Opportunistic pathogen n., plural: opportunistic pathogens [ˌɑpəɹˌtuːˈnɪstɪk ˈpæθəˌdʒɛn] Show
Definition: normally a commensal but can cause disease to its immunocompromised host How do we define opportunistic pathogen? The opportunistic pathogen is an infectious pathogen that is normally commensal in the body but can cause disease when the host’s resistance is altered. They can be some viruses (referred to as “opportunistic viruses”), fungi (referred to as “opportunistic fungi”), parasites (“opportunistic parasites”), and bacteria (“opportunistic bacteria“). They are normally present in the body without causing disease but cause an infectious disease in certain conditions, such as when the immunological response of the host is low. The low resistance of the body to opportunistic pathogens may occur due to many factors such as malnutrition, HIV, genetic factors, leukopenia (low WBC count), and aging. The opportunistic organism may exist in the body as a commensal. Let’s take commensal bacteria as an example. But first, let’s define commensal bacteria. Commensal bacteria are bacteria that do not necessarily cause harm to their host. This type of symbiosis occurring between the bacteria and the host where the host is neither generally harmed nor is benefitting in the relationship is referred to as commensalism. Commensal bacteria are essential to the well-being of humans. Their presence may even aid in the absorption of nutrients. Moreover, commensal bacteria can prevent the pathogenic invasion of the body and improve the function as well as the development of the immune system. Commensal bacteria produce antimicrobials that resist pathogenic invasion and colonization in the body. Under certain conditions, commensal bacteria may become opportunistic pathogenic bacteria.
Biology definition: An opportunistic pathogen is an organism that normally does not harm its host but can cause disease especially when the host’s resistance is low. Examples are Candida albicans (an opportunistic agent of oral and genital infections in humans), Staphylococcus aureus (normal flora on human skin but may cause infections), Pseudomonas aeruginosa, (may cause burn and external ear infections). Variant: (opportunistic) pathogene. What is an opportunistic disease?The opportunistic disease occurs mainly due to the suppression of host resistance, which, in turn, is due to the disruption or the absence of the components of the immune system of the host. Opportunistic pathogens are usually present in healthcare settings as hospitals. Such pathogens cause opportunistic diseases that they do not usually cause under normal conditions. Opportunistic pathogens cause infections by taking advantage of the weakened immunity of the host, disturbance in the normal microbiota, or penetrating barriers as in case of traumas. Moreover, opportunistic pathogens may cause mild infections in healthy individuals. However, the infection may lead to serious complications if the individual’s immunity was disturbed. Factors that induce a commensal organism to become pathogenicDisturbance of the host immunity may occur due to the following: HIV affects immunity because the virus can infect the T cells of the immune system. Because the immune system consequently becomes less effective, opportunist pathogens have an opportunity to become infectious. During the later stages of HIV, the host is at high risk of developing meningitis, tuberculosis, and conditions associated with viral infections, e.g., Kaposi’s sarcoma. Thus, opportunistic pathogens represent a major cause of death in AIDS patients. Opportunistic pathogens are also a major cause of infections and deaths in cancer patients as well as patients receiving organ transplantation. Severe immunocompromised drugs may lead to simultaneous infections with different opportunistic pathogens. What are the main characters of opportunistic pathogens?
What are the conditions that may influence the type of an opportunistic infection?
How to avoid infections of opportunistic pathogens during periods of low immunity?
Opportunistic Pathogen ExamplesFigure 1: (A) Candida albicans from a vaginal swab. (B) Scanning electron micrograph of Staphylococcus aureus, (C) Pseudomonas aeruginosa bacteria (pink-red rods, Gram-stained), (D) Clostridium difficile colonies after 48hrs growth on a blood agar plate, (E) Legionella pneumophila (under electron microscope), (F) Gram-stained sputum from a person with Haemophilus influenzae pneumonia. Credits: (A) Graham Beards, CC BY-SA 4.0, (B) CDC-PHIL (public domain), (C) Y_tambe, CC BY-SA 3.0, (D) CDC-PHIL (public domain), (E) CDC-PHIL (public domain), (F) Microman12345, CC BY-SA 4.0.Let’s get to know the different opportunistic pathogens and opportunistic infections. Examples of opportunistic microorganismsHere are examples of opportunistic microorganisms:
Common examples of opportunistic infectionsHere are examples of opportunistic infections and diseases:
Try to answer the quiz below to check what you have learned so far about opportunistic pathogens.
©BiologyOnline.com. Content provided and moderated by Biology Online Editors. |