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Pharmacology Exam 3 > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

Time dependent

A

activity correlates with the amount of time spent above the MIC
long time at low concentration
ex. B-lactam

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2
Q

Concentration dependent

A

activity correlates with peak concentration/MIC ratio; depend on concentration in the blood
short time at high concentration
ex. aminoglycosides

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3
Q

Acquired resistance

A
  1. inactivation of abx by enzyme
  2. decreased uptake of abx
  3. Efflux of abx
  4. Altered target site decreased abx affinity
  5. Bypass target process
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4
Q

Vertical transfer

A

spontaneous mutation

abx = selective pressure

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5
Q

Horizontal transfer

A

conjugation
transfer of plasmid DNA from one cell to another by direct contact
primarily gram (-), leads to MDR

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6
Q

High-level resistance

A

cannot be overcome by increasing the abx dose

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7
Q

Low-level resistance

A

can be overcome by increasing the dose and increase the efficacy
can become high level resistance

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8
Q

Superinfection

A

New (abx-induced) infx occurring during tx of a primary infx superimposed
Ex. CDIFF

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9
Q

Decreased kidney or liver function

A

1) Decrease dose/Decrease dose interval

2) Switch to abx cleared by liver or kidney

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10
Q

Pregnancy issues

A

reduce efficacy of contraceptives - metabolized faster
maternal toxicity - class D drugs
Tetracycline (bone), aminoglycosides (ototoxicity of fetus), sufonamide (kernicterus)

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11
Q

Combination therapy- why is it used? What’s bad about it?

A

Mixed bacterial infections
Unknown etiology/resistance suspected
Prevent emergence of resistant microbes (TB*)
Bad - increases the spectrum and increases risk of superinfection

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12
Q

Prophylactic tx what are some specific uses?

A
  1. before surgery
  2. bacterial endocarditis before dentist
  3. immunocompromised
  4. reccurent infections like UTI
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13
Q

Gram Positive Bacteria

A

Thick peptidoglycan wall

Hydrophilic and hydrophobic (lesser extent) can passively diffuse across

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14
Q

Gram Negative Bacteria

A

Thin cell wall!
Outer lipid membrane hinders transport of many abx
Small hydrophilic drugs can cross through porins

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15
Q

B lactam ring

A

High affinity for Penicillin Binding Protein (PBP) that are involved in polymerization and crosslinking of peptidoglycan

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16
Q

Innately resistant to B lactams

A

Chlamydia, Mycoplasma, Legionella - lack peptidoglycan

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17
Q

Beta lactam mechanism

A

Time dependent, Most effective during log growth phase
Bind to PBP = inhibition activates autolysins
Bactericidal

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18
Q

Penicillin

A 
B-lactam + 5 membered ring
PBP affinity
gram-negative outer envelope penetration
stability in gastric acid - oral 
R group can be altered
Most are well absorbed
Short half life, must give frequently
Excreted unchanged = highly concentrated in urine
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19
Q

Penicillin adverse reactions

A 
Least toxic
*Jarisch-Herxheimer rxn**
CNS toxicity
Pen G cannot be given by IV
Penicillin allergy - not due to allergy; due to non-enzymatic breakdown to penicilloyl that form haptens = maculopapular rash
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20
Q

Pen G and Pen V

A

Standard Penicillins
Active against gram+ and some gram-
Pen G unstable in stomach (need IM) - syphilis, rheumatic fever
Pen V acid stable, orally effective - strep

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21
Q

Naficillin

A 
Anti-staphylococcal
R group altered to protect against B lactamase
Active against Pen G resistant, MSSA
*No gram- or anaerobic activity*
MRSA emergence due to altered PBP
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22
Q

Amoxicillin

A

Aminopenicillin
+ charged R-group, can enter through gram- porins
in combo with B lacatamase inhibitor

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23
Q

Ticarcillin, piperacillin

A

Anti-pseudomonal
Susceptibility - aminopenicillin+P. aeruginosa
used w/ B lactamase inhibitor

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24
Q

Clavulanic acid

A

B-lactamase inhibitor
Amoxicillin/clavulanate (augmentin)
Ticarcillin/clavulanate (timentin)
piperacillin/tazobactam (zosyn)

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25
Q

Cephalosporin

A 
B lactam ring + 6 membered ring
Resistance due to B lactamase and altered PBP
5 generations
Most given parenterally, poor absorption
Cleared by kidney
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26
Q

Cefazolin

A

1st generation
surgical site prophylaxis (MSSA, S aureus)
alternative for MSSA when penicillin allergy

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27
Q

Cefoxitin

A

2nd generation
Gram(-) bacteria - higher affinity of PBPs, greater cell wall penetration, better resistance to B lactamase
Not as good for gram(+) as 1st gen
*Cephamycin works against GI anaerobes

28
Q

Ceftriaxone

A 
3rd generation
Higher activity against gram(-)
Good CNS penetration
Most widely used 
Tx: gram(-) meningitis (N. meningitis, H influenzae), and gonorrhea, less active against strep
29
Q

Cefepime

A

4th generation
Highly resistant B lactamases and broad antibacterial spectrum
Good CNS penetration
Useful for empiric tx, drug resistance

30
Q

Ceftaroline

A

5th generation

ONLY cephalosporin active against MRSA

31
Q

Carbapenems, imipenem-cilastatin (primaxin)

A

B lactams w/ broad spectrum
Structure similar to penicillin
Active against: gram(+) and gram(-), Pseudomonas and anaerobes
Resistant to inactivation by B-lactamases
Given parenterally, eliminated by kidney
Clistatin prevents renal inactivation
Tx: Used for MDR ESBL, anaerobic and mixed infections

32
Q

Aztreonam

A

Monobactam
B lactam not fused to second ring
NARROW SPECTRUM - gram(-) anaerobes including Pseudomonas
resistant to most B lactamases
IV systemic
Inhalation - CF and P aeruginosa
good for penicillin allergy* for gram(-) PNEU, meningitis or sepsis

33
Q

Vancomycin

A

serious resistant infxs
prevents polymerization of cell wall precursor NAM-NAG = bactericidal
Cannot penetrate gram(-) size
= ONLY Gram(+)
D-Ala-D-lactate, decreased binding affinity = resistance
Systemic IV, CDIFF oral

34
Q

Bacteria resistant to vancomycin are treated with:

A

Treated w/ Linezolid, Daptomycin, quinupristin/dalfopristin

35
Q

Adverse reactions of vancomycin

A

Ototoxic >30ug/mL
Nephrotoxic
***Rapid infusion “red man” syndrome - flushing urticaria, tachycardia, hypotension, histamine release

36
Q

Fosfomycin (nitrofurantoin)

A

Bactericidal, inhibits production of murein in CYTOSOL by inhibiting synthese of UDP-NAM from UDP-NAG
Enters via glycerophosphate transporter
Mutations in transporter = resistance
Tx: uncomplicated UTIs in women (E coli)

37
Q

Gentamicin and Amikacin

A

Highly polar, cation, not capable of passive diffusion
Bactericidal
Concentration dependent
Active against TB
Require O2 transporter to enter cell
Bind to 30S subunit
Combination tx for serious gram(-) infx (vanco)

38
Q

Adverse effects of Gentamicin

A

Ototoxicity
Nephrotoxicity (reversible damage to proximal tubules)
Neuromuscular blocakde at high doses -> respiratory paralysis
Contraindicated in myasthenia gravis

39
Q

Doxycycline

A

Active transported into bacterial cells
30s ribosome subunit inhibits binding of tRNA at A-site and prevent addition of amino acids
Oral effective
*DO NOT CONSUME w/ chelates (Ca2+, Mg2+ etc)

40
Q

Tigecycline

A

addition of side chain=resistant to efflux and increased binding affinity
restore efficacy
Tx: Highly resistant gram(-) infections
VERY TOXIC - other drugs preferred

41
Q

Azithromycin, Clarithromycin

A

Bind reversibly to 50S subunit, inhibit translocation
Overlap clindamycin/chloramphenicol binding sites = antagonism
Tx: Respiratory tract infections, atypical organisms, Peptic ulcer disease
CYP3A4 inhibitor = drug interactions

42
Q

Clindamycin

A 
Lincosamides
50S subunit, block peptide formation
bacteriostatic
Gram(+), anaerobs
Tx: SSIs, intraabdominal MRSA and Strep, severe acne, bacterial vaginosis, gas gangrene
Adverse: CDAD
43
Q

Chloramphenicol

A

50S subunit prevent tRNA attachment
Broad spectrum
Rarely used in U.S. except for meningitis
Adverse: Gray baby syndrome, blood dyscrasias (bone marrow suppression, aplastic anemia)

44
Q

Linezolid

A 
23S rRNA of 50S subunit
blocks formation of initation complex
Gram(+)
Tx: SSIs, MDR (MRSA, VRE) 
Interact w/ SSRIs and MAOs = serotonin syndrome
45
Q

Quiniupristin-dalfopristin

A

23S rRNA 50S
Same site as macrolide
Tx: SSIs (MRSA), VRE
Adverse: Hyperbilirubinemia, arthralgia, myalgia, phlebitis (necrosis at injection site)

46
Q

Ciprofloxacin

A

Fluoroquinolone
Bactericidal, Broad
DNA gyrase/topoisomerase IV
Tx: UTIs, ANTHRAX, diarrhea, Pseudomonas, H flu, respiratory infx
Adverse: Tendon rupture*, contraindicated in mysathenia gravis

47
Q

Metronidazole

A

Bactericidal
Prodrug -> p4 oxidoreductase
“SHOT GUN” Effect = no resistance
Tx: CDAD drug of choice, intra-abdominal anaerobic infx
Adverse: supposedly carcinogenic, ethanol

48
Q

Folic acid

A

synthesis of nucleic acids, AA, tRNA, metabolites
targeted by drugs
Mammals from diet, bacteria must create by PABA, pteridine, glutamate

49
Q

Sulfamethoxazole (SMX)

A

PABA structural analog, competitive inhibitor of Dihydropterorate synthase enzyme
*Adverse: kernicterus, SJS, Hemolytic anemia
Used w/ Trimethoprim usually

50
Q

Trimethoprim

A

Competitive inhibitor of dihyrofolate reductase (DHFR); >40,000 binding affinity for bacteria
Combine w/ sulfa
Tx: uncomplicated UTI and otitis media
Adverse: bone marrow suprression, hyperkalemia

51
Q

Co-trimoxazole (Bactrim)

A 
TMP/SMX
Bactericidal synergistic combo
#1 drug for UTIs
Tx: SSIs (MRSA), prophylaxis PCP PNEU
Adverse: HIV problems
52
Q

Fidaxomicin (rifampin)

A

Macrolide structure BUT
RNA polymerase inhibitor
Tx: CDIFF better than vanco and metronidazole because does not kill normal flora

53
Q

Daptomycin (cubicin)

A

“Bee stinger” Ca2+ dependent insertion of lipophilic tail into plasma membrane forms channel that permits influx of K+ = membrane depolarization
Bactericidal
ONLY Gram(+), inactivated by surfactant
IV administer
Tx: SSIs (resistant), staph endocarditis EOSINOPHILIC PNEU

54
Q

Colistin (polymixin)

A

Hydrophobic tail has detergent effect and disrupts outer and plasma membrane to increase permeability
Colistin sulfate - topical and oral
Colistimethate - anionic parenteral, prodrug
ESKAPE - MDR infxs
Adverse: nephrotoxicity

55
Q

Mycoplasma TB innate resistance

A

Highly complex cell wall (mycolic acid)
Efflux transporters
Intracellular location of infection
Slow proliferation

56
Q

Acquired resistance of TB

A

Spontaneous mutation - longterm therapy

57
Q

MDR TB

A

INH + rifampin resistance

58
Q

Extensively drug resistant TB (XTR)

A

MDR + resistance to fluoroquinolones and aminoglycosides

59
Q

Isoniazid (INH)

A

Inhibits synthesis of mycolic acid - free radical bind to NAD/NADPH
Active against both intracellular and extracellular
Toxic in slow acetylators
Adverse: HEPATOTOXICITY

60
Q

Rifampin (for TB)

A

Bind to B subunit of bacterial RNA polymerase, inhibiting RNA synthesis
Bactericidal
High resistance - mutation in rpoB gene
In combo with INH for TB, can tx MAC
Adverse: Hepatotoxicity, CYP450 induction (contraceptives, warfarin, HIV drugs),

61
Q

Ethambutol

A

Disrupt assembly of mycobacterial cell wall
Inhibit mycobacterial arabinosyl transferase
Resistance due to embAB gene (enzyme)
TX: in combo for TB, MAC
Adverse: *Optic neuritis, *NO liver effects

62
Q

Pyrazinamide

A 
Prodrug converted to pryazinoic acid (POA) by mycobacterial pyrazinamidase
Bactericidal
Unknown target
Tx: in combo for TB
Adverse: hepatotoxcityl
63
Q

Streptomycin

A

Second line antimycobacterial agent
Aminoglycoside for MDR TB
Severe life threatening forms of TB
Active against extracellular bacilli but not intracellular

64
Q

Prophylaxis TB Treatment

A

Monotherapy for latent prevent active
INH x9 months
Rifampin x4 months

65
Q

Active TB Treatment

A

IREP combination
Induction phase (2 months) - IREP; eliminate actively dividing extracellular organisms and make non-infectious
Continuation phase (4 months) - INH+rifampin usually after susceptibility testing
Monitor for hepatotoxicity

66
Q

Beta lactams

A

Penicillins
Cephalosporins
Carbapenems
Monobactams

67
Q

ESKAPE

A 
Enterococcus faecium
Staphylococcus aureus
Klebsiella pneumoniae
Acinetobacter baumannii
Pseudomonas aeruginosa
Enterobacter specie

Colistimethate targets

Pharmacology Exam 3 (4 decks)

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