On the disinfection of catheters,cystoscopes, bronchoscopes and similar instruments by means of a mixture of ethylene oxide and carbon dioxide

Summary An apparatus and a method are described for a simple and reliable disinfection of catheters, cystoscopes, bronchoscopes, etc. by means of a gas mixture consisting of 10% ethylene oxide and 90% carbon dioxide. The air is evacuated by suction from a disinfection vessel containing the instruments and replaced by the ethylene oxide-carbon dioxide mixture, which must be allowed to act for 8 hours at 37°C. After disinfection, the instruments which have previously been packed in cellophane bags can be stored and transported sterile for a considerable period. Bacterial spores with a resistance of 5 minutes at 100°C. are killed by this method, which has no damaging effect on the instruments.     

Advances in disinfection testing and modelling

AIMS: To develop a set of kinetic equations which more ably describe the disinfection process. METHODS AND RESULTS: A group of functions, the fat equations, based on the model used for the quantification of microbial inhibition, was produced. These functions introduce a limit to the numbers of micro-organisms capable of being disinfected. These new expressions were shown to be more general forms of currently-used (e.g. log-linear) disinfection models, and accommodate the lags and/or tails of non-linear log-survivor--time plots. An advance in the experimental procedures used to obtain disinfection data, using an optical density technique, was developed concomitantly. CONCLUSION: The methods of analyses (experimental and modelling) allow the researcher to examine, more ably, five-minute disinfection (or specific time disinfection tests) as well as the more important disinfection rate analyses. SIGNIFICANCE AND IMPACT OF THE STUDY: The fat equations are an improvement over commonly-used rate models of disinfection, which are shown to be special cases of these equations. This raises the question as to whether our current understanding of the kinetic basis of disinfection requires revision.     

Disinfection of animal manures,food safety and policy

Manure is a resource, but sometimes also a nuisance. Manure management strategies have traditionally focused on soil nutrients (N, P, K), COD, and more recently biological substances (antibiotics, hormones, etc.), with disinfection being a relative afterthought. Zoonotic pathogens (Salmonella and other bacteria, protozoa, etc.) may be present in manure, but only occasionally cause foodborne disease. In countries where food is relatively safe, requiring heroic manure disinfection measures may be a net detriment to public health. Decisions that a new, elegant disinfection technology can, should, or must be done may result from invoking the “precautionary principle.” Additional capital and operating costs must be passed to the consumer. Since such measures are likely to prevent very few human illnesses, policymakers should also consider the effect of increased prices on human nutrition and hunger. In most situations, not eating is more dangerous than eating.     

Environmental assessment of sewage effluent disinfection system: electron beam, ultraviolet, and ozone using life cycle assessment

Purpose

This study assesses the impacts of three different disinfection processes of sewage effluent, namely the electron beam (E-beam), ultraviolet (UV), and ozone systems, on the environment by using life cycle assessment (LCA).

Methods

The LCA employed was the comparative LCA which consists of three parts according to life cycle stages. Electricity consumption was the reference flow that can yield 99% disinfection efficiency for microorganisms present in a 1?×?10⁵?m³?day^?1 sewage treatment plant effluent over 20?years.

Results

The comparison of the LCA results indicated that the environmental impact of the UV disinfection system was the lowest, followed by the E-beam and ozone disinfection systems. The key issues of the E-beam, UV, and ozone disinfection systems are electricity consumption and SF₆ usage, electricity consumption and UV lamp, and electricity consumption and liquid oxygen feeding system, respectively.

Conclusions

Electricity consumption is the key input parameter that determines the LCA results.     

Inactivation of Adenoviruses,Enteroviruses, and Murine Norovirus in Water by Free Chlorine and Monochloramine

Inactivation of infectious viruses during drinking water treatment is usually achieved with free chlorine. Many drinking water utilities in the United States now use monochloramine as a secondary disinfectant to minimize disinfectant by-product formation and biofilm growth. The inactivation of human adenoviruses 2, 40, and 41 (HAdV2, HAdV40, and HAdV41), coxsackieviruses B3 and B5 (CVB3 and CVB5), echoviruses 1 and 11 (E1 and E11), and murine norovirus (MNV) are compared in this study. Experiments were performed with 0.2 mg of free chlorine or 1 mg of monochloramine/liter at pH 7 and 8 in buffered reagent-grade water at 5°C. CT values (disinfectant concentration × time) for 2- to 4-log₁₀ (99 to 99.99%) reductions in virus titers were calculated by using the efficiency factor Hom model. The enteroviruses required the longest times for chlorine inactivation and MNV the least time. CVB5 required the longest exposure time, with CT values of 7.4 and 10 mg·min/liter (pH 7 and 8) for 4-log₁₀ inactivation. Monochloramine disinfection was most effective for E1 (CT values ranged from 8 to 18 mg·min/liter for 2- and 3-log₁₀ reductions, respectively). E11 and HAdV2 were the least susceptible to monochloramine disinfection (CT values of 1,300 and 1,600 mg-min/liter for 3-log₁₀ reductions, respectively). Monochloramine inactivation was most successful for the adenoviruses, CVB5, and E1 at pH 7. A greater variation in inactivation rates between viruses was observed during monochloramine disinfection than during chlorine disinfection. These data will be useful in drinking water risk assessment studies and disinfection system planning.Disinfection is a critical step in the drinking water treatment process to inactivate infectious viruses because primary treatment is less effective for the removal of viruses. Chlorine and monochloramine are the most widely used disinfectants in the United States (2). Free chlorine is widely used as a primary disinfectant following filtration and also as a secondary disinfectant in distribution systems. Under the Long Term 2 Enhanced Surface Water Treatment Rule (38), monochloramine can also be used as a primary disinfectant, but because it requires longer contact times to achieve the same level of disinfection as free chlorine it is primarily used as a secondary disinfectant to maintain a stable disinfectant residual in the distribution system and minimize disinfection by-product formation and biofilm growth.The efficacy of chlorine disinfection for viruses has been evaluated in numerous studies over the years. Many early studies focused on the disinfection of polioviruses by chlorine (14, 17, 26, 28, 30, 39, 40, 43). Early investigators suggested a number of variables that must be controlled in the disinfection of viruses: contact time, temperature, ionic strength, pH, chlorine concentration, and virus aggregation (29, 30). These researchers concluded that comparisons and general trends of disinfection efficacy can only be discerned for viruses when the same disinfection parameters are applied.Fewer studies have investigated the disinfection efficacy of monochloramine, but monochloramine disinfection has been found to be less effective than free chlorine for viruses. In comparative studies of chlorine and monochloramine disinfection, coxsackievirus B5, adenovirus 2, and adenovirus 41 were found to be inactivated far more readily by chlorine than monochloramine (4, 5, 32). For drinking water treatment systems where monochloramine is used as a secondary disinfectant, it is important to know its efficacy for a wide range of viruses, as infectious viruses may be introduced in the distribution system where only monochloramine is present. In addition, relatively few studies have investigated the efficacy of monochloramine as systematically as free chlorine; frequently only one concentration, pH, or temperature has been investigated. Two notable exceptions were investigations that examined monochloramine disinfection of human adenovirus 2 (HAdV2) and coxsackievirus B5 (CVB5) at multiple pH levels (21, 31).In 2005, the U.S. Environmental Protection Agency (USEPA) published its second candidate contaminant list (CCL2). The CCL2 is comprised of unregulated microbial and chemical contaminants of potential public health concern that are known or anticipated to occur in drinking water systems and includes: echovirus, coxsackievirus, adenovirus, and calicivirus (36). A number of researchers have reported the disinfection efficacy of free chlorine for representatives of the CCL2 viruses (4, 5, 7, 11, 13, 18, 20, 22, 27, 33, 34, 35), but fewer studies have investigated the disinfection efficacy of monochloramine on these viruses (4, 5, 21, 31). In addition, comparison between existing studies of chlorine or monochloramine disinfection is difficult because of differences in the viruses examined, experimental parameters investigated, and analytical methods used.The present study compared the inactivation kinetics for representative CCL2 viruses with levels of free chlorine and monochloramine recommended for drinking water disinfection. Duplicate experiments with both disinfectants were carried out in pH 7 and 8 buffered chlorine-demand-free (CDF) water at 5°C, with eight viruses chosen to represent the CCL2 virus types. Coxsackieviruses B5 and B3 (CVB5 and CVB3) and echoviruses 1 and 11 (E1 and E11) were chosen based on existing data suggesting resistance to free chlorine, disease implications, and likelihood of presence in higher numbers in natural water. Three representative human adenoviruses were studied, including both serotypes of species F HAdV (40 and 41) that cause gastroenteritis and HAdV2, a representative of respiratory HAdV that may be found in water because they are present in fecal excretions (9). Murine norovirus (MNV), phylogenetically similar to human norovirus and the only norovirus that can be propagated in cell culture, was used as a surrogate for human norovirus. Kinetic inactivation curves are presented, and CT values (disinfectant concentration × time, reported in mg·min/liter) were calculated by using the efficiency factor Hom (EFH) model (16).     

Disinfection and hygiene in the veterinary field and disinfection of animal houses and transport vehicles

Disinfection in animal houses means always a combination between cleaning and disinfection because the high amount of organic material present in such an environment will neutralize rapidly each disinfectant brought to the surface if no cleaning step had been done before. Depending on the kind of material, cleaning gives a 3 log reduction of total bacterial count on the surface and disinfection another 3 log reduction. This means that under practical conditions generally 10³ cfu of bacteria remain per cm² of surface, mostly sporeformers. The choice of disinfectant depends on the purpose of disinfection. In the case of notifiable diseases, it must be active against a defined pathogen. In the case of prophylactic disinfection, it must be active against a broad spectrum of microorganisms.Only disinfectants which are tested for their activity on surfaces which are representative for animal houses e.g. wood should be used, otherwise the failure under practical conditions can be predicted and work, as well as money, will be wasted. The optimal temperature for the liquids used in cleaning and disinfection is 40°C and the optimal temperature of surfaces is 20°C. Colder surfaces require higher concentrations of active substances in the solution, below 10°C the effect of practical disinfection is incomplete. Low air humidity and high air velocity have a negative influence on the action of most disinfectants on surfaces. The amount of disinfectant necessary to disinfect a surface in an animal house is at least 0.4 l/m². Transport vehicles are very difficult to disinfect, especially in winter-time. They should be cleaned with hot water, the remaining liquid should be removed by a suitable vacuum cleaner and the concentration of the disinfectant should be elevated at least for the factor 3. Mechanic action will improve the disinfecting effect in vehicles as well as preliminary disinfection prior cleaning.     

Effects of ozone, ultraviolet and peracetic acid disinfection of a primary-treated municipal effluent on the immune system of rainbow trout (Oncorhynchus mykiss)

Municipal sewage effluents are complex mixtures that are known to compromise the health condition of aquatic organisms. The aim of this study was to evaluate the impacts of various wastewater disinfection processes on the immune system of juvenile rainbow trout (Oncorhynchus mykiss). The trout were exposed to a primary-treated effluent for 28 days before and after one of each of the following treatments: ultraviolet (UV) radiation, ozonation and peracetic acid. Immune function was characterized in leucocytes from the anterior head kidney by the following three parameters: phagocytosis activity, natural cytotoxic cells (NCC) function and lymphocyte (B and T) proliferation assays. The results show that the fish mass to length ratio was significantly decreased for the primary-treated and all three disinfection processes. Exposure to the primary-treated effluent led to a significant increase in macrophage-related phagocytosis; the addition of a disinfection step was effective in removing this effect. Both unstimulated and mitogen-stimulated T lymphocyte proliferation in fish decreased dramatically in fish exposed to the ozonated effluent compared to fish exposed to either the primary-treated effluent or to aquarium water. Stimulation of T lymphocytes proliferation was observed with the peracetic acid treatment group. In conclusion, the disinfection strategy used can modify the immune system in fish at the level of T lymphocyte proliferation but was effective to remove the effects on phagocytosis activity.     

消毒、伴生和微生物菌对连作基质性质及黄瓜生长发育的影响

以连续种植2茬的连作基质为对象,采用室内盆栽试验,设置连作基质太阳能消毒、热水消毒、多菌灵消毒、大蒜伴生栽培和施入微生物菌处理以及新基质对照,在种植黄瓜后观测基质理化性质、养分含量、酚类物质含量、相关酶活性的变化以及黄瓜结果期生长发育、光合作用和果实产量的变化,探究不同处理对连作基质栽培黄瓜生长发育影响的机制,以期在生产上为废旧基质重复利用提供新的思路和方法。结果表明:在连作基质栽培黄瓜后,太阳能消毒和热水消毒处理均能显著提高连作基质的pH,同时降低电导率;施入微生物菌处理的基质EC值、速效氮、速效磷、速效钾和总酚含量均显著低于连作基质,而其基质磷酸酶活性和过氧化氢酶活性显著高于连作基质。热水消毒还显著降低连作基质的总酚含量和复合态酚含量。黄瓜生长至结果期,太阳能消毒、热水消毒、多菌灵消毒、大蒜伴生栽培和施入微生物菌均显著增强黄瓜的根系活力和株高;其中热水消毒和施入微生物菌处理的产量增加最为显著,分别比连作基质栽培提高了16.56%和18.40%。可见,连作基质进行热水消毒处理和施入微生物菌处理均能降低基质盐分积累,减少总酚含量,进而显著提高黄瓜的根系活力和光合作用,从而增加产量。     

Effects of Source Water Quality on Chlorine Inactivation of Adenovirus,Coxsackievirus, Echovirus,and Murine Norovirus

More information is needed on the disinfection efficacy of chlorine for viruses in source water. In this study, chlorine disinfection efficacy was investigated for USEPA Contaminant Candidate List viruses coxsackievirus B5 (CVB5), echovirus 1 (E1), murine norovirus (MNV), and human adenovirus 2 (HAdV2) in one untreated groundwater source and two partially treated surface waters. Disinfection experiments using pH 7 and 8 source water were carried out in duplicate, using 0.2 and 1 mg/liter free chlorine at 5 and 15°C. The efficiency factor Hom (EFH) model was used to calculate disinfectant concentration × contact time (CT) values (mg·min/liter) required to achieve 2-, 3-, and 4-log₁₀ reductions in viral titers. In all water types, chlorine disinfection was most effective for MNV, with 3-log₁₀ CT values at 5°C ranging from ≤0.020 to 0.034. Chlorine disinfection was least effective for CVB5 in all water types, with 3-log₁₀ CT values at 5°C ranging from 2.3 to 7.9. Overall, disinfection proceeded faster at 15°C and pH 7 for all water types. Inactivation of the study viruses was significantly different between water types, but no single source water had consistently different inactivation rates than another. CT values for CVB5 in one type of source water exceeded the recommended CT values set forth by USEPA''s Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface Water Sources. The results of this study demonstrate that water quality plays a substantial role in the inactivation of viruses and should be considered when developing chlorination plans.Disinfection processes are critical for the reduction of infectious virus concentrations in source water, because viruses are less efficiently removed by primary treatment of drinking water (e.g., coagulation and filtration) than are other pathogen types of concern (e.g., bacteria and protozoa). Over the years, many disinfection studies have focused on the inactivation of viruses in purified and buffered, demand-free, reagent-grade water (RGW). However, relatively few investigators have examined the impact of water quality during the disinfection process, even though water quality has been found to be a significant factor for inactivation of viruses.Several researchers found that the inactivation rate of poliovirus by free chlorine increased as the ionic concentration of water increased. In one study, poliovirus 1 was inactivated three times faster in boric acid buffer than in purified water (3). In addition, several investigators found that when the ionic content of buffered water was raised by the addition of NaCl or KCl, poliovirus 1 was inactivated two to four times faster than in the buffered water alone (2, 16, 17). In another study, poliovirus 1 was inactivated 10 times more rapidly in drinking water than in purified water (4).Studies conducted with natural waters have demonstrated both increased and decreased disinfection efficacy of chlorine in these waters compared to purified or buffered waters. In a study comparing chlorine disinfection in purified water and Potomac estuarine water, coxsackievirus A9 was inactivated more rapidly in the source water. The remaining study viruses (coxsackievirus B1, echovirus 7, adenovirus 3, poliovirus 1, and reovirus 3) were all inactivated more slowly in the source water (13). Bacteriophage MS2 was inactivated more slowly by free chlorine in two types of surface water than in buffered, demand-free water. However, there was no difference between the inactivation rates of this virus in the buffered water and groundwater (10). In another study, both feline calicivirus and adenovirus 40 were inactivated more slowly in treated groundwater than in buffered, demand-free water (21).The United States Environmental Protection Agency''s (USEPA) Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface Water Sources (Guidance Manual) recommends disinfectant concentration × contact time (CT) values of 4, 6, and 8 to achieve 2-, 3-, and 4-log₁₀ inactivation, respectively, with chlorine at 5°C and pH 6 to 9 (23). These CT values, which incorporate a safety factor of 3, were obtained from inactivation experiments conducted with monodispersed hepatitis A virus (HAV) in buffered, demand-free water. As water quality can significantly affect the disinfection efficacy of chlorine, it is unclear whether these CT value recommendations are sufficient for inactivation of viruses in source water. More information is needed to systematically examine the role of water quality in chlorine disinfection of viruses.The objective of the present study was to examine the disinfection efficacy of free chlorine on selected viruses from USEPA''s Contaminant Candidate List (CCL) (22) in one untreated and two partially treated source waters from distinct geographical regions. By comparing the efficacy of chlorine disinfection in the source water types to disinfection in buffered, chlorine-demand-free RGW (7), the impact of water quality could be examined. The four representative CCL viruses selected for this study included human adenovirus 2 (HAdV2), echovirus 1 (E1), coxsackievirus B5 (CVB5), and murine norovirus (MNV), a surrogate for human norovirus (22). The viruses were selected because they were previously found to be the least effectively inactivated viruses of their type in RGW (6). Disinfection experiments were carried out in duplicate in pH 7 and 8 source water at 5 and 15°C using 0.2 and 1 mg/liter free chlorine. Inactivation curves were plotted using Microsoft Excel, and CT values were calculated using the efficiency factor Hom (EFH) model (9).     

Kinetics of ultrasonic disinfection of Escherichia coli in the presence of titanium dioxide particles

The ultrasonic disinfection of Escherichia coli was carried out in the presence of anatase-type TiO2 particles, and the effectiveness of the combination of ultrasonic irradiation with TiO2 addition was verified. The rate constant was determined from the plot of the common logarithm of the survival cell ratio versus the ultrasonic irradiation time using first-order kinetics. In the absence of particles, the rate constant was proportional to the ultrasonic power. When ultrasonic disinfection was carried out in the presence of TiO2 particles, which have a radical generation ability, the rate of disinfection was remarkably faster than that in the absence of TiO2. In the presence of silica particles, which have no radical generation ability, the rate of disinfection was the same as that in the absence of TiO2. These results suggest that the radical generation ability of TiO2 appeared as a result of the ultrasonic irradiation. The effect of the amount of TiO2 on the rate of disinfection was also examined. The rate constant for disinfection in the presence of TiO2 was saturated to a certain value and was represented using the Langmuir-type equation. The proposed model well describes the effects of the ultrasonic power and the amount of TiO2 on the rate constant for disinfection.     

Formation of natural biofilms during chlorine dioxide and u.v. disinfection in a public drinking water distribution system

AIMS: The influence of two disinfection techniques on natural biofilm development during drinking water treatment and subsequent distribution is compared with regard to the supply of a high-quality drinking water. METHODS AND RESULTS: The growth of biofilms was studied using the biofilm device technique in a real public technical drinking water asset. Different pipe materials which are commonly used in drinking water facilities (hardened polyethylene, polyvinyl chloride, steel and copper) were used as substrates for biofilm formation. Apart from young biofilms, several months old biofilms were compared in terms of material dependence, biomass and physiological state. Vital staining of biofilms with 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) and the DNA-specific 4',6-diamidino-2-phenylindole (DAPI) staining resulted in a significant difference in physiological behaviour of biofilm populations depending on the disinfection technique. Compared with chlorine dioxide disinfection (0.12-0.16 mg l-1), the respiratory activities of the micro-organisms were increased on all materials during u.v. disinfection (u.v.254; 400 J m-2). The biofilm biocoenosis was analysed by in situ hybridization with labelled oligonucleotides specific for some subclasses of Proteobacteria. Using PCR and additional hybridization techniques, the biofilms were also tested for the presence of Legionella spp., atypical mycobacteria and enterococci. The results of the molecular-biological experiments in combination with cultivation tests showed that enterococci were able to pass the u.v. disinfection barrier and persist in biofilms of the distribution system, but not after chlorine dioxide disinfection. CONCLUSIONS: The results indicated that bacteria are able to regenerate and proliferate more effectively after u.v. irradiation at the waterworks, and chlorine dioxide disinfection appears to be more applicative to maintain a biological stable drinking water. SIGNIFICANCE AND IMPACT OF THE STUDY: As far as the application of u.v. disinfection is used for conditioning of critical water sources for drinking water, the efficiency of u.v. irradiation in natural systems should reach a high standard to avoid adverse impacts on human health.     

The organization, control and coordination of measures for localization and liquidation of mass poultry loss and prevention of human diseases caused by avian flu in Ordynsk area of Novosibirsk region

Materials on the organization, the control and to coordination of actions of services in carrying out of actions on localization and liquidation of the centers of a mass destruction of birds and preventive measures of people diseases by avian flu during the period from July, 21 till September, 18, 2005 are submitted. The basic actions which have been carried out by a territorial department, the quarantine of poultry excluding contact with wild birds, depopulation of a sick and suspicious birds on disease and disinfection in the foci of a mass case, including installation disinfection barriers, etc. As a result of spent actions the bird's mass destruction has been stopped, quarantine is taken off 10.11.2005. The conclusion is made, that due to carrying out sanitary-preventive and antiepidemic measures it is possible not only to locate, but also completely to liquidate a mass destruction of birds.     

Organization and execution of the use of disinfectants, insecticides and rodenticides in the period of the eradication of the medical and sanitary consequences of a flood in Stavropol Territory in 2002

Materials on the organization and execution of disinfection, disinfestations and deratization works at the period of the liquidation of the medico-sanitary consequences of the high flood in the Stavropol Territory in 2002 are presented. Timely and full-scope treatment, carried out in the course of these works, played a positive role in preventing epidemiological aggravations among the affected population.     

Effect of a disinfection strategy on the methicillin‐resistant Staphylococcus aureus CC398 prevalence of sows,their piglets and the barn environment

Aims

To assess, in a cleaned and disinfected barn environment, the efficacy of an animal disinfection strategy to reduce the livestock‐associated methicillin‐resistant Staphylococcus aureus (LA‐MRSA) prevalence in sows, their offspring and the barn environment.

Methods and Results

On each farm, six sow rounds were sampled; sows were divided into either a test or control group. Per round, 20 sows and 40 of their piglets were sampled at different time points together with the barn environment. The disinfection strategy of the test groups consisted of washing the sows with a shampoo followed by disinfection of the skin with a solution containing chlorhexidine digluconate and isopropanol. On the first day of disinfection and 6 days after stopping the disinfection, a significant decrease (P < 0·01) of on average 68 and 66% in sow MRSA prevalence was observed on both farms, whereas no decrease was seen in the control groups. Just before weaning, 21–28 days after the end of the disinfection strategy, the difference in MRSA prevalence between both groups was reduced to 4% and no longer significant (P = 0·20). The MRSA prevalence of the piglets in the test groups was significantly lower (26%; P < 0·01) 6 days after the end of disinfection. Just before weaning, this difference was reduced to 5% but still significant (P < 0·01). In the swine nursery unit, no significant difference (P = 0·99) was seen between both groups. Based on semi‐quantitative counts, a relationship (r² > 0·6; P < 0·01) was seen between MRSA contamination in the barn environment and the MRSA prevalence in pigs.

Conclusion

Results show that the tested disinfection strategy reduces temporarily the sow and piglet MRSA status, but does not result in a final reduction in MRSA at weaning or in the nursery unit.

Significance and Impact of the Study

First report on the efficacy of an animal disinfection strategy to reduce LA‐MRSA prevalence in sows, their offspring and the barn environment.     

Disinfection of human musculoskeletal allografts in tissue banking: a systematic review

Musculoskeletal allografts are typically disinfected using antibiotics, irradiation or chemical methods but protocols vary significantly between tissue banks. It is likely that different disinfection protocols will not have the same level of microorganism kill; they may also have varying effects on the structural integrity of the tissue, which could lead to significant differences in terms of clinical outcome in recipients. Ideally, a disinfection protocol should achieve the greatest bioburden reduction with the lowest possible impact on tissue integrity. A systematic review of three databases found 68 laboratory and clinical studies that analyzed the microbial bioburden or contamination rates of musculoskeletal allografts. The use of peracetic acid–ethanol or ionizing radiation was found to be most effective for disinfection of tissues. The use of irradiation is the most frequently published method for the terminal sterilization of musculoskeletal allografts; it is widely used and its efficacy is well documented in the literature. However, effective disinfection results were still observed using the BioCleanse? Tissue Sterilization process, pulsatile lavage with antibiotics, ethylene oxide, and chlorhexidine. The variety of effective methods to reduce contamination rate or bioburden, in conjunction with limited high quality evidence provides little support for the recommendation of a single bioburden reduction method.     

Perspectives on air disinfection methods in the workplace of blood transfusion services

Blood collection and preparation is a relatively open operation in a conventional environment, and is vulnerable to be contaminated by various types of airborne pathogenic microorganisms. It is important to establish stable and effective air disinfection methods for all types of environments in blood transfusion services, in order to control air hygiene quality and thus reduce the probability of contamination during blood collection. This paper analyzes and summarizes the principles, advantages, and disadvantages of commonly used chemical and physical air disinfection methods and their application status. It is suggested that over-reliance on chemical reagents and disinfection facilities be reduced, so that better results can be achieved with the combination of multiple disinfection methods and dynamic air hygiene monitoring.     

Disinfection characteristics of waterborne pathogenic protozoaGiardia lamblia

Giardia lamblia is a parasitic protozoa which is transmitted in the form of a cyst through untreated water and also treated drinking water. Since its presence in water has led to frequent outbreaks of giardiasis and death in many countries, the removal and disinfection of this protozoan cyst from the water supply are of great concern for public health. This study examined the disinfection characteristics ofG. lamblia cysts isolated from a Korean patient with giardiasis. When using sodium hypochlorite includdig 5 or 10 ppm chlorine, the killing rate was initially rapid however, the disinfection slowed down and a Blog reduction could not be achieved even after 2 h. The disinfection effectiveness was also reduced at a lower temperature, thereby implying that the risk of a giardiasis outbreak will be higher in the winter season. A CT (concentration time) curve was constructed based on the results with sodium hypochlorite for use in designing and predicting disinfection performance. The organic chlorination disinfectant SDIC (sodium dichloroisocyanurate) produced a lower pH and a much higher residual effect than sodium hypochlorote. The disinfection of cysts by SDIC continued steadily throughout 2 h of contact, although the initial killing rate was lower than that with sodium hypochlorite.     

Shift in the Microbial Ecology of a Hospital Hot Water System following the Introduction of an On-Site Monochloramine Disinfection System

Drinking water distribution systems, including premise plumbing, contain a diverse microbiological community that may include opportunistic pathogens. On-site supplemental disinfection systems have been proposed as a control method for opportunistic pathogens in premise plumbing. The majority of on-site disinfection systems to date have been installed in hospitals due to the high concentration of opportunistic pathogen susceptible occupants. The installation of on-site supplemental disinfection systems in hospitals allows for evaluation of the impact of on-site disinfection systems on drinking water system microbial ecology prior to widespread application. This study evaluated the impact of supplemental monochloramine on the microbial ecology of a hospital’s hot water system. Samples were taken three months and immediately prior to monochloramine treatment and monthly for the first six months of treatment, and all samples were subjected to high throughput Illumina 16S rRNA region sequencing. The microbial community composition of monochloramine treated samples was dramatically different than the baseline months. There was an immediate shift towards decreased relative abundance of Betaproteobacteria, and increased relative abundance of Firmicutes, Alphaproteobacteria, Gammaproteobacteria, Cyanobacteria and Actinobacteria. Following treatment, microbial populations grouped by sampling location rather than sampling time. Over the course of treatment the relative abundance of certain genera containing opportunistic pathogens and genera containing denitrifying bacteria increased. The results demonstrate the driving influence of supplemental disinfection on premise plumbing microbial ecology and suggest the value of further investigation into the overall effects of premise plumbing disinfection strategies on microbial ecology and not solely specific target microorganisms.     

Effect of sub-lethal chemical disinfection on the biofilm forming ability,resistance to antibiotics and expression of virulence genes of Salmonella Enteritidis biofilm-surviving cells

Abstract

Although disinfection procedures are widely implemented in food environments, bacteria can survive and present increased virulence/resistance. Since little is known about these phenomena regarding biofilms, this study aimed to investigate the effect of chemical disinfection on biofilm-derived cells of Salmonella Enteritidis. Using a reference strain (NCTC 13349) and a food isolate (350), biofilm susceptibility to benzalkonium chloride (BAC), sodium hypochlorite (SH) and hydrogen peroxide (HP) was evaluated and biofilms were exposed to sub-lethal concentrations of each disinfectant. Biofilm-derived cells were characterized for their biofilm forming ability, antibiotic resistance and expression of virulence-associated genes. Except for a few instances, disinfectant exposure did not alter antibiotic susceptibility. However, SH and HP exposure enhanced the biofilm forming ability of Salmonella Enteritidis NCTC 13349. After BAC and HP exposure, biofilm-derived cells presented a down-regulation of rpoS. Exposure to BAC also revealed an up-regulation of invA, avrA and csgD on Salmonella Enteritidis NCTC 13349. The results obtained suggest that biofilm-derived cells that survive disinfection may represent an increased health risk.