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Pleomorphism (microbiology)
In microbiology, pleomorphism (from Ancient Greek , ''pléō'', "more", and , ''morphḗ'', form), also pleiomorphism, is the ability of some microorganisms to alter their morphology, biological functions or reproductive modes in response to environmental conditions. Pleomorphism has been observed in some members of the Deinococcaceae family of bacteria. The modern definition of pleomorphism in the context of bacteriology is based on ''variation'' of morphology or functional methods of the individual cell, rather than a heritable ''change'' of these characters as previously believed. Bacteria In the first decades of the 20th century, the term "pleomorphism" was used to refer to the idea that bacteria change morphology, biological systems, or reproductive methods dramatically according to environmental cues. This claim was controversial among microbiologists of the time, and split them into two schools: the monomorphists, who opposed the claim, and the pleomorphists such as Antoi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek
Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek Dark Ages, Dark Ages (), the Archaic Greece, Archaic or Homeric Greek, Homeric period (), and the Classical Greece, Classical period (). Ancient Greek was the language of Homer and of fifth-century Athens, fifth-century Athenian historians, playwrights, and Ancient Greek philosophy, philosophers. It has contributed many words to English vocabulary and has been a standard subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Homeric Greek, Epic and Classical periods of the language, which are the best-attested periods and considered most typical of Ancient Greek. From the Hellenistic period (), Ancient Greek was followed by Koine Greek, which is regar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axenic
In biology, axenic (, ) describes the state of a culture in which only a single species, variety, or strain of organism is present and entirely free of all other contaminating organisms. The earliest axenic cultures were of bacteria or unicellular eukaryotes, but axenic cultures of many multicellular organisms are also possible. Axenic culture is an important tool for the study of symbiotic and parasitic organisms in a controlled environment. Preparation Axenic cultures of microorganisms are typically prepared by subculture of an existing mixed culture. This may involve use of a dilution series, in which a culture is successively diluted to the point where subsamples of it contain only a few individual organisms, ideally only a single individual (in the case of an asexual species). These subcultures are allowed to grow until the identity of their constituent organisms can be ascertained. Selection of those cultures consisting solely of the desired organism produces the axenic c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacteriophage
A bacteriophage (), also known informally as a phage (), is a virus that infects and replicates within bacteria. The term is derived . Bacteriophages are composed of proteins that Capsid, encapsulate a DNA or RNA genome, and may have structures that are either simple or elaborate. Their genomes may encode as few as four genes (e.g. Bacteriophage MS2, MS2) and as many as hundreds of genes. Phages replicate within the bacterium following the injection of their genome into its cytoplasm. Bacteriophages are among the most common and diverse entities in the biosphere. Bacteriophages are ubiquitous viruses, found wherever bacteria exist. It is estimated there are more than 1031 bacteriophages on the planet, more than every other organism on Earth, including bacteria, combined. Viruses are the most abundant biological entity in the water column of the world's oceans, and the second largest component of biomass after prokaryotes, where up to 9x108 virus, virions per millilitre have b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virion
A virion (plural, ''viria'' or ''virions'') is an inert virus particle capable of invading a Cell (biology), cell. Upon entering the cell, the virion disassembles and the genetic material from the virus takes control of the cell infrastructure, thus enabling the virus to Replication (virus), replicate. The genetic material (''Viral core, core'', either DNA or RNA, along with occasionally present virus core protein) inside the virion is usually enclosed in a protection shell, known as the capsid. While the terms "virus" and "virion" are occasionally confused, recently "virion" is used solely to describe the virus structure outside of cells, while the terms "virus/viral" are broader and also include biological properties such as the infectivity of a virion. Components A virion consists of one or more nucleic acid genome molecules (single-stranded or double-stranded RNA or DNA) and coatings (a capsid and possibly a viral envelope). The virion may contain other proteins (for examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nosocomial
A hospital-acquired infection, also known as a nosocomial infection (from the Greek , meaning "hospital"), is an infection that is acquired in a hospital or other healthcare facility. To emphasize both hospital and nonhospital settings, it is sometimes instead called a healthcare-associated infection. Such an infection can be acquired in a hospital, nursing home, rehabilitation facility, outpatient clinic, diagnostic laboratory or other clinical settings. A number of dynamic processes can bring contamination into operating rooms and other areas within nosocomial settings. Infection is spread to the susceptible patient in the clinical setting by various means. Healthcare staff also spread infection, in addition to contaminated equipment, bed linens, or air droplets. The infection can originate from the outside environment, another infected patient, staff that may be infected, or in some cases, the source of the infection cannot be determined. In some cases the microorganism origi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacilli
Bacilli is a Taxonomy (biology), taxonomic Class (biology), class of bacteria that includes two orders, Bacillales and Lactobacillales, which contain several well-known pathogens such as ''Bacillus anthracis'' (the cause of anthrax). ''Bacilli'' are almost exclusively gram-positive bacteria. The name ''Bacillus'', capitalized and Italics, italicized, refers to a specific genus of bacteria. The name Bacilli, capitalized but not italicized, can also refer to a less specific taxonomic group of bacteria that includes two orders, one of which contains the genus ''Bacillus''. When the word is formatted with lowercase and not italicized, 'bacillus', it will most likely be referring to shape and not to the genus at all. Ambiguity Several related concepts make use of similar words, and the ambiguity can create considerable confusion. The term "''Bacillus''" (capitalized and italicized) is also the name of a genus (''Bacillus anthracis'') that, among many other genera, falls within the cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coccobacillus
Bacterial cellular morphologies are the shapes that are characteristic of various types of bacteria and often key to their identification. Their direct examination under a light microscope enables the classification of these bacteria (and archaea). Generally, the basic morphologies are spheres (coccus) and round-ended cylinders or rod shaped (bacillus). But, there are also other morphologies such as helically twisted cylinders (example '' Spirochetes''), cylinders curved in one plane (selenomonads) and unusual morphologies (the square, flat box-shaped cells of the Archaean genus '' Haloquadratum)''. Other arrangements include pairs, tetrads, clusters, chains and palisades. Types Coccus A coccus (plural ''cocci'', from the Latin ''coccinus'' (scarlet) and derived from the Greek ''kokkos'' (berry)), is any microorganism (usually bacteria) whose overall shape is spherical or nearly spherical. Coccus refers to the shape of the bacteria and can contain multiple genera, such as s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Corynebacterium
''Corynebacterium'' () is a genus of Gram-positive bacteria and most are aerobic. They are bacilli (rod-shaped), and in some phases of life they are, more specifically, club-shaped, which inspired the genus name ('' coryneform'' means "club-shaped"). They are widely distributed in nature in the microbiota of animals (including the human microbiota) and are mostly innocuous, most commonly existing in commensal relationships with their hosts. Some, such as '' C. glutamicum'', are commercially and industrially useful. Others can cause human disease, including, most notably, diphtheria, which is caused by '' C. diphtheriae''. Like various species of microbiota (including their relatives in the genera '' Arcanobacterium'' and '' Trueperella''), they are usually not pathogenic, but can occasionally capitalize opportunistically on atypical access to tissues (via wounds) or weakened host defenses. Taxonomy The genus ''Corynebacterium'' was created by Lehmann and Neumann in 18 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Legionnaires' Disease
Legionnaires' disease is a form of atypical pneumonia caused by any species of ''Legionella'' bacteria, quite often ''Legionella pneumophila''. Signs and symptoms include cough, shortness of breath, high fever, myalgia, muscle pains, and headaches. Nausea, vomiting, and diarrhea may also occur. This often begins 2–10 days after exposure. A legionellosis is any disease caused by ''Legionella'', including Legionnaires' disease (a pneumonia) and Pontiac fever (a related upper respiratory tract infection), but Legionnaires' disease is the most common, so mentions of legionellosis often refer to Legionnaires' disease. The bacterium is found naturally in fresh water. It can contaminate hot water tanks, hot tubs, and cooling towers of large air conditioners. It is usually spread by breathing in mist that contains the bacteria. It can also occur when contaminated water is Pulmonary aspiration, aspirated. It typically does not spread directly between people, and most people who are ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Legionella Pneumophila
''Legionella pneumophila'', the primary causative agent for Legionnaires' disease, Legionnaire's disease, is an Aerobic organism, aerobic, pleomorphic, Flagellum, flagellated, non-spore-forming, Gram-negative bacteria, Gram-negative bacterium. ''L. pneumophila'' is a intracellular parasite that preferentially infects soil amoebae and freshwater protozoa for replication. Due to ''L. pneumophila’s'' ability to thrive in water, it can grow in water filtration systems, leading to faucets, showers, and other fixtures. Aerosolized water droplets containing ''L. pneumophila'' originating from these fixtures may be inhaled by humans. Upon entry to the human respiratory tract, ''L. pneumophila'' is able to infect and reproduce within human Alveolar macrophage, alveolar macrophages. This causes the onset of Legionnaires' disease, also known as legionellosis. Infected humans may display symptoms such as fever, delirium, diarrhea, and decreased liver and kidney function. ''L. pneumophila' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helicobacter Pylori
''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, Flagellum#bacterial, flagellated, Bacterial cellular morphologies#Helical, helical bacterium. Mutants can have a rod or curved rod shape that exhibits less virulence. Its Helix, helical body (from which the genus name ''Helicobacter'' derives) is thought to have evolved to penetrate the gastric mucosa, mucous lining of the stomach, helped by its flagella, and thereby establish infection. While many earlier reports of an association between bacteria and the ulcers had existed, such as the works of John Lykoudis, it was only in 1983 when the bacterium was formally described for the first time in the English-language Western literature as the causal agent of peptic ulcer, gastric ulcers by Australian physician-scientists Barry Marshall and Robin Warren. In 2005, the pair was awarded the Nobel Prize in Physiology or Medicine for their discovery. Infection of the stomach with ''H. pylori'' doe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy, treatment and antibiotic prophylaxis, prevention of such infections. They may either bactericide, kill or bacteriostatic agent, inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. Antibiotics are not effective against viruses such as the ones which cause the common cold or influenza. Drugs which inhibit growth of viruses are termed antiviral drugs or antivirals. Antibiotics are also not effective against fungi. Drugs which inhibit growth of fungi are called antifungal drugs. Sometimes, the term ''antibiotic''—literally "opposing life", from the Greek language, Greek roots ἀντι ''anti'', "against" and βίος ''bios'', "life"—is broadly used to refer to any substance used against ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
