liveonearth (liveonearth) wrote,

Vocababble: Microbiology, Tuberculosis, Phages, CRP, more

petechial rash = little red spots on the skin caused by broken capillaries. Widespread petechiae and ecchymoses are signs of sepsis (meningococcemia). They also may indicate various causes of thrombocytopenia, and leukemia.

thrombocytopenia = not enough platelets in blood

lipocalins = a family of proteins which transport small hydrophobic molecules such as steroids, bilins, retinoids, and lipids. They share limited regions of sequence homology and a common tertiary structure architecture. Found in gram negative bacteria, vertebrate cells, and invertebrate cells, and in plants. Associated with many biological processes, among them immune response, pheromone transport, biological prostaglandin synthesis, retinoid binding, and cancer cell interactions.

BCG vaccine = Bacille Calmette-Guérin (BCG) is a vaccine against tuberculosis that is prepared from a strain of the attenuated (weakened) LIVE bovine tuberculosis bacillus, Mycobacterium bovis, that has lost its virulence in humans by being specially cultured in an artificial medium for years. The bacilli have retained enough strong antigenicity to become a somewhat effective vaccine for the prevention of human tuberculosis. At best, the BCG vaccine is 80% effective in preventing tuberculosis for a duration of 15 years, however, its protective effect appears to vary according to geography (lower efficacy closer to equator due to presence of "background tuberculosis" ). Having had a previous BCG vaccination is a cause of a false positive Mantoux test (the bump), although a very high-grade reading is usually due to active disease. The US has low TB levels relative to most of the world because we have worked to detect and heal all the latent cases. You can catch TB from a carrier. Approximately 10% of people with latent cases will develop the active disease at some point in life.

ecchymoses = bruising = contusions. It irks me to learn yet another name for bruising. So much of training to be a doc is learning fancy vocabulary that I am NOT going to use. I prefer to speak in plain English. Med-speak is useful in cases for which there is no plain English word that is specific enough. Using fancy vocabulary just to sound doctorly is bull.

sepsis = whole-body inflammatory state caused by infection

hidradentis = chronic abscesses in the apocrine sweat glands and hair follicles of the skin, can lead to cellulitis

cellulitis = deep tissue infection of the skin that shows streaking and swelling. This is a sign that a local infection may be going systemic, especially if the streaking follows the veins. I have seen this many times back when I worked as a river guide---staph infection was common among the guides, and we all learned how to recognize, prevent, and treat such infections. We also treated our rafts, because it was thought that the vector for transmission from one guide to the next was the places on the boats where our legs rubbed.

optochin = a chemical that is used to ID Streptococcus pneumoniae (which are sensitive to it). aka ethylhydrocupreine

furuncle = a boil, carbuncle = an interconnected network of boils

erythematous = red

hyaluronidase = enzyme that degrades hyaluronic acid, aka "spreading factor", a virulence factor of Strep group A (species pyogenes)

hyaluronic acid = a glycosaminoglycan present widely in neural, epithelial and connective tissues of animals

streptokinase = fibrinolysin, another strep A virulence factor, activates plasminogen in the un-clotting cascade, forming plasmin which dissolve the fibrin in clots

DNAse = enzyme that degrades DNA in necrotic tissue to give more nucleotides for bacteria to use, another virulence factor in strep A

phage = bacteriophage, any virus that infects bacteria. Phages are estimated to be the most widely distributed and diverse entities in the biosphere. Phages are ubiquitous and can be found in all reservoirs populated by bacterial hosts, such as soil or the intestine of animals. One of the densest natural sources for phages and other viruses is sea water, where up to 109 virions per milliliter have been found at the surface, and up to 70% of marine bacteria may be infected by phages. They are also found in drinking water and in some foods, including fermented vegetables and meats e.g. pickles, salami, where they serve the function of controlling any growth of bacteria. They have been used for over 60 years as an alternative to antibiotics in the former Soviet Union and Eastern Europe. They are now seen as a hope against multi drug resistant strains of many bacteria. However, in the case of MRSA, an infecting phage causes the bacteria to become more virulent and difficult to contain.

lytic vs lysogenic cycle = when a virus inhabits a bacterium or tissue, and it propages by destroying the cell it is in, that's lytic. In the lysogenic cycle the viral DNA become incorporated in the host cell and is replicated when the host cell divides. Herpes simplex is characterized by an initial lytic phase, then a lysogenic cycle after which it takes up residence in nerve cells as an episome. When it goes back into the lytic phase is when herpes carriers suffer an outbreak.

episome = a piece of hereditary material that can exist as free, autonomously replicating DNA or be attached to and integrated into the chromosome of the cell, in which case it replicates along with the chromosome

scarlet fever = caused by erythrogenic toxin on a lysogenic phage, how is this a group A strep toxin? Sore throat, fever, a 'strawberry' tongue, and a fine sandpaper rash over the upper body that may spread to cover almost the entire body. Scarlet fever is not rheumatic fever, but may progress into that condition. The rate of development of rheumatic fever in individuals with untreated streptococcal infection is estimated to be 3%.

rheumatic fever = approx 2 weeks aftger pharyngitis by strep A, S/Sx: fever, carditis, migratory polyarthritis. Mitral & aortic valves esp vulnerable. Re-infection must be prevented by long term prophylaxis.

Strep Lancefield groups: Group A is S. pyogenes, B is S. agalactiae (neonatal meningitis), D includes E. faecalis and S. bovis, while S. pneumoniae and Viridans group have no Lancefield group designation.

Quellung reaction = biochemical reaction in which antibodies bind to the capsule of Streptococcus pneumoniae (no Lancefield group) and thus allow it to be visualized under a microscope. If the reaction is positive, the capsule becomes opaque and appears to enlarge (quellung causes swelling).

CRP = C-reactive protein (in humans) is used mainly as a marker of inflammation. Strep pneumococci have a C-substance on the surface that reacts with CRP. Measuring and charting C-reactive protein values can prove useful in determining disease progress or the effectiveness of treatments. Blood, usually collected in a serum-separating tube, is analysed in a medical laboratory or at the point of testing. Arterial damage is thought to result from inflammation due to chemical insults. CRP is a general marker for inflammation and infection, so it can be used as a very rough proxy for heart disease risk. Since many things can cause elevated CRP, this is not a very specific prognostic indicator. Also, these values refer only to prolonged elevation, so a single measurement would be meaningless.

Tags: medicine, microbes, nd1, vocabulary

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