pathogenic bacteria

Examples of pathogenic bacteria in the following topics:

• Extent of Host Involvement

  • Host-pathogen interactions are the interactions taking place between a pathogen (e.g. virus, bacteria) and their host (e.g. humans, plants).
  • Host-pathogen interactions are the interactions that take place between a pathogen (e.g. virus, bacteria) and their host (e.g. humans, plants).
  • By definition, all pathogens damage their host to some extent.
  • The appearance and severity of disease resulting from the presence of 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.
  • Opportunistic diseases 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 or from the environment as a result of traumatic introduction.

• Overview of Human-Microbial Reactions

  • Human-microbial interactions can be commensal or mutualistic, as with many types of gut flora, or harmful, as with pathogenic bacteria.
  • The metabolic activities performed by these bacteria resemble those of an organ, leading some to liken gut bacteria to a "forgotten" organ.
  • The benefits of bacteria include preventing transient pathogenic organisms from colonizing the skin surface, either by competing for nutrients, secreting chemicals against them, or stimulating the skin's immune system.
  • Infectious pathogens include some viruses, bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions.
  • Opportunistic disease may be caused by microbes that are ordinarily in contact with the host, such as pathogenic bacteria or fungi in the gastrointestinal tract.

• Microorganisms and Water Quality

  • Although there are many pathogens which can be transmitted through water, bacteria and protozoa are some of the most common organisms that cause disease.
  • Monitoring for waterborne disease can be difficult because humans often shed very low numbers of pathogenic bacteria when they are infected.
  • To test whether disease causing bacteria might be present, researchers measure the presence of indicator species, such as coliform bacteria (which are the group to which the pathogenic E. coli belongs) or Pseudomonas aeruginosa.
  • If the number of bacteria exceeds the limits set by water quality standards, the next step is to test for the presence of specific pathogens.
  • An influx of human pathogens can cause problems for ecosystems in several ways.

• Intracellular Pathogens

  • Not all pathogens are undesirable to humans.
  • There are several types of intracellular pathogens.
  • Pathogenic viruses are mainly those of the families of Adenoviridae, bacteria Picornaviridae, Herpesviridae, Hepadnaviridae, Flaviviridae, Retroviridae, Orthomyxoviridae, Paramyxoviridae, Papovaviridae, Polyomavirus, Rhabdoviridae, and Togaviridae.
  • Although the vast majority of bacteria are harmless or beneficial, a few pathogenic bacteria can cause infectious diseases.
  • Bacteria can often be killed by antibiotics because the cell wall in the outside is destroyed, expelling the DNA out of the body of the pathogen, therefore making the pathogen incapable of producing proteins, so it dies.

• Direct Damage

  • The pathogenic organism typically causes damage due to its own growth process.
  • The ability of a pathogen to gain entrance to a host cell is fundamental in the ability of the pathogen to promote and cause disease.
  • This is accomplished by the ability of the bacteria to exhibit produce molecules that interfere with the phagocytes ability to internalize the bacteria.
  • Once the pathogen has successfully evaded engulfment and destruction by the immune system, it is detrimental because the bacteria then multiply.
  • Describe the different processes used by pathogens to damage the host and ensure infection

• Innate Immune Response

  • A host is the organism that is invaded and often harmed by a pathogen.
  • Pathogens, which include bacteria, protists, fungi, and other infectious organisms, can be found in food and water, on surfaces, and in the air.
  • Mammalian immune systems evolved for protection from such pathogens.
  • When pathogens are found, immune factors are mobilized to the site of an infection.
  • Features of the immune system (e.g., pathogen identification, specific response, amplification, retreat, and remembrance) are essential for survival against pathogens.

• Extracellular Immune Avoidance

  • A pathogen's success depends on its ability to evade the host's immune responses.
  • A pathogen's success depends on its ability to evade the host's immune responses.
  • Bacteria usually overcome physical barriers by secreting enzymes that digest the barrier in the manner of a type II secretion system.
  • Some bacteria even form biofilms which protect them from the proteins and cells of the immune system.
  • Some bacteria create surface proteins, such as Streptococcus, that will bind to antibodies making them ineffective.

• Plant Defenses Against Pathogens

  • Plants defend against pathogens with barriers, secondary metabolites, and antimicrobial compounds.
  • Pathogens are agents of disease.
  • These infectious microorganisms, such as fungi, bacteria, and nematodes, live off of the plant and damage its tissues.
  • Both protect plants against pathogens.
  • Plants can close stomata to prevent the pathogen from entering the plant.

• WBC Function

  • The innate immune system is non-specific and refers to the general ability of the body to prevent pathogen entry and destroy pathogens that do enter the body.
  • Phagocytosis of pathogens.
  • It involves the binding of an Fc receptor to a tail on a pathogen, engulfing the pathogen, and using enzymes and free radicals inside the leukocyte to destroy the pathogens.
  • The adaptive immune system is specific to each pathogen on the basis of antigens, which are molecular components of pathogens that are used by leukocytes to recognize that specific pathogen.
  • Here, neutrophils can be seen to phagocytose and completely engulf bacteria.

• Regulating Virulence

  • The ability of a microorganism to cause disease is described in terms of the number of infecting bacteria, the route of entry into the body, the effects of host defense mechanisms, and intrinsic characteristics of the microorganism called virulence factors.
  • Pathogen strains that kill the host can increase in frequency as long as the pathogen can transmit itself to a new host, whether before or after the host dies.
  • The evolution of virulence in pathogens is a balance between the costs and benefits of virulence to the pathogen.
  • After C. tetani bacteria enter a human wound, the bacteria may grow and divide rapidly, even though the human body is not their normal habitat.
  • The bacteria Mycobacterium tuberculosis can evolve to subvert the protection offered by immune defenses.