Antimicrobial Medications Flashcards by Melody Tovar

Selective Toxicity

More harmful to the microbe than harmful to us

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What do protein synthesis inhibitors act on?

act on ribosomes

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Antimicrobial that interfere with the synthesis of the cell wall do not interfere with

Eukaryotic cells (our cells)

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What does the cell wall contain?

peptidoglycan

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What is true about the therapeutic index and toxicity of drugs inhibiting the cell wall synthesis of microbes?

They have a very high therapeutic index, low toxicity with high effectiveness

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What antimicrobial inhibit cell wall synthesis

B-Lactam Drugs (Penicillin)
Vancomycin
Bacitracin

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Penicillin Binding Proteins

Synthesize the cell wall: build peptidoglycan, they were discovered when discovering penicillin

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What group of drugs are Penicillins and Cephalosporins a part of?

B-Lactam

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What does B-Lactam refer to?

The structure of the drug: Beta Lactam Ring

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What do Penicillins and Cephalosporins do?

Competitively inhibit function of penicillin-binding proteins: Inhibits peptide bridge formation between glycan molecules

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What does broad spectrum mean?

Can kill a broad spectrum of microbes

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What does a narrow spectrum mean?

Can only kill a narrow spectrum of microbes

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How can some organisms resist Penicillins and Cephalosporins?

B-lactamase enzyme: it breaks the B-Lactam ring

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What does vancomycin do to the glycan chains?

Inhibits the formation of them

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How does Vancomycin inhibit the formation of glycan chains?

Inhibits formation of PTG and cell wall construction

Does not cross lipid membrane of Gram(-)

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Why is vancomycin important?

treating infections caused by penicillin resistant Gram(+) organisms

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How much Vancomycin be given and why?

intravenously due to poor absorption from intestinal tract

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What does it mean that Vancomycin can have: Ototoxicity

can cause deafness in people

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What acts as a target for many antimicrobials that inhibit protein synthesis

Structure of prokaryotic ribosome

What is responsible for selective toxicity?

Differences in prokaryotic and eukaryotic ribosomes

What are the 7 types of drugs that inhibit protein synthesis

Aminoglycosides 
Tetracyclins 
Macrolides
Chloramphenicol 
Lincosamides
Oxazolidnones 
Streptogramins

Tetracyclins

Broad Spectrum drugs that block attatchment of tRNA to ribsome

What are tetracyclins effective against?

certain Gram(+) and Gram (-)

What is an example of a tetracyclin and what does is have?

Doxycycline; has longer half life because it is newer

What can tetracyclins cause in young children?

Discoloration of teeth

What types of drugs are included in the inhibition of nucleic acid synthesis?

Fluoroquinolones | Rifamycins

What do Rifamycins block?

Prokaryotic RNA polymerase; block initiation of transcription

What is the most widely used rifamycin?

rifampin

What are rifamycins effect against and what does this classify them as?

Broad Spectrum: Effective against many Gram (+) and some Gram (-) as well as members of genus Mycobacterium

What are rifamycins primarily used to treat and prevent?

Treat tuberculosis and used as a prophylactic in preventing meningitis after exposure to N. meningitis

What is resistance to rifamycins due to?

Mutation coding RNA polymerase; resistance develops rapidly

Susceptibility of organism to specific antimicrobials is

unpredictable

What was done with serious infections?

Several drugs were prescribed at one time with hope that one was effective

What is MIC

Minimum Inhibitory Concentration: QUANTITATIVE test to determine lowest concentration of specific antimicrobial drug needed to prevent growth of specific organism

How is MIC determined?

by examining strain's ability to grow in broth containing different concentrations of test drug: Determined by Serial Dilutions

How is growth in MIC testing determined?

turbidity of growth medium

Kirby-Bauer Disc method

diffusion routinely used to qualitatively determine susceptibility

What reflects susceptibility in Kirby-Bauer Disc Method?

Clear zone of inhibition

What can some organisms produce that chemically modify a drug and what is an example of this?

Produce enzymes | Penicillinase breaks B-Lactam ring of penicillin antibiotics

Minor Structural changes

in antibiotic target can prevent binding

What is an example of minor structural changes?

changes in ribosomal RNA prevent macrolides from binding to ribosomal subunits

What can acquisition of resistance be from and what are they called?

Spontaneous mutations | called vertical evolution

What is the resistance acquired by transfer of new genes called?

horizontal transfer

What was Staphylococcus aureus resistant to and usually treated with now?

In past 50 years most strains resistant to penicillin | Until recently most could be treated with methicillin

What is MRSA? How can it be treated now?

Methicillin resistant staphylococcus aureus | : treated with vancomycin

What two things can be done by healthcare workers to slow the emergence of resistance?

Increase efforts to prescribe antibiotics for specific organisms Educate patients on proper use of antibiotics

What can be done by the patients to slow the emergence of antimicrobial resistance?

Follow instructions carefully Complete prescribed course of treatment MISUSE leads to resistance