Antimicrobial Therapy Flashcards

1
Q

What does bacteriostatic mean?

A

antimicrobial drug that requires host defense mechanism to get rid of bug. Use in healthy people

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2
Q

What does bactericidal mean?

A

Antimicrobial that eradicates bug without use of host defense

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3
Q

What is minimum inhibitory concentration?

A

lowest concentration of antimicrobial drug that can inhibit growth of organism on a defined medium. This will vary from person to person

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4
Q

What patient factors affect MIC to kill bug

A

Pregnancy and lactation, immune system, age, disease

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5
Q

What drugs are avoided in pregnancy?

A

tetracycline - causes tooth dysplasia and inhibits bone growth

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6
Q

with what type of drugs is a compromised immune system problematic?

A

bacteriostatic drugs

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7
Q

What differs typically in young and old patients compared to older children and adults?

A

rental, hepatic and CV function differs

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8
Q

Which drugs block cell wall synthesis by inhibition of peptidoglycan cross-linking

A

penicillin, methicillin, ampicillin, piperacillin, cephalosporins, azteronam, imipenem

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9
Q

Which drugs block peptidoglycan synthesis of cell wall?

A

Bacitracin, vancomycin

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10
Q

Which drugs block nucleotide synthesis (metabolism)?

A

sulfonamides, trimethoprim

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11
Q

Which drugs block DNA topoisomerases, nucleic acid function or synthesis

A

Fluoroquinolones and rifampin

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12
Q

Which drugs inhibit cell membrane function?

A

isoniazide, amphotericin B

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13
Q

Which drugs block protein synthesis at 50S ribosomal subunit?

A

Chloramphenicol, macrolides, clindamycin, streptogramins, linezolid

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14
Q

Which drugs block protein synthesis at 30 S ribosomal subunit

A

Aminoglycosides, tetracyclines

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15
Q

What is the mechanism of penicillin?

A
  1. binds PCPs (penicillin-binding proteins)
  2. Blocks transpeptidase cross-linking of peptidoglycan
  3. Activates autolytic enzymes
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16
Q

What is the clinical use of penicillin?

A

Used for gram positive organisms mostly: S. pneumoniae, S. pyogenes, Actinomyces and syphilis. Bactericidal for gram + cocci & rods, gram-negative cocci, spirochetes.

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17
Q

What has penicillin resistance?

A

Beta Lactamases - cleave Beta lactam ring

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18
Q

What are the penicillinase-resistant penicillins and what are they used to treat?

A

Methicillin, Nafcillin, dicloxacillin. Use Naf for Staph. (not MRSA)

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19
Q

How do ampillicin/amoxicillin differ from penicillin?

A

Wider spectrum, but still penicillinase sensitive. Combine with clavulanic acid to protect against beta lactamase. AmOxicillin = greater Oral bioavailability than ampicillin.

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20
Q

What are aminopenicillins (amox/amp) used to treat?

A

HELPSS kill enterococci

Haemophilus influenza, E. coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, Shigella, Enterococci.

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21
Q

What are Ticarcillin, carbenicillin, and piperacillin used for?

A

anti-pseudomonals. TCP - takes care of pseudomonas (and gram - rods).

Penicillinase sensitive, use with clauvulanic acid.

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22
Q

What are the beta lactamase inhibitors?

A
CAST:
Clauvulanic Acid
Sulfbactam
Tazobactam
- often added to penicillin antibiotics to evade destruction
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23
Q

What are the beta lactam drugs that inhibit cell wall synthesis and are less susceptible to penicillinases

A

Cephalosporins

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24
Q

Which organisms are not covered by cephalosporins?

A
LAME!
Listeria
Atypicals (Chlamydia, Mycoplasma)
MRSA
Enterococci
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25
Q

What are the clinical use of first generation cephalosporins and what are the names of these drugs?

A
Drugs: cefazolin, cephalexin
PEcK
P - proteus mirabilis
E. coli
Klebsiella
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26
Q

What do the 2nd generation cephalosporins treat and what are the drug names?

A
Drugs: cefoxitin, cefaclor, cefuroxime
HEN PEcKS
H- H.influenza
E - enterobacter aerogenes
N - neisseria
P =- proteus mirabilis
E. coli
K - Kleibsiella
S - serratia
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27
Q

What are the third generation cephalosporins and what are they used to treat?

A

Drugs: ceftriaxone - used for meningitis and gonorrhea
cefotaxime,
ceftazidime - used for pseudomonas
Treat serious gram negative infections resistant to other beta lactams

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28
Q

What are the 4th generation cephalosporins and what are they used for?

A

Drugs: cefepime. Increased activity against pseudomonas and gram positive organisms.

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29
Q

What is aztronam used to treat?

A

Gram-negative rods only. No effect on gram-positives or anaerobes. It is resistant to beta lactamases, inhibits cell wall synthesis by binding to PBP.

30
Q

What is Imipenem combined with and what is it used for?

A

the kill is “lastin” with ciLASTatIN
combined with cilastatin to decrease inactivation of drug in renal tubules.
Wide spectrum but used to treat nosocomial infections and multiple infections of unknown origin. Low susceptibility to beta lactamases

31
Q

What is the mechanism of action of vancomycin?

A

inhibits cell wall formation by binding to D-ala D-ala to D-ala D-lac. Bacteriocidal. “pay back 2 D-ala’s for VANdalizing”

32
Q

What is vancomycin used to treat?

A

Gram positive only, serious, multidrug resistant Staph Aureus, enterococci and C diff.

33
Q

What is the toxicity of Vancomycin?

A
does NOT have many problems except
N - nephrotoxicity
O- ototoxicity
T- thrombophlebitis 
and diffuse flushing - red man syndrome
34
Q

Buy AT 30, CCEL at 50

A

30S inhibitors:
A: Aminoglycosides (SIDAL)
T: Tetracyclines (bacteriostatic)

50S inhibitors:
C: Chloramphenicol
C: Clinamycin
E: erythromycin (macrolides) 
L: Linezolid
35
Q

What are the aminoglycosides?

A
MIN GNATS canNOT kill anaerobes
G: gentamicin
N: neomycin
A: amikacin
T: tobramycin
S: streptomycin
36
Q

What is the mechanism of action of Aminoglycosides?

A

Bactericidal - inhibit formation of initation complex and cause misreading of mRNA. “A” “initiates” the alphabet. Require oxygen for uptake, therefore ineffective against anaerobes

37
Q

What is the toxicity of aminoglycosides?

A

NOT
Nephrotoxicity (especially when combined with cephalosporins), Ototoxicity (especially when used with loop diuretics), and Teratogen.

38
Q

What are the tetracyclines?

A

Tetracycline, doxycycline, tigecycline, minocycline

39
Q

What is the mechanism of action of the tetracyclines.

A

Bacteriostatic, binds to 30S and prevents attachment of aminoacyl-tRNA. Limited CNS penetration. Doxy is fecally eliminated so can be used in patients with renal failure

40
Q

What is the clinical use of tetracyclines?

A

Borrelia Burgdorferi, Mycoplasma pneumoniae, rickettsia, Chlamydia.

41
Q

What is toxicity of tetracyclines>

A

GI distress (C diff), bone and tooth irregularities in children, photosensitivity, hepatotoxicity, bone deformities in fetuses - crosses placenta, vestibular toxicity

42
Q

How is resistance conferred in tetacyclines?

A

decreased uptake into cells or increased efflux out of cells by plasmid-encoded transport pumps

43
Q

What are the macrolides?

A

Erythromycin, Azithromycin, Clarithromycin, Telithromycin, Clindamycin

44
Q

What are the macrolides mechanism of action?

A

bind to 50S subunit to inhibit translocation and stop peptide synthesis

45
Q

how is resistance conferred in the macrolides

A

increased synthesis of methylase (methylation of 50S rRNA binding site); increased efflux

46
Q

What is the clinical use of the macrolides?

A

Atypical pneumonias (Mycoplasma, Chlamydia, Legionella), URIs, STDs, Gram + cocci (strep and syphilis in patients allergic to penicillin), Neisseria

47
Q

What is the toxicity of the Macrolides?

A

Prolonged QT interval, especially erythromycin. GI discomfort, acute cholestatic hepatitis, eosinophilia, skin rash

48
Q

What is the mechanism of Chloramphenicol

A

Blocks peptide bond formation at 50S ribosomal subunit. Bacteriostatic

49
Q

What is the clinical use of Clindamycin?

A

Blocks peptide bond formation at 50S. Bacteriostatic.

50
Q

What are the clinical uses for clindamycin?

A

anaerobic infections like bacteroides fragilis, clostridium perfringens in aspiration pneumonia or lung abcesses

51
Q

What are the sulfonamides?

A

Sulfasalazine, sulfadiazine, sulfapyridine, Sulfamethoxazole, Sulfisoxazole

52
Q

What is the mechanism of sulfonamides?

A

PABA antimetabolites inhibit dihydropteroate synthetase. Bacteriostatic. Blocks bacterial folate synthesis.

53
Q

What is the clinical use for sulfonamides?

A

Nocardia, Chlamydia, active against enterobacteria in urinary tract (UTI)

54
Q

What is sulfasalazine broken up into in the body?

A

Sulfapyridine &

Amino salicylate

55
Q

What sulfa drug is used to treat chronic bowel disorders?

A

sulfasalazine - poor oral absorption, stays in gut

56
Q

What are the adverse effects of Sulfonamides?

A
  1. crysalluria - crystallize in bladder
  2. Hypersensitivty - rashes, angioedema
  3. Hemolytic anemia in G6PD deficiency
  4. Kernicterus in infants caused by increased bilirubin
57
Q

What is the function of trimethoprim?

A

Inhibits bacterial dihydrofolate reductase. Bacteriostatic.

58
Q

What is the clinical use of trimethoprim?

A

combine with sulfonamides to create cotrimoxazole “Bactrim”

59
Q

What is the mechanism of Cotrimoxazole?

A

Blocks dihydropteroate (sulfonamide)
Blocks dihydrofolate reductase
penetrates CSF

60
Q

What adverse effects does trimethoprim alone cause?

A

megaloblastic anemia, leukopenia, granulocytopenia

61
Q

What can trimethoprim be used to treat?

A

UTIs, prostatitis, vaginitis

62
Q

What are the 1st generation fluoroquinolones?

A

Nalidixic acid, norfloxacin. Used for gram negatives typically uncomplicated UTIs.

63
Q

What are the 2nd generation fluoroquinolones?

A

Ciprofloxacin, Ofloxaxin. Expanded gram negative activity and atypical mycoplasma and chlamydia pneumoniae.

64
Q

What are the 3rd and 4th generation fluoroquinolones?

A

3- levofloxacin, gemifloxacin. Gram neg, Gram pos, and atypical pneumoniae.
4 - moxifloxacin - gains anaerobic coverage

65
Q

What are the fluoroquinolines used for?

A

gram negative rods of urinary and GI tracts (pseudomonas, neisseria, and some gram + organisms)

66
Q

What is the drug of choice for anthrax?

A

Ciprofloxacin

67
Q

Why is ciprofloxacin not used for pneumonia or sinusitis? What should you use instead?

A

Because it was weak activity against strep pneumoniae. Use Levofloxacin or moxifloxacin instead.

68
Q

What is the mechanism of action of fluroquinolones

A

inhibits topoisomerase II in gram negative (inhibiting DNA gyrase) and inhibits topoisomerase IV in gram positive (interferes with separation of strands). Decreases bacterial DNA synthesis.

69
Q

What is the “black box” warning for fluoroquinolones?

A

increased risk of tendonitis, tendon rupture after systemic use.

70
Q

Why are fluoroquinolones not recommended in growing children?

A

Lones are bad for the Bones. affect cartilage formation, increases joint pain.

71
Q

What are other adverse effects of fluoroquinolones?

A

diarrhea, nausea, headache, dizziness, nephrotoxicity - reduce kidney function

72
Q

Which drug is not appropriate in the treatment of Legionella pneumonia out of erythromycin, gentamicin, ciprofloxin, doxycyclin, azithromycin?

A

gentamicin