B

Bacilli (singular bacillus): Elongated or rod-shaped bacteria.
Bacillus anthracis: The bacterium that causes anthrax.
Bacteraemia (also spelled bacteremia): A poisoning of the bloodstream by bacteria.
Bacteria (singular bacterium): An anaerobic prokaryotic microorganisms that are larger than viruses and smaller than fungi and protozoa and not members of the domain Archaea. The correct way to describe any single type of bacterium is by using two italicised words. The first word begins with a capital letter and refers to the genus or general group. The second letter is not capitalized and refers to the species type. For example, Staphylococcus aureus is a common bacterium. Related bacteria is expressed collectively simply as 'staphylococci.'
Bacterial spore: An environmentally stable and persistent form used by some bacteria as protection against lack of nutrients, heat, or drying.
Bacterial toxin: A protein substance released by some growing bacteria in food, water, or the human body. The toxin produces damage by interacting with one or more tissues. Some toxins are resistant to cooking temperatures.
Bactericide: That which kills bacteria.
Bacteriocidal: Having the capacity to kill bacteria when used as a therapeutic or a disinfectant. Bactericidal is an agent that kills bacteria.
Bacteriocin: Agents produced by certain bacteria that inhibit or kill closely related species.
Bacteriology: The study of bacteria.
Bacteriophage (phages): Specialized viruses that can infect a bacterial cell and are structurally similar to animal viruses. Each bacteriophage has a limited host range and can infect only specific kinds of bacteria.
Bacteriostat: An agent that prevents bacterial growth, but does not kill it.
Bacteriuria: A condition caused by bacteria in the urine.
Bacteroides: A genus of bacteria found as normal flora in anaerobic areas of the body. Some species are potential pathogens capable of causing fatal abscesses and bacteremias.
Balanitis: The inflammation or infection of the penis.
Barophile: A microbe capable of growing at very high pressures.
Base: A foundational chemical compound that combines with acids to form salts. Bases containing nitrogen are the building blocks of DNA and RNA.
Basophil: A type of white blood cell involved in allergic reactions.
BCG (Bacillus Calmette-Guérin): The tuberculosis vaccine developed by the French scientists Albert Calmette and Camille Guérin. They took a strain of tuberculosis from cattle and grew it in artificial culture in the laboratory for more than ten years (1908-1918) until it no longer caused disease. Each dose contains at least a million living bacteria, which multiply at the injection site in the arm and in nearby lymph nodes to give lasting immunity. It is an attenuated mycobacterium vaccine used throughout the world to immunize against tuberculosis.
Beta hemolysis: The complete rupture of red blood cells by bacterial enzymes (contrast alpha hemolysis).
Beta lactamase: An enzyme that hydrolyzes the beta lactam ring structure essential to the antibacterial activity of penicillins and cephalosporins.
Bilirubin: A yellow-orange pigment that results from the metabolism of the red blood cell protein, hemoglobin.
Binomial nomenclature: The system of taxonomy originated by Linnaeus in which each organism is assigned a genus and species name.
Bioconversion: The use of microorganisms, in industrial microbiology, to convert an added chemical to a chemically modified form.
Biogenic: Something produced by living organisms.
Biogeochemistry: The study of microbially mediated chemical transformations of geochemical interest.
Biological Warfare: A weapon that uses pathogenic microorganisms.
Biopsy: The microscopic removal of tissue from the body for examination, usually performed to establish a precise diagnosis. Bioremediation; The use of microorganisms to remove or detoxify unwanted chemicals from an environment.
Bipolar stain: Happens when some bacteria stain more intensely at each end of their cell than in the middle giving a "safety pin" appearance under the microscope.
B lymphocyte (B cell): A type of cell originating in the bone marrow (thus the letter B) that produces plasma cells specialized to produce antibodies when exposed to foreign invaders. B cell proliferation, maturation, and antibody production are stimulated by T helper infected cells.
Black water fever: A condition resulting in kidney failure caused by malaria.
Blastocystis hominis: An organism originally classified as a nonpathogenic yeast, but is now being recognized as a protozoan, even though it does not have the typical cyst and trophozoite stages typical. It is responsible for an infection of the region where the small intestine meets the colon. When the organism is found in great enough numbers, it causes symptoms of nausea, gas, abdominal pain, diarrhea, and malaise.
Blastomycosis: A fungal skin disease caused by Blastomyces dermatitidis, that enters the body through wounds.
Blood Poisoning: A prolonged invasion of the bloodstream caused by pathogenic bacteria resulting from an infectious disease or skin lesions. Other names include bacteremia, septicemia, and toxemia.
Blood-Brain Barrier: A group of anatomical barriers and transport systems that tightly control what types of substances enter the extracellular space of the brain.
Bloom: The name given to a major outgrowth of algae during periods referred to as "red tide." (see pfeisteria)
Boil (furuncle): A tender, inflamed, pus-filled area of skin, often as a result of staphylococcal infection. A carbuncle is a cluster of boils.
Bordetella pertussis: The bacterium responsible for the disease called whooping cough.
Botulism: A serious life-threatening food poisoning caused by a toxin produced by the bacterium Clostridium botulinum, and is characterized by generalized weakness, defective vision, and respiratory paralysis. Botulism is an intoxication rather than an infection; therefore, it is not communicable even though the bacteria is excreted in the feces for months following the illness. There are three types: classic (a food borne illness), infant (uncommon illness striking only babies), and wound (a rare infection). The classic incubation period is twelve to twenty-six hours after eating tainted food, but symptoms have been known not to appear until eight days later. Without treatment, most die from respiratory failure.
Brain abscesses: A rare condition often caused by more than one organism, but usually associated with anaerobic bacteria. They are typically caused by members of the genus Nocardia. Brain abscesses associated with dental infections are commonly caused by members of the genus Bacteroides along with streptococci. Even rarer, are brain abscesses caused by bacteria that include Mycobacterium tuberculosis, Treponema pallidum, and Borrelia burgdorferi. Fungal causes stem from Cryptococcus neoformans members of the genus Aspergillus, Coccidioides immitis, Candida albicans, Histoplasma capsulatumand Blastomyces dermatitidis have also been implicated in brain abscesses. Treatment includes surgical drainage of the lesion and an extended course of the appropriate antimicrobial.
Broad spectrum: Antimicrobial agents effective against more than one kind of bacterium, and usually suggesting antibacterial activity against both gram-positive and Gram-negative bacteria.
Bronchial pneumonia: A type of pneumonia that begins in the bronchi of the lungs that can spread through surrounding tissue toward the alveoli.
Bronchitis: An inflammation of the bronchi that may be an acute or a chronic disorder. Bacterial causes are found in only 50% of the cases of bronchitis, yet antibiotics are given almost 100% of the time. Often theophylline is prescribed to help dilate or expand the airways. This drug is also found in black tea and orange pekoe tea. Expectorants are also often prescribed. Instead, herbs can be used. Eucalyptus not only has expectorant properties, but also is an antibacterial and antivirual agent. It was once smoked as a treatment for respiratory problems, but it is now diffused in steam. A few drops of eucalyptus oil in a pan of hot water and breathing in the fumes will help dilate the passages, as well as acting as an expectorant. The oil should never be taken internally. Eucalyptus can also be diluted in oil or an ointment and rubbed on the chest to clear mucus (as opposed to using "Vicks"). Horehound (Marrubium vulgare) is also used for sore throats and bronchitis. It promotes the expulsion of phlegm and can also quieten a cough. Drink as a cold tea, one cup per day by the spoonful. Yerba Santa (Eriodictyon californicum), can also be used for bronchitis. Sip a strong tea made from the leaves. One to three cups of tea a day made from the leaves of Plantain (Plantago major); also a tea made from thyme three times a day and, by adding honey, the benefits increase.
Brucella: A genus of bacteria responsible for the disease brucelliosis or "Bang's disease," transmitted to humans from livestock, especially cattle; also known as undulant fever.
Bruxism: The continuous unconscious grinding of the teeth.
Buboe: An enlarged, infected lymph node, typically seen in bubonic plague, but also a clinical feature of the sexually transmissible disease lymphogranuloma venereum.
Bubonic plague: A highly contagious and severe disease caused by the bacillus Yersinia pestis, carried by rat fleas and then transmitted to humans.
Bunyaviruses: Viruses of the family Bunyaviridae, made up of over 200 interrelated viruses, mostly arboviruses, which cause such diseases as Korean Hemorrhagic fever, California encephalitis, Sandfly fever, and Rift Valley fever.