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Midterm

BIOL 459 Study Guide - Midterm Guide: Polymyxin B, Antimicrobial Peptides, Vancomycin

6 pages76 viewsFall 2017

Department
Biology
Course Code
BIOL 459
Professor
Roy Real
Study Guide
Midterm

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Topic 8: Disease Control Antimicrobials
Difference between antibiotics and
antimicrobial drugs?
Antibiotics are substances produced
by a microbe that in small amounts,
inhibits another microbe
Antimicrobial drugs are synthetic
substance that interfere with the
growth of microbes
What is Chemotherapy?
The use of chemicals to treat a disease
History of chemotherapy:
1990- Hata discovers Salvarsan
(arsphenamine) which if 1st effective
medicinal treatment for syphilis
Ehrlich popularizes concept of magic
bullet
1928- Fleming discovers penicillin
1932- Prontosil red dye used for strep
infections
1940- First clinical trials of penicillin
What is a current problem regarding
antibiotics?
More antibiotic resistance
Some common sources of antibiotics
Bacillus subtilis
(Gram-positive rod)
Streptomyces
(Actinomycetes)
Penicillium and Cephalosporium
(Fungi)
What is the difference between bactericidal
and bacteriostatic?
Bactericidal kill microbes directly while
bacteriostatic only prevent microbes from
growing
How do antimicrobials drugs act upon the
microbe?
1. Inhibit cell wall synthesis
2. Inhibit protein synthesis
3. Inhibition of nucleic acid
replication/transcription
4. Injure the plasma membrane
5. Inhibit essential metabolite synthesis
Inhibition of cell wall synthesis
Penicillins prevent the synthesis of
peptidoglycan
Inhibition of protein synthesis
Target bacterial 70S ribosomes
Chloramphenicol, erythromycin and
streptomycin, tetracyclines
Injuring the plasma membrane
Polypeptide antibiotics change
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membrane permeability
Antifungal drugs combine w/
membrane sterols
Inhibiting nucleic acid synthesis
Interfer w/ DNA replication and transcription
Inhibiting the synthesis of essential
metabolites
Antimetabolites compete w/ normal
substrates for an enzyme
ex) sulfanilamide competes w/ PABA, which
stops synthesis of folic acid
Inhibitors of cell wall synthesis
Penicillin
Contain a B-lactam ring
Prevents cross-linking of
peptidoglycans
Natural penicillin from cultures
G is injected, V is oral
Semisynthetic penicillins
Contain chemically added side
chains → resistance to
penicillinases
Penicillinase-resistant penicillins
Extended-spectrum penicillins
Penicillins plus B-lactamase inhibitors
Carbapenems
Substitute C for an S and add
double bond; broad spectrum
ex) Primaxin
Monobactam
Synthetic; single ring instead
of B-lactam; low toxicity; works
against certain gram-negatives
ex) Aztreonam
Cephalosporins
Works similar to penicillins but
B-lactam is different
Polypeptide antibiotics
Bacitracin is topical and works
against gram-positives
Vancomycin is the last line
against antibiotic-resistant
MRSA
Antimycobacterial antibiotics
Isoniazid
Inhibits the mycolic acid
synthesis in mycobacteria
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