Unit 4 ch15 microbial mechanisms of pathogenicity flashcards. Pathogenesis of bacterial infections in animals, fourth edition captures the rapid developments in understanding the mechanisms of virulence of the major bacterial pathogens of animals. Bacterial pathogenesis a molecular strategy third version pdf, because the second version of bacterial pathogenesis was written, the. Brett finlay on the molecular basis of bacterial pathogenicity. Microbes express their pathogenicity by means of their virulence, a term which refers to the degree of pathogenicity of the microbe. The bacterial ligand, called an adhesin, is typically a macromolecular component of the bacterial cell surface which interacts with the host cell receptor. Microbial pathogenesis an overview sciencedirect topics. Although humans have been combating microbial pathogens since prehistoric times, infectious disease remains one of our greatest public health challenges. Microbial pathogenesis how do bacteria cause disease.
Pathogenicity is the ability to produce disease in a host organism. Pathogenesis of bacterial infection microbiology module microbiology notes zdifferentiate colonization and pathogens zexplain steps involved in the bacterial pathogenesis zdescribe toxins zdifferentiate endotoxins and exotoxins zdiscuss the various diseases caused by bacteria 8. Principles of bacterial pathogenesis sciencedirect. Mechanisms of bacterial pathogenicity arizona state. Outline the mechanisms of action of ab toxins, membrane.
Recently, two novel but widespread themes have emerged in the field of bacterial virulence. Hence, the determinants of virulence of a pathogen. Pathogenicity ability of pathogento cause disease by overcoming the defenses of the host virulence degree of pathogenicity virulence factors the various traits or features that allow or enhance the microorganisms ability to cause disease. Research is focused on the pathogenesis of mycoses due to yeasts such as candida albicans or c. Be able to list enzymes produced by microbes than enhance pathogenicity and virulence as well as describe the effects. Protozoa adhere to target cells through complex mechanisms and can cause cellular damage through release of cytopathic substances. One of the pathogenicity factors with evasion function is the ability that also can alter host cell apoptosis or cause other forms of cell death 16. This general microbiology video gives an explanation of how bacteria attach, invade the host, evade the host defenses, and the bacterial enzymes used in bacterial pathogenesis. When the balance between host and microbe is tipped in favor of the microbe, an infection or disease results. Scientists have identified a new mechanism of bacterial pathogenesis. May 15, 2008 chapter 15 microbial mechanisms of pathogenicity mechanisms of pathogenicity click here for word document version. Hopefully, further analysis of the genomes of bacterial pathogens will reveal some unifying principles underlying this complexity. Types of pathogens, bacterial infection and antibiotic therapy jassin m.
A comprehensive creation model for the origin of bacterial pathogenicity is needed. Study microbial mechanisms of pathogenicity ch 15 flashcards at proprofs tortora funke case. Bacteremia is defined as the presence of viable bacteria in the bloodstream and can occur in daily activities like toothbrushing and some minor medical procedures like dental work but also during infection. Smallest living organisms that contain all of the machinery required for growth and selfreplication unicellular. Factors affecting bacterial pathogenicity bacteriology. A pathogen is a microorganism that is able to cause disease in a plant, animal or insect. The underlying mechanisms of bacterial pathogenicity. Microbial pathogenicity mechanisms leibniz institute for. Mechanisms of pathogenicity in mycobacteria sciencedirect. A upon encountering a human host, a bacterial pathogen may illicit several host responses and use a variety of mechanisms to evade. Many properties that determine a microbes pathogenicity or virulence are unclear or.
The purpose of this chapter is to provide an overview of the many bacterial virulence factors and, where possible, to indicate how they interact with host defense mechanisms and to describe their role in the pathogenesis of disease. Oct 28, 2009 francis 2003 suggests that pathogenicity may be the result of the lateral transfer of pathogenicity islands or the modification of current symbiotic relationships. These adjustments have necessitated an intensive rewriting of the textbook. Bacterial pathogens express a wide range of molecules that bind host cell targets to facilitate a variety of different host responses. New mechanism of bacterial pathogenesis discovered. This chapter provides an update on the mechanisms of microbial pathogenesis and the host response to bone infections, with a focus on immune and bone cell interactions during this process. Learning these mechanisms of microbial pathogenicity is fundamental to understanding how pathogens are able to overcome the hosts defenses.
The outcome of such a relationship depends on the virulence of the pathogen and the relative degree of resistance or susceptibility of the host, due mainly to the effectiveness of the host defense mechanisms. Pathogenicity and virulence pathogenicity the ability of a microbe to cause disease this term is often used to describe or compare species virulence the degree of pathogenicity in a microorganism this term is often used to describe or compare strains within a species. Mechanisms of bacterial pathogenicity postgraduate medical. Bacterial infections affect world health today as a leading cause of morbidity and mortality. The diversity of bacterial pathogenicity mechanisms. These concepts resulted in the recognition and identification of numerous etiological agents and provided natural and synthetic agents effective in therapy and prevention of diseases. Module pathogenesis of bacterial infection microbiology 90 notes adhesion adhesion is necessary to avoid innate host defense mechanisms such as peristalsis in the gut and the flushing action of mucus, saliva and urine, which remove nonadherent bacteria. To stress the role of immune mechanisms in virusinduced cell damage. The molecular structure of these molecules is depicted in fig. Bacterial pathogens use common regulatory mechanisms, such as alternative sigma factors and two component signal transduction systems, to control the expression of their virulence genes in response to environmental conditions encountered during infection of the human host, including changes in temperature, ph, osmotic strength, oxygen. Mutation displacement in origin of bacterial pathogenicity. Mechanisms of bacterial pathogenesis flashcards quizlet. Determinants of bacterial pathogenicity are encoded by different types of genetic elements.
These factors subvert normal host cell functions in ways that seem beneficial to. Bacteria that cause chronic infections have an amazing but yet poorly known ability to subvert immune response, live and. Actually, mechanisms of bacterial resistance to slayer proteins are not yet clear 14 15. Efforts to control infectious diseases more comprehensively are undermined not only by socioeconomic conditions but also by the. Now including a color plate section, the book presents an overview of pathogenesis, including relevant events that occur in the herd or flock and its environment, and activities that take place at the cellular. Original research papers should report complete findings and include only. Of particular note are large loci including pathogenicity islands, bacteriophages, integrative and conjugative elements, plasmids and integrons. Bacterial pathogenesis a molecular strategy third version pdf. Staphylococcus aureus, arguably the most prevalent pathogen of humans, may cause up to one third of all bacterial diseases ranging from boils and pimples to food poisoning, to septicemia and toxic shock. The bacterial capsule plays an important role in conferring the virulence on bacteria by enabling them to resist phagocytosis and bactericidal substances in body fluids, therefore the capsulation is important for the virulence of pneumococci, streptococci of group a and group c, the anthrax bacillus, the plague. For bacteria, adhesion is an essential preliminary to colonization and then penetration.
Two broad qualities of pathogenic bacteria underlie the means by which they cause. This has lead to a renaissance in research into bacterial disease mechanisms and the birth of a new discipline cellular microbiology. By contrast, several thousand species exist in the human digestive system. He graduated from ross university school of medicine and has completed his clinical clerkship training in. The genes that code for virulence factors are commonly found clustered on the pathogens chromosome or plasmid dna, called pathogenicity islands. Pathogenic bacteria routinely command a broad spectrum of niches in the human host, making an understanding of pathogenesis mechanisms crucial to the development of prophylactics and. Outbreaks of diphtheria in eastern europe threatens the population with a disease that had previously seemed to be overcome. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Introduction to microbial mechanisms of pathogenicity. Microbial mechanisms of pathogenicity biology libretexts. To develop the concept of the target organ in viral pathogenicity.
Endotoxins cause fever by inducing the release of interleukin1 and shock because of a tnfinduced decrease in blood pressure. To contrast the mechanisms of viral pathogenicity with those of bacterial pathogenicity. Type iii secretion systems, which are found in various gramnegative organisms, are specialized for the export of virulence factors delivered directly to host cells. Mechanisms of bacterial pathogenicity arizona state university. A microbe that is capable of causing disease is referred to as a pathogen. These studies represent the first significant findings in the research efforts made concerning the molec ular mechanisms of pathogenicity of the myco bacterial pathogens. Interestingly, the molecular mechanisms underlying these shifts show commonalities.
Biological concept of bacterial pathogenicity theoretical. Virulent strains of escherichia coli can be divided into two classes. An introduction, 12e tortora chapter 15 microbial mechanisms of pathogenicity 15. The mechanisms of bacterial pathogenicity introduction. Microbial mechanisms of pathogenicity exercises these are exercises for chapter 15 microbial mechanisms of pathogenicity in openstaxs microbiology textmap. Sometimes they are the direct result of a pathogenic infection, but in other cases they result from a response by our immune system to a pathogen or another perceived threat. Chapter 15 microbial mechanisms of pathogenicity mechanisms of pathogenicity click here for word document version. Mechanisms of bacterial pathogenicity postgraduate. Microbial mechanisms of pathogenicity ch 15 flashcards by. Ppt mechanism of bacterial pathogenesis powerpoint.
Choose from 500 different sets of mechanisms of pathogenicity flashcards on quizlet. The molecular strategies used by bacteria to interact with the host can be unique to specific pathogens or conserved across several different species. Bacterial pathogenic mechanisms are complex and specific in relation to their host. Pathogens vary in their ability to produce disease. The mechanisms of bacterial pathogenicity bohat ala. Describe the bacterial pathogenesis of rheumatic heart disease. The concepts of pathogenicity and virulence have governed our perception of microbial harmfulness since the time of pasteur and koch. Although most bacteria are harmless or often beneficial, some are pathogenic, with the number of species estimated as fewer than a hundred that are seen to cause infectious diseases in humans. Compare the effects of coagulases, kinases, hyaluronidase, and collagenase. Learn mechanisms of pathogenicity with free interactive flashcards. Both microbes produce infections in 50% of the inoculated hosts.
Aug 28, 20 staphylococcus aureus, arguably the most prevalent pathogen of humans, may cause up to one third of all bacterial diseases ranging from boils and pimples to food poisoning, to septicemia and toxic shock. Conjunctiva mucus membrane the lines the eyelids skin the parental. Figure 1 an overview of bacterial mechanisms for pathogenicity. Principles of bacterial pathogenesis presents a molecular perspective on a select group of bacterial pathogens by having the leaders of the field present their perspective in a clear and authoritative manner. A free powerpoint ppt presentation displayed as a flash slide show on id. Jun 07, 2012 mechanisms of bacterial pathogenicity endotoxins may be released from growing bacterial cells and cells that are lysed as a result of effective host defense e.
Gene loss can also play a significant role in determining bacterial pathogenicity and should not be disregarded. Chapter 15 microbial mechanisms of pathogenicity my nursing. In a classic sense, the term endotoxin refers to the. Mechanisms of bacterial pathogenicity page 2 this chapter has 8 pages. Bacteria may produce two types of toxins called exotoxins and endotoxins. One of the main takehome messages of the meeting was that not only is there a wide diversity of pathogenic bacterial species, but there is even an enormous diversity of virulence genes in strains of the same species. Study unit 4 ch15 microbial mechanisms of pathogenicity flashcards at proprofs microbial mechanisms. If you continue browsing the site, you agree to the use of cookies on this website. Review the diversity and significance of bacterial flora in the. Our laboratory works to identify and develop novel strategies to overcome resistance through mechanistic characterization of enzymes involved in bacterial virulence chlamydial pathogenesis project as well as peptidoglycan biosynthesis and teichoic acid biosynthesis antimicrobial peptide project.
Provide an example of direct damage, and compare this to toxin production. Study notes on microbial pathogenicity biology discussion. The journal covers infectious agents of bacterial, fungal, viral, and protozoal origin. Mechanisms of bacterial pathogenicity bio science portal. Jane woke up one spring morning feeling not quite herself. Bacterial cell death, antibiotics, and antibodies may cause the release of endotoxins. Molecular mechanisms of bacterial pathogenicity springerlink. Pathogenesis of bacterial infections in animals, 4th. It encompasses mechanisms for colonization adherence and initial multiplication, production of extracellular substances which facilitate invasion invasins and ability to bypass or overcome host defense mechanisms. Antibiotic resistance and our consequent inability to treat many bacterial infections had fuelled an urgent need to understand the means by which bacteria cause disease. Pathogenic bacteria utilise a number of mechanisms to cause disease in human hosts. Aug 26, 2010 15 microbial mechanisms of pathogenicity slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The growing number of complete microbial genome sequences provides a powerful.
Pathogenesis refers both to the mechanism of infection and to the mechanism by which disease develops. Mechanisms of pathogenicity austin community college. Chapter 15 microbial mechanisms of pathogenicity my. Bacterial resistance to antibiotic agents has become a crisis in modern society. In its simplest form, bacterial adherence or attachment to a eucaryotic cell or tissue surface requires the participation of two factors. Bacterial pathogenesis a molecular approach 3rd edition pdf. Exotoxins are released from bacterial cells and may act at tissue sites removed from the site of bacterial growth. The department of microbial pathogenicity mechanisms mpm investigates infections caused by human pathogenic fungi. Microbiology active lecture questions chapter 15 microbial mechanisms of pathogenicity p 2 of 5 6 the id50 for campylobacter sp. Pathogenic bacteria are bacteria that can cause disease.