Ab Flashcards

1
Q

Cell Wall Synthesis Inhibitors

A

β-lactam drugs: Penicillins, Cephalosporins, Carbapenems, Monobactams
Beta-lactamase inhibitors: NOT antibiotics but are used in a combination with extended-spectrum PCN

Non-β-lactam drugs
All bactericidal since cell lyses without wall.

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2
Q

Classical PCNs

A
gram (+), bactericidal, relatively narrow spectrum (mostly active against Gram-positive such as Staphylococcus)
Penicillin G (IV)
Penicillin V (oral)
Procaine penicillin G (IM)
Benzathine penicillin G (IM)
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3
Q

b-lactamase-resistant (anti-Staphyloccocal)

PCNs

A

gram (+), b-lactamase resistant (resistant to hydrolysis by beta-lactamase (penicilinase) found in many Staphylococcus aureus), bactericidal,

  • -bacteria sensitive to this class of PCNs are called methicillin-sensitive SA (MSSA).
  • -bacteria that are resistant to this class of PCNs are called methicillin-resistant SA (MRSA)
Methicillin (Don’t use since toxic to kidney-nephritis)
Nafcillin
Oxacillin
Cloxacillin
Dicloxacillin
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4
Q

Extended-Spectrum

PCNs

A

gram (+) and (-), bactericidal, more active against gram-negative bacteria compared to penicillin G/V
AMINOpenicillins: AMipicillin, AMoxicillin
Anti-pseudomonal PCNs:
CARBOXYpenicillins: CARbenicillin, TiCARcillin
UREIDOpenicillins: Piperacillin, Mezlocillin
-often used in a combination with beta-lactamase inhibitors to treat infections caused by Pseudomonas aeruginosa

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5
Q

Cephalosporins

A
gram (+): 1st gen
gram (-): 2nd, 3rd
b-lactamase resistant: 3rd/4th/5th
broad spectrum: 4th, 5th
bactericidal
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6
Q

Carbapenems

A

gram (+), gram (-), b-lactamase resistant, broad spectrum, bactericidal

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7
Q

Monobactams

A

gram (-), bactericidal, only aztreonam

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8
Q

Non-b-lactams

A

gram (+), bactericidal

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9
Q

Penicillins structure and MOA

A

D-Ala-D-Ala analogs, belong to beta-Lactams
MOA: Bind to PBP, inhibit transpeptidation
three sub groups of drugs that are of different antibacterial spectrum

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10
Q

Pros and Cons of Classical PCNs

A

penicillin G, penicillin V

pros: Active against G(+), some G(-) cocci and anaerobes
cons: Inactive against G(-) rods; hydrolyzed by β-lactamase
- -narrow spectrum and are often used to treat infections caused by gram-positive bacteria such as Staphylococcus aureus
- -penicillin G remains the drug of choice for treating syphilis which is caused by a spirochete

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11
Q

Pros and Cons of b-lactamase resistant PCNs (Anti-Staphylococcal PCN)

A

methicillin, nafcillin, cloxacillin, dicloxacillin

  • -not broad spec. just good for beta lactam resistant bugs
  • -even narrower spectrum than classical PCNs
    pros: Resistant to Staphylococcal β-lactamase
    cons: Inactive against G(-), anaerobes, enterococci
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12
Q

Pros and Cons of Extended-spectrum PCNs

A

ampicillin, amoxicillin, carbenicillin, ticarcillin, piperacillin, mezlocillin

pros: Improved activity against G(-) organisms
cons: Hydrolyzed by β-lactamase
- -can be used in fixed combinations with beta-lactamase inhibitors to broaden their antibacterial spectrum

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13
Q

Cephalosporins and Cephamycin

A

Structure: D-Ala-D-Ala analogs, belong to beta-Lactams
MOA: Bind to PBP, inhibit transpeptidation
Same MOA and major side effects as all beta-lactams
-Different spectrums
-Cross-allergenicity with PCN
-Most are renally cleared
-Many 3rd generation cephalosporins are also more likely to cross BBB to reach CNS and are thus useful for treating CNS infections.
-4th and 5th aren’t called broad spectrum since it kills many positive and negatives but not all.
-Covers even anaerobes.
-5th generation ceftobiprol is active against MRSA

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14
Q

1st generation Cephalosporins

A

Cefazolin (Inj.)
Cephalexin
Cephalothin
Cephradine

–more active against G(+), but less effective against most G(-)
Structure: D-Ala-D-Ala analogs belong to beta-Lactams
MOA: Bind to PBP, inhibit transpeptidation
Same MOA as all beta-lactams
Different spectrums
Cross-allergenicity
Most are renally cleared

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15
Q

2nd generation Cephalosporins and Cephamycin*

A
Cefaclor
Cefprozil
Loracarbef
Cefuroxime
Cefoxitin*
Cefotetan*
Cefonicid

–more active against G(-), but less active against G(+) compared to 1st generation
Structure: D-Ala-D-Ala analogs belong to beta-Lactams
MOA: Bind to PBP, inhibit transpeptidation
Same MOA as all beta-lactams
Different spectrums
Cross-allergenicity
Most are renally cleared

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16
Q

3rd generation Cephalosporins

A
Cefoperazone
Cefotaxime
Ceftazidime
Ceftizoxime
Ceftriaxone
Cefixime
Cefpodoxime
Cefdiner
Cefibuten
--more active against G(-), but less effective against most G(+)
--Many are also more likely to cross BBB to reach CNS and are thus useful for treating CNS infections.
Structure: D-Ala-D-Ala analogs belong to beta-Lactams
MOA: Bind to PBP, inhibit transpeptidation
Same MOA as all beta-lactams
Different spectrums
Cross-allergenicity
Most are renally cleared
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17
Q

4th generation Cephalosporins

A
cefepime
most active against both G(+) and G(-)
Structure: D-Ala-D-Ala analogs belong to beta-Lactams
MOA: Bind to PBP, inhibit transpeptidation
Same MOA as all beta-lactams
Different spectrums
Cross-allergenicity
Most are renally cleared
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18
Q

5th generation Cephalosporins

A

Ceftaroline
Structure: D-Ala-D-Ala analogs belong to beta-Lactams
MOA: Bind to PBP, inhibit transpeptidation
Same MOA as all beta-lactams
Different spectrums
Cross-allergenicity
Most are renally cleared

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19
Q

Other b-lactams: Carbapenems

A

Imipenem*
Ertapenem
Meropenem

Structure: D-Ala-D-Ala analogs belong to beta-Lactams
MOA: Bind to PBP, inhibit transpeptidation
–broad-spectrum beta-lactams that are useful for treating mixed infections
*Imipenem + cilastatin (inhibits renal dehydropeptidase: prolongs imipenem’s bioavailability)
Imipenem inhibited by dehydropeptidase

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20
Q

Other b-lactams: Monobactams

A

Aztreonam
Structure: D-Ala-D-Ala analogs belong to beta-Lactams
MOA: Bind to PBP, inhibit transpeptidation
–is active against gram-negative only
–does not share drug resistance with PCNs and is therefore useful for treating PCN-resistant infections.

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21
Q

Other b-lactams: β-lactamase inhibitors*

A

Clavulanic acid
Sulbactam
Tazobactam

  • -Little/no antibiotic activity: are beta-lactams but are NOT antibiotics
  • -MOA: inh. b-lactamase)
  • -Used only in fixed combination with specific extended-spectrum penicillins to broaden their antibacterial activity
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22
Q

Non-b-lactam Cell Wall Syn. Inh. - Fosfomycin

A
Spectrum/Use: G(+), G(-)
MOA: Inh. enolpyruvate transferase
--blocks NAM
--"F" for first step
--good for uti when other drugs don’t work
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23
Q

Non-b-lactam Cell Wall Syn. Inh. - Cycloserine

A

Spectrum/Use: TB

MOA: Inh. alanine racemase, blocks synthesis of linking pentapeptide (PEP)

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24
Q

Non-b-lactam Cell Wall Syn. Inh. - Vancomycin

A

Spectrum/Use: G(+)
MOA: Binds to D-Ala-D-Ala
–not orally absorbed since it is a glycopeptide
–doesn’t get in through gut easily since it is charged
–so not orally bioavailable
–used in general as injection/infusion except for C. diff colitis (overgrowth from too much ab)

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25
Q

Non-b-lactam Cell Wall Syn. Inh. - Bacitracin

A

Spectrum/Use: G(+), topical
MOA: Inh. recycling of lipid carrier BPP (Bactoprenol phosphate). NAM and NAG need a carrier through the lipid membrane
–Used in antibiotic ointment since it’s too toxic if taken internally.

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26
Q

Non-b-lactam Cell Wall Syn. Inh. - Daptomycin

A

Spectrum/Use: G(+)
MOA: Binds to and depolarize cell membrane
–Lipophilic drug (make pores in membrane so contents spill out)

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27
Q

Severe Side Effects/Toxicities: b-lactams

A

Hypersensitivity, renal toxicity
–don’t give if have seizures beause it binds gaba receptor so more likely to have a seizure if the drug is not released properly

28
Q

Severe Side Effects/Toxicities: Amoxicillin

A

Non-allergic rash (nonhistamine (IgE) mediated)
GI toxicity
–Most orally bioavailable drug

29
Q

Severe Side Effects/Toxicities: Cephalosporins –MTT (cefoperazone, cefotetan)

A

Disulfiram-like rx (w/alcohol)

  • -Disulfiram: treatment of chronic alcoholism by producing an acute sensitivity to ethanol by inhibiting the enzyme acetaldehyde dehydrogenase
  • -Mtt ring gives additional side effects
30
Q

Severe Side Effects/Toxicities: Vancomycin

A

Ototoxicity
renal toxicity
red man syndrome (caused by histamine release)
–injected

31
Q

Severe Side Effects/Toxicities: Cycloserine

A

CNS toxicity

32
Q

Severe Side Effects/Toxicities: Daptomycin

A

Muscle pain, liver toxicity

33
Q

linezolid MOA

A

Protein translation: Initiation inhibited

34
Q

tetracyclines MOA

A

Protein translation: Elongation - attachment of aa-tRNA is inhibited

35
Q

macrolides, clindamycin, and chloramphenicol MOA

A

Protein translation: Peptidyl transfer from P to A site inhibition
–chloramphenicol blocks peptide bond formation

36
Q

aminoglycosides MOA

A

Protein translation: Translocation of peptidyle-tRNA from A site to P site inhibited
–also block mRNA proofreading

37
Q

Protein Synthesis Inhibitors

inhibit 30S ribosomal subunit

A
Tetracyclines:
Chlortetracycline
Oxytetracycline
Tetracycline
Demeclocycline
Methacycline
Doxycycline
Minocycline
Tigecycline
--Broad spectrum
--Bacteriostatic (except for tigecycline, which is bactericidal)
Aminoglycosides:
Streptomycin
Gentamicin
Neomycin
Kanamycin
Amikacin
Tobramycin
Paromomycin
--G(-) and some G(+)
--Bactericidal
--big and charged so cant be absorbed in gut membrane
--becomes ionized even more in acidic stomach, so use as injection
38
Q

Protein Synthesis Inhibitors

inhibit 50S ribosomal subunit

A

Relatively Broad spectrum:
Macrolides: Erythromycin, Clarithromycin, Azithromycin
–use erytho is allergic to PCN
–Azithro and claritho have bad drug interaction

Ketolides: Thelithromycin

Broad spectrum:
Clindamycin, Chloramphenicol
–Clinda for acne. Patient can develop C. diff colitis since kills too much bacteria and this outgrows. Diarrhea too

Streptogramins: Quinupristin-dalfopristin (combo)
G(+), Bactericidal

Oxazolidones: Linezolid
G(+)

39
Q

Severe Side Effects/Toxicities: Tetracyclines

A

Teeth/bone damage, photosensitivity, liver/kidney/GI toxicities
–Tetracyclines are avoided in pregnancy and <8 yr old.
Avoid dairy products and antacids (cations). Binds to calcium. Cant kill bacteria effectively if calcium is bound.

40
Q

Severe Side Effects/Toxicities: Aminoglycosides

A

Ototoxicity, renal toxicity

–inj only and against gram (-)

41
Q

Severe Side Effects/Toxicities: Macrolides

A

Liver toxicity

42
Q

Severe Side Effects/Toxicities: Clindamycin

A

Pseudomembraneous colitis (c diff overgrowth)

43
Q

Severe Side Effects/Toxicities: Chloramphenicol

A

Aplastic anemia, Grey baby syndrome

44
Q

Severe Side Effects/Toxicities: Streptogramins

A

Arthralgiamyalgia (muscle pain)

45
Q

Severe Side Effects/Toxicities: Linezolid

A

Hematological toxicity

46
Q

p450 inhibitors

A

erythromycin, clarithromycin, chloramphenicol, fluoroquinolones

47
Q

DNA Synthesis Inhibitors: Antifolates

A
Sulfonamide: inhibits DHPS, Broad Spectrum, Bacteriostatic
Sulfacytine
Sulfisoxazole
Sulfamethizole
Sulfadiazine
Sulfamethoxazole
Sulfapyridine
Sulfadoxine
Sulfasalazine

Pyrimidines: Broad Spectrum, Bacteriostatic
Trimethoprim - inhibits DHFR
Pyrimethamine - protozoa-specific

48
Q

DNA Synthesis Inhibitors: DNA Gyrase Inhibitors

A

Fluoroquinolones: inhibits Topoisomerase IV, DNA gyrase (Topo II), G(+) & G(-), Bactericidal

Norfloxacin 
Ciprofloxacin (drug of choice for anthrax), better against (-) 
Levofloxacin (better for (+)) 
Enoxacin
Ofloxacin
Pefloxacin
Lomefloxacin
Moxifloxacin
Gemifloxacin
49
Q

Severe Side Effects/Toxicities: Sulfonamides

A

Urinary tract disturbance (drink tons of water otherwise crystallize in urinary tract)
SJS: Stevens–Johnson syndrome, a form of toxic epidermal necrolysis

50
Q

Severe Side Effects/Toxicities: Trimethoprim

A

Hematological toxicity

51
Q

Severe Side Effects/Toxicities: Fluoroquinolones

A

QT-prolongation (arrhythmias), photosensitivity, tendonitis, tendon rupture, arthropathy, avoid cations (dairy products, antacids), avoided in patients <18 yr old

52
Q

Empirical therapy: Acute bacterial endocarditis

A

Vancomycin + Gentamicin

53
Q

Empirical therapy: Acute Otitis Media, sinusitis

A

Amoxicillin

54
Q

Empirical therapy: Cellulitis

A

b-lactamase-resistant penicillin, 1st generation cephalosporin

55
Q

Empirical therapy: Meningitis (child & adult)

A

cefotaxime (3rd) + vancomycin

56
Q

Empirical therapy: Meningitis (neonate)

A

Ampicillin + cephalosporin (3rd)

57
Q

Empirical therapy: Community-acquired pneumonia

A

Macrolide, amoxicillin, tetracycline (outpatient)

Macrolide+ cefotaxime (inpatient)

58
Q

Empirical therapy: Septicemia

A

Vancomycin+ cephalosporin (3rd) or piperacillin/tazobactam or imipenem

59
Q

Empirical therapy: Uncomplicated Cystitis

A

TMP-SMZ (trimethoprim and sulfamethoxazole synergy), Nitrofurantoin, (Fluoroquinolone for resistant strains)

60
Q

G(+) only

A

Bacitracin, Vancomycin, Daptomycin, Streptogramins, Linezolid

61
Q

Mostly used for G(+)

A

PCNs

62
Q

G(-) only

A

Aztreonam

63
Q

Mostly used for G(-)

A

Extended-spectrum PCNs, 3rd gen cephalosporins, Aminoglycosides

64
Q

Broad-spectrum

A

Carbapenems, Tetracyclines, Macrolide, Chloramphenicol, Clindamycin, anti-folates, Quinolones

65
Q

Bactericidal

A

Cell wall inhibitors, Tigecycline, Aminoglycosides, Streptogramins, TMP/SMZ, Quinolones