the infectivity of infectious bronchitis virus and avian pneumovirus but allow detection by reverse transcriptase-polymerase chain reaction

A method is described for enabling safe transit of denatured virus samples for polymerase chain reaction (PCR) identification without the risk of unwanted viable viruses. Cotton swabs dipped in avian infectious bronchitis virus (IBV) or avian pneumovirus (APV) were allowed to dry. Newcastle disease virus and avian influenza viruses were used as controls. Autoclaving and microwave treatment for as little as 20 sec destroyed the infectivity of all four viruses. However, both IBV and APV could be detected by reverse transcriptase (RT)-PCR after autoclaving and as long as 5 min microwave treatment (Newcastle disease virus and avian influenza viruses were not tested). Double microwave treatment of IBV and APV with an interval of 2 to 7 days between was tested. After the second treatment, RT-PCR products were readily detected in all samples. Swabs from the tracheas and cloacas of chicks infected with IBV shown to contain infectious virus were microwaved. Swabs from both sources were positive by RT-PCR. Microwave treatment appears to be a satisfactory method of inactivating virus while preserving nucleic acid for PCR identification.

Evaluation of five decontamination methods for filtering facepiece respirators

Concerns have been raised regarding the availability of National Institute for Occupational Safety and Health (NIOSH)-certified N95 filtering facepiece respirators (FFRs) during an influenza pandemic. One possible strategy to mitigate a respirator shortage is to reuse FFRs following a biological decontamination process to render infectious material on the FFR inactive. However, little data exist on the effects of decontamination methods on respirator integrity and performance. This study evaluated five decontamination methods [ultraviolet germicidal irradiation (UVGI), ethylene oxide, vaporized hydrogen peroxide (VHP), microwave oven irradiation, and bleach] using nine models of NIOSH-certified respirators (three models each of N95 FFRs, surgical N95 respirators, and P100 FFRs) to determine which methods should be considered for future research studies. Following treatment by each decontamination method, the FFRs were evaluated for changes in physical appearance, odor, and laboratory performance (filter aerosol penetration and filter airflow resistance). Additional experiments (dry heat laboratory oven exposures, off-gassing, and FFR hydrophobicity) were subsequently conducted to better understand material properties and possible health risks to the respirator user following decontamination. However, this study did not assess the efficiency of the decontamination methods to inactivate viable microorganisms. Microwave oven irradiation melted samples from two FFR models. The remainder of the FFR samples that had been decontaminated had expected levels of filter aerosol penetration and filter airflow resistance. The scent of bleach remained noticeable following overnight drying and low levels of chlorine gas were found to off-gas from bleach-decontaminated FFRs when rehydrated with deionized water. UVGI, ethylene oxide (EtO), and VHP were found to be the most promising decontamination methods; however, concerns remain about the throughput capabilities for EtO and VHP. Further research is needed before any specific decontamination methods can be recommended.

Infection control in cystic fibrosis

Over the past 20 years there has been a greater interest in infection control in cystic fibrosis (CF) as patient-to-patient transmission of pathogens has been increasingly demonstrated in this unique patient population. The CF Foundation sponsored a consensus conference to craft recommendations for infection control practices for CF care providers. This review provides a summary of the literature addressing infection control in CF. Burkholderia cepacia complex, Pseudomonas aeruginosa, and Staphylococcus aureus have all been shown to spread between patients with CF. Standard precautions, transmission-based precautions including contact and droplet precautions, appropriate hand hygiene for health care workers, patients, and their families, and care of respiratory tract equipment to prevent the transmission of infectious agents serve as the foundations of infection control and prevent the acquisition of potential pathogens by patients with CF. The respiratory secretions of all CF patients potentially harbor clinically and epidemiologically important microorganisms, even if they have not yet been detected in cultures from the respiratory tract. CF patients should be educated to contain their secretions and maintain a distance of >3 ft from other CF patients to avoid the transmission of potential pathogens, even if culture results are unavailable or negative. To prevent the acquisition of pathogens from respiratory therapy equipment used in health care settings as well as in the home, such equipment should be cleaned and disinfected. It will be critical to measure the dissemination, implementation, and potential impact of these guidelines to monitor changes in practice and reduction in infections.

Microwave sterilization of femoral head allograft

The potential shortage of allograft bone has led to the need to investigate other sources of bone for allografts. Some allograft bone donated from primary total hip arthroplasty recipients must be discarded or treated to become usable as a result of bacterial contamination. Femoral head allografts were contaminated with Staphylococcus aureus and Bacillus subtilis. A domestic microwave oven was used. The contaminated bone was exposed to microwave irradiation for different time periods. The samples were then cultured to attempt to grow the two bacterial species. The contaminated bone samples failed to grow any organisms after 2 min of exposure to microwave irradiation. This study shows that sterilization of femoral head allografts contaminated with S. aureus and B. subtilis can be achieved with microwave irradiation in a domestic microwave oven. This method of sterilization of bone allografts is cheap, easily used, and an effective way to process contaminated bone.

Infection control recommendations for patients with cystic fibrosis: microbiology, important pathogens, and infection control practices to prevent patient-to-patient transmission

Infection Control Recommendations for Patients With Cystic Fibrosis: Microbiology, Important Pathogens, and Infection Control Practices to Prevent Patient-to-Patient Transmissionupdates, expands, and replaces the consensus statement,Microbiology and Infectious Disease in Cystic Fibrosispublished in 1994. This consensus document presents background data and evidence-based recommendations for practices that are intended to decrease the risk of transmission of respiratory pathogens among CF patients from contaminated respiratory therapy equipment or the contaminated environment and thereby reduce the burden of respiratory illness. Included are recommendations applicable in the acute care hospital, ambulatory, home care, and selected non-healthcare settings. The target audience includes all healthcare workers who provide care to CF patients. Antimicrobial management is beyond the scope of this document.

Transurethral microwave thermotherapy for the treatment of prostatitis

The lethal action of microwaves on various microorganisms is well established and has been exploited in various clinical settings. Transurethral microwave thermotherapy (TUMT) has become a recognized modality for the treatment of prostatic diseases. Recently, it has been applied for the treatment of patients with nonbacterial prostatitis unresponsive to traditional therapeutic schemes. We review the current literature and present our recent encouraging experience with the in vitro bactericidal effect of microwaves on bacteria considered possible etiologic agents of prostatitis. Thus, we may consider the application of TUMT in patients with chronic bacterial prostatitis.

Killing activity of microwaves in milk

The killing activity of microwaves of 2450 MHz frequency and 600 W power on Pseudomonas aeruginosa, Escherichia coli, Enterobacter sakazakii, Klebsiella pneumoniae, Staphylococcus aureus, Candida albicans, Mycobacterium terrae and poliomyelitis vaccine-virus suspended in five infant formula preparations was investigated. The samples were brought to the boil (85-100 s depending on milk type). They had reached average temperatures of 82-93 degrees C at this point. Most of the vegetative organisms were killed. In those samples where growth was still detectable after microwave treatment, a significant reduction in viable micro-organisms (at least 5000-fold) was noted. We conclude that microwave beating to the boil is a convenient and fast method to reduce microbial contamination of infant feeds. However, care should be taken to ensure that milk is adequately cooled to the required temperature before it is fed to an infant.