No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Cross-contamination in dishwashers
Abstract
Dishwashers are used in central hospital kitchens and ward kitchens to provide clean crockery. Soil recipes based on international standards were tested in order to evaluate the performance of a general dishwasher. In normal use of dishwashers, adherent soils are left on the crockery before cleaning. Different adherent soils, both with and without bacterial contamination, were used to show the effectiveness of the dishwasher to remove this type of soil. It was shown that contamination will occur from the dishwater to crockery with adherent soil. These results demonstrate the importance of cleaning soiled surfaces of crockery mechanically in the dishwashing process. Otherwise cross-contamination, and thereby the spread of infections, may occur.
... The output of dishwashers in hospitals is particularly critical, as nosocomial foodborne infections have to be avoided at all costs [81]. Noting that bacteria such as E. faecium are not easily exterminated by the high temperatures prevailing within the dishwasher during and after the rinse cycle, Ståhl Wernersson and co-authors in [78] stressed the need to ensure that dishwashers are able to provide a high degree of mechanical cleaning, which reportedly has a negative correlation to the yeast colonies detected in dishwashers [52]. Kerschgens and colleagues [82], in hygienic performance tests carried out with M. Luteus, found that higher washing temperatures were more successful in reducing viable cell count than higher rinsing temperatures. ...
... Pathogens lurk in the water used for dishwashing, as well as in the biodegradable organic food residues on the dishes [12][13][14][15][16]52,78], some of which may get trapped inside the dishwasher for long times, forming in the process, substrates for saprobial growth. The repeatedly oxidative, moist, alkaline, and high-temperature environs prevailing within a dishwasher are conducive for a phylogenetically diverse mycobacterial-algal biofilm formation on rubber seals [17][18][19]52,83], and the development of antibiotic resistance among bacteria [69], with new dishwashers, operated frequently with moderately hard water and low temperatures, emerging as the best 'harbours' of such active biofilms, as per a study done in [15]. ...
... The repeatedly oxidative, moist, alkaline, and high-temperature environs prevailing within a dishwasher are conducive for a phylogenetically diverse mycobacterial-algal biofilm formation on rubber seals [17][18][19]52,83], and the development of antibiotic resistance among bacteria [69], with new dishwashers, operated frequently with moderately hard water and low temperatures, emerging as the best 'harbours' of such active biofilms, as per a study done in [15]. Frequent operation, evidently, ensures a regular supply of organic matter to the microbial colonies and higher humidity [78]. While Zupančič and colleagues in [13] conclusively discovered that tap water is the predominant vector for fungi, as they were found even in kitchens which did not have dishwashers. ...
An automatic dishwasher is a water-using, energy-demanding contraption with 40-50 different component parts fashioned out of different materials-metals and non-metals-which over the last 70 years has evolved in its role as a comfort-enhancing, convenience-providing, time-saving white good in the kitchen of the modern urban household, especially in the countries of the developed world. Its lifecycle, which spans about 12-13 years on average, lends itself to research in a variety of sustainability aspects-politico-legal/regulatory, economic, environmental, social and techno-functional-and fields-thermodynamics, fluid mechanics, acoustics, economics, chemistry, microbiology, materials science, design engineering, wastewater treatment, energy engineering, consumer behaviour, and, of late, sustainable consumption and production. The end goal of this review is to present the automatic dishwasher-almost ubiquitous and taken-for-granted in the western world these days-as a candidate for progressive research and development, resulting in its continued evolution. The author facilitates this by providing an overview of the different aspects of sustainability addressed by researchers thus far. It at once reinforces the importance of transdis-ciplinary research, finds answers to a clutch of 'what', 'why', 'where', 'how', 'who', and 'when' questions, and reminds us that improvement/s in one aspect must not undermine or thwart those in any of the others. It is the first of its kind, as far as the automatic dishwasher is concerned; it is a well-structured review of 84 peer-reviewed journal publications focusing on the dishwasher, ac-cessed through Scopus and contacting researchers through ResearchGate, spanning the time period 1980-2021, originating in 21 countries (with Germany leading the pack, with 22% of the publications), and sourced from 63 different journals. Over a 16-year period between 1998 and 2014, both the energy use and water consumption of dishwashers decreased by well over 40%. Consumers in the USA, reportedly, are willing to pay up to 90% more for a higher-rated dishwasher. Interestingly, a publication from Germany states that manual dishwashing, if done in accordance with the Best Practice Tips (recommended by another German study), can have a 20% lower environmental footprint than automatic dishwashers.
... The presence of food soil in the water and on the food contact surface may retard thermal inactivation by providing nutrition and shelter to microorganism (Stahl Wernerssson et al. 2004). It is, however, expected that during a washing cycle performed by the dishwasher tested in this work, all food soil is removed after the cleaning phase, which should render the food contact surface visually clean. ...
... (around 200) much higher than that required for chemical sanitizing. These conditions may be required to ensure that the removal of all visible soil and detergent from utensils in washing tests require more than 3,600 HUEs (Stahl Wernerssson et al. 2004). Although food residues may protect microorganisms from heat or direct contact of detergents and chemicals used in dishwashing operations (Lee et al. 2007), this work is based on the rationale that all food soil and dirt should be removed during the cleaning phase to obtain visually clean food contact surfaces. ...
This paper presents an experimental investigation on the thermal sanitization of food contact surfaces in a pilot dishwashing machine. The reduction of counts for Escherichia coli inoculated on clean glass surfaces was assayed in several tests performed under different conditions of temperature and duration of the washing cycles. The main aim of the measurements was to establish the relationship between operating conditions and sanitizing performance. The experimental results show that reduction of microbial counts clearly increases with the volume of water used for rinsing. On the other hand, the effect of the rinsing water temperature is less remarkable. It is inferred from these results that the reduction of microbial counts on food contact surfaces is mainly due to the mechanical elution of water jets rather than to thermal inactivation. The experimental results are analyzed using available kinetic data for reference organisms. The kinetic analysis confirms that the thermal effect is not sufficient to obtain a significant reduction of microbial counts on food contact surfaces under typical conditions of temperature and washing cycle length.
Unsanitized food contact surfaces can be a direct or indirect source of foodborne illness, as pathogens can be transferred to food from crockery and utensils that are not properly sanitized. Improper cleaning and sanitizing of food contact surfaces is the factor most commonly related to the occurrence of foodborne illness risk in hospital, schools and restaurants. In this work, the effect of the operating conditions on the inactivation of reference microorganism (Escherichia coli) was experimentally investigated in a dishwashing machine. The experimental results on the logarithmic reduction on food contact surfaces under different conditions of temperature and contact time show that the microbial reduction in the washing machine is mainly due to the mechanical effect of elution of water jets rather than temperature. The results of this investigation can be used to determine the optimal operating conditions for the washing machine, resulting in the minimum requirement of energy and water.
... The dishwater in professional machine dishwashers is usually reused for about 20 dishwashing cycles. Therefore, both for hand dishwashing and machine dishwashing, crosscontamination from dishwater to dishware can occur if the wares are not properly cleaned (Mattick et al. 2003b;Ståhl Wernersson et al. 2004a). ...
... Dishwater in dishwashers is kept in the machine for long times due to recycling of the dishwater. During the contact time between dishwater and dishware in dishwashing processes, cross-contamination may occur (Ståhl Wernersson et al. 2004a). ...
In this study, the effect of dishwater parameters on the survival of Staphylococcus aureus and vegetative cells and spores of Bacillus cereus was evaluated. Both types of bacteria have been found in dishwater and are presumed to be pathogenic; both have also been reported to cause outbreaks of foodborne illness. Experiments were conducted in a 2-L beaker, and temperature, pH, type of detergent and broth concentrations were altered. The influence of nutrition, which normally exists in dishwater, has a substantial effect on the survival rate of S. aureus. The survival of S. aureus in dishwater solutions at 45°C and pH 7 is similar for two different types of detergents, hand dishwashing and machine dishwashing, after a longer time exposure (50 min). The effect of the temperatures on the survival of S. aureus and B. cerus was investigated for the range typical for professional dishwashers and hand dishwashing (45°−65°C). Only a slight reduction of S. aureus takes place at 45°C; however, at 55°C, no more than seven minutes is required to achieve a 3-log10 reduction. Vegetative cells of B. cereus revealed a similar temperature dependence; however, for the spores of B. cereus, not even a temperature of 65°C is enough to reduce the bacterial counts. The influence of pH on the bacteria was also investigated. For S. aureus and vegetative cells of B. cereus, the pH influence is moderate and is only apparent after longer exposure times. For B. cereus spores, the results showed that they are not influenced by pH up to 10.6. This investigation points out that the most effective strategy for reducing bacterial counts in dishwashing solutions is to use high temperatures (>55°C) in the dishwater, which reduces the risk for cross-contamination from dishwater to dishware.
... A 2006 study by Weese et al in which food dishes were inoculated with Salmonella-containing raw meat showed persistent contamination in the majority of pet dishes after washing with routine measures including a dishwasher or with soap and water [14]. Other studies have found dishwashers can disperse and harbor bacteria [15,16]. Concerns regarding cross-contamination may extend beyond bacteria when one considers that 9% of pet owners reported adding medications or supplements into their pets' food bowls. ...
In-home pet food handling and food dish hygiene practices can have adverse health impacts for both humans and pets. Safe food and dish handling guidelines are not easily evidenced for pet owners. The study was designed to investigate dog owners’ feeding habits and evaluate the impact of the Food and Drug Association (FDA) hygiene protocols on dog food dish contamination. Procedures and surveys were approved by North Carolina State University Institutional Animal Care and Use Committee and Institutional Review Board. Pet feeding and food dish hygiene data were collected from 417 dog owner surveys and 68 food dish swabs. Total aerobic plate counts (APC) were performed on 68 dishes and randomly assigned into Group A (FDA pet food handling and dish hygiene guidelines), Group B (FDA pet and human food handling and dish hygiene guidelines), or Group C (no guidelines). Hygiene protocols were instituted in-home for 1 week, followed by a second APC and follow-up survey. Survey from dog owners-households indicated: 4.7% were aware of FDA pet food handling and dish hygiene guidelines; 36% have individuals ≤ 13 years old and/or immunocompromised; 43% stored dog food 0–5 feet from human food; 34% washed their hands after feeding; and 33% prepared their dog food on human food preparation surfaces. The hygiene protocols followed by Groups A and B resulted in significant decreases in food dish APC (p<0.001; 1.4; (0.9, 2.0); p<0.05; 0.604 (0.02, 1.2), respectively), as compared to Group C (p≥0.05). Hot water (>160° F or 71.1°C) washing decreased APC (p<0.01; 1.5 (0.4, 2.6)) over cold/lukewarm water. In the follow-up survey, 8% of Group A and B respondents reported likely to adhere to protocols long-term. This study suggests a need for pet food handling and dish hygiene guideline education to minimize bacterial contamination of dishes, especially for high-risk populations.
... Already in 1999, Beadle and Verran stated that lower temperatures for washing and less aggressive detergents without bleach became commonly used (Beadle and Verran 1999). While becoming more permissive, these conditions are still harsh enough to select for the more stress-resistant, but also often, virulent microbes, with greater potential to cause opportunistic human infections (Byrd-Bredbenner et al. 2013;Callewaert et al. 2015;Döğen et al. 2013a, b;Dunn et al. 2013;Gümral et al. 2016;Gostinčar et al. 2011Gostinčar et al. , 2015Raghupathi et al. 2018;Rehberg et al. 2017;Sasahara et al. 2011;Ståhl Wernersson et al. 2004;Zalar et al. 2011;Zupančič et al. 2016Zupančič et al. , 2018. ...
Modernisation of our households created novel opportunities for microbial growth and thus changed the array of microorganisms we come in contact with. While many studies have investigated microorganisms in the air and dust, tap water, another major input of microbial propagules, has received far less attention. The quality of drinking water in developed world is strictly regulated to prevent immediate danger to human health. However, fungi, algae, protists and bacteria of less immediate concern are usually not screened for. These organisms can thus use water as a vector of transmission into the households, especially if they are resistant to various water treatment procedures. Good tolerance of unfavourable abiotic conditions is also important for survival once microbes enter the household. Limitation of water availability, high or low temperatures, application of antimicrobial chemicals and other measures are taken to prevent indoor microbial overgrowth. These conditions, together with a large number of novel chemicals in our homes, shape the diversity and abundance of indoor microbiota through constant selection of the most resilient species, resulting in a substantial overlap in diversity of indoor and natural extreme environments. At least in fungi, extremotolerance has been linked to human pathogenicity, explaining why many species found in novel indoor habitats (such as dishwasher) are notable opportunistic pathogens. As a result, microorganisms that often enter our households with water and are then enriched in novel indoor habitats might have a hitherto underestimated impact on the well-being of the increasingly indoor-bound human population.
Key points
Domestic environment harbours a large diversity of microorganisms.
Microbiota of water-related indoor habitats mainly originates from tap water.
Bathrooms, kitchens and household appliances select for polyextremotolerant species.
Many household-related microorganisms are human opportunistic pathogens.
... Besides fungi, also bacteria can contaminate dishwashers as revealed in limited studies focusing on dishwasher bacterial contamination (Rehberg et al., 2017;Raghupathi et al., 2018. Surprisingly, the prevous studies performed on bacteria in dishwashers were focused on dishwasher sanitising performance, in terms of the determination of the survival of certain selected pathogenic bacterial species during the washing cycle and on the washed eating utensils (Ståhl Wernersson et al., 2004;Lee et al., 2007;Nicolella et al., 2011). ...
Bacteria that colonise the extreme environment of household dishwasher rubber seals were investigated using cultivation-dependent and metagenomic approaches. All 30 dishwashers investigated were colonised by various bacteria. Cultivation approaches resulted in 632 bacterial isolates in total, belonging to four phyla, eight classes, 40 genera and 74 species. The majority were Gram-positive, as solely Firmicutes and Actinobacteria. Bacilli represented half of the Gram-positive isolates, and were dominated by the Bacillus cereus group. Gammaproteobacteria were primarily represented by Stenotrophomonas maltophilia, Pseudomonas aeruginosa and Escherichia coli. All isolates were tested for resistance to seven selected antibiotics. Metagenomic assessment of the bacterial biodiversity of the dishwasher rubber seals confirmed the predominance of Gram-positive bacteria, as primarily Actinobacteria dominated by Gordonia, followed by Proteobacteria dominated by Gammaproteobacteria, and by pathogenic species such as Escherichia sp., Acinetobacter baumannii, Pseudomonas sp., Stenotrophomonas maltophilia, and Enterobacter sp.. Metagenomic assessment of bacterial biodiversity in the tap water connected to dishwashers revealed predominance of Gram-negative bacteria, and in particular Proteobacteria, dominated by Betaproteobacteria, mainly represented by Tepidimonas sp.. Both Actinobacteria and Firmicutes showed low numbers, while there were markedly more Alphaproteobacteria and Betaproteobacteria in the tap water. These data indicate that colonisation of dishwasher rubber seals depends primarily on the bacterial input from the dirty vessels, and much less on the bacteria in the tap water.
... Besides fungi, also bacteria can contaminate dishwashers as revealed in limited studies focusing on dishwasher bacterial contamination (Rehberg et al., 2017;Raghupathi et al., 2018. Surprisingly, the prevous studies performed on bacteria in dishwashers were focused on dishwasher sanitising performance, in terms of the determination of the survival of certain selected pathogenic bacterial species during the washing cycle and on the washed eating utensils (Ståhl Wernersson et al., 2004;Lee et al., 2007;Nicolella et al., 2011). ...
Bacteria that colonise the extreme environment of household dishwasher rubber seals were investigated using cultivation-dependent and metagenomic approaches. All 30 dishwashers investigated were colonised by various bacteria. Cultivation approaches resulted in 632 bacterial isolates in total, belonging to four phyla, eight classes, 40 genera and 74 species. The majority were Gram-positive, as solely Firmicutes and Actinobacteria. Bacilli represented half of the Gram-positive isolates, and were dominated by the Bacillus cereus group. Gammaproteobacteria were primarily represented by Stenotrophomonas maltophilia, Pseudomonas aeruginosa and Escherichia coli. All isolates were tested for resistance to seven selected antibiotics. Metagenomic assessment of the bacterial biodiversity of the dishwasher rubber seals confirmed the predominance of Gram-positive bacteria, as primarily Actinobacteria dominated by Gordonia, followed by Proteobacteria dominated by Gammaproteobacteria, and by pathogenic species such as Escherichia sp., Acinetobacter baumannii, Pseudomonas sp., Stenotrophomonas maltophilia, and Enterobacter sp.. Metagenomic assessment of bacterial biodiversity in the tap water connected to dishwashers revealed predominance of Gram-negative bacteria, and in particular Proteobacteria, dominated by Betaproteobacteria, mainly represented by Tepidimonas sp.. Both Actinobacteria and Firmicutes showed low numbers, while there were markedly more Alphaproteobacteria and Betaproteobacteria in the tap water. These data indicate that colonisation of dishwasher rubber seals depends primarily on the bacterial input from the dirty vessels, and much less on the bacteria in the tap water.
... Besides fungi, also bacteria can contaminate dishwashers as revealed in limited studies focusing on dishwasher bacterial contamination [52,53,72]. Surprisingly, the prevous studies performed on bacteria in dishwashers were focused on dishwasher sanitising performance, in terms of the determination of the survival of certain selected pathogenic bacterial species during the washing cycle and on the washed eating utensils [40,46,62]. ...
Background:
In modern lifestyles, people make their everyday tasks easier by using household appliances, for example dishwashers. Previous studies showed massive contamination of dishwasher rubber seals with fungi, thus bacterial community, able to survive under harsh conditions, remain undetermined.
Methods:
Bacteria that colonise the extreme environment of household dishwasher rubber seals were investigated using cultivation-dependent and metagenomic approaches. All bacterial isolates were tested for resistance to seven selected antibiotics. Same time bacterial diversity of tap water, connected to the dishwashers was investigated.
Results:
All 30 dishwashers investigated were colonised by various bacteria. Cultivation approaches resulted in 632 bacterial isolates in total, belonging to four phyla, eight classes, 40 genera and 74 species. The majority were Gram-positive, as solely Firmicutes (dominated by the Bacillus cereus group) and Actinobacteria. Gammaproteobacteria were primarily represented by Stenotrophomonas maltophilia, Pseudomonas aeruginosa and Escherichia coli. Metagenomic assessment of the bacterial biodiversity of the dishwasher rubber seals confirmed the predominance of Gram-positive bacteria, as primarily Actinobacteria, followed by Proteobacteria dominated by Gammaproteobacteria, and by pathogenic species such as Escherichia sp., Acinetobacter baumannii, Pseudomonas sp., Stenotrophomonas maltophilia, and Enterobacter sp.. Metagenomic assessment of bacterial biodiversity in the tap water connected to dishwashers revealed predominance of Gram-negative bacteria, in particular Proteobacteria, mainly represented by Tepidimonas sp.. Actinobacteria showed low numbers while no Firmicutes were detected in the tap water. The bacterial diversity of tap water was also lower, 23 genera compared to 39 genera on dishwasher rubber seals. Only 13 out of 49 genera identified by metagenomics approach was found in both environments, of those Gordonia was enriched while half of 13 genera were depleted in dishwashers compared to tap water.
Conclusions:
These data indicate that colonisation of dishwasher rubber seals probably depends primarily on the bacterial input from the dirty vessels, and much less on the bacteria in the tap water. Based on the antibiotic resistance data, the dishwasher rubber seal bacterial isolates do not represent a serious threat for the spread of antibiotic resistance into the household environment. Nevertheless dishwashers cannot be ignored as potential sources of human infections, in particular for immuno-compromised individuals.
... Washing in a dishwasher is usually carried out at high temperatures of 55-65°C, followed by a shorter hot water rinse cycle (~85°C) and the use of alkaline detergents. The mechanical power of water jets cleans the vessels [31]. The dishwashers do not disinfect the dishes, but reduce the number of microorganisms to a level that is considered safe [32]. ...
Candidiasis is one of the common fungal opportunistic infections, usually
associated with diverse Candida species. Candida albicans, C. glabrata complex, C.
parapsilosis complex, C. tropicalis and C. auris are often identified in affected patients.
Candida parapsilosis sensu stricto is an emerging cause of hospital-acquired Candida
infections, predominantly in Southern Europe, South America and Asia. Home environment is a less known source of infection despite frequent isolation of C. parapsilosis from kitchen surfaces and household appliances such as dishwashers, washing
machines and refrigerators. C. parapsilosis is one of the first colonisers of novel
dishwashers and a member of stable fungal communities on rubber seals worldwide
in concentrations up to 102
CFU/cm2
. It colonises also drawers for detergents in washing machines and drainage channels in refrigerators. Tap water and groundwater
act as vector for entrance of C. parapsilosis in the indoor environments. Within C.
parapsilosis, four clinically relevant phenotypes can be distinguished. Experimental
data on the prevalence of C. parapsilosis isolates phenotypes, obtained from indoor
environments, will be presented. Smooth phenotype prevails in dishwashers and
washing machines, while crepe and crater dominate in water. In conclusion, the ability to colonise diverse environments and accordingly switch phenotypes defines C.
parapsilosis as a versatile, domestic environment-related opportunistic pathogen.
... Foodborne diseases continue to be a public health concern, especially in the restaurants and food service outlets (Steffen et al. 2010). In the US, the high incidence of foodborne outbreaks could be associated to food service facilities due to poor personal hygiene of food handlers, incorrect storage conditions, and cross contamination (Wernersson et al. 2004). EW has successfully been used as a disinfectant for food service establishments, especially restaurant and hygiene maintenance in factory Sigua et al. 2011;Steffen et al. 2010). ...
Foods of animal origin, such as red meat and poultry products, are primary sources of superior protein for humans. With the production and consumption of these products increasing rapidly in recent decades, microbial safety and food quality are vital issues. Electrolyzed water (EW) as a sanitizer has awakened high interest in the food industry of many countries. The use of EW to decontaminate fresh red meat, ready-to-eat meat, poultry and shell eggs has been effective in reducing pathogenic microorganisms. Moreover, EW presents many advantages over traditional decontaminants; it provides effective antimicrobial activity and is environmentally friendly, simple to handle and relatively inexpensive. However, no complete elimination of pathogens on red meat and chicken meat was obtained after treatment of the meats with EW. This result probably occurs because organic matter and blood residue were present. This chapter provides a brief overview of how EW treatment affects foods of animal origin, especially the microbial safety and the physicochemical and sensory qualities of the food.
... Foodborne diseases continue to be a public health concern, especially in the restaurants and food service outlets (Steffen et al. 2010). In the US, the high incidence of foodborne outbreaks could be associated to food service facilities due to poor personal hygiene of food handlers, incorrect storage conditions, and cross contamination (Wernersson et al. 2004). EW has successfully been used as a disinfectant for food service establishments, especially restaurant and hygiene maintenance in factory (Handojo et al. 2009;Sigua et al. 2011;Steffen et al. 2010). ...
A number of studies have considered environment surfaces of food processing and medical equipment and facilities as potential source of food contamination and transmission of pathogens to hospitalized patients. To prevent food contamination and infection transmission, there is a need for good cleaning and disinfection programs. Excellent cleaning and disinfection program require sequential washing steps with clean and water, alkaline, acidic, and rinsing water applications in numerous combinations of temperature and concentration. Electrolyzed water is effective and an alternative sanitizer with a number of advantages. Regarding pH, it can be produced in the same electrolytic cell to obtain alkaline and AEW solutions. Therefore, it has the potential to play both cleaning and disinfecting functions on environmental surfaces. EW solutions have pertinent potentials for preventing cross contamination and infection transmission in the food industry and hospital. EW solutions have been found to provide an excellent cleaning and disinfection results compared to traditional treatments. The on-site production of EW solutions requires few and safe ingredients to produce EW which are environmental friendly. In this chapter, we review the mode of application and factors affecting the efficacy of EW on environment cleaning and disinfection. We also discuss its potential impact on cleaning and disinfecting environmental surfaces in food processing and healthcare facilities.
... Bacillus is ubiquitous in domestic environments (Gorny et al., 1999;Park et al., 2006) and is widely used in industry as a microbial indicator for cleaning procedures during washing cycles (Ståhl Wernersson et al., 2004;Lee et al., 2007;Nicolella et al., 2011). The diversity of fungi isolated from DWs was in accordance with previous studies Gümral et al., 2015;Zupančič et al., 2016).Black yeasts, E. dermatitidis and E. phaeomuriformis were represented in most dishwashers; followed by white yeasts, Candida parapsilosis and red yeasts, Rhodotorula mucilaginosa. ...
Interactions between bacteria belonging to different species are vital for the development of complex microbial communities, including multispecies biofilm. Multispecies biofilms are ubiquitous in most natural and man-made environments; their presence is now subject to ever-increasing attention. Several studies have shown that bacterial species living in complex bacterial communities interact, both intra- and interpecifically, and that these interactions are instrumental in structural establishment and distribution of bacterial species within multispecies biofilm. These complex interactions often result in the bacteria developing properties that would not been present when grown alone. These emergent properties include increased tolerance to antibiotics, host immune responses, and other stressors, which has proven to provide increased fitness benefits to members of the mixed community. Co-cultivation studies using in-vitro multispecies settings have shown that bacteria in mixed communities produce increased biomass, and many studies have documented the formation of microbial aggregates, microcolonies or biofilm formation in response to the presence of predatory protozoa. The threat from bactericidal protozoans can affect the physiological state of the bacterial community and result in bacterial responses at both species and social levels, which is in turn influenced by the combination of different interactions and parameters. The purpose of this Ph.D. thesis was to address various aspects of bacterial interactions, all of which support multispecies biofilm formation, and to investigate the role of biofilms as protective mechanisms when grazing is widespread. More specifically, the microbial diversity of multispecies biofilm and selected eukaryotic organisms (protozoa and fungi, reespectively) associated with toothbrushes (manuscript 1) and dishwashers (manuscripts 2 and 3) were investigated. Multiple bacterial communities isolated from dishwashers were screened for their ability to produce biofilm; both individually and in co-cultures. The influence of bacterial interactions on population dynamics in a model culture with four different bacterial strains exposed to grazing (manuscript 4) was also studied. The results presented in this thesis shows that studies conducted under the conditions of multiple species, even though they are less complex than naturally occurring bacterial communities, allow us to characterize biofilms representing their natural environments where they most often exist as multispecies microbial communities. The resulting emerging properties such as increased biomass production and fitness benefits (protection against grazing) associated within the biofilm architecture, substantiate the presence of synergistic interactions in multispecies biofilm and further emphasize their influence on individual bacterial species during biofilm formation.
... Another highly represented bacterial genus was Bacillus. Bacillus is ubiquitous in domestic environments (Gorny et al., 1999;Park et al., 2006) and is widely used in industry as a microbial indicator for cleaning procedures during washing cycles (Ståhl Wernersson et al., 2004;Lee et al., 2007;Nicolella et al., 2011). The diversity of fungi isolated from DWs was in accordance with previous studies (Zalar et al., 2011;Dögen et al., 2013;Gümral et al., 2016;Zupančič et al., 2016). ...
Biofilms formed on rubber seals in dishwashers harbor diverse microbiota. In this study, we focussed on the microbial composition of bacteria and fungi, isolated from a defined area of one square centimeter of rubber from four domestic dishwashers and assessed their abilities to in vitro multispecies biofilm formation. A total of 80 isolates (64 bacterial and 16 fungal) were analyzed. Multiple combinations of bacterial isolates from each dishwasher were screened for synergistic interactions. 32 out of 140 tested (23%) four-species bacterial combinations displayed consistent synergism leading to an overall increase in biomass, in all experimental trails. Bacterial isolates from two of the four dishwashers generated a high number of synergistically interacting four-species consortia. Network based correlation analyses also showed higher co-occurrence patterns observed between bacterial members in the same two dishwasher samples, indicating cooperative effects. Furthermore, two synergistic four-species bacterial consortia were tested for their abilities to incorporate an opportunistic fungal pathogen, Exophiala dermatitidis and their establishment as biofilms on sterile ethylene propylene diene monomer M-class (EPDM) rubber and polypropylene (PP) surfaces. When the bacterial consortia included E. dermatitidis, the overall cell numbers of both bacteria and fungi increased and a substantial increase in biofilm biomass was observed. These results indicate a novel phenomenon of cross kingdom synergy in biofilm formation and these observations could have potential implications for human health.
... For this QMRA, it was assumed that all individuals may be susceptible to infections by any of the reference pathogens, despite the fact that up to 20% of the population may have genetic resistance to norovirus (Soller et al., 2010). Greywater from dishwashing could become contaminated by food preparation materials, and contaminated water in dishwashers can cross-contaminate dishware (Ståhl Wernersson et al., 2004). The use of electrocoagulation, ultrafiltration and chlorination should have high efficiency for pathogen removal from greywater, however there may be some exceptions. ...
As the demand for reliable and safe water supplies increases, both water quality and available quantity are being challenged by population growth and climate change. Greywater reuse is becoming a common practice worldwide; however, in remote locations of limited water supply, such as those encountered in military installations, it is desirable to expand its classification to include dishwashing water to maximize the conservation of fresh water. Given that no standards for dishwashing greywater reuse by the military are currently available, the current study determined a specific set of water quality standards for dishwater recycling systems for U.S. military field operations. A tentative water reuse standard for dishwashing water was developed based on federal and state regulations and guidelines for non-potable water, and the developed standard was cross-evaluated by monitoring water quality data from a full-scale dishwashing water recycling system using an innovative electrocoagulation and ultrafiltration process. Quantitative microbial risk assessment (QMRA) was also performed based on exposure scenarios derived from literature data. As a result, a specific set of dishwashing water reuse standards for field analysis (simple, but accurate) was finalized as follows: turbidity (<1NTU), Escherichia coli (<50cfumL(-1)), and pH (6-9). UV254 was recommended as a surrogate for organic contaminants (e.g., BOD5), but requires further calibration steps for validation. The developed specific water standard is the first for dishwashing water reuse and will be expected to ensure that water quality is safe for field operations, but not so stringent that design complexity, cost, and operational and maintenance requirements will not be feasible for field use. In addition the parameters can be monitored using simple equipment in a field setting with only modest training requirements and real-time or rapid sample turn-around. This standard may prove useful in future development of civilian guidelines.
Copyright © 2015 Elsevier B.V. All rights reserved.
... These can shield the attached organic matter from the rigors of cleaning. The findings of this study are supported by various researchers who reported on the effectiveness of manual washing on the elimination of foodborne bacteria such as Salmonella spp., E. coli, Staphylococcus aureus, Campylobacter spp., and Enterococcus faecium (Johansson, Ståhl Wernersson, & Håkanson, 2005; Kusumaningrum et al., 2002; Mattick et al., 2003b; Ståhl Wernersson et al., 2004a, 2004b ). These reports stated that the bacterial viability decreased with increasing air-drying time, washing temperature, washing time, and the choice of detergent. ...
This study evaluated the sanitization efficacies of manual three-compartment dishwashing processes as a function of washing temperature/time, contaminating organic matter, sanitizing condition, and bacterial type. Ceramic plates, drinking glasses, stainless-steel forks, spoons and knives and plastic serving trays were contaminated with egg, cheese, jelly, lipstick and milk. Each was inoculated with E. coli and L. innocua. Greater than 5-log bacterial reductions were achieved for all samples after washing at the combination of low washing temperature (24 °C) and minimal sanitizer concentration (150 ppm), except for bacteria on the milk-contaminated regular glasses. The viability of the bacterial species was affected by both organic matter types and the washing water temperature. Although E. coli showed better survival when compared with L. innocua for jellied utensils, there was no significant difference in survival between them for all other washing conditions. The use of quaternary ammonium compounds had similar killing effect against both bacteria.
... When possible, wash reusable items in a dishwasher (210,211). If dishwashers are not available, the items should be washed by hand with detergents. ...
There is a phrase in the English language: “pigs might fly”. The phrase is used, since pigs will never fly, as a metaphor for something that will never, or is highly unlikely to ever happen. It is perhaps somewhat ironic then that although the pigs are not flying it is due to the interaction between pigs, as the source, and aviation, as the vector, that the current influenza outbreak has spread so rapidly around the world. It is reasonable to ask how this has come about and what the implications are for the respiratory community.
Three criteria must be fulfilled for a pandemic to occur. First, a novel virus, to which a significant proportion of the world population have no immunity, must evolve. Secondly, this novel virus must have the capacity to cause human disease. Thirdly, and most critically, this virus must be easily transmissible between humans. Recent experience with avian influenza viruses has shown the development of novel and virulent viruses, which although able to cause very severe disease in humans, do not have the capacity to be transmitted easily from person to person. Many will not realise that human cases of avian influenza are continuing to occur in 2009, in Indonesia, China, Viet Nam and Egypt (http://www.who.int/csr/disease/avian\_influenza/Timeline\_09\_03\_23.pdf). However, infection is only occurring in those in direct contact with infected birds. The new H1N1 virus, that is believed to have evolved in pigs in Mexico, differs from the previous avian influenza viruses in that it is more easily transmissible between humans and this is why the current outbreak is occurring.
Influenza viruses are adapted to a number of avian and mammalian hosts and reach their greatest diversity in birds where they probably originally evolved. Most influenza viruses are host-specific, partly due to molecular interactions between the virus and host, …
In-home pet food handling and food dish hygiene practices can have adverse health impacts for both humans and pets. Safe food and dish handling guidelines are not easily evidenced for pet owners. The study was designed to investigate dog owners’ feeding habits and evaluate the impact of the Food and Drug Association (FDA) hygiene protocols on dog food dish contamination. Procedures and surveys were approved by NCSU-IACUC and -IRB. Pet feeding and food dish hygiene data were collected from 417 dog owner surveys and 68 food dish swabs. Total aerobic cell counts (TAC) were performed on 68 dishes and randomly assigned into Group A (FDA pet food handling and dish hygiene guidelines), Group B (FDA pet and human food handling and dish hygiene guidelines), or Group C (no guidelines). Hygiene protocols were instituted in-home for 1 week, followed by a second TAC and follow-up survey. Survey from dog owners-households indicated: 4.7% were aware of FDA pet food handling and dish hygiene guidelines; 36% have individuals ≤ 13 years old and/or immunocompromised; 43% store dog food 0-5 feet from human food; 34% wash their hands after feeding; and 33% prepare their dog food on human food preparation surfaces. The hygiene protocols followed by Groups A and B resulted in significant decreases in food dish TAC (P<0.001; 1.40; p=0.026; 0.604, respectively), as compared to Group C (p=0.373). Hot water (>160F) washing decreased TAC (p=0.005) over cold/lukewarm water. In the follow-up survey, 8% of Group A and B respondents reported likely to adhere to protocols long-term. This study suggests a need for pet food handling and dish hygiene guideline education to minimize bacterial contamination of dishes, especially in high-risk households.
The abundance of antibiotic-resistant bacteria and ARGs is steadily increasing and has been comprehensively analyzed in natural environments, animals, foods, and wastewater treatment plants. In this respect, β-lactams and colistin are of particular interest due to the emergence of multidrug-resistant Gram-negative bacteria. Despite the connection of private households to these environments, only a few studies have focused on the domestic environment so far. Therefore, the present study further investigated the occurrence of ARGs and antibiotic-resistant bacteria in shower drains, washing machines, and dishwashers. The analysis of the domestic environment as a potential reservoir of resistant bacteria is crucial to determine whether households contribute to the spread of ABR or may be a habitat where resistant bacteria from the natural environment, humans, food, or water are selected due to the use of detergents, antimicrobial products, and antibiotics. Furthermore, ABR could limit the options for the treatment of infections arising in the domestic environment.
Background: Medical foods could be vehicles of pathogenic microbes for vulnerable people in the hospitals. Hospital kitchen is considered as the main source of this cross-contamination. Objectives: The current study aimed at investigating the frequency of bacterial species and their antimicrobial resistance patterns in foods, food handlers, and utensils compared with those of the clinical isolates in a hospital kitchen in Tehran, Iran. Methods: This cross sectional study was performed in a hospital in Tehran, Iran from April 2011 to January 2013. Accordingly, simple random sampling of raw and cooked food materials, swab samples of cooking utensils, and hands and noses of food staff were done. Clinical samples were collected from blood, urine, wound, and respiratory aspirates of patients with hospital acquired infections. Bacterial isolates were identified according to biochemical standard identification schema. Antimicrobial susceptibility of the strains was determined by disk diffusion method according to the CLSI (the clinical and laboratory standards institute) guidelines. Molecular diversity of indicator bacterial isolates of Staphylococcus aureus and Escherichia coli in the kitchen and those of the isolated ones from intensive care unit were also investigated by molecular typing method. The occurrence of cross-contamination was hypothesized based on the results of phylogenetic investigation and resistance biotyping. Results: Out of the 200 kitchen samples, S. aureus, E. coli, Acinetobacter spp., Pseudomonas spp., and Enterococcus spp. were isolated in frequencies of 15.5%, 8%, 2.5%, 0.5%, and 0.5%, respectively. Prevalence of multidrug resistant-methicillin resistant strains of S. aureus (MDR-MRSA) in the samples of the hospital kitchen vs the intensive care unit (ICU) was 18.7% (6/32), compared with 91.6% (22/24), respectively. Among the kitchen E. coli isolates, MDR pattern was detected in a frequency of 52.9%; the highest frequency was detected among the isolates of utensils. Although the results of the phylogenetic and resistance biotyping analyses did not confirm significant relationship between the isolates of the ICU and hospital kitchen, this similarity was confirmed among the strains isolated from the foods, food handlers, and utensils. In this regard, food staff and utensils were considered as the main sources of cross-contamination for S. aureus and E. coli, respectively. Conclusions: Weak health conditions of food workers and inadequate cooking to eliminate the contaminants during food processing were postulated as the main risk factors for transmission of these bacteria, through medical foods. into hospital.
Regardless of whether a pathogen is viral, bacterial, parasitic, fungal or an emerging unknown, the mainstay of infectious disease control is hygiene, and the cornerstone of good hygiene is effective disinfection.
Certain pathogens present a challenge to kill effectively: parvovirus, protozoal oocysts, mycobacteria, bacterial spores and prions resist most disinfectants but can be eliminated through heat, especially steam, which will kill protozoal oocysts. Heat is the safest and most effective disinfectant, but cannot be universally applied. Temperatures in washing machines and dishwashers should be at least 60°C to eliminate pathogenic spores and resistant viruses. Enveloped viruses are susceptible to most disinfectants; of the non-enveloped viruses, parvovirus is recognised as being the most difficult to eradicate. Sodium hypochlorite is recommended for many applications: cleaning of floors, laundry, food preparation surfaces and utensils. Skin scrubs and rubs containing alcohols are more effective than those containing chlorhexidine, and less subject to contamination.
Deficiency of the enzyme UDP-glucuronosyl transferase renders the cat susceptible to the toxic effects of phenol-based disinfectants (including many essential oils), so these should be avoided in feline environments. Quaternary ammonium compounds (eg, benzalkonium chloride) are also probably best avoided.
Veterinary disinfection approaches in the future may include use of ultraviolet radiation and, increasingly, silver.
© Published by SAGE on behalf of ISFM and AAFP 2015.
The adhesion of pathogenic bacteria on food contact surfaces increases the risk of cross-contamination in the food industry. However, food-borne disease introduced by the production process can be mitigated by surfactant use. This study investigates the effect of food residues (milk, beef gravy and tuna gravy) on the bactericidal efficiency of benzalkonium chloride (BAC) and alkyldiaminoethylglycine hydrochloride (AGH). The test was conducted on pathogenic bacteria (Escherichia coli O26, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, and B. cereus spores) dried and adhered to the surfaces of polystyrene and ceramic dishes at room temperature for 1.5 h. The protein and lipid rich food residues protected the bacterial cells from dehydration and from the adverse effects of disinfectants, although bacterial numbers were decreased after drying and the surfaces were clearly sterilized after disinfectant treatment at typical concentrations (0.5 mg/ml–2.0 mg/ml) for 10 min. Following general and proper washing processes, the bactericidal effect of the disinfectants became clearly visible. These results indicate that applying a proper washing process prior to disinfectant treatment can prevent cross-contamination.
Quality assurance of cleaning procedures is important as regards production efficiency, food safety and food quality. Model routines for the assessment of cleaning methods require that materials can be fouled in a reliable manner. The present study was performed to demonstrate that a reproducible soiling of stainless steel can be achieved as long as the flow characteristics of the soiling fluid (i.e., different types of gelatinized starch) and specific aspects of the corresponding procedure for the quantification of soil residues are considered.
In all types of professional and domestic dishwashing, water is used as a rinse medium. This article describes the difference between the quality of the dishwaters used in hand dishwashing and machine dishwashing. The dishwashing process and the detergents determine the dishwashing parameters like pH, temperature, and time. The microbiological activity and COD in the dishwater have been evaluated for the above parameters. Differences in the aerobic plate count (APC) for dishwater coming from hand dishwashing and dishwashers are compared, as well as the content of Enterobacteriaceae and Bacillus cereus. The environmental aspects on the water consumption for different types of dishwashing processes are reported. Also the methods to reduce the microbiological activity in dishwater are discussed.
The cleanliness of plates and dishes washed in two different types of machines was investigated. Both machines were one-tank dishwashers; one of them used water and detergent, the other used plastic granules, water and detergent as the cleaning medium. The mechanical effect of plastic granules, water and detergent cleaned the dishes better than water and detergent alone. For easily removed soil, as characterized in the international standards ANSI/NSF 3 and DIN 10512, both dishwashing machines resulted in clean dishes. Dishes covered with a more adhesive soil were clean only after washing in the granule-assisted washer. The importance of cleaning plates and dishes, in order to avoid cross-contamination and the spread of infection, is discussed.
Microorganisms have been frequently found in dishwaters despite high temperatures and pH levels. Therefore, this study investigates the dishwater in dishwashing processes to determine the survival rate of a heat-resistant test organism, Enterococcus faecium. The experiments are conducted in a 2-L beaker, and the temperature and the pH are varied in the spans typical for hand dishwashing and mechanical dishwashers (45–65C and pH 7–9). Tryptic soy is added to the beaker to study the influence of nutrition (which normally exists in dishwater). A three-log reduction of E. faecium after 50 min at 65C is noted and compared with 300 min at 55C, at pH 7. For 45C, no reduction of E. faecium is observed. The findings emphasize the importance of maintaining a high temperature in dishwaters during dishwashing processes.
Objective: To determine the microbiological quality of home meals and salads samples. Methodology: A total of 180 samples were collected between May 2007 and July 2007 in Ankara, Turkey. The samples were analysed for the presence of total aerobic bacteria (TAB), thermotolerant coliform bacteria (TCB), Esherichia coli, Salmonella spp. and Staphylococcus aureus. Results: In the present study, S.aureus, coliforms, E.coli, and Salmonella were not detected in cooked meat meals samples. TAB was detected in 22 (24.4%) meat dishes ranges 10 2 -10 4 . The cooked meat dishes samples were analyzed for the presence of TCB, and detected in 2 (2.2%) meat dishes ranges 10 3 -10 4 . Numbers of the aerobic mesophilic bacteria ranged from 10 2 to 10 5 cfu/g and coliforms from 37 to 1400 MPN/g in 17 (18.9%) of salad samples. E.coli was detected at level 10 2 -10 3 (n=12, 13.3%) and S. aureus was detected in 9 (10.0%) at levels of 10 3 -10 4 cfu/ g salad samples tested. In 4 (4.4%) of the salads samples S.aureus and E.coli were isolated together. Conclusion: The results indicate that the type of vegetable salads analysed may contain pathogenic bacteria and thereby represent a risk to the consumers in regard to foodborne diseases. Thus, it remains essential to include the significance of effective hygiene practices as an important safety measure in programmes of home hygiene, consumer education, and advice quality of home cooked meat meals and vegetable salads. Pak J Med Sci 2010;26(2):416-419.
This study compared the efficacies of two traditional with two experimental sanitizers for use in tableware cleaning operations in restaurants and foodservice operations. This was done by investigating the maximum number of cleaning cycles that a single recommended quantity of each sanitizer could treat and still produce a 5-log bacterial reduction on test tableware items. Cream cheese and whole milk were inoculated with Escherichia coli K12 and Listeria innocua and subsequently used for contamination of the tableware items. These items were washed with automatic (49 °C) and manual (43 °C) dishwashers then treated with electrolyzed-oxidizing water (EO), quaternary ammonium compound, sodium hypochlorite and an acidic sanitizer. For the lowest efficacies, after six and eight manual washing cycles in the same solution, ≥5 log reductions were achieved on both E. coli K12 contaminated trays and plates, respectively, exposed to the chlorine and quaternary ammonium sanitizers. For automatic washing with chlorine sanitizer, the minimum wash cycles for the bacteria were seven and nine for the trays and plates, respectively. For drinking glasses contaminated with bacteria, 14 and 17 washing cycles produced ≥5 log reductions for manual and automatic washings, respectively.
To review recent publications relevant to hospital disinfection (and cleaning) including the reprocessing of medical instruments.
The key question as to whether the use of disinfectants on environmental surfaces rather than cleaning with detergents only reduces nosocomial infection rates still awaits conclusive studies. New disinfectants, mainly peroxygen compounds, show good sporicidal properties and will probably replace more problematical substances such as chlorine-releasing agents. The safe reprocessing of medical devices requires a well-coordinated approach, starting with proper cleaning. New methods and substances show promising activity for preventing the transmission of prions. Different aspects of virus inactivation have been studied, and the transmissibility, e.g. of norovirus, shows the need for sound data on how different disinfectant classes perform. Biofilms or other forms of surface-adherent organisms pose an extraordinary challenge to decontamination. Although resistance to biocides is generally not judged to be as critical as antibiotic resistance, scientific data support the need for proper use, i.e. the avoidance of widespread application, especially in low concentrations and in consumer products.
Chemical disinfection of heat-sensitive instruments and targeted disinfection of environmental surfaces are established components of hospital infection control. To avoid danger to staff, patients and the environment, prudent use as well as established safety precautions are required. New technologies and products should be evaluated with sound methods. As emerging resistant pathogens will challenge healthcare facilities in the future even more than at present, there is a need for well-designed studies addressing the role of disinfection in hospital infection control.
This paper investigates the effect of chlorine and silver ion solutions on the survival of Bacillus cereus (vegetative phase) and Staphylococcus aureus in batch cultures, representing dishwater. Dishwater contains organic matter and bacteria and bacterial activities are partly reduced by high pH (11-12) and temperature (55-65 degrees C) in professional and domestic dishwashers. In manual dishwashing, temperature and pH are kept lower (45 degrees C and pH 7), which is less sufficient for the reduction of bacteria. In a broth, organic loaded in order to mimic dishwater, solutions of Ag or hypochlorite were added at 45 degrees C and pH 7 and samples were withdrawn for a period of 40 minutes. 1 ppm Ag+ was required to obtain a 1 to 2 log unit reduction of B. cereus and S. aureus in 10 minutes. An addition of 160 ppm hypochlorite reduced B. cereus and S. aureus by 4 log units in two minutes, whereas 16 ppm of hypochlorite had no effect on the survival of S. aureus. The level of free residual chlorine varied with the COD value of the cultured solutions. We found that both silver and hypochlorite can be used as antibacterial agents in dishwater. The disadvantage with the use of hypochlorite is that the COD value determines the antibacterial effect. Using Ag+ solutions to reduce bacteria has the drawback that they are toxic to water-living organisms and are considered to develop Ag+ resistant bacteria. To reduce the risk of cross-contamination from dishwater to dishware high temperature and detergent with high pH is to be preferred.
Over time, changes to food production and eating habits lead to changes in the organisms that are seen as important in causing foodborne disease. New pathogens also arise and species can become associated with foods that were not previously identified as foodborne. This chapter covers examples of some of the organisms that are less widely viewed as causing foodborne disease: this may be due to their underreporting; the organism being an opportunistic pathogen, causing disease only in particular situations; their association with causing gastrointestinal disease via a food route not being conclusively demonstrated; or the organism's association with disease not being clearly established.
After extensive laboratory tests and practical multicentre studies carried out in addition the most important parameters that influence the hygienic condition of the washed devices has been found out. Thus hygienic processing can be monitored in several biological test steps. The methods tested and their statements are described thoroughly. Suitable methods has been integrated in the DIN Standard NAL 10510. The norm has been accepted on 16.11.95 by the board of foodhygiene and is going to be printed.
Fifteen dishwashing machines tested in four different hospitals failed to satisfy the minimum heat treatment requirement of 82 degrees C for 2 min for satisfactory thermal disinfection. The causes of failure included design faults in the machines with lack of time temperature controls, hard water supply, inadequately treated water, improper softening and inadequate preventative maintenance.
A comparison of the cleaning efficiency and thermal disinfection capabilities of 12 small dishwashers being used in hospital wards was carried out. Machines installed prior to the establishment of a local purchase policy failed to achieve the standards required for hygienic washing up. Machines conforming to the purchasing criteria gave a satisfactory performance.
The supply of food to patients and staff is the responsibility of hospital support services. This article considers the provision of catering services and the production of safe food in hospitals in the UK. The responsibilities of food handlers and the role of the infection control team, the environmental health officer and the occupational health staff are also described.
In hospitals, medical instruments are usually cleaned and disinfected in a washer/disinfector. However, it is not efficient for small hospitals or general practitioners to purchase such machines as they would not be working to capacity. We investigated the possibility of cleaning and disinfecting medical equipment in a conventional household dishwasher modified to achieve a temperature of 71 degrees C. For this purpose we contaminated screws with different test soils containing either bacterial (100 screws) or viral (106 screws) suspensions. Test organisms were re-isolated from 2% of the screws after bacterial contamination and 4.7% of those with viral contamination. In both cases we found dishwasher-processing to be a suitable means of disinfecting medical instruments.
Hygiene in warewashers utilizing blasting granules that foodservice establishments use
- E Wernersson
- H Hå
- E Lindvall
- Trägå
Wernersson E, Hå H, Lindvall E, Trägå C. Hygiene in warewashers utilizing blasting granules that foodservice establishments use. Food Prot Trends 2003;23: 21—31.
The sanitizing efficiency of dishwashing machines
- Poledore
Poledore AP. The sanitizing efficiency of dishwashing machines. J Foodservice Syst 1980;1:17—25.
Microbiological food safety at retail
- S Huddle
- F Busta
- T Freier
- S Cohn
- S Sumner
- D Theno
Huddle S, Busta F, Freier T, Cohn S, Sumner S, Theno D. Microbiological food safety at retail, International Association for Food Protection. 89th Annual Meeting San Diego 2002, Symposium abstracts, p. 144.
U ¨ berprü der Dekontamina-tionswirkung in Mehrtank-Spü
- Krü Von S
- Zschaler
Krü von S, Zschaler R. U ¨ berprü der Dekontamina-tionswirkung in Mehrtank-Spü. Archiv fü Lebensmittelshygiene 1996;47:105—128.
Granule assisted warewashing improves hygiene
- E Wernersson
- E Johansson
- Hå
Wernersson E, Johansson E, Hå H. Granule assisted warewashing improves hygiene. Unpublished obser-vations.
Granule assisted warewashing improves hygiene
- E Ståhl Wernersson
- E Johansson
- H Håkanson
Hygiene in warewashers utilizing blasting granules that foodservice establishments use
- Ståhl Wernersson