Chapter 20 - Antimicrobial Agents Flashcards by Ella Thorsteinson

Five mechanisms of action

-cell wall
-protein synthesis
-nuclei acid

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Spectrum

How many bacteria can they kill?

Narrow—> only kill one group ( eg gram n only)
Extended—> could kill more (eg gram n/p only)

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Cell wall

Weakens cell, which bursts and dies
-assume that will target organism, since humans do not have a cell wall

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What types attack cell wall

-penicillin
-cephalosporin

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Penicillin

Destroys peptidoglycan, penicillin breaks peptide part of PG —> cell death—> recovery

-destroy beta lactam ring

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Natural penicillin

Pen g or pen v

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Pen g is given..

Given IM or IV
-gram positive (staph or strep)

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Pen B

Can take orally
-resistant to stomach acid

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Semi synthesis penicillin

Methicillin, oxacillin, ampicillin

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MRSA

Methicillin

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Narrow spectrum (gram positive)

Oxacillin
-resistant

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Gram n/p

Ampicillin

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Adverse effects of penicillin

Development of allergies

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Cephalosporins

-resistant to B actin ring
-expensive
-drug of choice for tough to kill bacteria
-form generations (1 to 5 and improve each gen)

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Adverse effects of cephalosporins

GI distress

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Protein synthesis drugs

-Chloramphenicol
-erythromycin
-tetracyclin
-aminoglycosides

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Chloramphenicol

-binds to. 50s subunit (bacterial ribosome)
-inhibit peptide bond formation
-structure very simple

-meningitis

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Chloramphenicol structure

-can be made in lab
-penetrates BBB

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Adverse effects of chloramphenicol

-aplastic anaemia
-grey baby syndrome

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Aplastic anaemia

Suppress bone marrow production: fatal

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Grey baby syndrome

Literally turn baby grey

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Erythromycin

-Binds to 50s subunit
-larger molecule
-macrocyclic ring family
-choice of drug for allergy to penicillin
-can come in syrup form

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Adverse effects of erythromycin

GI tract discomfort

Aminoglycosides—> streptomycin

Attach to 30s subunit
-changes shape and can no longer read mRNA/reads it incorrectly
-end translation early
-incomplete protein

Adverse effect of streptomycin

Auditory nerve and kidney failure

Tetracyclin

-attach 30s subunit (interfere with tRNA) -broadest spectrum -good for animal herds

Adverse effects of tetracyclin

-destroy GI tract normal flora (diarrhea) -pregnancy: severe skull deformation and affect mothers kidney/liver -children: discolouration of teeth

Medication that attacks nucleic acid

-rifamycin -quinolones/fluroqunolones

Rifamycin

-good for TB since inhibits RNA polymerase (transcription of RNA) -easily absorbed orally

Adverse effects of rifamycin

In high doses, causes liver damage -never taken pregnant or with oral contraceptives

Quinolones/fluroquiolones

Q: Missing fluoride atom F: better penetration -inhibit action of DNA gyrase

Adverse effect of q/F

Block cartiledge development

Medicine targeting plasma membrane

-polymyxin B -amphotericin B

Polymyxin B

-topical ointment (very toxic to kidneys) -deals with infection outside body -pseudommonas species

Amphotericin B

Fungal agents

Medicine targets metabolic activity

-sulpha drug -trimethoprim

Sulpha drug

-competitive inhibitors -attack early Shut down PABA, used to create folic acid, without DNA/RNA synthesis

Adverse effects of sulpha drugs

Third trimester: potential mental defects -jaundice -anemia -allergic response

Trimethoprim

-lower enzymatic reaction

Adverse effect of trimethoprim

Jaundice and allergies

Antivirals are

Nucleoside analog

Mimics nucleotide S+B minus a phosphate

Examples of nucleoside analog/false nucleotides: Acyclorir

Herpes 2, mimics G

Examples of nucleoside analog/false nucleotides: gancicolvir

Herpes 5, mimics G -eye infection

Examples of nucleoside analog/false nucleotides: axidothymidine

HIV, mimics T -anti retro viral drug

Examples of nucleoside analog/false nucleotides: lamivudine

HIV and Hep B, mimics C

Examples of nucleoside analog/false nucleotides: ribavirin

Influenza, mimics G

Drug can treat meningitis

Chloramphenicol

Used for legionnaires disease, skin diseases

Erythromycin

Used for TB but not anymore because of resistance

Streptomycin

Drug of choice for mycoplasma

Tetracycline

Drug for TB

Rifamycin

Legionnaires and UTI

Quinolones and fluoroquinolones

Drug for Blue/green pus —> pseudomonas infections

Polymyxin B

Commonly used for UTIs

Trimethoprim

What is a nucleotide

It is a base plus sugar and phosphate

What is a nucleoside

Base plus sugar minus the phosphate