Antibiotics

What is one organism that produces a chemical substance that harms, inhibits, or kills another organism?

Antibiotic

Who rediscovered penicillin?

Alexander Fleming

Who proposed that bacteria and molds engage in a perpetual battle for survival?

Ernest Dichesne

Who purified Penicillin?

Howard Florey and Ernst Chain

Who discovered sulfa drugs that stay inactive until the body coverts it to active agents?

Gerhard Domagk

Who discovered streptomycin which is an antibiotic found in soil?

Selman Waksman

Is broad or narrow spectrum effective against many species (Both Gram + and Gram -)

Broad Spectrum

Is isoniazid only working for M. tuberculosis an example of broad spectrum or narrow spectrum?

Narrow Spectrium

Is bacteriostatic or bactericidal antibiotics that kill target organisms?

Bactericidal

Is bacteriostatic or bactericidal antibiotics that prevent growth of organisms?

bacteriostatic

What is the lowest concentration that prevents growth?

Minimal Inhibitory Concentration (MIC)

What is the lowest concentration that kills bacteria?

Minimal Lethal Concentration (MLC)

Is MLC or MIC higher?

MLC

What does the strip test identify?

It identifies the zone of inhibition without the need for dilutions

What does the Kirby-Bauer assay allow for?

Test the sensitivity to multiple antibiotics

What does no zone of inhibition on a Kirby-Bauer disk indicate?

Resistance

What does Vancomycin do?

Inhibits Cell Wall synthesis

How does Vancomycin inhibit cell wall synthesis?

Binds to D-Ala-D-terminal and prevents the action of transflycosylases and transpeptidases

What does Gramicidin do?

Disrupts Cell Membranes

How does Gramicidin disrupt cell membranes?

Forms a cation channel through which ions leak

What do Polymyxin do?

Disrupt Cell Membrane

How does Polymyxin Disrupt Cell Membrane?

Destroys it like a detergent

What does Quinolones do?

Affect DNA synthesis

How does Quinolones affect DNA synthesis?

Block DNA gyrase which prevents DNA replication

What do Sulfa drugs do?

Affect DNA Synthesis

What does Rifamycin B do?

Inhibit RNA Synthesis

How does Rifamycin B inhibit RNA synthesis?

It prevents the elongation step of transcription

What does Actinomycin D do?

Inhibit RNA Synthesis

How does Actinomycin D inhibit RNA synthesis?

prevents the initiation and elongation step of transcription

What does aminoglycosides do?

Protein Synthesis Inhibitor

What does Tetracyclines do?

Protein Synthesis Inhibitor

How does aminoglycosides inhibit protein synthesis?

Cause translational misreading of MRNA

How does tetracyclines inhibit protein synthesis?

blocks the binding of charged tRNA to the A site of the ribosome

Aminocglycosides cause the translational misreading of mRNA, are they bactericidal or bacteriostatic?

Bactericidal

Tetracyclines block the binding of charged tRNAs to the A site, are they bactericidal or bacteriostatic?

Bacteriostatic

What does Erythromycin do?

Protein Synthesis Inhibitor

What does Chloramphenicol do?

Protein Synthesis Inhibitor

What does Clindamycin and Metronidazole do?

Protein Synthesis Inhibitor

How does Penecillin work?

B-lactams target the enzymes (PBPs) directly; they work extracellularly, and bacteria resist them mainly by B-lactamases and altered PBPs

How does Vancomycin work

targets the substrate, not the enzyme; works on Gram + because it cannot penetrate the outer membrane of gram -

Why are antibiotics ineffective against viruses?

They do not have cell membranes so antibiotics are ineffective against them

Amantadine is an antiviral, what does it do?

inhibits viral uncoating

Neuraminidase is an antiviral, what does it do?

It prevents the release of mature viruses

Why do mycoses (fungal diseases) require different types of antimicrobials than either bacterial pathogens or viruses?

Fungi are eukaryotes and are selectively toxic and they have a drug detoxification system

Are superficial mycoses antifungals that are treated topically or systematically?

Topically

Are deep mycoses mycoses antifungals that are treated topically or systematically?

Systematically

What are the two most common antifungals?

Azoles and Polyenes

What do Azoles do?

Inhibit the synthesis of membrane sterols

What do Polyenes do?

Form pores in fungal cell membrane