Opportunistic infection
| Opportunistic infection | |
|---|---|
| Classification and external resources | |
| MeSH | D009894 |
An opportunistic infection is an infection caused by pathogens, particularly opportunistic pathogens—those that take advantage of certain situations—such as bacterial, viral, fungal or protozoan infections that usually do not cause disease in a healthy host, one with a healthy immune system. A compromised immune system, however, presents an "opportunity" for the pathogen to infect.
Causes
Immunodeficiency or immunosuppression can be caused by:
- Malnutrition
- Fatigue
- Recurrent infections
- Immunosuppressing agents for organ transplant recipients
- Advanced HIV infection
- Chemotherapy for cancer
- Genetic predisposition
- Skin damage
- Antibiotic treatment leading to disruption of the physiological microbiome, thus allowing some microorganisms to outcompete others and become pathogenic (e.g. disruption of intestinal flora may lead to Clostridium difficile infection, disruption of vaginal flora may lead to Candida infection)
- Medical procedures
- Pregnancy Further information: Susceptibility and severity of infections in pregnancy
- Ageing
- Leukopenia (i.e. neutropenia and lymphocytopenia)
Types of infections
Further information: Immunodeficiency
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- Aspergillus sp.
- Candida albicans
- Clostridium difficile
- Cryptococcus neoformans
- Cryptosporidium
- Cytomegalovirus
- Geomyces destructans
- Histoplasma capsulatum
- Isospora belli
- Polyomavirus JC polyomavirus, the virus that causes Progressive multifocal leukoencephalopathy.
- Kaposi's Sarcoma caused by Human herpesvirus 8 (HHV8), also called Kaposi's sarcoma-associated herpesvirus (KSHV)
- Legionnaires' Disease (Legionella pneumophila)
- Microsporidium
- Mycobacterium avium complex (MAC) (Nontuberculosis Mycobacterium)
- Pneumocystis jirovecii, previously known as Pneumocystis carinii f. hominis
- Pseudomonas aeruginosa
- Staphylococcus aureus
- Streptococcus pneumoniae
- Streptococcus pyogenes
- Toxoplasma gondii
Treatment
Treatment depends on the type of opportunistic infection, but usually involves different antibiotics.
Veterinary treatment
Opportunistic infections caused by Feline Leukemia Virus and Feline immunodeficiency virus retroviral infections can be treated with Lymphocyte T-Cell Immune Modulator.
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