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Pharmacology > Antimicrobial Agents > Flashcards

Antimicrobial Agents Flashcards

0
Q

What is the difference between bacteriostatic and bacteriocidal? Which one is better for perioperative ABX?

A

Bacteriostatic = stops bacteria from growing and reproducing
disrupts protein formation
disrupts DNA synthesis-> prevents reproduction
Bacteriocidal = kills the bacteria
better choice for perioperative ABX
better choice for the critically ill and immunocompromised
Disrupts cell wall or cell membrane

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1
Q

Give two reasons for giving Antimicrobial agents

A
  1. Prevent surgical site infection (SSI)

2. Treat known/ suspected infection

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2
Q

What is MIC (minimum inhibitory concentration)?

A

the minimum serum concentration that is needed to be effective. Want to avoid under dosing bc it could promote bacterial resistance. Exception- hepatic and renal dysfunction

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3
Q

What is the difference between narrow spectrum and braod spectrum ABX?

A

A broad-spectrum antibiotic
-acts against a wide range of disease-causing bacteria
-acts against both Gram-(+) & Gram-(-) bacteria,
-in contrast to a narrow-spec which is effective against specific families of bacteria.
Narrow Spectum
-only effective against agents of concern
-minimize effects on other “normal” flora (broad spectrum)

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4
Q

When are broad spectrum ABXs used?

A
  1. Before the formal ID of the causative bacteria, when there is a wide range of possible illnesses and a potentially serious illness would result if treatment is delayed.
    • This occurs, for example, in meningitis, where the patient can become fatally ill within hours if B.S. ABX aren’t started
  2. For drug resistant bacteria that do not respond to other, more narrow-spectrum antibiotics.
  3. In the case of superinfections, where there are multiple types of bacteria causing illness, thus warranting either a broad-spectrum antibiotic or combination antibiotic therapy.
  4. Empirically (i.e., based on the experience of the practitioner)
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5
Q

What is the difference between aerobic bacteria and anaerobic bacteria? Where are each type found in/on the body?

A

Aerobic = able to use O2, gets energy from breaking down food
-skin (gram +)
-gut (gram -)
Anaerobic = can sustain itself w/o O2, can’t break down food
-intestinal
-GYN

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6
Q

What is the difference between Gram (+) and Gram (-) bacteria?

A 
Gram (+)
	- thinner cell wall
	- more easily penetrated by ABX
Gram (-)
	- more resilient cell wall
	- less susceptible to most ABX
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7
Q

Identify the following aerobe as gram(+) or gram(-) and identify where it is found:
strep

A

gram +, skin

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8
Q

Identify the following aerobe as gram(+) or gram(-) and identify where it is found:
staph

A

gram +, skin

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9
Q

Identify the following aerobe as gram(+) or gram(-) and identify where it is found:
enterobacilli

A

gram -, gut

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10
Q

Identify the following aerobe as gram(+) or gram(-) and identify where it is found:
E. coli

A

gram -, gut

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11
Q

What are the three ways to classify ABXs?

A

Bacteriostatic vs Bacteriocidal
Narrow Spectrum vs Broad Spectrum
Gram(-) vs Gram(+)

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12
Q

What are the 3 types of ABX cellular targets? (sites of action)

A
  1. cell wall
  2. protein synthesis (ribosomes)
  3. nucleic acid synthesis
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13
Q
  1. What type/class of ABXs most commonly cause allergic rxns?
  2. What are 4 symptoms of this immune-related rxn?
  3. Will a test dose trigger an allergic rxn?
A
  • beta-lactams and derivatives
  • rash, pruritus, bronchospasm, anaphylaxis
  • yes
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14
Q

After administration of vancomycin, your patient displays the following symptoms: rash, pruritus, bronchospasm and flushing. Is your patient having an allergic reaction?

A

Not necessarily. They can be having a non-immune mediated histamine release. Certain drugs can cause release of histamine in a dose- and/or rate-dependent fashion. This used to be called anaphylactoid, but this term is not really used much anymore. This reaction can be just as severe as immune-mediated anaphylaxis.

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15
Q

Cefazolin is the preferred ABX is which 4 types of surgeries?

A
  1. Cardiac or vascular
  2. Neuro
  3. Ortho: TKA/THA
  4. General (hernia repair, breasts)
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16
Q

For a given procedure, cefazolin is the preferred ABX; however, the patient has a B-lactam allergy. What ABX should be used instead? What if the patient had a known history of MRSA?

A

B-lactam allergy - Clindamycin or vancomycin

MRSA - vancomycin

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17
Q

What types of surgeries is cefoxitin the preferred ABX? What if the pt has a B-lactam allergy?

A
  1. Colon
  2. General (gastroduodenal, hepatobiliary)
  3. Gynecological (hysterectomy, c-section)

B-lactam allergy -> gentamicin + metronidazole OR
Ciprofloxacin + metronidazole

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18
Q

When are ABXs not indicated?

A

not indicated for elective “clean” surgical procedures

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19
Q

Name 4 ABX groups that target the cell wall/membrane.

A

PCNs (B-lactam)
Cephalosporins (B-lactam)
Vancomycin
Daptomycin

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20
Q

What are beta lactamase inhibitors? Name 3 examples.

A

They overcome resistance to PCNs. Resistance is caused by inactivation by beta lactamases.

Unasyn, Zosyn, Aumentin

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21
Q

Name 3 common Cephalosporins.

A

Cefazolin, Cefoxitin, Ceftriaxone

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22
Q

What are cephalosporins excellent coverage for?

A

skin flora

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23
Q

What are cephalosporins commonly used for?

A

cardiovascular, orthopedic, biliary, pelvic, intraabdominal surgry

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24
Q

What do the later generations of cephalosporins have?

A

more gram-negative coverage (GI cases), more resistance to beta lactamases, and better penetration of BBB

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25
Q

What is the dosing for cephalosporins?

A

1 g every 3-4 hours up to max dose of 2g

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26
Q

In regards to the cross-reactivity with PCNs, when is it probably safe to give a pt with a PCN allergy a cephalosprin?

A

probably safe to give to pts with minor PCN allergy (fever, rash), reasonable to avoid in pts with anaphylaxis to PCN; controversial debate

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27
Q

Is anaphylaxis a common reaction to cephalosporins?

A

NO! it is rare

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28
Q

What does vancomycin inhibit?

A

cell wall synthesis

29
Q

In what type of pt is vancomyosin commonly used instead of cephalosporin?

A

pts with Methicillin-resistant staphylococcus aureus (MRSA)

30
Q

When would you want to be cautious in using vancomycin? What type of pt?

A

renal insufficiency- must modify dosing

31
Q

When do you redose vancomyosin and what do you use oral dosing for?

A

every 12 hours; for C. difficile colitis

32
Q

What are the adverse reactions to Vancomyosin?

A

fever/chills, irritation; ototoxcity/nephrotoxicity (rare)

red man syndrome

33
Q

What is red-man syndrome caused from and how can you prevent it?

A

due to non-immune mediated histamine release with fast infusion; infuse over 1 hour

34
Q

What is daptomycin good for?

A

vacomycin-resistant bacteria

35
Q

How do you give daptomycin?

A

give as a “slow bolus”

36
Q

Name the four protein synthesis/ribosomal agents

A

Tetracyclines (doxycycline), macrolides (Erythromycin), clindamycin, aminoglycosides (Gentamycin)

37
Q

Tetracyclines, Macrolides, clindamycin, and aminoglycosides all inhibit _______ and bind to _________.

A

Protein synthesis; ribosome

38
Q

What ion do tetracyclines bind to?

A

Ca (teeth and bones in children)

39
Q

Tetracyclines are used in these certain procedures because they cross what?

A

D&Cs, they crossed the placenta

40
Q

What antibiotic is characterized by the following are adverse effects?

GI upset- local irritation,
bone/tooth deformation/inhibition/discoloration
sunlight sensitivity, dizziness, N/V,
neuromuscular blockade

A

Tetracyclines (Doxycycline)

41
Q

The following adverse effects are caused by what protein synthesis/ribosomal agent: GI upset, partially due to increase GI motility, fever, rash, esoinophilia, inhibit CYP450–> increased drug concentrations (prolonged effects of midazolam, alfentanil

A

Macrolides (Erythromycin)

42
Q

Which protein synthesis/ribosomal agent is a common alternative to PCN/cephalosporins?

A

clindamycin

43
Q

What is the dose of clindamycin?

A

600-900 mg IV every 6 hours

44
Q

What are the adverse effects of clindamycin?

A

GI upse, rashes, C. difficile, histamine release with quick administration, cause/potentiate neuromuscular blockade

45
Q

Cell-wall agents, Nafcillin and vancomycin, are commonly used together with which protein synthesis, ribosomal agent?

A

aminoglycosides- gentamycin

46
Q

What are the two different doses aminoglycosides- gentamycin?

A

low dose: 80 mg IV; high dose: 5 mg/kg IV (max 400 mg); redose every 8 hours

47
Q

What are the two major adverse effects of gentamycin?

A

ototoxicity (irreversible) and nephrotoxicity (mild)- give slowly to keep serum levels low

48
Q

What effect on the body can gentamycin have at high doses? How can you treat it?

A

neuromuscular blockade- tx Ca gluconate, neostigmine

49
Q

What are the two other names for Bactrim and what pathway does it interfere with?

A

Trimethoprim, sulfamethoxazole; folic acid pathway- hits two steps in conversion of PABA–> THF

50
Q

What rare syndrome can be caused by Batrim?

A

stevens-johnson sx

51
Q

What is bactrim necessary for?

A

purine synthesis–> DNA

52
Q

What are the adverse reactions of Bactrim?

A

fever, rash, photosenstitivity, N/V/ diarrhea

53
Q

What antimicrobial agent is a DNA gyrase inhibitor, used frequently in GU cases, you give it over an hour (per package), may cause N/V and diarrhea, tendinitis and arthropathy (But rarely)

A

Fluoroquinolones- ciprofloxacin

54
Q

Which antimicrobial agent is an anti-protozoal, bactericidal that disrupts the electron transport, and is used in treatment for bacterial vaginitis/ trichomoniasis, C diff, abdominal infections, brain abscess, and has a disulfiram-like effect?

A

Metronidazole- Flagyl

55
Q

T or F. The 4 Protein Synthesis/ Ribosomal Agents are bacteriostatic ABXs.

A

False.

Tetracyclines, Erythromycin, and Clindamycin are bacteriostatic

Aminoglycosides (Gentamycin) is bacteriocidal

56
Q

T or F. Tetracyclines cause normal flora suppression -> overgrowth (bacterial, candidal).

A

true

57
Q

Which protein synthesis/ ribosomal agent causes C. Difficile?

A

Clindamycin

58
Q

Which ABX is characterized by the following?

ototoxicity (irreversible) and nephrotoxicity (mild)- give slowly to keep serum levels low

A

Gentamycin

59
Q

What ABX is characterized by the following:

bacteriostatic - Hits 2 steps in the conversion of PABA->THF (folic acid pathway)

A

Bactrim

60
Q

can pts who have sulfa allergies take Bactrim?

A

No

61
Q

What ABX disrupts the electron transport chain?

A

Metronidazole (Flagyl)

62
Q

Lis the 4 ABXs that cause C diff

A

PCNs
Cephalosporins
Clindamycin
Metronidazole (Flagyl)

63
Q

List the 4 ABXs that are teratogenic

A

tetracyclines, trimethoprim, metronidazole, fluoroquinolones

(TTMF - take that mother f’er)

64
Q

Which 2 ABXs are associated with ototoxicity?

A

Aminoglycosides and vancomycin

65
Q

What ABX is used to treat C diff?

A

Vancomycin

66
Q

T or F. Vancomycin is used for C. Diff, MRSA, and in pts w/ B-lactam allergies but is not effective for VRE?

A

True

67
Q

T or F. GI upset is most common with Tetracyclines and Macrolides.

A

True

68
Q

T or F. Neuromuscular blockade is seen with aminoglyccosides (in high doses) and more often with tetracyclines.

A

True

69
Q

T or F. Most people are not allergic to the B-lactam rings, they are allergic to the side chains.

A

True

Pharmacology (22 decks)

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