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Bacteriophages In The Control Of Food And Waterborne Pathogens Pdf

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Waterborne diseases are conditions caused by pathogenic micro-organisms that are transmitted in water. These diseases can be spread while bathing, washing, drinking water, or by eating food exposed to contaminated water. While diarrhea and vomiting are the most commonly reported symptoms of waterborne illness, other symptoms can include skin, ear, respiratory, or eye problems.

Foodborne viral infections

Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. The transmission of infectious diseases via contaminated water continues to be a risk to public health in the United States and throughout the rest of the. Source and finished drinking waters are vulnerable to microbial pathogen contamination from a variety of sources of human and animal fecal wastes and from the introduction and proliferation of nonfecal pathogenic microbes.

Throughout most of the modem history of drinking water supply, concerns about pathogenic microbes have focused on enteric bacteria of human fecal origin. These concerns led to the development of criteria and standards for bacteriological quality intended to protect against excessive risks from enteric bacterial pathogens such as Salmonella typhi and other nontyphoid Salmonella spp. The infectious disease risks in drinking water supplies from enteric viruses such as hepatitis A virus , enteric parasites such as Entamoeba histolytica and Giardia lamblia , and nonfecal bacterial pathogens such as Legionella spp.

These risks were recognized initially by the occurrence of waterborne outbreaks of disease mused by these pathogens. Until recently there were no formal, legally required processes to identify or consider new or emerging water. Environmental Protection Agency EPA was required to identify through a structured process candidate microbial pathogens for possible regulation in drinking water supplies.

Prior to this the agency used an informal and largely reactive process to recognize, identify, and prioritize microbial pathogens for possible regulation. The new requirement for a proactive rational process to identify and consider microbial pathogens for possible regulation in drinking water is the essential motivation for this paper. As part of this process it is necessary to detect and quantify microbial pathogens in drinking water and its sources; to establish dose-response relationships as an essential step in health effects characterization for waterborne pathogens; and to identify, characterize, and quantify the virulence properties of these pathogens that influence their human health effects.

The purpose of this report is to consider and address the following questions: How should microbial contaminants for possible regulation in drinking water be identified, characterized, and quantified with respect to their risks to public health? What should be the essential elements of the process for waterborne microbial pathogen identification and characterization? What should be the basis for prioritizing, ranking, or choosing among the many potential drinking water pathogens for possible regulation?

How should the microbial pathogen identification and selection process be integrated into the overall process of improving drinking water quality and reducing health risks through drinking water regulations? How should analytical methods for detection, characterization, and quantification of microbial contaminants be applied to the process of identifying, characterizing, and quantifying the risks from waterborne pathogens being considered for regulation?

The recognition, identification, prioritization, and characterization of microbial pathogens in drinking water should be risk based and should consider the relationships and interactions of the microbes, their hosts, and the environment. The microbial world consists of a wide variety of different types or classes of microbial agents potentially present in water. Viruses, bacteria, protozoans, fungi, and algae are widespread in soil, sediments, water, air, and food and on objects and surfaces with which humans have contact "fomites".

Most of these microbes are not pathogenic harmless and are incapable of infecting or colonizing immunocompetent persons unless they somehow gain access to sterile internal sites in the body such as the bloodstream and various organs through trauma, surgery, or other such means. However, persons with immunodeficiencies are at risk of infection, colonization, and illness from microbes considered nonpathogenic for immunocompetent persons. Therefore, recognition and identification of a possible waterborne pathogen depends in part on the susceptibilities of the population to infection, colonization, and illness from a microorganism.

Some pathogens are always potentially pathogenic and are often referred to as "frank" pathogens. Other pathogens are never or rarely pathogenic for immunocompetent and otherwise "healthy" people. However, these microbes can sometimes cause infection, colonization, and illness in persons who have an immune deficiency, have other conditions that make them susceptible, or because they encounter the microbe in an unusual or atypical way.

Such microbes are sometimes referred to as "conditional" or "opportunistic" pathogens. As previously noted, there are nonpathogenic microbes in the environment that are capable of infecting, colonizing, and causing illness in humans only if they are able to dramatically breach the body's natural barriers.

These nonpathogenic or "saprophytic" microbes are common in aquatic and other environments. A waterborne pathogen may emerge or acquire increased public health importance because of changes in host susceptibility to infection.

Factors influencing host susceptibility in the population include increases in the number of immunocompromised persons, increased use of immunosuppressive agents among persons receiving cancer chemotherapy or undergoing organ transplants , increases in the elderly segment of the population, and poor nutrition. In identifying and prioritizing emerging waterborne pathogens the susceptibilities of these higher-risk population subgroups to specific infectious diseases is an important consideration Morris and Potter, The relationships between waterborne microbes and their human hosts are complex and are influenced by a variety of factors involving the characteristics and conditions of the microbe, the human and in some cases animal hosts, and the environment.

Therefore, it seems necessary to identify, characterize, and quantify these relationships in order to determine if a potentially waterborne microbe should be considered or classified as a drinking water contaminant for possible regulation. Furthermore, the need to prioritize or otherwise determine the importance of a microbe for possible regulation in water suggests that a structured and quantitative approach must be used for such an evaluation or assessment. Over the past two decades considerable progress has been made in quantitative risk assessment QRA for making management decisions about waterborne pathogens.

This process consists of hazard identification, exposure assessment, effects assessment, and risk characterization. Using this approach, quantitative risk assessments were done initially for several recognized waterborne pathogens, such as Giardia lamblia and rotaviruses. This effort resulted in a modified quantitative risk assessment system that specifies the criteria, information needs, and analytical approaches for quantitative risk assessment for waterborne microbes See Figure Furthermore, it certainly is not the only way to identify, prioritize, and assess the risks from microbes in drinking water.

However, this microbial QRA system does specify information needs and analytical methods that can be readily adapted to the recognition, identification, prioritization, and initial characterization of risks from a possible waterborne microbe. Considering that the EPA and many of the nation's scientists in the areas of water microbiology, infectious diseases, water treatment, epidemiology, and risk assessment invested much effort and time in the development of this system, it seems appropriate to interface it with the process for microbial contaminant selection.

Known and potential human pathogens in water include the spectrum of agents ranging, in order of increasing complexity, from prions, to viruses, to bacteria, and other prokaryotes, and the microbial eukaryotes the protists , including protozoans, fungi, and algae Moe, Prions have not been implicated in waterborne disease, but recent evidence for human spongiform encephalopathies from ingestion of beef contaminated with bovine spongiform agents suggests that vehicles such as food and possibly water contaminated with prions pose a risk of exposure Ironside, ; Knight and Stewart, Furthermore, these agents are very small compared to other microbes, which makes them difficult to remove by physical-chemical processes, and they are extremely resistant to virtually all physical and chemical agents, which makes them persistent in the environment and resistant to virtually all drinking water disinfectants.

Spatial distribution clumping, particle-association, clustering. Niche potential to multiply or survive in specific media. Temporal nature of exposure single or multiple; intervals.

Demographics of the exposed population age, density, etc. A variety of enteric and respiratory viruses of humans and in some cases other animals as well are potential agents of waterborne disease.

For many of these viruses the role of water has been clearly established because of documented waterborne outbreaks, or it is strongly suspected because the viruses have been detected in drinking water or its sources. Some of these viruses are shown in Table , but other viruses and virus groups may also pose risks from exposure via drinking water.

A notable feature of all of these viruses except the coronaviruses and picobirnaviruses is that they are nonenveloped consisting only of a nucleic acid surrounded by an outer protein coat or capsid. Nonenveloped viruses tend to be more resistant to various physical and chemical agents and more stable in the environment than the enveloped viruses, which probably contributes to their potential to cause waterborne disease. Another important feature of some of these viruses, as well as many of the bacterial and parasitic pathogens of concern in drinking water, is that they have known or suspected animal hosts and therefore are transmissible directly or indirectly from other animals to humans.

The potential for animal-to-human transmission creates concerns about contamination of drinking water supplies with animal wastes containing these pathogens. As previously noted, similar concerns also apply to many bacterial and parasitic pathogens. Many enteric and respiratory bacteria infect and cause morbidity and mortality in humans via the water route.

Some of these bacteria also infect other. For many of these bacteria the role of waterborne transmission has been documented by waterborne outbreaks, or it is strongly suspected because the bacteria have been detected in drinking water and its sources see Table In the case of some of these waterborne bacteria their risks to human health from ingestion or inhalation of water or contact with water are uncertain because they have not been conclusively documented by outbreaks or other epidemiological evidence of waterborne disease.

However, their presence in drinking water and the uncertainty of their risks to human health from drinking water exposure suggest the need for further investigation and analyses.

The risks posed by various bacteria potentially present in drinking water differ among the various genera and species as well as within the same genus and species of a bacterium.

These differences in risks to human health pose considerable challenges to the detection and identification of these bacteria in water. Similar concerns apply to the protozoan parasites, algae, and fungi. Strains or variants of the same genus and species of bacterium can differ dramatically in their ability to cause disease because this ability is largely dependent on the presence of virulence factors or properties.

In some cases the virulence factors or properties of the bacterium responsible for disease are essential constituents of the cell. This appears to be the case for Salmonella typhi, the causative agent of typhoid fever, whose essential virulence properties are the O antigen the lipopolysaccharide outer membrane of the cell wall; an endotoxin and the Vi antigen a capsule polysaccharide Salyers and Whitt, ; Levine, For many other bacteria, such as strains of Escherichia coli, Aeromonas hydrophila, and Yersinia enterocolitica, the ability to be a pathogen and cause disease is clearly associated with the presence of specific virulence properties that may or may not be present in specific strains or types.

These virulence factors are often transmissible from one cell to another via transmissible plasmids or bacterial viruses bacteriophages. Plasmids are extrachromosomal, small, circular DNA molecules that replicate separately from the bacterial chromosome and can move from one cell to another by a process called conjugation.

Bacteriophages also can transmit virulence factors from one host cell to another, especially if the infecting bacteriophages do not kill the cell and instead integrate their DNA into the bacterial chromosome. Strains of a species bacterium possessing no virulence factors generally are not pathogenic and do not produce disease. Strains of the same species of bacterium possessing one or more specific virulence factors are pathogenic and capable of producing disease. Furthermore, the pathology and clinical features of the disease depend on the properties and activities of these virulence factors.

For example, strains of E. Mycobacterium avium-intracellulare a and other Mycobacterium spp. However, E. For example, enterohemorrhagic strains of E. Other strains of E. These enterotoxigenic strains of E.

The roles of human and animal hosts as well as the environment in the selection for and emergence of new strains of virulent bacteria are becoming increasingly appreciated. For example, there is growing evidence that cattle and other agricultural livestock animals are major reservoirs of such waterborne and foodborne bacterial pathogens as enterohemorrhagic E. The role of the aquatic environment as a reservoir for and source of emergence of new virulent strains of bacteria is becoming increasingly recognized in the case of some bacteria.

For example, the genes coding for the cholera toxin of Fibrio cholerae are borne on and can be infectiously transmitted. The natural history of V.

Molecular epidemiological studies reveal clonal diversity among toxigenic V. The continual emergence of new epidemic clones may be taking place in aquatic ecosystems through interaction of the phages bearing the cholera toxin with different strains or antigenic types of V.

These new strains may then be selected for during epidemics in human populations. This appears to be an example of the evolution of new toxigenic strains of a human pathogen in natural aquatic ecosystems systems and its selection during outbreaks in human hosts.

Within the aquatic ecosystem, interactions of the genetic elements of the microbes and their host reservoirs mediate the transfer of virulence genes, thereby resulting in the creation and the subsequent selection in humans of these new pathogenic strains.

The extent to which such evolution and selection occurs for other human pathogens in aquatic ecosystems is unknown and deserves further investigation. In the past three decades, protozoan parasites have emerged as important waterborne pathogens Marshall, Some of the important protozoan parasites infecting humans and found in water are listed in Table The ameba Entamoeba histolytica, the cause of amebic dysentery, has long been recognized as a waterborne pathogen.

However, outbreaks of waterborne amebic dysentery have not been reported for decades in the United States and there are no major nonhuman reservoirs of this parasite. It was only with the recognition in the s and s of Giardia lamblia as a waterborne pathogen having important animal reservoirs and considerable resistance to chlorination and other drinking water disinfection practices that serious attention began to focus on this agent and other human pathogenic protozoans in drinking water.

Since then, Cryptosporidium parvum has become a high-priority pathogen for regulation in drinking water because of documented waterborne disease, many animal reservoirs, ubiquitous presence in drinking water sources, relatively small size, and resistance to chlorine and other drinking water disinfectants.

Bacteriophages in the control of food- and waterborne pathogens.

Foodborne illnesses remain a major cause of hospitalization and death worldwide despite many advances in food sanitation techniques and pathogen surveillance. Traditional antimicrobial methods, such as pasteurization, high pressure processing, irradiation, and chemical disinfectants are capable of reducing microbial populations in foods to varying degrees, but they also have considerable drawbacks, such as a large initial investment, potential damage to processing equipment due to their corrosive nature, and a deleterious impact on organoleptic qualities and possibly the nutritional value of foods. Perhaps most importantly, these decontamination strategies kill indiscriminately, including many—often beneficial—bacteria that are naturally present in foods. One promising technique that addresses several of these shortcomings is bacteriophage biocontrol, a green and natural method that uses lytic bacteriophages isolated from the environment to specifically target pathogenic bacteria and eliminate them from or significantly reduce their levels in foods. Since the initial conception of using bacteriophages on foods, a substantial number of research reports have described the use of bacteriophage biocontrol to target a variety of bacterial pathogens in various foods, ranging from ready-to-eat deli meats to fresh fruits and vegetables, and the number of commercially available products containing bacteriophages approved for use in food safety applications has also been steadily increasing.

The study examined the efficacy of using bacteriophage as an additive in a cooked-meat model system to control growth of contaminating Listeria monocytogenes during subsequent storage. Studies were designed where Listeria bacteriophage A and L. These scenarios include: 1 A and L. Under the conditions tested, application of A directly on top of L. Although A titers remained stable when applied as an additive in meat, they were not successful in controlling growth of the contaminating L. Similarly, application of A on the surface of the meat could not control growth of L.

Bacteriophage biocontrol in wastewater treatment

Sanna M. The interest for natural antimicrobial compounds has increased due to alterations in consumer positions towards the use of chemical preservatives in foodstuff and food processing surfaces. Bacteriophages fit in the class of natural antimicrobial and their effectiveness in controlling bacterial pathogens in agro-food industry has led to the development of different phage products already approved by USFDA and USDA. The majority of these products are to be used in farm animals or animal products such as carcasses, meats and also in agricultural and horticultural products. Treatment with specific phages in the food industry can prevent the decay of products and the spread of bacterial diseases and ultimately promote safe environments in animal and plant food production, processing, and handling.

Carbapenem-resistant Acinetobacter baumannii CRAB is associated with nosocomial infections worldwide.

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Waterborne bacterial pathogens are a major public health concern worldwide, taking many lives and imposing huge economical burden. Rapid and specific detection of pathogens and proper water quality monitoring is an urgent need for preventing the spread of bacterial pathogens and disease outbreaks. Bacteriophages, or phages for short, are the most abundant and ubiquitous biological entities on our planet. These bacterial viruses exist in every niche of the biosphere and target their host bacteria with high specificity. Phages can be employed as bio-probes to not only detect a pathogen of interest, but differentiate between viable and non-viable bacteria, and detect their host where traditional lab cultures may fall short.

Waterborne bacterial pathogens in wastewater remains an important public health concern, not only because of the environmental damage, morbidity and mortality that they cause, but also due to the high cost of disinfecting wastewater by using physical and chemical methods in treatment plants. Bacteriophages are proposed as bacterial pathogen indicators and as an alternative biological method for wastewater treatment. Phage biocontrol in large scale treatment requires adaptive and aggressive phages that are able to overcome the environmental forces that interfere with phage—host interactions while targeting unwanted bacterial pathogens and preventing biofilms and foaming. This review will shed light on aspects of using bacteriophage programming technology in wastewater plants to rapidly target and reduce undesirable bacteria without harming the useful bacteria needed for biodegradation. This is a preview of subscription content, access via your institution.

Bacteriophages and Their Role in Food Safety

Original Research ARTICLE

The system can't perform the operation now. Try again later. Citations per year. Duplicate citations. The following articles are merged in Scholar.

The world is currently facing a serious health burden of waterborne diseases, including diarrhea, gastrointestinal diseases, and systemic illnesses. The control of these infectious diseases ultimately depends on the access to safe drinking water, properly managed sanitation, and hygiene practices. Therefore, ultrasensitive, rapid, and specific monitoring platforms for bacterial pathogens in ambient waters at the point of sample collection are urgently needed. We conducted a literature review on state-of-the-art research of rapid in-field aquatic bacteria detection methods, including cell-based methods, nucleic acid amplification detection methods, and biosensors. The detection performance, the advantages, and the disadvantages of the technologies are critically discussed.

Bacteriophage biocontrol in wastewater treatment

The interest for natural antimicrobial compounds has increased due to alterations in consumer positions towards the use of chemical preservatives in foodstuff and food processing surfaces. Bacteriophages fit in the class of natural antimicrobial and their effectiveness in controlling bacterial pathogens in agro-food industry has led to the development of different phage products already approved by USFDA and USDA. The majority of these products are to be used in farm animals or animal products such as carcasses, meats and also in agricultural and horticultural products. Treatment with specific phages in the food industry can prevent the decay of products and the spread of bacterial diseases and ultimately promote safe environments in animal and plant food production, processing, and handling.

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Viral infections are the leading cause of gastroenteritis globally and in Europe and may also cause enterically transmitted hepatitis and illness after migrating from the human intestine to other organs. Various viruses have been implicated in foodborne illness, with two types of virus, Norovirus and Hepatitis A, causing the most significant burden of foodborne illness and outbreaks, as they are highly contagious. Rotavirus is one of the major causes of diarrhoea in children and Hepatitis E, while primarily associated with waterborne infections, has been associated with foodborne outbreaks. Food borne transmission is important in the epidemiology of these four viruses, in addition to person-to-person contact and environmental transmission.

Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. The transmission of infectious diseases via contaminated water continues to be a risk to public health in the United States and throughout the rest of the. Source and finished drinking waters are vulnerable to microbial pathogen contamination from a variety of sources of human and animal fecal wastes and from the introduction and proliferation of nonfecal pathogenic microbes. Throughout most of the modem history of drinking water supply, concerns about pathogenic microbes have focused on enteric bacteria of human fecal origin.

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Послание террористов удалось расшифровать всего за двадцать минут до готовившегося взрыва и, быстро связавшись по телефону с кем нужно, спасти триста школьников. - А знаешь, - Мидж без всякой нужды перешла на шепот, - Джабба сказал, что Стратмор перехватил сообщение террористов за шесть часов до предполагаемого времени взрыва. У Бринкерхоффа отвисла челюсть. - Так почему… чего же он так долго ждал. - Потому что ТРАНСТЕКСТ никак не мог вскрыть этот файл.

Однако она отлично знала, чем занимался Хейл. Он был законченным компьютерным маньяком.

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