#bacteria

• Abacterial — A medical term used to describe an environment, biological sample (urine, cerebrospinal fluid), or inflammatory process where no bacteria are present. An abacterial inflammation (such as abacterial cystitis or prostatitis) produces symptoms similar to an infection but is triggered by chemical, immune, traumatic factors, or viruses, with laboratory microbial cultures remaining negative.
• Abscessation / Abscess formation — The pathological process of abscess formation; the transformation of an acute inflammation or diffuse inflammatory infiltrate (such as cellulitis or phlegmon) into a well-circumscribed purulent collection, accompanied by liquefactive tissue necrosis.
• Abscess / Purulent pocket — A localized collection of pus, well-circumscribed by a newly formed pyogenic membrane, resulting from tissue destruction and liquefactive necrosis caused by an acute infection, most commonly bacterial (staphylococci, streptococci). Clinically characterized by classic signs of inflammation: pulsatile pain, swelling, local heat, redness, and fluctuance.
• abscess — (Medicine) A localized collection of pus within a tissue or organ, formed as a result of an acute inflammatory process, usually caused by a local bacterial infection.
• Acroposthitis — An acute or chronic inflammatory pathological process localized strictly at the level of the prepuce (the distal cutaneous sheath of the penis). This structural urological condition is most frequently caused by bacterial, fungal (such as candidiasis), or viral infections, poor local hygiene, chemical irritations, or mechanical traumas, clinically manifesting through marked edema, erythema (redness), intense pain, pruritus, and abnormal discharge, being closely correlated or frequently coexisting with balanitis (inflammation of the glans) to form the clinical picture known as balanoposthitis.
• Actinomycete — A gram-positive, predominantly aerobic bacterium belonging to the order Actinomycetales. Although evolutionarily and structurally prokaryotes (bacteria), these organisms exhibit a unique morphology, forming elongated branched filaments that mimic fungal mycelium. They are widespread in soil, playing a crucial ecological role in organic matter decomposition and possessing immense industrial value as the primary natural source for antibiotic production (such as streptomycin).
• Actinomycete — Common feminine form for the noun 'actinomicet'; a gram-positive, predominantly aerobic bacterium that exhibits a structural network of thin branched filaments mimicking the appearance of a fungal mycelium. Living primarily as a saprophyte in soil, an actinomycete is responsible for synthesizing many important bioactive compounds, being notable for producing geosmin (the substance giving the earthy smell after rain) and for manufacturing the majority of antibiotics used in modern medicine.
• Actinomycetales — Romanian name for the taxonomic order Actinomycetales, which groups gram-positive bacteria with a high guanine and cytosine content in their DNA, structurally characterized by their capacity to form branched filaments resembling fungal hyphae. These microorganisms play a major ecological role in decomposing complex organic matter in soil and are essential in biotechnology, serving as the primary natural source of secondary metabolites with antibiotic, antifungal, and immunosuppressive properties.
• Aerobacter — A genus of gram-negative, rod-shaped bacteria, motile or non-motile, aerobic or facultatively anaerobic, commonly found in soil, water, dairy products, and the digestive tract of humans and animals. These microorganisms possess the ability to ferment glucose and lactose, producing a large amount of gases and acids, and are sometimes involved in opportunistic urinary or respiratory tract infections in clinical settings.
• Aerobioscope — A laboratory apparatus used for collecting, filtering, and determining the number of microorganisms (bacteria, fungal spores) present in a specific volume of air. This device operates by bubbling air through a sterile liquid or by impacting particles onto a solid culture medium, being essential for air hygiene monitoring in hospitals, laboratories, and pharmaceutical industries.
• Aerobe — As a noun, it designates any organism (especially a microorganism, such as a bacterium or fungus) that requires free molecular oxygen to live and develop. As an adjective, it represents a less frequent linguistic variant of the term 'aerob', describing phenomena, environments, or beings adapted to the presence of air.
• Aerogenesis — A biological, chemical, or pathological process of formation, production, and release of gases or air; in microbiology, it specifically refers to the capacity of certain anaerobic or facultative bacteria to generate gases (such as carbon dioxide or hydrogen) following carbohydrate metabolism and fermentation.
• Aerotaxis — A specific form of taxis or directed orientation and movement reaction of mobile microorganisms (bacteria, protozoa) triggered by the presence, concentration level, or partial pressure variation of oxygen or other gases in their living environment. This structural phenomenon guides aerobic bacteria toward oxygen-rich zones and anaerobic ones away from them.
• Aerotaxis — A specific form of taxis encountered in motile microorganisms, consisting of a reflex movement of orientation and displacement toward or away from a source of oxygen or other gases. This structural biological mechanism governs the attraction of aerobic bacteria to zones with optimal air concentration and the repulsion of strict anaerobes from oxygenated environments.
• Alexin — A historical term used in early immunology, introduced by Hans Buchner and popularized by Jules Bordet, to designate the complement system; a thermolabile protein substance present in normal blood serum capable of destroying bacteria and other foreign cells in cooperation with specific antibodies (sensitizers). In modern biochemistry, its action is studied as an integral part of the innate non-specific immune response of cell lysis.
• Amphitrichous — Having flagella or cilia arranged in tufts or clusters at both extremities of the cell; a morphological term typically used in microbiology to describe amphitrichous bacteria, whose locomotion and structural dynamics are facilitated by opposite polar cilia.
• Amphitrichous — An orthographic variant of the term 'amfitrih'; describing a bacterial cell or microorganism that possesses cilia or flagella arranged in tufts at both polar extremities. This morphological structure ensures efficient bidirectional mobility in liquid media with high viscosity.
• Tonsillitis — An acute or chronic inflammation of the palatine tonsils, caused by a viral or bacterial infection (frequently group A beta-hemolytic streptococcus). This structural pathology manifests clinically through severe odynophagia, dysphagia, fever, cervical adenopathy, and swelling of the lymphoid tissue, requiring differential diagnosis to determine the appropriateness of antibiotic treatment.
• Amylobacter — A generic name for an anaerobic bacterium, often belonging to the genus Clostridium (such as Clostridium butyricum), capable of fermenting starch and other polysaccharides in the absence of oxygen. This microorganism plays an essential structural role in the natural decomposition of plant matter and in the industrial production of butyric acid or solvents, having the property of accumulating starch inclusions inside its cell.
• Amniotitis — An acute or chronic inflammation of the amniotic membrane, usually caused by an ascending bacterial infection from the vaginal tract following membrane rupture or during prolonged labor. This pathological condition is closely correlated with chorioamnionitis and represents a major risk for neonatal infection or preterm birth.