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Pharmacology Exam 3 > Antibiotics > Flashcards

Antibiotics Flashcards

(67 cards)

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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
Cephalosporin
``` B lactam ring + 6 membered ring Resistance due to B lactamase and altered PBP 5 generations Most given parenterally, poor absorption Cleared by kidney ```
26
Cefazolin
1st generation surgical site prophylaxis (MSSA, S aureus) alternative for MSSA when penicillin allergy
27
Cefoxitin
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
Ceftriaxone
``` 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
Cefepime
4th generation Highly resistant B lactamases and broad antibacterial spectrum Good CNS penetration Useful for empiric tx, drug resistance
30
Ceftaroline
5th generation | ONLY cephalosporin active against MRSA
31
Carbapenems, imipenem-cilastatin (primaxin)
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
Aztreonam
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
Vancomycin
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
Bacteria resistant to vancomycin are treated with:
Treated w/ Linezolid, Daptomycin, quinupristin/dalfopristin
35
Adverse reactions of vancomycin
Ototoxic >30ug/mL Nephrotoxic ***Rapid infusion "red man" syndrome - flushing urticaria, tachycardia, hypotension, histamine release
36
Fosfomycin (nitrofurantoin)
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
Gentamicin and Amikacin
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
Adverse effects of Gentamicin
Ototoxicity Nephrotoxicity (reversible damage to proximal tubules) Neuromuscular blocakde at high doses -> respiratory paralysis Contraindicated in myasthenia gravis
39
Doxycycline
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
Tigecycline
addition of side chain=resistant to efflux and increased binding affinity restore efficacy Tx: Highly resistant gram(-) infections VERY TOXIC - other drugs preferred
41
Azithromycin, Clarithromycin
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
Clindamycin
``` Lincosamides 50S subunit, block peptide formation bacteriostatic Gram(+), anaerobs Tx: SSIs, intraabdominal MRSA and Strep, severe acne, bacterial vaginosis, gas gangrene Adverse: CDAD ```
43
Chloramphenicol
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
Linezolid
``` 23S rRNA of 50S subunit blocks formation of initation complex Gram(+) Tx: SSIs, MDR (MRSA, VRE) Interact w/ SSRIs and MAOs = serotonin syndrome ```
45
Quiniupristin-dalfopristin
23S rRNA 50S Same site as macrolide Tx: SSIs (MRSA), VRE Adverse: Hyperbilirubinemia, arthralgia, myalgia, phlebitis (necrosis at injection site)
46
Ciprofloxacin
Fluoroquinolone Bactericidal, Broad DNA gyrase/topoisomerase IV Tx: UTIs, ANTHRAX, diarrhea, Pseudomonas, H flu, respiratory infx Adverse: Tendon rupture*, contraindicated in mysathenia gravis
47
Metronidazole
Bactericidal Prodrug -> p4 oxidoreductase "SHOT GUN" Effect = no resistance Tx: CDAD drug of choice, intra-abdominal anaerobic infx Adverse: supposedly carcinogenic, ethanol
48
Folic acid
synthesis of nucleic acids, AA, tRNA, metabolites targeted by drugs Mammals from diet, bacteria must create by PABA, pteridine, glutamate
49
Sulfamethoxazole (SMX)
PABA structural analog, competitive inhibitor of Dihydropterorate synthase enzyme *Adverse: kernicterus, SJS, Hemolytic anemia Used w/ Trimethoprim usually
50
Trimethoprim
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
Co-trimoxazole (Bactrim)
``` TMP/SMX Bactericidal synergistic combo #1 drug for UTIs Tx: SSIs (MRSA), prophylaxis PCP PNEU Adverse: HIV problems ```
52
Fidaxomicin (rifampin)
Macrolide structure BUT RNA polymerase inhibitor Tx: CDIFF better than vanco and metronidazole because does not kill normal flora
53
Daptomycin (cubicin)
"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
Colistin (polymixin)
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
Mycoplasma TB innate resistance
Highly complex cell wall (mycolic acid) Efflux transporters Intracellular location of infection Slow proliferation
56
Acquired resistance of TB
Spontaneous mutation - longterm therapy
57
MDR TB
INH + rifampin resistance
58
Extensively drug resistant TB (XTR)
MDR + resistance to fluoroquinolones and aminoglycosides
59
Isoniazid (INH)
Inhibits synthesis of mycolic acid - free radical bind to NAD/NADPH Active against both intracellular and extracellular Toxic in slow acetylators Adverse: HEPATOTOXICITY
60
Rifampin (for TB)
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
Ethambutol
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
Pyrazinamide
``` Prodrug converted to pryazinoic acid (POA) by mycobacterial pyrazinamidase Bactericidal Unknown target Tx: in combo for TB Adverse: hepatotoxcityl ```
63
Streptomycin
Second line antimycobacterial agent Aminoglycoside for MDR TB Severe life threatening forms of TB Active against extracellular bacilli but not intracellular
64
Prophylaxis TB Treatment
Monotherapy for latent prevent active INH x9 months Rifampin x4 months
65
Active TB Treatment
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
Beta lactams
Penicillins Cephalosporins Carbapenems Monobactams
67
ESKAPE
``` Enterococcus faecium Staphylococcus aureus Klebsiella pneumoniae Acinetobacter baumannii Pseudomonas aeruginosa Enterobacter specie ``` *Colistimethate targets*

Pharmacology Exam 3 (4 decks)

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