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?
2
Q
name that drug: Augmentin
A
amoxacillin/clavulonic acid
3
Q
name that drug: Zosyn
A
piperacillin/tazobactam
4
Q
name that drug: Unasyn
A
ampicillin/sulbactam
5
Q
name that drug: Timentin
A
ticarcillin/clavulonic acid
6
Q
name that drug: Zyvox
A
linezolid
7
Q
name that drug: Invanz
A
ertapenem
8
Q
name that drug: Cubicin
A
daptomycin
9
Q
name that drug: Tygacil
A
tigecycline
10
Q
name that drug: Bactrim
A
trimethoprim/sulfamethoxazole
(TMP/SMX)
11
Q
name that drug: Rocephin
A
ceftriaxone
12
Q
name that drug: Avelox
A
moxifloxacin
13
Q
name that drug: Zithromax
A
azithromycin
14
Q
name that drug: Primaxim
A
imipenem/cilastatin
15
Q
name that drug: Synercid
A
dalfopristin-quinupristin
16
Q
name that drug: Cleocin
A
clindamycin
17
Q
name that drug: Flagyl
A
metronidazole
18
Q
augmentin: dosage(s)
A
500 or 875 mg PO BID
19
Q
how much clavulonic acid is in Augmentin 500 mg?
Augmentin 875 mg?
A
both have 125 mg
20
Q
augmentin: indication
A
PO antibiotic for outpatient therapy of polymicrobial infections
21
Q
augmentin: spectrum of activity
A
- Staph (not MRSA)
- Strep
- Enterococci
- Gram negatives
- anaerobes
22
Q
does augmentin cover pseudomonas?
A
no
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
24
Q
zosyn: indication(s)
A
approved for use in adults for the treatment of moderate to severe diabetic foot infections
25
**zosyn:** spectrum of coverage
* Staph (not MRSA)
* Strep
* Enterococci
* Gram negatives
* anaerobes
26
does zosyn cover pseudomonas?
Yes!
27
**unasyn:** dosage(s)
* **3.0 IV q6h**
* _Renal_ dose – **1.5 g IV q6h**
28
**unasyn**: indication(s)
empiric therapy for polymicrobial diabetic foot infections
29
**unasyn**: spectrum of activity
* Staph (not MRSA)
* Strep
* Enterococci
* Gram negatives
* anaerobes
30
does Unasyn cover pseudomonas?
No
31
what is an appropriate alternative to Unasyn for a patient with a Penicillin (PCN) allergy?
* Clinda/Cipro
* Levaquin
* (there are others)
32
**timenten:** dosage(s)
**3.1 g IV q4-6h**
33
**timentin:** indication(s)
broad spectrum antibiotic for polymicrobial infections
34
**timentin:** spectrum of activity
* Staph (not MRSA)
* Strep
* Gram negatives
* anaerobes
35
does timentin cover pseudomonas?
Yes!
36
what should you watch for when giving **Timentin**?
Increased Na+ (sodium) load
| (5.2 meq/gram)
37
**penicillins** that cover pseudomonas?
* (4th and 5th generations)
* piperacillin, Zosyn
* ticarcillin, Timentin
* carbenicillin, mezlocillin, azlocillin
38
what are IV alternatives for PCN allergic patients?
* clindamycin
* vancomycin
* Levaquin
* Bactrim
39
how are penicillins (PCNs) excreted?
All are renally excreted, \*except:
* mezlocillin
* azlocillin
* piperacillin
* (the ureidopenicillins are 20-30% renal)
40
what concern is there of a patient on **both PCN and probenecid**?
probenecid will **increase duration of serum levels** of PCN and most cephalosporins
41
what is the cross-reactivity of cephalosporins and PCN?
1-10%
| (depending on whom you talk to)
42
are cephalosporins contraindicated for a patient with a PCN allergy?
* 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.
43
how to treat serious hospital-acquired Gram negative infections?
* 3rd generation cephalosporins
* aminoglycoside (i.e. Rocephin, gentamycin)
44
what is the coverage of cephalosporins for each class?
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
45
what is the coverage of cephalosporins for **1st generation**?
1st Generation
* Gram positive – Staph (not MRSA) and Strep
* Gram negative – Proteus, E. coli, Klebsiella, Salmonella, Shigella (PECKSS)
* Anaerobes – not Bacteroides
46
what is the coverage of cephalosporins for **2nd generation**?
2nd Generation
* Gram positive – similar to 1st gen
* Gram negative – more coverage, H. influenza, Neisseria, Proteus, E. coli, Klebsiella, Salmonella, Shigella (HEN PECKSS)
47
what is the coverage of cephalosporins for **3rd generation**?
3rd Generation
* Gram positive – less than 1st and 2nd gen
* Gram negative – expanded coverage, ceftazadime covers Pseudomonas
48
what is the coverage of cephalosporins for **4th generation**?
4th Generation
* Gram positive – similar to 1st gen
* Gram negative – similar to 3rd gen, including Pseudomonas
* No anaerobic coverage
49
name a couple of **cephalosporins for each generation**
1st Generation – cefazolin (Ancef), cephalexin (Keflex)
2nd Generation – cefaclor (Ceclor), cefuroxime (Ceftin)
3rd Generation – ceftriaxone (Rocephin), ceftazidime (Fortaz), cefdinir (Omnicef)
4th Generation – cefepime (Maxipime)
50
**cephalosporins:** excretion
**Renally**, \*EXCEPT for:
* ceftriaxone (renal/hepatic)
* cefoperazone (hepatic)
51
**vancomycin:** main indication
MRSA
52
**vancomycin**: spectrum of activity
All Gram positives,
including MRSA and MRSE
53
**vancomycin**: dosage(s)
1 g IV q12h with slow infusion
54
when are **vancomycin levels drawn**?
* **Peak** taken _30 min **after** the 3rd_ dose
* **Trough** taken _30 min **before** the 4th_ dose
55
What should the **vancomycin peaks and troughs** be?
**Peak: 15-30 mg/mL**
**Trough: \< 10 mg/mL**
56
how do you adjust the **vancomycin** dose?
* 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
what happens when you infuse **vancomycin** too quickly?
**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
how can you decrease the risks of Red Man syndrome?
slow infusion over one hour
59
how do you treat Red Man syndrome?
* Antihistamines (**Benadryl 25-50 mg IV q2-4h**) until symptoms resolve
* Symptoms are **self-limiting**
60
in addition to red man syndrome, what are other side effects of **vancomycin**?
* ototoxicity
* nephrotoxicity
61
does the **duration** a patient has been on vancomycin
**increase the risks of side effects**?
Yes.
## Footnote
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
when should PO vancomycin be used?
treatment of Pseudomembranous colitis
## Footnote
**(125 mg PO q6h)**
63
**bactrim:** dosage(s)
One tab PO BID
64
how much is in the **single strength tablet of bactrim**?
**double** strength?
* **Single strength – TMP 80 mg / SMX 400 mg**
* Double strength (DS) – TMP 160 mg / SMX 800 mg
65
**bactrim:** mechanism of action
trimethoprim and sulfamethoxazole **inhibit folate synthesis in bacteria** which prevents DNA replication
66
**bactrim:** spectrum of activity
Broad spectrum covering Gram positives (MRSA) and Gram negatives
67
does **bactrim** cover pseudomonas?
NO
68
should avoid **bactrim** in patients with which **allergy**?
sulfa allergy
*(should never use Bactrim in a patient with a sulfa allergy)*
69
**bactrim:** side effects
* hemolytic anemia
* hypersensitivity
70
**bactrim:** contraindications
* 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
**zithromax:** dosage(s)
**250 mg PO, two tabs on the first day**, then
## Footnote
**one tab for the next four days**
*(5 days total)*
72
**zithromax**: spectrum of activity
* Staph
* Strep
* some anaerobes **(but not bacteroides)**
73
can you give **Zithromax** to a patient with a PCN allergy?
Yes
74
**zithromax:** half-life
68 hours
75
**primaxin:** dosage(s)
**500 mg IV q6-8h** (most common) or **1 gm IV q6-8h**
76
**primaxin**: spectrum of activity
Very broad spectrum including most Gram positive, Gram negative, and most anaerobes
77
does **primaxin** cover MRSA?
pseudomonas?
No and no!
78
**primaxin:** side effects
Seizure in patients with history of seizures
1% risk with 500 mg dose, 10% risk with 1 g dose
79
**primaxin:** mechanism of action
* **imipenem** – antibiotic
* **cilastatin** – renal dehydropeptidase inhibitor, which prevents imipenem from being metabolized by the kidneys
80
which antibiotic is nicknamed "Gorillamycin"?
**imipenem**
(because of its very broad of spectrum activity)
81
**invanz:** dosage(s)
**1 g IV q24h**
82
**invanz:** indication
Approved for use in adults for the treatment of moderate to severe diabetic foot infections
83
**invanz**: spectrum of activity
* Gram positive
* Gram negative
* anaerobes
84
does **invanz** cover pseudomonas?
No
85
what class is **invanz**?
It is a structurally unique **1-β-methyl-carbapenem** related to β-lactams
86
**zyvox:** dosage(s)
**400-600 mg PO/IV q12h**
87
**zyvox**: indication
_Oral_ Zyvox may be used for **outpatient treatment of MRSA infections**
88
**zyvox**: spectrum of activity
* All Gram positives, including MRSA and VRE
89
**zyvox:** major side effect
Thrombocytopenia (check CBC)
*a condition characterized by abnormally low levels of platelets, also known as thrombocytes, in the blood*
90
why isn't **zyvox** used more often?
it is expensive
91
list some common **quinolones**
* ciprofloxacin (Cipro)
* levofloxacin (Levaquin)
* moxifloxacin (Avelox)
92
**cipro** (ciprofloxacin): dosage(s)
* 250-750 mg PO q12h
* 200-400 mg IV q12h
93
**levaquin** (levofloxacin): dosage(s)
**250-500 mg PO/IV q24h**
94
**Avelox** (moxifloxacin): dosage(s)
**400 mg PO/IV q24h**
95
**quinolones:** spectrum of activity
* Gram negative, including Pseudomonas
* **Cipro** – _limited Gram positive_
* **Levaquin and Avelox** – _better Gram positive_
96
**quinolones:** side effects
Tendonitis and tendon ruptures
97
which patients should NOT be given quinolones?
* quinolones are contraindicated in children with open growth plates
* Risk of cartilage degeneration
98
**aztreonam:** dosage(s)
**1-2 g IV q8h**
99
**aztreonam**: spectrum of activity
Gram negative aerobes and pseudomonas
## Footnote
*(pseudomonas is its main indication)*
100
**aztreonam:** major side effects
None
101
why isn't **aztreonam** used more often?
it is expensive!
102
name some major **aminoglycosides**
TAG
* Tobramycin
* Amikacin
* Gentamycin
103
**aminoglycosides:** spectrum of activity
gram negative aerobes
104
**aminoglycosides:** side effects
* **Ototoxicity** – irreversible
* **Nephrotoxicity** – reversible
* **Neuromuscular blockade** – prevented by slow infusion
105
what are the doses, peaks, and troughs of the aminoglycosides?
106
**gentamycin:** dosage(s)
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
**clindamycin:** dosage(s)
**600-900 mg IV q8h** OR
## Footnote
**150-300 mg PO BID**
108
**clindamycin:** spectrum of activity
most gram positive and most anerobes
109
**clindamycin:** side effect
pseudomembranous colitis
110
**clindamycin:** how is it metabolized?
by the LIVER
111
**flagyl:** dosage(s)
**500 mg PO TID**
112
**flagyl:** spectrum of activity
_Some_ Gram positive anaerobes and _most_ Gram negative anaerobes
113
which antibiotics cover **MRSA**?
* **PO** – linezolid, Minocycline, Cipro/rifampin, Bactrim/rifampin
* **IV** – vancomycin, linezolid, minocycline, Cipro/rifampin, Bactrim/rifampin, Synercid, tigecyclin, telavancin
* **Topical** – Bactroban
114
what are the only **FDA-approved drugs for treating MRSA?**
* vancomycin
* linezolid
* daptomycin
* tigecyclin
* telavancin (Vibativ)
115
how do you treat **VRE?**
## Footnote
*(VRE = vancomycin-resistant enterococci)*
* **linezolid** or
* **dalfopristin-quinupristin**
116
what is the only **PO therapy for VRE?**
## Footnote
*(VRE = vancomycin-resistant enterococci)*
**linezolid**
117
what drugs cover **pseudomonas**?
* Aztreonam
* Aminoglycosides – gentamycin, tobramycin, amikacin
* Cipro
* Ceftazidime, cefepime
* Timentin
* Zosyn
118
what are some _empiric therapies_ for **polymicrobial foot infections**?
* Vanco/Zosyn
* Clinda/Cipro
* Vanco/Invanz
119
what are the only _FDA-approved drugs_ for treating **diabetic foot infections**?
**(The 3 Z’s)**
* **_Z_**osyn
* **_Z_**yvox
* Invan**_z_**
120
what are two main causes of **antibiotic-associated diarrhea**?
* **(1) Pseudomembranous colitis – Clostridium difficile**
* (2) Non-specific colitis – _Staph aureus_
121
how to test for **Clostridium difficile**?
Order "check stool for C diff"
122
what is the **most common** cause of Clostridium difficile colitis?
**clindamycin**
| (though any antibiotic can cause it)
123
how do you treat clostridium difficile colitis?
* Vanco 125 mg PO q6h
* Flagyl 500 mg PO TID
124
which antibiotics are metabolized by the **liver**?
**(3 C’s and 1 E)**
* Clindamycin
* Cefoperazone
* Chloramphenicol
* Erythromycin
125
can antibiotics affect **PT/INR**?
Yes.
## Footnote
Antibiotics can affect normal flora, which alters Vitamin K.
Therefore, the PT/INR can increase.
126
**β-lactams:** side effects
Leukopenia
## Footnote
*(a reduction in the number of white cells in the blood, typical of various diseases)*
127
**aminoglycosides:** mechanism of action
**macrolides:** mechanism of action
**(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
which antibiotics can be safely used with **PMMA beads?**
*(Recall: Polymethyl methacrylate beads*)
* Vancomycin
* Gentamycin
* Tobramycin
* Cefazolin
The curing of PMMA is exothermic, therefore the antibiotic must be not be heat-labile
129
what open fractures should be treated with antibiotics?
Grades 2 and 3 open fractures should be treated with antibiotics
