Antibiotics

Front 1

Major antibiotic mechanisms

Back 1

1) inhibition of cell wall synthesis
2) inhibition of protein synthesis
3) inhibition of nucleic acid function or production
4) disruption of metabolic pathways (folate metabolism)
5) disruption of cell membrane

Front 2

Mechanisms of antibiotic selectivity

Back 2

1) absence of target from host
2) permeability differences
3) structural differences in the target

Front 3

bacteriostatic abx

Back 3

-reversibly inhibit cell growth
-typically target metabolic processes

Front 4

bacteriocidal abx

Back 4

-kill bacteria
-typically target cell walls or membranes
-bacteria needs to be growing for these to work

Front 5

Determination of antimicrobial activity

Back 5

1) Tube dilution assay
2) Disc diffusion method

Front 6

Situations for using multi-abx therapy

Back 6

1) chronic infection
2) emergencies
3) mixed infection
4) drug synergies

Front 7

Types of drug interactions

Back 7

1) indifference: combined action is not greater than the more effective drug alone

2) additive response: response is the sum of the two drugs used separately

3) synergistic response: response is greater than the sum of the two drugs used individually

ex: Bactrim- sulfa drug (inhibits THF synthesis) + trimethoprim (inhibits THF use)
ex: Augmentin- amoxicillin (cell wall disruptor) + a beta lactamase inhibitor like clavulanic acid

4)antagonistic response: response is less than the sum of the two drugs used alone

ex: penicillin + erythromycin - erythromycin slows bacterial growth, but penicillin only kills growing bacteria. NOT a good combo

Front 8

Factors limiting successful antimicrobial therapy

Back 8

1) location: failure to cross BBB, some drugs can't penetrate eukaryotic cells

2) abcess formation and necrosis: decreased circulation in area of abcess will limit drug conc., low nutrient levels may slow bacterial growth making some abx less effective

3) presence of foreign bodies/obstructions: foreign bodies can lead to biofilms or damaging inflammatory reactions that limit drug access

4) emergence of drug resistance

Front 9

Mechanisms of abx resistance

Back 9

1) enzymatic inactivation of abx
ex: beta lactamases

2) inadequate of decreased uptake of the drug into the microbe
ex: downregulation or loss-of-function mutation of porins

3) increased efflux of antibiotic out of microbe

4) alteration of drug target
ex: mutations in pencillin-binding proteins (PBPs), transpepsidases that cross-link peptidoglycans in the cell wall

5) altered metabolic pathways

Front 10

Abx: cell wall/membrane inhibitors

Back 10

1) penicillins-ampicillin, penicillin
2) cephalosporins
3) carbapenems/monobactams
4) glycopeptides/polypeptides-vancomycin, bacitracin

Front 11

Abx: protein synthesis inhibitors

Back 11

1) macrolides-azithromycin (Z-Pak), erythromycin
2) aminoglycosides-gentamycin, neomycin
3) tetracyclins
4) chloramphenicol
5) oxazolidones-linezolid
6) lincosamides-clindamycin

Front 12

Abx: nucleic acid synthesis inhibitors

Back 12

1) quinolones-ciprofloxacin (Cipro)
2) Rifampin
3) Metronidazole

Front 13

Abx: antimetabolites

Back 13

1) Sulfonamides-trimethoprim (Bactrim)