Med. Microbio Final Exam Chapter 20

Magic Bullet Concept
*bullet kills only selected target (pathogen) and not the innocent bystander (host)
* developed by Paul Ehrilich in early 1900s
~tested many compound- #606 worked
*#606-cured trypanosomal infections in mice (causes encephalitis in humans), then used it to treat syphilis in humans
Thereputic Index
the maximum dose that is toxic to the patient/minimum effective dose
high ratio=high TI=less toxic to patient
Spectrum of Drugs
*range of different types of microbes that will be susceptible to a particular antibiotic.
*wide: amipicillin, choramphenicol/tetracycline,stepomycin
*narrow:penicillin,polymyxin B, isoniazid
*Biological origin.
*produced by microbes or plants
*Beta-lactum ring with side R group.
*R group can be added in manufacture to change activity.
*prevents peptide cross linking of the peptidoglycan
*Flemming 1928
*production moved to US in 1940 (pre-WWII), death rate from infection went down
*enzyme made by bacteria that makes it resistant to penicillin
*breaks beta-lactum ring
Routes of Administration
*Intervenus, intramuscular, oral
*Quickest to slowest: IV,IM,oral
Antibiotics Cell Targets
*inhibition of cell wall synthesis
*inhibition of protein synthesis (target ribosomes):
*inhibition to DNA synthesis
*inhibition to metabolic functions
*injury to plasma membrane
Resistant Genes (antibiotic resistance mechanism)
*antibiotic degrading enzymes
*efflux pump(removes antibiotic from cell before harm occurs)
*antibiotic altering (chemically alters the antibiotic)
Cell Mutations (antibiotic resistant mechanism)
*prevention of antibiotic entering the cell
*target is altered
ex: ribosome altered by mutation so antibiotic doesn't bind
Multiple resistance
*plasmid transfer of several gene sets that confer resistance by different mechanisms
Antiviral Drugs
*not technically antibiotics
*considered chemotherapeutic drugs
*interfere with viral replication stages (attachment,penetration,biosynthesis, release)
* HIV,Herpes, Influenza, Hepatitis with antivirals