An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable disease, is an illness resulting from an infection.
Cryptococcus neoformans is an encapsulated yeast belonging to the class Tremellomycetes and an obligate aerobe that can live in both plants and animals. Its teleomorph is a filamentous fungus, formerly referred to Filobasidiella neoformans. In its yeast state, it is often found in bird excrement. Cryptococcus neoformans can cause disease in apparently immunocompetent, as well as immunocompromised, hosts.
An emergent virus is a virus that is either newly appeared, notably increasing in incidence/geographic range or has the potential to increase in the near future. Emergent viruses are a leading cause of emerging infectious diseases and raise public health challenges globally, given their potential to cause outbreaks of disease which can lead to epidemics and pandemics. As well as causing disease, emergent viruses can also have severe economic implications. Recent examples include the SARS-related coronaviruses, which have caused the 2002-2004 outbreak of SARS (SARS-CoV-1) and the 2019–21 pandemic of COVID-19 (SARS-CoV-2). Other examples include the human immunodeficiency virus which causes HIV/AIDS; the viruses responsible for Ebola; the H5N1 influenza virus responsible for avian flu; and H1N1/09, which caused the 2009 swine flu pandemic. Viral emergence in humans is often a consequence of zoonosis, which involves a cross-species jump of a viral disease into humans from other animals. As zoonotic viruses exist in animal reservoirs, they are much more difficult to eradicate and can therefore establish persistent infections in human populations.
A subclinical infection—sometimes called a preinfection or inapparent infection—is an infection by a pathogen that causes few or no signs or symptoms of infection in the host. Subclinical infections can occur in both humans and animals. Depending on the pathogen, which can be a virus or intestinal parasite, the host may be infectious and able to transmit the pathogen without ever developing symptoms; such a host is called an asymptomatic carrier. Many pathogens, including HIV, typhoid fever, and coronaviruses such as COVID-19 spread in their host populations through subclinical infection.
Eikenella corrodens is a Gram-negative facultative anaerobic bacillus that can cause severe invasive disease in humans. It was first identified by M. Eiken in 1958, who called it Bacteroides corrodens. E. corrodens is a rare pericarditis associated pathogen. It is a fastidious, slow growing, human commensal bacillus, capable of acting as an opportunistic pathogen and causing abscesses in several anatomical sites, including the liver, lung, spleen, and submandibular region. E. corrodens could independently cause serious infection in both immunocompetent and immunocompromised hosts.
Mycobacteroides abscessus is a species of rapidly growing, multidrug-resistant, nontuberculous mycobacteria (NTM) that is a common soil and water contaminant. Although M. abscessus most commonly causes chronic lung infection and skin and soft tissue infection (SSTI), it can also cause infection in almost all human organs, mostly in patients with suppressed immune systems. Amongst NTM species responsible for disease, infection caused by M. abscessus complex are more difficult to treat due to antimicrobial drug resistance.
Ralstonia is a genus of bacteria, previously included in the genus Pseudomonas. It is named after the American bacteriologist Ericka Ralston. Ericka Ralston was born Ericka Barrett in 1944 in Saratoga, California, and died in 2015 in Sebastopol, California. While in graduate school at the University of California at Berkeley, she identified 20 strains of Pseudomonas which formed a phenotypical homologous group, and named them Pseudomonas pickettii, after M.J. Pickett in the Department of Bacteriology at the University of California at Los Angeles, from whom she had received the strains. Later, P. pickettii was transferred to the new genus Ralstonia, along with several other species. She continued her research into bacterial pathogenesis under the name of Ericka Barrett while a professor of microbiology at the University of California at Davis from 1977 until her retirement in 1996.
Ralstonia pickettii is a Gram-negative, rod-shaped, soil bacterium.
Vaginal flora, vaginal microbiota or vaginal microbiome are the microorganisms that colonize the vagina. They were discovered by the German gynecologist Albert Döderlein in 1892 and are part of the overall human flora. The amount and type of bacteria present have significant implications for an individual's overall health. The primary colonizing bacteria of a healthy individual are of the genus Lactobacillus, such as L. crispatus, and the lactic acid they produce is thought to protect against infection by pathogenic species.
Streptococcus dysgalactiae is a gram positive, beta-haemolytic, coccal bacterium belonging to the family Streptococcaceae. It is capable of infecting both humans and animals, but is most frequently encountered as a commensal of the alimentary tract, genital tract, or less commonly, as a part of the skin flora. The clinical manifestations in human disease range from superficial skin-infections and tonsillitis, to severe necrotising fasciitis and bacteraemia. The incidence of invasive disease has been reported to be rising. Several different animal species are susceptible to infection by S. dysgalactiae, but bovine mastitis and infectious arthritis in lambs have been most frequently reported.
In biology, a pathogen, in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ.
Corynebacterium amycolatum is a gram-positive, non-spore-forming, aerobic or facultatively anaerobic bacillus capable of fermentation with propionic acid as the major end product of its glucose metabolism. One of its best known relatives is Corynebacterium diphtheriae, the causative agent of diphtheria. C. amycolatum is a common component of the natural flora found on human skin and mucous membranes, and therefore is an occasional contaminant in human blood cultures but can rarely cause infections such as endocarditis.
Human coronavirus 229E (HCoV-229E) is a species of coronavirus which infects humans and bats. It is an enveloped, positive-sense, single-stranded RNA virus which enters its host cell by binding to the APN receptor. Along with Human coronavirus OC43, it is one of the viruses responsible for the common cold. HCoV-229E is a member of the genus Alphacoronavirus and subgenus Duvinacovirus.
Fannyhessea vaginae is a species of bacteria in the family Atopobiaceae. It is a facultative anaerobic, Gram-positive rod-shaped or elliptical coccobacillus found as single elements or in pairs or short chains. It is typically isolated from 80% of women with bacterial vaginosis and it is implicated in treatment failures. Invasive infections such as bacteremia have been reported.
Helicobacter canadensis is a bacterium in the Helicobacteraceae family, Campylobacterales order, first isolated from humans with diarrhea. Its genome has been sequenced.
Kocuria is a genus of gram-positive bacteria. Kocuria is named after Miloslav Kocur, a Czech microbiologist. It has been found in the milk of water deer and reindeer. Cells are coccoid, resembling Staphylococcus and Micrococcus, and can group in pairs, chains, tetrads, cubical arrangements of eight, or irregular clusters. They have rigid cell walls and are either aerobic or facultative anaerobic. Kocuria can usually survive in mesophilic temperatures.
Infections associated with diseases are those infections that are associated with possible infectious etiologies that meet the requirements of Koch's postulates. Other methods of causation are described by the Bradford Hill criteria and evidence-based medicine.
Actinobaculum is a bacterial genus in the family Actinomycetaceae.
Sporothrix brasiliensis is a fungus that is commonly found in soil. It is an emerging fungal pathogen that is causing disease in humans and cats mainly in Brazil and other countries in South America.
