2. Antibiotics Flashcards

1
Q

what should you always consider before starting an antibiotic?

A
  • What is the most likely infecting organism?
  • Have a gram stain and C&S been done? What are the results?
  • Allergies?
  • Kidney function (check BUN and Cr)? Many antibiotics are renally metabolized so it is imperative to make sure the kidneys are functioning properly.
  • What medications is the patient currently taking? Be concerned of possible drug interactions.
  • Any other reason you may or may not want to give the antibiotic?
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2
Q

name that drug: Augmentin

A

amoxacillin/clavulonic acid

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3
Q

name that drug: Zosyn

A

piperacillin/tazobactam

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4
Q

name that drug: Unasyn

A

ampicillin/sulbactam

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5
Q

name that drug: Timentin

A

ticarcillin/clavulonic acid

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6
Q

name that drug: Zyvox

A

linezolid

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7
Q

name that drug: Invanz

A

ertapenem

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8
Q

name that drug: Cubicin

A

daptomycin

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9
Q

name that drug: Tygacil

A

tigecycline

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10
Q

name that drug: Bactrim

A

trimethoprim/sulfamethoxazole

(TMP/SMX)

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11
Q

name that drug: Rocephin

A

ceftriaxone

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12
Q

name that drug: Avelox

A

moxifloxacin

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13
Q

name that drug: Zithromax

A

azithromycin

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14
Q

name that drug: Primaxim

A

imipenem/cilastatin

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15
Q

name that drug: Synercid

A

dalfopristin-quinupristin

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16
Q

name that drug: Cleocin

A

clindamycin

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17
Q

name that drug: Flagyl

A

metronidazole

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18
Q

augmentin: dosage(s)

A

500 or 875 mg PO BID

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19
Q

how much clavulonic acid is in Augmentin 500 mg?

Augmentin 875 mg?

A

both have 125 mg

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20
Q

augmentin: indication

A

PO antibiotic for outpatient therapy of polymicrobial infections

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21
Q

augmentin: spectrum of activity

A
  • Staph (not MRSA)
  • Strep
  • Enterococci
  • Gram negatives
  • anaerobes
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22
Q

does augmentin cover pseudomonas?

A

no

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23
Q

zosyn: dosage(s)

A
  • 3.375 g IV q6h
  • Renal dose – 2.25 g IV q6h
  • Alternate dose – 4.5 g IV q6h
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24
Q

zosyn: indication(s)

A

approved for use in adults for the treatment of moderate to severe diabetic foot infections

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25
Q

zosyn: spectrum of coverage

A
  • Staph (not MRSA)
  • Strep
  • Enterococci
  • Gram negatives
  • anaerobes
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26
Q

does zosyn cover pseudomonas?

A

Yes!

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27
Q

unasyn: dosage(s)

A
  • 3.0 IV q6h
  • Renal dose – 1.5 g IV q6h
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28
Q

unasyn: indication(s)

A

empiric therapy for polymicrobial diabetic foot infections

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29
Q

unasyn: spectrum of activity

A
  • Staph (not MRSA)
  • Strep
  • Enterococci
  • Gram negatives
  • anaerobes
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30
Q

does Unasyn cover pseudomonas?

A

No

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31
Q

what is an appropriate alternative to Unasyn for a patient with a Penicillin (PCN) allergy?

A
  • Clinda/Cipro
  • Levaquin
  • (there are others)
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32
Q

timenten: dosage(s)

A

3.1 g IV q4-6h

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33
Q

timentin: indication(s)

A

broad spectrum antibiotic for polymicrobial infections

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34
Q

timentin: spectrum of activity

A
  • Staph (not MRSA)
  • Strep
  • Gram negatives
  • anaerobes
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35
Q

does timentin cover pseudomonas?

A

Yes!

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36
Q

what should you watch for when giving Timentin?

A

Increased Na+ (sodium) load

(5.2 meq/gram)

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37
Q

penicillins that cover pseudomonas?

A
  • (4th and 5th generations)
  • piperacillin, Zosyn
  • ticarcillin, Timentin
  • carbenicillin, mezlocillin, azlocillin
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38
Q

what are IV alternatives for PCN allergic patients?

A
  • clindamycin
  • vancomycin
  • Levaquin
  • Bactrim
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39
Q

how are penicillins (PCNs) excreted?

A

All are renally excreted, *except:

  • mezlocillin
  • azlocillin
  • piperacillin
  • (the ureidopenicillins are 20-30% renal)
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40
Q

what concern is there of a patient on both PCN and probenecid?

A

probenecid will increase duration of serum levels of PCN and most cephalosporins

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41
Q

what is the cross-reactivity of cephalosporins and PCN?

A

1-10%

(depending on whom you talk to)

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42
Q

are cephalosporins contraindicated for a patient with a PCN allergy?

A
  • Many people will say yes, and according to Dr. Warren Joseph, “Cephalosporins should be avoided entirely in patients with a history of anaphylaxis to penicillin”
  • However, he states that if there is a questionable allergy history (rash or upset stomach), “Cephalosporins can be used with little worry”
  • Personally, I will give a cephalosporin to a patient with a PCN allergy if all he or she had was an upset stomach and I document this.
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43
Q

how to treat serious hospital-acquired Gram negative infections?

A
  • 3rd generation cephalosporins
  • aminoglycoside (i.e. Rocephin, gentamycin)
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44
Q

what is the coverage of cephalosporins for each class?

A

1st Generation

  • Gram positive – Staph (not MRSA) and Strep
  • Gram negative – Proteus, E. coli, Klebsiella, Salmonella, Shigella (PECKSS)
  • Anaerobes – not Bacteroides

2nd Generation

  • Gram positive – similar to 1st gen
  • Gram negative – more coverage, H. influenza, Neisseria, Proteus, E. coli, Klebsiella, Salmonella, Shigella (HEN PECKSS)

3rd Generation

  • Gram positive – less than 1st and 2nd gen
  • Gram negative – expanded coverage, ceftazadime covers Pseudomonas

4th Generation

  • Gram positive – similar to 1st gen
  • Gram negative – similar to 3rd gen, including Pseudomonas
  • No anaerobic coverage
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45
Q

what is the coverage of cephalosporins for 1st generation?

A

1st Generation

  • Gram positive – Staph (not MRSA) and Strep
  • Gram negative – Proteus, E. coli, Klebsiella, Salmonella, Shigella (PECKSS)
  • Anaerobes – not Bacteroides
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46
Q

what is the coverage of cephalosporins for 2nd generation?

A

2nd Generation

  • Gram positive – similar to 1st gen
  • Gram negative – more coverage, H. influenza, Neisseria, Proteus, E. coli, Klebsiella, Salmonella, Shigella (HEN PECKSS)
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47
Q

what is the coverage of cephalosporins for 3rd generation?

A

3rd Generation

  • Gram positive – less than 1st and 2nd gen
  • Gram negative – expanded coverage, ceftazadime covers Pseudomonas
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48
Q

what is the coverage of cephalosporins for 4th generation?

A

4th Generation

  • Gram positive – similar to 1st gen
  • Gram negative – similar to 3rd gen, including Pseudomonas
  • No anaerobic coverage
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49
Q

name a couple of cephalosporins for each generation

A

1st Generation – cefazolin (Ancef), cephalexin (Keflex)
2nd Generation – cefaclor (Ceclor), cefuroxime (Ceftin)
3rd Generation – ceftriaxone (Rocephin), ceftazidime (Fortaz), cefdinir (Omnicef)
4th Generation – cefepime (Maxipime)

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50
Q

cephalosporins: excretion

A

Renally, *EXCEPT for:

  • ceftriaxone (renal/hepatic)
  • cefoperazone (hepatic)
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51
Q

vancomycin: main indication

A

MRSA

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52
Q

vancomycin: spectrum of activity

A

All Gram positives,

including MRSA and MRSE

53
Q

vancomycin: dosage(s)

A

1 g IV q12h with slow infusion

54
Q

when are vancomycin levels drawn?

A
  • Peak taken 30 min after the 3rd dose
  • Trough taken 30 min before the 4th dose
55
Q

What should the vancomycin peaks and troughs be?

A

Peak: 15-30 mg/mL

Trough: < 10 mg/mL

56
Q

how do you adjust the vancomycin dose?

A
  • If the peak is too high, decrease the dose
  • If the peak is too low, increase the dose
  • If the trough is too high, increase the interval between doses
  • If the trough is too low, decrease the interval between doses
57
Q

what happens when you infuse vancomycin too quickly?

A

Red Man syndrome

  • erythema and pruritis to the head, neck, and upper torso.
  • It is caused by an anaphylactoid reaction where histamine is released by mast cells.

(A different Red Man syndrome is associated with excessive Rifampin that causes a bright reddish-orange pigmentation of the skin.)

58
Q

how can you decrease the risks of Red Man syndrome?

A

slow infusion over one hour

59
Q

how do you treat Red Man syndrome?

A
  • Antihistamines (Benadryl 25-50 mg IV q2-4h) until symptoms resolve
  • Symptoms are self-limiting
60
Q

in addition to red man syndrome, what are other side effects of vancomycin?

A
  • ototoxicity
  • nephrotoxicity
61
Q

does the duration a patient has been on vancomycin

increase the risks of side effects?

A

Yes.

Vancomycin has a reservoir effect: the more often a patient receives vancomycin, the higher the chance of getting either ototoxicity or nephrotoxicity. Therefore, use vancomycin carefully; it is a powerful drug with severe side effects.

62
Q

when should PO vancomycin be used?

A

treatment of Pseudomembranous colitis

(125 mg PO q6h)

63
Q

bactrim: dosage(s)

A

One tab PO BID

64
Q

how much is in the single strength tablet of bactrim?

double strength?

A
  • Single strength – TMP 80 mg / SMX 400 mg
  • Double strength (DS) – TMP 160 mg / SMX 800 mg
65
Q

bactrim: mechanism of action

A

trimethoprim and sulfamethoxazole inhibit folate synthesis in bacteria which prevents DNA replication

66
Q

bactrim: spectrum of activity

A

Broad spectrum covering Gram positives (MRSA) and Gram negatives

67
Q

does bactrim cover pseudomonas?

A

NO

68
Q

should avoid bactrim in patients with which allergy?

A

sulfa allergy

(should never use Bactrim in a patient with a sulfa allergy)

69
Q

bactrim: side effects

A
  • hemolytic anemia
  • hypersensitivity
70
Q

bactrim: contraindications

A
  • patient on oral hypoglycemic
  • or patient with G6PD deficiencies (glucose-6-phosphate dehydrogenase)
    • This enzyme helps red blood cells work correctly.
    • A lack of this enzyme can cause hemolytic anemia (when the red blood cells break down faster than they are made)
71
Q

zithromax: dosage(s)

A

250 mg PO, two tabs on the first day, then

one tab for the next four days

(5 days total)

72
Q

zithromax: spectrum of activity

A
  • Staph
  • Strep
  • some anaerobes (but not bacteroides)
73
Q

can you give Zithromax to a patient with a PCN allergy?

A

Yes

74
Q

zithromax: half-life

A

68 hours

75
Q

primaxin: dosage(s)

A

500 mg IV q6-8h (most common) or 1 gm IV q6-8h

76
Q

primaxin: spectrum of activity

A

Very broad spectrum including most Gram positive, Gram negative, and most anaerobes

77
Q

does primaxin cover MRSA?

pseudomonas?

A

No and no!

78
Q

primaxin: side effects

A

Seizure in patients with history of seizures
1% risk with 500 mg dose, 10% risk with 1 g dose

79
Q

primaxin: mechanism of action

A
  • imipenem – antibiotic
  • cilastatin – renal dehydropeptidase inhibitor, which prevents imipenem from being metabolized by the kidneys
80
Q

which antibiotic is nicknamed “Gorillamycin”?

A

imipenem

(because of its very broad of spectrum activity)

81
Q

invanz: dosage(s)

A

1 g IV q24h

82
Q

invanz: indication

A

Approved for use in adults for the treatment of moderate to severe diabetic foot infections

83
Q

invanz: spectrum of activity

A
  • Gram positive
  • Gram negative
  • anaerobes
84
Q

does invanz cover pseudomonas?

A

No

85
Q

what class is invanz?

A

It is a structurally unique 1-β-methyl-carbapenem related to β-lactams

86
Q

zyvox: dosage(s)

A

400-600 mg PO/IV q12h

87
Q

zyvox: indication

A

Oral Zyvox may be used for outpatient treatment of MRSA infections

88
Q

zyvox: spectrum of activity

A
  • All Gram positives, including MRSA and VRE
89
Q

zyvox: major side effect

A

Thrombocytopenia (check CBC)

a condition characterized by abnormally low levels of platelets, also known as thrombocytes, in the blood

90
Q

why isn’t zyvox used more often?

A

it is expensive

91
Q

list some common quinolones

A
  • ciprofloxacin (Cipro)
  • levofloxacin (Levaquin)
  • moxifloxacin (Avelox)
92
Q

cipro (ciprofloxacin): dosage(s)

A
  • 250-750 mg PO q12h
  • 200-400 mg IV q12h
93
Q

levaquin (levofloxacin): dosage(s)

A

250-500 mg PO/IV q24h

94
Q

Avelox (moxifloxacin): dosage(s)

A

400 mg PO/IV q24h

95
Q

quinolones: spectrum of activity

A
  • Gram negative, including Pseudomonas
  • Ciprolimited Gram positive
  • Levaquin and Aveloxbetter Gram positive
96
Q

quinolones: side effects

A

Tendonitis and tendon ruptures

97
Q

which patients should NOT be given quinolones?

A
  • quinolones are contraindicated in children with open growth plates
  • Risk of cartilage degeneration
98
Q

aztreonam: dosage(s)

A

1-2 g IV q8h

99
Q

aztreonam: spectrum of activity

A

Gram negative aerobes and pseudomonas

(pseudomonas is its main indication)

100
Q

aztreonam: major side effects

A

None

101
Q

why isn’t aztreonam used more often?

A

it is expensive!

102
Q

name some major aminoglycosides

A

TAG

  • Tobramycin
  • Amikacin
  • Gentamycin
103
Q

aminoglycosides: spectrum of activity

A

gram negative aerobes

104
Q

aminoglycosides: side effects

A
  • Ototoxicity – irreversible
  • Nephrotoxicity – reversible
  • Neuromuscular blockade – prevented by slow infusion
105
Q

what are the doses, peaks, and troughs of the aminoglycosides?

A
106
Q

gentamycin: dosage(s)

A
  1. Loading dose is 2 mg/kg for Gent and Tobra (7.5 mg/kg for Amikacin)
  2. Determine creatinine clearance (CC)
    • CC = (140 - Age) x Weight (in kg)
      • 72 x Serum Creatinine
    • For females, multiply the CC by 0.85
  3. Maintenance dose is adjusted for CC
    • (e.g. If the CC is 0.75, then the patient has 75% kidney function. Give 75% of a normal dose.)
107
Q

clindamycin: dosage(s)

A

600-900 mg IV q8h OR

150-300 mg PO BID

108
Q

clindamycin: spectrum of activity

A

most gram positive and most anerobes

109
Q

clindamycin: side effect

A

pseudomembranous colitis

110
Q

clindamycin: how is it metabolized?

A

by the LIVER

111
Q

flagyl: dosage(s)

A

500 mg PO TID

112
Q

flagyl: spectrum of activity

A

Some Gram positive anaerobes and most Gram negative anaerobes

113
Q

which antibiotics cover MRSA?

A
  • PO – linezolid, Minocycline, Cipro/rifampin, Bactrim/rifampin
  • IV – vancomycin, linezolid, minocycline, Cipro/rifampin, Bactrim/rifampin, Synercid, tigecyclin, telavancin
  • Topical – Bactroban
114
Q

what are the only FDA-approved drugs for treating MRSA?

A
  • vancomycin
  • linezolid
  • daptomycin
  • tigecyclin
  • telavancin (Vibativ)
115
Q

how do you treat VRE?

(VRE = vancomycin-resistant enterococci)

A
  • linezolid or
  • dalfopristin-quinupristin
116
Q

what is the only PO therapy for VRE?

(VRE = vancomycin-resistant enterococci)

A

linezolid

117
Q

what drugs cover pseudomonas?

A
  • Aztreonam
  • Aminoglycosides – gentamycin, tobramycin, amikacin
  • Cipro
  • Ceftazidime, cefepime
  • Timentin
  • Zosyn
118
Q

what are some empiric therapies for polymicrobial foot infections?

A
  • Vanco/Zosyn
  • Clinda/Cipro
  • Vanco/Invanz
119
Q

what are the only FDA-approved drugs for treating diabetic foot infections?

A

(The 3 Z’s)

  • Zosyn
  • Zyvox
  • Invanz
120
Q

what are two main causes of antibiotic-associated diarrhea?

A
  • (1) Pseudomembranous colitis – Clostridium difficile
  • (2) Non-specific colitis – Staph aureus
121
Q

how to test for Clostridium difficile?

A

Order “check stool for C diff”

122
Q

what is the most common cause of Clostridium difficile colitis?

A

clindamycin

(though any antibiotic can cause it)

123
Q

how do you treat clostridium difficile colitis?

A
  • Vanco 125 mg PO q6h
  • Flagyl 500 mg PO TID
124
Q

which antibiotics are metabolized by the liver?

A

(3 C’s and 1 E)

  • Clindamycin
  • Cefoperazone
  • Chloramphenicol
  • Erythromycin
125
Q

can antibiotics affect PT/INR?

A

Yes.

Antibiotics can affect normal flora, which alters Vitamin K.

Therefore, the PT/INR can increase.

126
Q

β-lactams: side effects

A

Leukopenia

(a reduction in the number of white cells in the blood, typical of various diseases)

127
Q

aminoglycosides: mechanism of action

macrolides: mechanism of action

A

(A boy at 30 does not become a Man until 50)

  • Aminoglycosides bind to bacterial 30s ribosomes inhibiting protein synthesis
  • Macrolides bind to bacterial 50s ribosomes inhibiting protein synthesis
128
Q

which antibiotics can be safely used with PMMA beads?

(Recall: Polymethyl methacrylate beads)

A
  • Vancomycin
  • Gentamycin
  • Tobramycin
  • Cefazolin

The curing of PMMA is exothermic, therefore the antibiotic must be not be heat-labile

129
Q

what open fractures should be treated with antibiotics?

A

Grades 2 and 3 open fractures should be treated with antibiotics