chemotherapeutic agents Flashcards
: the use of chemicals to kill or inhibit microorganisms
Chemotherapy
1928____________ - is known for the accidental discovery of penicillin on petri plate contaminated with the fungus Penicillium notatum
Alexander Fleming
1939 Howard Florey and Ernst Chain - based on Fleming’s publications, demonstrated effectiveness of penicillin and gave penicillin to
mice… those that survived were affected and those that died were not affected
who discovered streptomycin?
Selman Waksman
streptomycin is made from what ?
made by streptomyces (soil organisms)
natural (derived from bacteria or fungi) or artificial compounds that can kill (-cidal) or inhibit (-static) `bacteria or fungi.
Antibiotics:
Broad Spectrum Antibiotic: can kill or inhibit the growth of
both Gram positive and Gram negative bacteria, and/or fungi.
what type of antibiotic is used when you dont know what type of infection it is ?
Broad spectrum antibiotic
Narrow Spectrum Antibiotic:
can kill or inhibit only specific bacteria or fungi.
which type of antibiotic is used when you know what the organism is ?
Narrow spectrum antibiotic
- Competition:
compounds that chemically (structurally) resemble a bacterial metabolite
- Inhibition of Cell wall synthesis
Example: penicillin, cephalosporins
- Inhibition of nucleic acid synthesis
Example: actinomycin, rifampin, griseofulvin(antifungal)
4.Inhibition of protein synthesis
Example: chloramphenic, gentamycin, kanamycin, streptomycin, erythromycin, tetracycline
Disruption of Cell membranes
Example: amphotericin B, Nystatin (antifungals)
what are the 3 problems with antibiotics?
- allergy
- toxicity
- bacterial resistance
Allergy:
ranges from mild to fatal
Toxicity:
damage to specific organs
Example: Tetracyclines - irritate intestinal tract, liver damage and discoloration of primary teeth.
Example: Streptomycin: kidney damage and hearing loss
- Bacterial Resistance:
some bacteria contain plasmids which contain genes that produce enzymes that destroy or inactivate antibiotics
which drug is structural analogue of para-aminobenzoic acid (PABA) which is used in the synthesis of the cofactor Folic Acid
Sulfonamides
When ___________ enters a bacterial cell it competes with PABA for the active site of an enzyme involved in Folic Acid synthesis
sulfonamide
Folic Acid is essential to synthesis of purines and pyrimidines in a ________ drug
sulfonamide
which drug drug does not affect human cells
Sulfonamides
5 % of the population is allergic (fever, hives, rash) to the ____________ drug
Sulfonamides
this drug also Also inhibits Folic acid synthesis but at a different step in the process
Trimethoprim (Trimethoprim-Sulfamethoxazole)
this drug Acts by inhibiting bacterial DNA gyrase or Topoisomerase II, probably by binding to the DNA gyrase complex
Quinolones
this drug disrupts DNA Replication, Repair and Transcription
Quinolones
Quinolones could be considered a _____________ antibiotic
Broad spectrum
this drug Works well on
E. coli + Klebsiella pneumoniae
Quinolones
this drug also works on Haemophilus, Neisseria, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogenes (Cuases strep throat) , Mycobacterium tuberculosis and Chlamydia
Quinolones
what is the name of the first antibiotic discovered?
penicillin aka Benzylpenicillin
Most penicillins are derive from
6-aminopenicillanic acid
_____________ is essential for activity of a penicillin
B-lactam ring
this drug is thought to block the synthesis of a complete, fully cross-linked peptidoglycan —> osmotic lysis (act only on growing bacteria)
Penicillins
this drug inhibits the growth of peptidoglycan
penicillin
____________is destroyed by stomach acid, works on N. gonorrhoeae, N. meningitidis and
Gram (+) pathogens (Staphylococci and Streptococci)
Penicillin G
_________is more acid resistant of the penicillins
Penicillin V
this antibiotic __________(broader spectrum, oral) —-> works on Gram negative Haemophilus, Salmonella, Shigella
Ampicilin
these drugs are Broad-Spectrum, works on Pseudomonas and Proteus
Carbenicillin and Ticarcillin —
1 - 5 % of the population is allergic to
penicillin
_____________ were Isolated from Cephalosporium fungus in 1948
Cephalosporins
this drug Inhibits transpeptidation reaction during peptidoglycan synthesis
Cephalosporins
Cephalosporins are _______spectrum antibiotics
Broad
4 ring structure with different side chains are
Tetracyclines
Inhibit protein synthesis by combining with the small (30 S) subunit of the ribosome therefore aminoacyl-tRNA cannot bind to the ribosomal A site —> therefore bacteriostatic
Tetracyclines
this antibacterial drug is a Broad spectrum [Gram (+), Gram (-), Rickettsias, Chlamydiae, Mycoplasmas]
Tetracyclines
High dose of this drug can cause nausea, diarrhea, yellowing of 1o teeth, kidney and liver damage
Tetracyclines
(Aminoglycosides)
Streptomyces produce
Streptomycin, Kanamycin, Neomycin, Tobramycin
(Aminoglycosides)
Micromonospora purpurea produces
Gentamicin
