Opportunistic pathogen

Examples of Opportunistic pathogen 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).
  • Clinicians therefore classify infectious microorganisms or microbes according to the status of host defenses - either as primary pathogens or as opportunistic pathogens.
  • Organisms which cause an infectious disease in a host with depressed resistance are classified as opportunistic pathogens.
  • 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.
  • Differentiate between primary and opportunistic pathogens in regards to host involvement

• Opportunistic Microorganisms

  • HIV is an opportunistic infections that feeds on the fact the the immune system is suppressed.
  • Opportunistic microorganisms are typically non-pathogenic microorganisms that act as a pathogen in certain circumstances.
  • Patients with Human Immunodeficiency Virus (HIV) are particularly susceptible to opportunistic infections.
  • These opportunistic pathogens thrive while the human body slowly deteriorates.
  • An example of an opportunistic microorganism is Haemophilus ducreyi.

• The Diagnostic Scheme

  • 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.
  • Clinicians therefore classify infectious microorganisms or microbes according to the status of host defenses - either as primary pathogens or as opportunistic pathogens.
  • Culture allows identification of infectious organisms by examining their microscopic features, by detecting the presence of substances produced by pathogens, and by directly identifying an organism by its genotype.

• Overview of Human-Microbial Reactions

  • Skin flora are usually non-pathogenic and either commensal or mutualistic.
  • Primary pathogens cause disease as a result of their presence or activity within the normal, healthy host.
  • 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 tract.
  • The success of any pathogen depends on its ability to elude host immune responses.

• Penetrating Host Defenses

  • Normal flora bacteria can act as opportunistic pathogens at times of lowered immunity.
  • It is important to keep in mind that although the immune system has evolved to be able to control many pathogens, pathogens themselves have evolved ways to evade the immune response.
  • This section briefly summarizes other ways in which pathogens can "outwit" immune responses.
  • But keep in mind, although it seems as if pathogens have a will of their own, they do not.
  • Recognize the ways a host can be infected by, and resist, pathogens

• Host Risk Factors

  • Individuals who have a suppressed immune system or who are on immunosuppressive drugs are particularly susceptible to opportunistic infections.
  • Risk of infection is a nursing diagnosis which is defined as "the state in which an individual is at risk to be invaded by an opportunistic or pathogenic agent (virus, fungus, bacteria, protozoa, or other parasite) from endogenous or exogenous sources. " The risk of infection depends on a number of endogenous sources.
  • One should not take antibiotics for longer than needed or when they are not needed—long term use of antibiotics leads to resistance and increased the chance of developing opportunistic infections like clostridium difficile colitis .

• Fungi

  • A fungus is a member of a large group of eukaryotic organisms that includes microorganisms that exhibit pathogenicity.
  • Candida species are commonly known to cause opportunist infections in immunocompromised hosts.
  • The study of pathogenic fungi is referred to as a medical mycology.
  • Candida species are commonly known to cause opportunist infections in immunocompromised hosts .
  • One of the most commons fungal pathogenic species includes Aspergillus strains, specifically Aspergillus fumigatus and Aspergillus flavus.

• Fungi as Plant, Animal, and Human Pathogens

  • Many plant pathogens are fungi that cause tissue decay and eventual death of the host .
  • In addition to destroying plant tissue directly, some plant pathogens spoil crops by producing potent toxins.
  • Opportunistic mycoses are fungal infections that are either common in all environments or are part of the normal biota.
  • Patients in the late stages of AIDS suffer from opportunistic mycoses that can be life threatening.
  • Give examples of fungi that are plant and animal parasites and pathogens

• Colonization and Growth

  • Some colonizing bacteria, such as Corynebacteria sp. and viridans streptococci, prevent the adhesion and colonization of pathogenic bacteria.
  • Individuals who have a suppressed immune system are particularly susceptible to opportunistic infections.
  • Some pathogens grow within the host cells (intracellular) whereas others grow freely in bodily fluids.
  • Non-pathogenic organisms can become pathogenic given specific conditions and even the most virulent organism requires certain circumstances to cause a compromising infection.
  • Some colonizing bacteria, such as Corynebacteria sp. and viridans streptococci, prevent the adhesion and colonization of pathogenic bacteria.

• Immunodeficiency

  • Failures, insufficiencies, or delays at any level of the immune response can allow pathogens or tumor cells to gain a foothold to replicate or proliferate to high enough levels that the immune system becomes overwhelmed, leading to immunodeficiency; it may be acquired or inherited.
  • Immunodeficiency can be acquired as a result of infection with certain pathogens (such as HIV), chemical exposure (including certain medical treatments), malnutrition, or, possibly, by extreme stress.
  • The person has a high probability of becoming infected, including from opportunistic infections and tumors that do not usually affect people who have working immune systems.
  • This weakens the immune system, allowing opportunistic infections.