Biological Sciences
Opportunistic Pathogens
Opportunistic pathogens are microorganisms that typically do not cause disease in a healthy host but can become pathogenic under certain conditions, such as a weakened immune system or disruption of the normal microbiota. These pathogens take advantage of opportunities presented by the host's compromised defenses to cause infection and disease. Examples include Candida albicans and Pseudomonas aeruginosa.
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8 Key excerpts on "Opportunistic Pathogens"
eBook - ePubFood Safety and Preservation
Modern Biological Approaches to Improving Consumer Health
- Alexandru Mihai Grumezescu, Alina Maria Holban(Authors)
- 2018(Publication Date)
- Academic Press(Publisher)
Chapter 10 Opportunistic Food-Borne Pathogens Vincenzina Fusco ⁎ ; Hikmate Abriouel † ; Nabil Benomar † ; Jan Kabisch ‡ ; Daniele Chieffi ⁎ ; Gyu-Sung Cho ‡ ; Charles M.A.P. Franz ‡ ⁎ Institute of Sciences of Food Production, National Research Council of Italy (CNR-ISPA), Bari, Italy † University Jaen, Jaén, Spain ‡ Max Rubner-Institute, Kiel, Germany Abstract Opportunistic Pathogens are microbes that usually do not cause disease in healthy people, but may become virulent with immunocompromised and unhealthy individuals. In the past decades, several microorganisms normally occurring in foods have emerged as Opportunistic Pathogens in humans and animals. The situation is being complicated by the emergence of multiply antibiotic-resistant strains of such Opportunistic Pathogens, which in the context of disease makes hospital acquired infections in susceptible hosts difficult to treat. This is the case for lactic acid bacteria species belonging to the genus Enterococcus, as well as for multidrug-resistant enterobacteria. Also, strains of other lactic acid bacterial species, such as Weissella or Lactobacillus species may be Opportunistic Pathogens in immunocompromised or hospitalized persons and cause severe infections. In this chapter, we will provide an overview of the main Opportunistic Pathogens occurring in foods and the most promising strategies to control their occurrence in foods. Keywords Opportunistic Pathogens; Food; Antibiotic resistance; Food-borne transmission; Virulence 10.1 Introduction Opportunistic Pathogens are microorganisms that are usually harmless in healthy, immunocompetent persons but may become virulent in compromised hosts such as the immunocompromised, or people with underlying disease. These microorganisms may cause severe infections or diseases, such as hospital acquired infections, including bloodstream infections, pneumonia, surgical site infections, diarrhea, and urinary tract infections
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Research World(Publisher)
An infection is not synonymous with an infectious disease, as some infections do not cause illness in a host. Classification Among the almost infinite varieties of microorganisms, relatively few cause disease in otherwise healthy individuals. Infectious disease results from the interplay between those few pathogens and the defenses of the hosts they infect. The appearance and severity of disease resulting from any pathogen depends upon the ability of that pathogen to damage the host as well as the ability of the host to resist the pathogen. Infectious microorganisms, or microbes, are therefore classified as either primary pathogens or as Opportunistic Pathogens according to the status of host defenses. Primary pathogens cause disease as a result of their presence or activity within the normal, healthy host, and their intrinsic virulence (the severity of the disease they cause) is, in part, a necessary consequence of their need to reproduce and spread. Many of the most common primary pathogens of humans only infect humans, however many serious diseases are caused by organisms acquired from the environment or which infect non-human hosts. Organisms which cause an infectious disease in a host with depressed resistance are classified as Opportunistic Pathogens . Opportunistic disease may be caused by microbes that are ordinarily in contact with the host, such as pathogenic bacteria or fungi in the gastrointestinal or the upper respiratory tract, and they may also result from (otherwise innocuous) microbes acquired from other hosts (as in Clostridium difficile colitis) or from the environment as a result of traumatic introduction (as in surgical wound infections or compound fractures).
No longer available |Learn more- (Author)
- 2014(Publication Date)
- College Publishing House(Publisher)
An infection is not synonymous with an infectious disease, as some infections do not cause illness in a host. Classification Among the almost infinite varieties of microorganisms, relatively few cause disease in otherwise healthy individuals. Infectious disease results from the interplay between those few pathogens and the defenses of the hosts they infect. The appearance and severity of disease resulting from any pathogen depends upon the ability of that pathogen to damage the host as well as the ability of the host to resist the pathogen. Infectious micro-organisms, or microbes, are therefore classified as either primary pathogens or as Opportunistic Pathogens according to the status of host defenses. Primary pathogens cause disease as a result of their presence or activity within the normal, healthy host, and their intrinsic virulence (the severity of the disease they cause) is, in part, a necessary consequence of their need to reproduce and spread. Many of the most common primary pathogens of humans only infect humans, however many serious diseases are caused by organisms acquired from the environment or which infect non-human hosts. Organisms which cause an infectious disease in a host with depressed resistance are classified as Opportunistic Pathogens . Opportunistic disease may be caused by microbes that are ordinarily in contact with the host, such as pathogenic bacteria or fungi in the gastrointestinal or the upper respiratory tract, and they may also result from (otherwise innocuous) microbes acquired from other hosts (as in Clostridium difficile colitis) or from the environment as a result of traumatic introduction (as in surgical wound infections or compound fractures).
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Research World(Publisher)
An infection is not synonymous with an infectious disease, as some infections do not cause illness in a host. Classification Among the almost infinite varieties of microorganisms, relatively few cause disease in otherwise healthy individuals. Infectious disease results from the interplay between those few pathogens and the defenses of the hosts they infect. The appearance and severity of disease resulting from any pathogen depends upon the ability of that pathogen to damage the host as well as the ability of the host to resist the pathogen. Infectious microorganisms, or microbes, are therefore classified as either primary pathogens or as Opportunistic Pathogens according to the status of host defenses. Primary pathogens cause disease as a result of their presence or activity within the normal, healthy host, and their intrinsic virulence (the severity of the disease they cause) is, in part, a necessary consequence of their need to reproduce and spread. Many of the most common primary pathogens of humans only infect humans, however many serious diseases are caused by organisms acquired from the environment or which infect non-human hosts. Organisms which cause an infectious disease in a host with depressed resistance are classified as Opportunistic Pathogens . Opportunistic disease may be caused by microbes that are ordinarily in contact with the host, such as pathogenic bacteria or fungi in the gastrointestinal or the upper respiratory tract, and they may also result from (otherwise innocuous) microbes acquired from other hosts (as in Clostridium difficile colitis) or from the environment as a result of traumatic introduction (as in surgical wound infections or compound fractures). An opportunistic disease requires impairment of host defenses,
eBook - ePub- Stephen P. Denyer, Norman A. Hodges, Sean P. Gorman, Brendan F. Gilmore, Stephen P. Denyer, Norman A. Hodges, Sean P. Gorman, Brendan F. Gilmore(Authors)
- 2011(Publication Date)
- Wiley-Blackwell(Publisher)
Part 2 Pathogens and host responses
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7 Principles of microbial pathogenicity and epidemiology
David Allison and Andrew McBain
University of Manchester, Manchester, UK
1 Introduction
2 The human microbiome
3 Portals of entry
3.1 Skin
3.2 Respiratory tract
3.3 Intestinal tract
3.4 Urinogenital tract
3.5 Conjunctiva
4 Consolidation
4.1 Nutrient acquisition
4.2 Biofilms
4.3 Resistance to host defences
4.3.1 Modulation of the inflammatory response
4.3.2 Avoidance of phagocytosis
4.3.3 Survival following phagocytosis
4.3.4 Killing of phagocytes
5 Manifestation of disease
5.1 Non-invasive pathogens
5.2 Partially invasive pathogens
5.3 Fully invasive pathogens
5.3.1 Active spread
5.3.2 Passive spread
6 Damage to tissues
6.1 Direct damage
6.1.1 Specific effects
6.1.2 Non-specific effects
6.2 Indirect damage
7 Recovery from infection: exit of microorganisms
8 Epidemiology of infectious disease
9 Further reading
1 Introduction
Microorganisms are ubiquitous, and most of them are free-living and derive their nutrition from inert organic and inorganic materials. The association of humans with such microorganisms is generally harmonious, as the majority of those encountered are benign and, indeed, are often vital to commerce, health and a balanced ecosystem. The ability of bacteria and fungi to establish infections of plants, animals and humans varies considerably. Some are rarely, if ever, isolated from infected tissues, while opportunist pathogens (e.g. Pseudomonas aeruginosa or Staphylococcus epidermidis ) can establish themselves only in compromised individuals. Only a few species of bac-teria may be regarded as obligate pathogens, for which animals or plants are the only reservoirs for their exist-ence (e.g. Neisseria gonorrhoeae, Mycobacterium tubercu-losis and Treponema pallidum ). Viruses (Chapter 5), on the other hand, must parasitize host cells in order to replicate and are therefore inevitably associated with disease. Even among the viruses and obligate bacterial pathogens the degree of virulence varies, in that some (particularly the bacteria) are able to coexist with the host without causing overt disease (e.g. Staph. aureus
eBook - ePub- Brendan F. Gilmore, Stephen P. Denyer, Brendan F. Gilmore, Stephen P. Denyer(Authors)
- 2023(Publication Date)
- Wiley-Blackwell(Publisher)
The ability of bacteria and fungi to establish infections of plants, animals and humans varies considerably. Some are rarely, if ever, isolated from infected tissues, while opportunist pathogens such as Pseudomonas aeruginosa and Staphylococcus epidermidis can establish themselves most commonly in compromised individuals. Only a few species of bacteria may be regarded as obligate pathogens, for which animals or plants are the only reservoirs for their existence (e.g., Neisseria gonorrhoeae, Mycobacterium tuberculosis and Treponema pallidum). Viruses (see Chapter 5), on the other hand, must parasitise host cells to replicate and are therefore inevitably associated with disease. Even among the viruses and obligate bacterial pathogens, the degree of virulence varies, in that some (particularly the bacteria) can potentially coexist with the host without causing overt disease (e.g., Staphylococcus aureus), while others will always cause some detriment to the host (e.g., rabies virus). Organisms such as these invariably produce their effects, directly or indirectly, by actively growing on or in the host tissues. Other groups of microorganisms may cause disease through ingestion of substances (toxins) produced during microbial growth on foods (e.g., Clostridium botulinum, botulism; Bacillus cereus, vomiting). In this case, the organisms themselves do not have to proliferate in the host for the effects of the toxin to be manifested. Animals and plants constantly interact with bacteria present within their environment. For an infection to develop, such microorganisms must remain associated with host tissues and increase their numbers more rapidly than they can be either eliminated or killed
eBook - ePubUnifying Microbial Mechanisms
Shared Strategies of Pathogenesis
- Michael F. Cole(Author)
- 2019(Publication Date)
- Garland Science(Publisher)
Chapter 1: Introduction to PathogenesisINTRODUCTION
The aim of this text, is to examine and discuss common themes in microbial pathogenesis. Despite the class of pathogen – whether virus, bacterium, fungus or parasite – they all cause tissue injury and evade the host immune system in much the same ways and attack the same targets. Therefore, it seems only sensible to discuss pathogenic mechanisms in the context of all of these classes of pathogens. With rare exception, texts on pathogenesis have focused on a single class of pathogen, such as bacteria, without conveying any sense that the pathogenic mechanisms described can just as easily be applied to any other class of pathogen. Pathogenics is at the interface of microbiology and immunology because it considers the properties of a microorganism that harm the host and the innate and acquired host defence mechanisms that can neutralise them. The relationship between the pathogen and host is dynamic and reflects thrust and counter thrust. The fulcrum of this interaction can be moved to benefit either combatant by, for example, enhancing or compromising the host immune system or by the acquisition of new genes or loss of existing genes by the microorganism. We will return to this concept later. Because one cannot consider the microbe in the absence of the host, most texts of microbial pathogenesis feel obliged to devote a considerable amount of the text to basic immunology and basic microbiology as a prelude to the consideration of the mechanisms of pathogenesis of microbes. However, there is a plethora of excellent immunology and microbiology texts, both concise and comprehensive, that are superior to the coverage of these disciplines in pathogenesis texts. It is reasonable to say that students should be competent in immunology and microbiology before embarking on a course in microbial pathogenesis. For these reasons, basic microbiology and immunology are not covered in this book beyond that essential to understand particular pathogenic mechanisms.
eBook - PDFIntestinal Microbiota in Health and Disease
Modern Concepts
- Eduardo J. Schiffrin, Philippe Marteau, Dominique Brassart(Authors)
- 2014(Publication Date)
- CRC Press(Publisher)
8 Opportunistic Pathogens in In lammatory Bowel Disease, and the Relation with Speci ic Gene Susceptibilities Marianne Fraher* and Fergus Shanahan Introduction The inflammatory bowel diseases, Crohn’s disease and ulcerative colitis, are distinct and heterogeneous syndromes. However, a consensus of evidence suggests that most cases of inflammatory bowel disease (IBD) represent the outcome of complex interplay among genetic susceptibility risk factors, environmental triggers, and disturbed immune responses to the enteric microbiota. Genetic risk factors appear to code for proteins involved in sensing or regulating the host response to the microbiota or in maintenance of mucosal barrier function (Jostins et al . 2012). Given the underpinning disturbance of host-microbe interactions, and the degree of mucosal tissue injury in both Crohn’s disease and ulcerative colitis, it is remarkable that opportunistic infections are not more common than has been evident to date. This may be about to change as increasing concern is voiced in relation to the increasing use of immunosuppressive and immunomodulatory drugs and the persistent, albeit diminishing, concomitant use of corticosteroids. Department of Medicine and Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland. E-mail: [email protected] * Corresponding author: [email protected] Opportunists in IBD 197 An opportunistic infection may be defined as a serious, usually progressive infection by a micro-organism that has limited (or no) pathogenic capacity under ordinary circumstances, but which has been able to cause serious disease as a result of the predisposing effect of another disease or of its treatment (Symmers 1965). A diversity of potential opportunistic infections may occur in patients with IBD but include intracellular organisms, such as Mycobacterium tuberculosis and Listeria monocytogenes .
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