5B - Antibiotics Flashcards
Dr. Joseph Lister
found that mould inhibited growth of bacteria
“discovered” antiseptic surgery by killing bacteria
“Listerine” named after him
Listerine and other mouthwashes
Often contain up to 25% alcohol
Long term use of high alcohol mouthwashes increases risk of oral cancer
Does Listerine kill germs? Yes, but many more remain
Salt water rinse an effective alternative
Sulfa Drugs: the 1st antibacterials
Benzene sulfonamides-not antibiotics, but did inhibit bacterial growth by disrupting folic acid synthesis
could be applied as powders to wounds in the field WWII.
Antibiotic
a compound that kills bacteria (by destroying bacterial cell walls.
Antibacterial agent
antimetabolite (starves the bacteria, often of folic acid), eg. sulfa drugs
Discovery of penicillin(20th century’s most important one?
Fleming grew a pure mould culture: discovered it was Penicillium notatum
Later isolated the pure chemical “antibiotic”component, named it “penicillin”
But needed a good large scale source of the mould
The Process of Penicillin
Start “cold stored” penicillium culture on agar plate
Transfer to “shake flasks” ,with food (Sugars) and nutrients (ammonium salts), aa’s needed for growth
Resulting suspension can be transferred to seed tanks for further growth
Transfer to larger fermentation tank (30,000 gallons)
After 3-5 days , isolation
Temp, pH, mixing essential, sterilized air pumped in.
Penicillins
ear/skin/respiratory/digestive/urinary infections, syphilis, scarlet fever
Tetracyclines
respiratory/urinary infections, acne, bronchitis, whooping cough, typhus fever
Cephalosporins
ear/throat/skin/urinary infections
Chloramphenicol
typhoid fever, meningitis, eye/ear infections
Erythromycins
skin/eye/respiratory/tissue infections, diphtheria.
Spectinomycin
gonorrhea
Gentamycin
bone/skin/lungs/abdomen infections
New legislation re: farm animals
Antibiotics use would only be permisable to treat sick animals
At present, on many farms, low doses of antibiotics are included in the animal feed of healthy animals..results in weight gain
Why no antimalarial drug?
Viewed as an African problem
No money in it for the Pharmaceutical industry
Quinine
An alkaloid
Also antipyretic, analgesic, anti-inflammatory, anti-smallpox
British “colonial’ days-quinine was added to water in an attempt to prevent malaria
Chloroquine
Used to prevent and treat malaria
BUT…many adverse side effects: itch, mood changes, blurred vision
Dangerous in overdose: doubling the normal dosage can be fatal
Malaria parasites now have developed widespread resistance to it
Viruses
A virus contains a core of DNA or RNA(never both) wrapped in a protective shell(usually protein, maybe some carbos/lipids).
Viruses are parasites
Fighting Viruses, #1 - Vaccines
A weakened strain of the virus is injected into the host so that antibodies can be produced against that specific virus(an ‘invading’ compound). These antibodies are then always ready to protect against future exposure to that particular virus(sometimes!).
Fighting Viruses, #2 - Antiviral agents
General: stop DNA synthesis with modified nucleic acids For HIV*: inhibit production of the protein sheath (proteases, reverse transcriptase inhibitors) with non-nucleosidic compounds
Immune Response - Antibody vs Antigen
An antibody* is a specific protein(immunoglobulin, -globulin) that is synthesized by white blood cells(B-lymphocytes) to eliminate/inactivate a pathogen that enters our body. These ‘invading’ compounds are usually disease-bearing bacteria or viruses. The ‘action’ occurs in the extracellular fluids, including the circulatory system. The invading material that causes antibody generation is termed an antigen
Immune Response - the Down Side
The immune system cannot distinguish ‘good’ from ‘bad’ antigens. Hence organ transplants can be ‘rejected’ so that immuno-suppressants must be used with potentially dangerous consequences.
An overactive or misdirected immune system can attack its own tissue, eg.AUTOIMMUNE DISEASE
Allergies - Immune Response Reversal
The body generates an antibody to some antigen. On subsequent exposure when the antibody/antigen reaction occurs, certain cells(especially in nose and bronchial system) are disrupted and release some potent chemicals of which the best known is histamine(from the amino acid, histidine). These particular antigens are called allergens.
