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Med Year 1 - Foundation > Antibiotics > Flashcards

Flashcards in Antibiotics Deck (37)
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30S inhibitors

Amino glycosides and tetracycline

1

50S inhibitors

Linezolid, macrolides, chloramphenicol, clindamycin, quinupristin/dalfopristin

2

Blocks initiation

Linezolid, amino glycoside

3

Blocks elongation

Amino glycosides, tetracycline, macrolides, chloramphenicol, clindamycin, quinupristin/dalfopristin

4

Blocks termination

Amino glycoside

5

Mitochondrial ribosomes

Linezolid, tetracycline, chloramphenicol

6

Linezolid binds what part of ribosome

P site on 50S

7

Oxazolidinones

Mech: binds 23S RNA on 50S unit prevents forming of initiation com
Spec: gram+, MRSA and vanco resistant enterococci
Resis: alterations in 23 rRNA
AdvE: bone marrow suppression, serotonin syndrome if taken with SSRI, hallucinations, increased heart beat, nausea. Linezolid

8

Gentamicin amikacin tobramycin

Amino glycosides - bactericidal mech: prevents formation of initiation complex, causes misread mRNA, induces early termination
Spec: gram neg aerobes (in combo)...intrinsic resis- can't enter cell = treat with cell wall inhibitor, acquire resis - enzymes that inactivate drugs...amikacin is special to pseudomonas

9

Mechanisms of amino glycosides

Blocks initiation of synthesis
Blocks further translation and elicits premature termination
Incorporates incorrect amino acid
Creates fissures in cell membrane

10

Side effects of amino glycosides

Tubular necrosis: nephrotoxicity- drug held in renal cortex (reversible)
Ototoxicity - vestibular and auditory dysfunction (irreversible)
Pregnancy class D - hearing loss in fetus

11

Important facts of amino glycosides

Poor absorption - usually administered through IV
Polar and excluded from CSF

12

Concentration dependent killers

Amino glycosides and fluoroquinolones

13

Time dependent killers

Vancomycin and beta lactams

14

Tetracycline mechanism

Prevents attachment of tRNA to A site bacteriostatic

15

Chloramphenicol mechanism

Inhibits peptide bond formation

16

Mechanism of macrolides streptotagims and clindamycin

Inhibit translocation (tRNA moving from A site to P site)

17

The tetracyclines

Tetracycline doxycycline and minocycline

18

Spectrum of tetracycline

Broad at first but due to resistance
B. burgdorferi, h. Pylori, mycoplasma pneumoniae

19

Resistance of tetracycline

Intrinsic - decreased uptake
Acquired - increased efflux, alteration of ribosome target, rarely enzymatic inactivation of drug

20

Adverse effects of tetracycline

Chelates with metal ions decreases absorption
GI irritation and photosensitive
Discoloration of teeth and inhibits bone growth in children
Don't use during pregnancy class D

21

What is drug persistence? And what bacteria displays this?

Shifts between different genetically homogenous forms depending on presence of drug
Borrelia burgdorferi

22

Spectrum of chloramphenicol

Extended but limited due to severe side effects

23

Resistance to chloramphenicol

Acetyltransferase modifies drug to prevent binding to ribosome

24

Adverse effects of chloramphenicol

TOXIC. Bone marrow depression. Aplastic anemia. Gray baby syndrome

25

Gray baby syndrome

Premature infants lack enzyme UDP-glucuronyl transferase and have decreased renal function so high levels of the drug accumulate which can lead to cardiovascular and respiratory collapse

26

Macrolides, what are they and the mechanism?

Erythromycin, azithromycin and clarithromycin
Bacteriostatic
Inhibit translocation by binding 23S rRNA of the the 50S subunit

27

Spectrum of macrolides

Broad coverage of respiratory pathogens
Chlamydia (single dose)

28

Atypical pneumonia - what causes it and treatment?

Mycoplasma pneumonia
Treat with doxycycline, azithromycin, levofloxacin
Beta lactams are not effective

29

Resistance to macrolides

Methylation of 23S rRNA binding site (associated with clindamycin and quinupristin/dalfopristin resistance)
Increased efflux
Hydrolysis of macrolides by esterases

30

Adverse effects of macrolides

GI
Liver failure, prolonged QT interval
Inhibitors of cyp450 enzymes
Clarithromycin is not safe during pregnancy

31

Mechanism and spectrum of clindamycin

Bacteriostatic - blocks translocation of at 50S ribosomal subunit

Gram positive anaerobic....treat ance

32

Resistance and adverse effects of clindamycin

Mutation of ribosome, methylation of rRNA...cross resistance with macrolides and inactivation by adenylation
Hypersensitivity - rash and fever
Diarrhea, abdominal pain, mucus and blood in stool
Superinfection with C. difficile

33

Streptogramins - what are they and what is their mechanism

Quinupristin/dalfopristin

Combined action can be bactericidal
Bind 50S to inhibit translocation

34

Spectrum of quinupristin/dalfopristin

For infections of multiple drug resistant gram positive bacteria

35

Resistance of quinupristin/dalfopristin

Ribosomal methylase prevents binding of drug to its target
Enzymes can inactivate the drugs
Efflux of proteins that put them out of the cells
Cross resistance with macrolides and clindamycin

36

Adverse effects of quinupristin/dalfopristin

High incidence including arthralgias, myalgias
Inhibits cyp450 enzymes and likely to have significant drug-drug interaction