Chapter 20 - Antimicrobial Agents Flashcards
Five mechanisms of action
-cell wall
-protein synthesis
-nuclei acid
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)
Cell wall
Weakens cell, which bursts and dies
-assume that will target organism, since humans do not have a cell wall
What types attack cell wall
-penicillin
-cephalosporin
Penicillin
Destroys peptidoglycan, penicillin breaks peptide part of PG —> cell death—> recovery
-destroy beta lactam ring
Natural penicillin
Pen g or pen v
Pen g is given..
Given IM or IV
-gram positive (staph or strep)
Pen B
Can take orally
-resistant to stomach acid
Semi synthesis penicillin
Methicillin, oxacillin, ampicillin
MRSA
Methicillin
Narrow spectrum (gram positive)
Oxacillin
-resistant
Gram n/p
Ampicillin
Adverse effects of penicillin
Development of allergies
Cephalosporins
-resistant to B actin ring
-expensive
-drug of choice for tough to kill bacteria
-form generations (1 to 5 and improve each gen)
Adverse effects of cephalosporins
GI distress
Protein synthesis drugs
-Chloramphenicol
-erythromycin
-tetracyclin
-aminoglycosides
Chloramphenicol
-binds to. 50s subunit (bacterial ribosome)
-inhibit peptide bond formation
-structure very simple
-meningitis
Chloramphenicol structure
-can be made in lab
-penetrates BBB
Adverse effects of chloramphenicol
-aplastic anaemia
-grey baby syndrome
Aplastic anaemia
Suppress bone marrow production: fatal
Grey baby syndrome
Literally turn baby grey
Erythromycin
-Binds to 50s subunit
-larger molecule
-macrocyclic ring family
-choice of drug for allergy to penicillin
-can come in syrup form
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
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