Opportunistic infection

Types of opportunistic infections

Bacteria

• is an anaerobic bacterium recognized for its role in the development of bacterial vaginosis.
• Clostridioides difficile is a bacteria that is known to cause gastrointestinal infection and diarrhea. It is typically associated with being the most common hospital acquired infection.
• Cutibacterium acnes can act as an opportunistic agent in infections associated with implanted medical devices, forming biofilms.
• are E. coli strains that can lead to diseases beyond the gut, notably urinary tract infections, meningitis, and bacteremia.
• is a bacterium implicated in causing illnesses such as meningitis, epiglottitis which can obstruct airways, pneumonia, otitis media affecting the ear, sinusitis involving the sinuses, and potentially leading to complications like mastoiditis, parameningeal abscess, and pericarditis.
• Klebsiella pneumoniae, a member of a group including pathogens, can be responsible for various infections in hospitalized individuals as it is frequently isolated from hospital admissions and the broader group is known to cause diverse infections.
• Legionella pneumophila is a bacterium that causes Legionnaire's disease, a respiratory infection.
• Mycobacterium avium complex is a group of two bacteria, M. avium and M. intracellulare, that typically co-infect, leading to a lung infection called mycobacterium avium-intracellulare infection.
• Mycobacterium tuberculosis is a species of bacteria that causes tuberculosis, a respiratory infection.
• Pseudomonas aeruginosa is a bacterium that can cause respiratory infections. It is frequently associated with nosocomial infections and cystic fibrosis which can lead to organ dysfunctions and shortened life expectancy.
• Salmonella is a genus of bacteria that is known to cause gastrointestinal infections causing an inflammatory response accompanied with fever and diarrhea.
• Staphylococcus aureus is a bacterium known to cause skin infections and sepsis, among other pathologies. Notably, S. aureus has evolved several drug-resistant strains, including MRSA.
• has emerged as a challenging nosocomial agent frequently associated with respiratory tract infections like pneumonia and exacerbations in individuals with COPD, and can also cause bacteremia, particularly linked to central lines in vulnerable patients.
• Streptococcus pneumoniae is a bacterium that causes respiratory infections as well as meningitis and bacteremia.
• Streptococcus pyogenes is a bacterium that can cause a variety of conditions, including impetigo and strep throat, as well as other illnesses.

  Fungi

• Aspergillus is a fungus, commonly associated with respiratory infection.
• Candida albicans is a species of fungus that is a part of the normal human microbiome. It acts as a commensal unless there is a change in concentrations. It can be associated with various conditions such as oral thrush and gastrointestinal infection.
• Coccidioides immitis is a fungus known for causing coccidioidomycosis, more commonly known as Valley Fever.
• : This emerging fungal pathogen can cause severe and often fatal infections, manifesting as pulmonary disease and meningitis in both immunocompromised and immunocompetent individuals.
• Cryptococcus neoformans is a fungus that causes cryptococcosis, which can lead to pulmonary infection as well as nervous system infections, like meningitis.
• : These fungi are responsible for a range of diseases including phaeohyphomycosis, chromoblastomycosis, eumycotic mycetoma, invasive sinusitis, and allergic fungal sinusitis; cerebral infections can also occur.
• : These fungi can cause hyalohyphomycosis, particularly in immunocompromised individuals, as well as mycotic keratitis and onychomycosis.
• : This group encompasses various molds, including . causing hyalohyphomycosis, mycotic keratitis, and onychomycosis, as well as commonly causing pneumonia, sinusitis, and cutaneous lesions that may disseminate in neutropenic patients; . associated with sinusitis and pneumonia; Lomentospora prolificans causing a varied range of infections and disseminated disease; Scopulariopsis spp. and Acremonium spp. linked to sinopulmonary diseases; Paecilomyces variotii causing sinopulmonary disease; and Penicillium species implicated in necrotizing esophagitis and disseminated infections.
• Histoplasma capsulatum is a species of fungus known to cause histoplasmosis, which can present itself with an array of symptoms, but often involves respiratory infection.
• : This fungus can cause a remarkably varied range of infections and disseminated disease, including keratitis, mycotic aneurysms, external otitis, sinusitis, peritonitis, onychomycosis, and esophagitis.
• Pseudogymnoascus destructans is a fungus that causes white-nose syndrome in bats.
• Microsporidia is a group of fungi that infect species across the animal kingdom, one species of which can cause microsporidiosis in immunocompromised human hosts.
• Pneumocystis jirovecii is a fungus that causes pneumocystis pneumonia, a respiratory infection.
• : These yeasts can cause fungemia, often linked to central venous catheter use, as well as localized infections including meningitis, skin infections, ocular infections, peritonitis, and prosthetic joint infections.
• : This group can cause infections like rhinocerebral mucormycosis, and Mucor has been associated with respiratory infections; specifically, Absidia corymbifera is considered a human pathogen.

  Parasites

• Cryptosporidium is a protozoan that causes the condition Cryptosporidiosis. This condition affects the gastrointestinal tract.
• Toxoplasma gondii is a protozoan, known for causing toxoplasmosis which is known to lead to impairment of the brain.

  Viruses

• is known to cause various illnesses, including lower respiratory tract infections, pneumonia, acute respiratory diseases, epidemic keratoconjunctivitis affecting the eyes, acute hemorrhagic cystitis of the bladder, and gastroenteritis affecting the digestive system.
• LCMV causes lymphocytic choriomeningitis disease and death in immunocompromised organ-transplant patients.
• HSV is considered a member of the human herpesvirus family and is most frequently associated with immunocompromisation diseases and JAK inhibitors.
• Cytomegalovirus is considered a member of the human herpesvirus family and is most frequently associated with respiratory infection.
• can lead to acute liver infection manifesting as anicteric hepatitis, icteric hepatitis, or fulminant hepatitis, and chronic infection can progress to an asymptomatic carrier state, chronic hepatitis, cirrhosis of the liver, and hepatocellular carcinoma. Severe liver damage can result in complications like jaundice, hepatic encephalopathy, ascites, gastrointestinal bleeding, and coagulopathy.
• infection can become chronic, leading to liver damage that can progress to cirrhosis, portal hypertension, hepatic decompensation with encephalopathy, and hepatocellular carcinoma.
• is responsible for seasonal flu epidemics and can be categorized into types affecting various hosts, such as avian flu, canine flu, swine /variant flu, and can cause pandemic flu, all generally resulting in respiratory illnesses.
• commonly causes upper and lower respiratory tract infections, with symptoms such as cough, mucous production, fever, and dyspnea, and can lead to more severe conditions like pneumonia and bronchiolitis.
• is the initiating force behind multiple conditions, including cutaneous and anogenital warts, which in some cases can progress to various carcinomas.
• Human polyomavirus 2 is known to cause progressive multifocal leukoencephalopathy which affects the central nervous system.
• Human herpesvirus 8 is a virus associated with Kaposi sarcoma, a type of skin cancer.
• causes a chronic lifelong infection that can lead to general immunosuppression, uveitis affecting the eyes, dermatitis of the skin, pneumonitis in the lungs, adult T-cell leukemia, and HTLV-1 associated myelopathy also known as tropical spastic paraparesis.
• commonly causes upper and lower respiratory illnesses with symptoms similar to the common cold, such as fever, runny nose, cough, sneezing, and sore throat, and can also cause more serious illnesses in children including croup, bronchitis, and bronchiolitis.
• is the virus that causes Coronavirus Disease 2019, with symptoms that can include fever, cough, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, congestion or runny nose, nausea or vomiting, and diarrhea.
• Varicella-Zoster Virus causes .