Biological Sciences
Bacterial Diseases
Bacterial diseases are caused by harmful bacteria that invade the body and cause infections. These infections can range from mild to severe and can affect various parts of the body, including the skin, respiratory system, and digestive system. Treatment for bacterial diseases typically involves antibiotics and other supportive therapies.
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8 Key excerpts on "Bacterial Diseases"
eBook - PDF- Kathleen A. Ireland(Author)
- 2018(Publication Date)
- Wiley(Publisher)
Bacteria Are Single-Celled Wonders That Can Cause Disease 205 Although our bodies are wonders of natural science, we often need help in maintaining our health. Our lifestyle necessitates that humans live in close contact with one another. Unless this changes, we will always be faced with new viral and bacterial threats to our pop- ulation’s continued health. In many cases, the best thing we can do to protect ourselves is wash our hands thoroughly and often! The Disease Process Has Several Stages As with any disease, an epidemic begins with a simple process: the pathogen enters the human body (or host) and alters the physiology of that body to ensure its own survival, in turn causing discomfort and possibly death of the host. Entry into the host occurs through a specific mode of trans- mission. Pathogens can be transmitted via physical contact with an infected person, contact with airborne pathogenic particles, or direct injection of the pathogen into the body. Ebola virus, for example, is transmitted from one person to another through direct contact with the live virus on the tissues or skin of a patient. It can then migrate to the mucous membranes of the second person and infect him or her. Tuberculosis is small enough to travel in airborne droplets, and when inhaled into the lungs of another person, it will begin another infec- tious cycle. Dengue fever, malaria, HIV, Zika, and chikungunya fever are all transmitted via direct contact with the host’s blood supply. Once in the body, each pathogen causes a specific series of symp- toms. Bacterial infections can cause disease by adhering to host cells, colonizing host tissues, or even inhibiting the host’s typical immune responses. Viruses often invade and take over host cells, as discussed later in the chapter. Viral infection requires that the host cells exhibit virulence factors—specific proteins that the viral particle can bind to.
eBook - PDF- Edward Bittar(Author)
- 1998(Publication Date)
- Elsevier Science(Publisher)
These diseases are caused by normal flora (e.g., urinary tract infections in women), or by microorganisms that reside in the environment (e.g., cholera). Zoonoses are dis- eases that primarily occur in animals but can be transmitted to humans (e.g., bubonic plague). The different routes of transmission of bacterial infection are shown in Table 2. PATHOGENIC MICROORGANISMS The development of disease after exposure to an infectious agent depends on properties of both the bacterium and the host. Microorganisms vary in their ability Principles of Bacterial Pathogenesis 89 to cause disease. Those that are successful are pathogens and the manner in which a disease originates is referred to as its pathogenesis. Bacterial characteristics that contribute to pathogenicity are virulence factors. A pathogens' ability to cause disease in a given host varies due to individual differences in the host's defense mechanisms (immune response), and due to strain differences (these are sometimes referred to as differences in virulence or differences in pathogenicity). If one could infect the same individual multiple times with different strains of the same species of bacteria (and the host did not develop an immune response to the infection), differences in the outcome of each infection would reflect differences in the pathogenic potential of each strain. The severity of the disease reflects the total of the expression of the virulence determinants of the infecting strain(s). These differences in the severity of the disease are due to differential expression of virulence determinants. Some commensal microorganisms are unable to cause disease when present alone in certain biological niches. However, when other strains are present, the two nonpathogens can interact and cause disease. This synergistic interaction is commonly seen in infections caused by anaerobic micro- organisms.
eBook - ePub- Britannica Educational Publishing, Kara Rogers(Authors)
- 2010(Publication Date)
- Britannica Educational Publishing(Publisher)
Viral diseases cannot be treated with antimicrobial agents. This point is made because of a distressing tendency among individuals to take penicillin or another antibiotic for a common cold. Although no cure is available for most viral infections, prevention of infection through the administration of vaccines has proven valuable in reducing the incidence of certain viral diseases, including polio and measles. In addition, antiviral drugs have been developed to reduce the severity of symptoms associated with some viral infections, particularly those involving influenza or HIV.BACTERIAL DISEASESThe diseases produced by bacteria are the most common of infectious biotic diseases. They range from trivial skin infections to such devastating disorders as bubonic plague and tuberculosis. Various types of pneumonia; infections of the cerebrospinal fluid (meningitis), the liver, and the kidneys; and the sexually transmitted diseases syphilis and gonorrhea are all forms of bacterial infection.All bacteria induce disease by one of three methods: (1) the production of an exotoxin, a harmful chemical substance that is secreted or excreted by the bacterium (as in food poisoning caused by Clostridium botulinum ); (2) the elaboration of an endotoxin, a harmful chemical substance that is liberated only after disintegration of the microorganism (as in typhoid, caused by Salmonella typhi ); or (3) the induction of sensitivity within the host to antigenic properties of the bacterial organism (as in tuberculosis, after sensitization to Mycobacterium tuberculosis ).Human rickettsial diseases are caused by microorganisms that fall between viruses and bacteria in size. These minute agents are barely visible under the ordinary light microscope. Like viruses, they multiply only within the cells of susceptible hosts. They are found in nature in a variety of ticks and lice and, when transmitted to humans by the bite of one of these arthropods, usually cause acute febrile (fever-producing) illnesses, most of which are characterized by skin rashes. Rocky Mountain spotted fever, a systemic rickettsial infection, invades and kills the cells lining blood vessels and causes hemorrhage, inflammation, blood clots, and extensive tissue death. If untreated, it is fatal in about 20 to 30 percent of cases.E. COLIEscherichia coli, or simply E. coli, is a species of bacterium that normally inhabits the stomach and intestines. When
eBook - PDF- Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Brian M. Forster, Philip Lister(Authors)
- 2016(Publication Date)
- Openstax(Publisher)
In some cases, signs and symptoms alone are enough to correctly identify the causative agent of a disease, but since few diseases produce truly unique symptoms, it is often necessary to confirm the identity of the infectious agent by other direct and indirect diagnostic methods. Chapter 15 | Microbial Mechanisms of Pathogenicity 657 15.1 Characteristics of Infectious Disease Learning Objectives • Distinguish between signs and symptoms of disease • Explain the difference between a communicable disease and a noncommunicable disease • Compare different types of infectious diseases, including iatrogenic, nosocomial, and zoonotic diseases • Identify and describe the stages of an acute infectious disease in terms of number of pathogens present and severity of signs and symptoms A disease is any condition in which the normal structure or functions of the body are damaged or impaired. Physical injuries or disabilities are not classified as disease, but there can be several causes for disease, including infection by a pathogen, genetics (as in many cancers or deficiencies), noninfectious environmental causes, or inappropriate immune responses. Our focus in this chapter will be on infectious diseases, although when diagnosing infectious diseases, it is always important to consider possible noninfectious causes. Signs and Symptoms of Disease An infection is the successful colonization of a host by a microorganism. Infections can lead to disease, which causes signs and symptoms resulting in a deviation from the normal structure or functioning of the host. Microorganisms that can cause disease are known as pathogens. The signs of disease are objective and measurable, and can be directly observed by a clinician.
eBook - PDFHuman Biology
A Text Book of Human Anatomy, Physiology and Hygiene
- C. J. Wallis(Author)
- 2014(Publication Date)
- Butterworth-Heinemann(Publisher)
(By Courtesy of the Wright-Fleming Institute of Microbiology, St. Mary's Hospital, Paddington, London.) diseases in man and it is these pathogenic bacteria and the diseases they cause which concern us in this chapter. Bacteria can be cultured in the laboratory on culture media made from a jelly-like substance, agar-agar, obtained from certain VIBRIO CHOLER/E X5000 FIG. 25.5. Photomicrograp (By Courtesy of Dr. A. J. Duggan director of of pathogenic bacteria. Burroughs Wellcome Medical Museum.) MICRO-ORGANISMS AND INFECTIOUS DISEASES 331 oriental seaweeds to which nutrient substances have been added. This is done in sterile Petri dishes or bacteriological test-tubes. When the medium has been inoculated the Petri dish or tube is kept at body temperature in an incubator. The bacteria multiply and produce colonies which are visible to the naked eye (see the practical work at the end of this chapter). These colonies are charac-teristic in shape, form, and colour for different species of bacteria. A few examples of diseases caused by bacteria are given below. Tuberculosis (B. tuberculosis), diphtheria (Corynebacterium* diph-theriae), typhoid (enteric) fever (B. typhosus or Salmonella* typhi), bacilliary dysentery (Shigella* dysenteriae), pneumonia (Diploccocus pneumoniae), meningitis (Meningococcus), gonorrhoea (Gonococcus), lockjaw (B. tetanus or Clostridium tetani), anthrax (B. anthracis), erysipelas (Streptococcus pyogenes), cholera (Vibrio cholerae), syphilis (Treponema'f pallidum), relapsing fever (Borreliaf recurrentis) and leprosy (Mycobacterium leprae). Boils are caused by Staphylococcus aureus. One of the most serious menaces in our hospitals is the airborne Staphyloccus aureus which spreads infection rapidly from ward to ward and into the operating theatre. Many people are innocent carriers who only suffer when their resistance is lowered by illness.
eBook - PDF- Thomas E. Cloete, Joan B. Rose, L. H. Nel, T. Ford(Authors)
- 2004(Publication Date)
- IWA Publishing(Publisher)
2 Emerging infectious waterborne diseases: bacterial agents L.H. Nel and W. Markotter 2.1 INTRODUCTION Bacterial pathogens, together with protozoa, fungi, viruses and infectious proteins (prions), are the cause of infectious disease, which plague all the higher forms of life, including humanity. Of all these diseases, it is the Bacterial Diseases that, in general, have become most controllable due to the discovery and continued devel-opment of antibiotics, a class of anti-microbials that specifically act against bacte-ria. Additional factors, such as the development of vaccines, education, improved diagnostics, improved public health systems and improvements in the quality of water and sanitation have also contributed significantly to the control of infectious diseases. However, despite these spectacular sociological and scientific advances, infectious diseases have become increasingly less manageable in recent years. Today, infectious diseases that are resurging, emerging or re-emerging, or are being recognized as a new disease, contribute largely to the infectious disease problems of the world. An appropriate and popular definition for emerging infections has been put forward in a recent report of the Institute of Medicine (http://fas.org/promed): “Emerging infections are those whose incidence in humans has increased within the past two decades or threatens to increase in the near future. Emergence may be C IWA Publishing 2004. Microbial Waterborne Pathogens edited by T.E. Cloete, J. Rose, L.H. Nel and T. Ford. ISBN: 1 84339 055 8. Published by IWA Publishing, London, UK. 56 L.H. Nel and W. Markotter due to the spread of a new agent, recognition of an infection that has been present in the population but has gone undetected or realization that an established disease has an infectious origin.
eBook - PDF- David Applin(Author)
- 1997(Publication Date)
- Cambridge University Press(Publisher)
O N E What is disease? Disease and good health are two sides of the same coin - how well we feel. A healthy person feels well because all parts of the body are working efficiently. Disease disrupts normal bodily functions and makes a person feel ill. A feeling of wellness is not just the absence of illness. Wellness includes mental health as well as bodily health - both are part of the equation defining good health. The human body is an ideal environment for a range of organisms that cause different diseases. Bacteria are blamed for most human ailments, but viruses are also important disease-causing agents. Protists, fungi and different animal parasites also cause disease as a result of their activities inside our bodies. Disease-causing organisms are called pathogens. Diseases are said to be infectious (communicable) if the organisms can be passed from one person to another. Not all diseases are infectious. Many non-infectious diseases develop because the body is not working properly. Increasing age and the way we treat our bodies affect the onset of non-infectious diseases. Many disorders can be avoided or at least delayed by changing our life-style. 1.1 Infectious diseases During the nineteenth century the population of Britain more than trebled. People in search of work flocked to the cities, which were growing fast in the wake of the Industrial Revolution. London was typical of the times. With no proper means of waste disposal or sanitation, London's teeming population piled household rubbish and excrement outside the home. Water that was safe to drink was virtually unobtainable. Wells were contaminated by the filthy water draining from the streets; and the Thames, which was also a source of drinking water, was grossly polluted by raw sewage from most of the city. The insanitary conditions were ideal for the spread of infectious diseases. What is disease? ^ : - (c) R TIIAMKS INTItOIXiCIN'li HIS 01'1'SIMUNG TO THE FAIR CITY OF LONDON.
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).
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