Antibiotics Flashcards
(168 cards)
1
Q
What is the process for abx (antibiotic) selection?
A
- Establish presence of infection
- Identify site of infection
- Direct Empiric antibiotic tx towards likely organism
- Identify primary pathogen(s) in the specific pt.
- Choose the most appropriate antibiotic for the PATHOGEN, SITE OF INFECTION, AND PATIENT
2
Q
What will a gram stain tell you?
A
Solubility and shape
3
Q
What will cultures and sensitivities tell you?
A
What abx is the pathogen sensitive to/ what is it resistant to
What the pathogen is
Quantity of the pathogen
4
Q
What are the three key things that need to be considered when choosing the most appropriate antibiotic for a pt?
A
- Pathogen
- Site of infection
- Patient (age, renal function, allergies etc)
5
Q
t/f? In order to properly identify the infecting pathogen it is good to obtain a culture shortly after starting the pt on an antibiotic?
A
F. Obtain culture samples prior to abx therapy
6
Q
t/f? You should always perform blood cultures with any type of infection?
A
F. You should obtain blood cultures on all acutely ill febrile pt’s. Not every infection warrants a blood culture.
7
Q
How do gram negative cells appear on microscopy?
A
RED: Decolorized by alcohol and take on the red color when counterstained with safranin
8
Q
How do gram positive cells appear on microscopy?
A
VIOLET: not decolorized by the alcohol so they retain the violet color.
9
Q
What might be indicated by presence of epithelial cells on a sputum culture?
A
A bad sample, especially when multiple organisms are identified.
10
Q
What might recovery of Staph. epidermindis or Corynebacterium from a sterile sample such as CSF, blood, or joint fluid indicate?
A
Contamination. These are bacteria usually found on the skin
11
Q
What does the term infection refer to in a culture report?
A
The isolated organisms are from the specimen and causing the infection.
12
Q
What does the term colonization refer to in a culture report?
A
Isolated organisms are from the specimen but are NOT causing the symptoms.
13
Q
What does the term contamination refer to in a culture report?
A
The isolated organisms came from the pt’s skin/environment
14
Q
How soon can you expect results from a C&S?
A
about 24-48 hours
15
Q
What does a C&S provide?
A
The final identification of the organism and information on the effectiveness of antimicrobials.
16
Q
How are results in a C&S reported?
A
S-Sensitive
R-Resistant
I-Intermediate
17
Q
What must you consider when identifying what medication will work for a specific pathogen?
A
Antimicrobial spectrum of activity, susceptibility testing, and local susceptibility patterns.
18
Q
Define minimum inhibitory concentration (MIC)
A
The lowest serum antimicrobial concentration that prevents visible growth of an organism
19
Q
Define Susceptibility relative to MIC
A
You can get enough drug into the patient to t the infection (MIC<attainable serum levels)
20
Q
Define intermediate susceptibility relative to MIC
A
You may not be able to get enough drug into the pt to tx the infection unless the drug is safe enough to give in high doses or the drug concentrates exceptionally well at the infection site (MIC~/= attainable serum levels)
21
Q
Define resistance relative to MIC
A
You cannot get enough drug into the pt to tx the infection (MIC>attainable serum levels)
22
Q
What drug factors should you consider when prescribing an Abx?
A
Clinical efficacy (does the drug reach the site of infection) Antimicrobial spectrum Available routes of admin. cost Bactericidal vs. bacterostatic P'kinetics, and P'dynamics Safety (concerns with preg. etc.)
23
Q
What are “time dependent killers”?
A
killing is dependent upon the amount of time the organism is in contact with the drug. So the duration that drug concentrations are above the MIC is important.
24
Q
What are “concentration dependent killers”?
A
Killing is dependent upon the concentration of the drug that organism is exposed to. The higher the concentration the greater the killing.
25
When is synergy, or the use of 2 abx used together, used?
enterococcus endocarditis or bacteremia, sepsis, pseudomonal infeections
26
Define post antibiotic effect (PAE)
Organism growth is suppressed for a period of time after the drug concentration falls below the MIC.
27
What are the two types of antibiotic resistance?
1. Intrinsic resistance
| 2. Acquired resistance
28
Define intrinsic resistance
Naturally occurring resistance (drug cannot penetrate the organisms cell wall)
29
Define acquired resistance
A normally sensitive organism becomes resistant
30
What mechanisms cause acquired resistance?
- Detoxifying enzymes - alter antibiotic structure and function (ex. ESBL Beta Lactamase - breaks down the beta-lactam ring of pan antibiotics)
- Alteration in antibiotic target site- (Ex MRSA)
- Decreased cellular accumulation of abx. (impaired influx-decreased permeability, and enhanced eflux)
31
What type of infection is IV admin most often used?
1. Severe infections: endocarditis, meningitis, sepsis, osteomelitis
2. When pt can't tolerate oral meds or has non-functioning GI tract
32
MOA Beta-Lactams
Bind to penicillin binding proteins and inhibit cell wall synthesis causing cell death.
33
What are the 4 subclasses of PCN?
Natural PCN
Aminopenicillins
Penicillinase resistant PCN
Extended spectrum PCN
34
What do Natural PCN cover (Gram +/-, anaerobes?)
Gram +, a few Gram -
35
What do Aminopenicillins cover (Gram +/-, anaerobes?)
Gram +, some Gram -
36
What do Penicillinase resistant penicillins cover (Gram +/-, anaerobes?)
Gram + only
37
What do extended spectrum penicillin /beta-lactamase combo cover (Gram +/-, anaerobes?)
Gram +, Gram -, and anaerobes
38
What medications are Natural PCN?
PCN VK
| PCN G
39
What is the spectrum of activity for PCN VK and PCN G? and what is the most common use?
GRAM +: Strep Pyogenes
| Some Gram -: Pharyngitis, erysipelas, and syphilis (PCN G)
40
T/F >90% of staph produce penicillinase so PCN is not effective
TRUE
41
What medications are Aminopenicillins?
| What are the most common uses?
Ampicillin
Amoxicillin (amoxicillin/clavulanate)
URI, Enterococcal infection, amox/clavulunate used for skin infections, UTI, CAP, Lymphadenitis
42
What meds are penicillinase resistant penicillins?
Dicloxacillin
Nafcillin-IV
Oxacillin-IV
Methacillin (pulled from market)
43
What bacteria does PCNase resistant PCN cover?
| What are the most common uses.
Gram Positive; Staphylococcus spp, and Streptococcus spp.
Drug of choice for B-lactam producing staph
Used to tx - cellulitis, endocarditis
44
What are extended-spectrum penicillins?
Tirarcillin/clavulanate
Piperacillin/tazobactam
*the "big guns" only available IV
45
What bacteria do Extended-sepctrum pcns cover?
| Common uses?
Gram positive: Streptococcus, Staphylococcus (MSSA)
Gram negative: Enterobacteriaceae (E. Coli, proteus)
Anaerobes: Bacteriodes
Nosocomial pneumonia, Intra-abdominal infections, Skin and soft tissue infections
46
MOA for B-lactamase inhibitors?
Enhances the antimicrobial activity against certain beta-lactamase producing organisms, extending the abx antimicrobial spectrum
47
What bacteria are covered by B-lactamase inhibitors?
Gram positive-S. aureus
Anaerobes-bacteriodes sp.
Gram negative- H. flu, E coli
48
ADE PCN
Rash
Anyphylaxis, angioedema
Ampicillin/amoxicillin - GI upset/diarrhea
49
Options for management of PCN allergy?
Option 1 - administer a cephalosporin
Option 2 - Prescribe/recommend a non beta-lactam abx.
Option 3 - Perform pcn desensitization
Option 4 - Perform a PCN skin test 80-95% of
50
What are the renal adjustments for PCN's
Must adjust for PCN, Amoxicillin/ampicillin
| No adjustment for Dicloxacillin, nafcillin, oxacillin
51
What DI does Probenecid have with PCN?
Probenecid decreases the renal tubular secretion of PCN's co-admin causes increased serum levels of abx.
52
```
Which of the following abx would be the best choice for treatment of cellulitis caused by Staph aureus (MSSA)?
A. Amoxicillin
B. Piperacillin/tazobactam
C. Penicillin
D. Nafcillin
```
D. Nafcilin-Is a PCNase resistant PCN and is drug of choice for B-lac producing staph
Amox-is broken down by B-lac
Piperacillin/tazo is empiric and very broad-an option but not specific enough
PCN-is broken down by B-lac
53
What are the 5 groups of Cephalosporins?
```
1st gen
2nd gen
3rd gen
4th gen
Newer gen
```
(4th and newer gen are IV only)
54
Which drugs are first generation cephalosporins?
Cephalexin-oral
| Cefazolin-IV
55
What drugs are 2nd generation cephalosporins?
Cefuroxime-oral
| Cefoxitin-IV
56
What drugs are 3rd gen Cephalosporins?
Cefpodoxime-oral
| Ceftriaxone-IV
57
What drugs are 4th gen cephalosporins?
Cefepime-IV
58
Newer gen
IV only
59
What do first gen cephalosporins cover?
Gram positive
| some Gram negative
60
What do 2nd gen cephalosporins cover?
Gram pos
| some increased gram neg
61
What do 3rd gen cephalosporins cover?
Less gram positive
| More gram neg
62
What do 4th gen cephalosporins cover?
Gram pos
| Gram neg
63
What is the spectrum of activity for First gen cephalosporins?
Gram positive: Staphlococcus, Streptococcus spp.
Gram negative: Proteus, Escherichia coli, Klebsiella pneumoniae
(SPEcK)
64
What are the common uses for first gen cephalosporins?
Mild skin or soft tissue infections
65
What is the spectrum of activity for 2nd gen cephalosporins?
Gram positive: Staphlococcus, Strepococcus spp.
Gram Negative: H. flu, Moraxella catarrhalis, Proteus mirabilis, E. coli, Klebsiella pneumo.
(HMSPEcK)
66
What is the spectrum of activity for 3rd gen cephalosporins?
Gram positive: Strep pneumo
| Gram Negative: Enterobacteriaceae, H. flu, Moraxella catarhalis.
67
Common uses for 3rd gen cephalosporins?
CAP
OM
URI
68
Spectrum of activity for 4th gen cephalosporins?
| Common uses?
Gram +, Gram -, Anaerobes
Nosocomial infections
69
Which cephalosporins require renal adjustment
1st gen
2nd gen
3rd gen?
all of them.
70
What class of medications have similar adverse reactions to cephalosporins?
PCN
71
What special considerations need to be made when taking cephalosporin?
Take with food
72
What is the cross sensitivity rate for PCN allergic patients with cephalosporins?
~3-7%
73
What effect does probenicid have on concetrations of cephalosporins?
Increases concentrations
74
MOA for Monobactams?
Bind to pcn binding protein and inhibit cell wall synth which leads to cell death.
75
What is the only monobactam available in the USA?
Aztreonam.
76
What are the administration forms of aztreonam?
IV or IM admin
77
t/f Doses must be adjusted for renal function with aztreonam?
T
78
MOA carbapenems?
Bind to PCN binding protein and inhibit cell wall synthesis which leads to cell death.
79
What medications are Carbapenems?
Imipenem/cilastin
Meropenem
Doripenem
Ertapenem
80
What are carbapenems the drug of choice for?
They are resistant to most beta-lactam and are the drugs of choice for infections caused by ESBL's
81
Are there any dose adjustments for carbapenems?
yes-renal function
82
What is MOA for glycopeptide abx?
Prevents cross-linking of the cell wall peptidoglycan during cell wall synthesis
83
What medications are glycopeptides?
Vancomycin
Telavancin
Dalbavancin
oritavancin
84
What is Vancomycin most commonly used for?
MRSA-sepsis, endocarditis etc.
85
What forms of admin exist for vancomycin?
PO - only used for C. Diff bc. oral dosage is not absorbed.
| IV
86
What is red man syndrome?
Vancomycin, Telavancin, infusion related rxn that is caused by the release of histamine. Erythematous urticarial reactions, flushing, tachycardia, hypotension. This is NOT an allergic rxn.
87
What is the management of red man syndrome?
Stop infusion and wait for sx to subside. Then restart but slow infusion rate down. May admin Benadryl prior to to help.
88
What is the Black Box warning for Telavancin?
May cause abnormal fetal development. Preg test should be performed on women of child bearing age.
89
What is Telavancin used for?
Complicated skin and soft tissue infection and nosocomial pneumonia.
90
"other" cell wall/membrane active agents?
Daptomycin
fosfomycin
bacitracin
cycloserine
91
What is the spectrum of activity for daptomycin?
Vacnomycin resistant enterococci (VRE) and Vanco intermediate and resistant S. aureus (VRSA)
92
What is common use of Daptomycin?
skin/soft tissue infection, bacteremia, endocarditis (not pneumonia)
93
What must you monitor when placing a pt on Daptomycin?
CPK and d/c drug if muscle pain and elevation of CPK >5x ULN occurs.
94
Fosfomycin: formulation, coverage, usage?
Oral form, gram neg and gram pos, UTI's in women
95
Bactiracin: form, caution, usage?
Topical only, highly nephrotoxic if given IV, tx surface lesions on skin or irrigation of wounds
96
Cycloserine: Coverage, Usage, ADE
Gram pos, and gram neg, TX of TB, serious ADE-headaches, tremors, acute psychosis.
97
What is the MOA of tetracyclines (TCNs)
TCN binds to the 30S ribosomal subunit, which prevents binding of tRNA to the mRNA-ribosome complex, this interfering with protein synthesis
98
What medications are TCN's
Tetracycline (TCN)
Minocycline
Doxycycline
99
What do TCNs cover?
| Common uses?
Gram +: S. pneumo, S. pyogenes, CA-MRSA
Gram -: Ecoli, Klebsiella etc.
Atypicals-chlamydia etc.
Resp. infection
CA-MRSA
Doxycycline-anthrax, chlamydia, lyme, CA-MRSA
100
What are the possible ADE of TCN's
Tooth discoloration, and abnormal bone growth-Do no use in second 1/2 of pregnancy or in children
101
What are the special considerations when taking TCN
Admin must be separated from food containing aluminum, magnesium , calcium, and iron by at least 1-2 hours.
Careful with this because this is tricky!!!
- Minocycline-take w/wout food
- TCN-take on an EMPTY STOMACH
- Doxycycline- take WITH FOOD due to GI intolerance (crackers by not milk)
102
Which of the 3 TCN's mentioned does not require renal adjustment?
Doxycycline
103
Tigecycline: Efficacy, admin form, class?
works for MRSA, MRSE, VRE, PCN resistant strep pneumo, IV only (very very broad spectrum), Derivative of minocycline,
104
What is the MOA of macrolides?
Bind to the 50S ribosomal subunit, inhibiting bacterial protein synthesis.
105
What medications are macrolides?
Erythromycin
Clarithromycin
Azithromycin
Fidaxomicin
106
What is the spectrum of activity for E-mycin, C-mycin, and Az-mycin?
Common use?
Gram pos: Streptococcus
Gram Neg: H. flu
Atypicals-mycoplasma etc.
Alternative for PCN allergic pts, CAP
107
What is the only bacteria that Fidaxomicin is approved for?
C. diff
108
ADE of E-mycin, A-mycin, C-mycin?
N/V, Abd pain, Diarrhea, renal failure,
***QT prolongation (if tx for CAP b/c of atypicals Doxycycline is a good alternative)
109
ADE Fidaxomicin?
GI-mc
Hematologic (rare)-anemia, neutropenia
110
DI for erythromycin and Clarithromycin?
metablized via Cyt-p450 so can cause increase concentrations of theophylline, warfarin, cyclosporine
111
What might Azitromycin cause in regards to digoxin and cyclosporine levels?
increase
112
clindamycin MOA
same as macrolides-binds to 50S ribosomal subunits of bacteria, which inhibits protein synthesis
113
What bacteria does Clindamycin cover?
| and MC uses?
Staph aureus (CA-MRSA and MSSA)
Anaerobes
skin and soft tissue infection (CA-MRSA), Alternative for dental prophylaxis in PCN allergic pt.s
114
ADE Clindamycin?
GI upset, skin rash
HIGHER INCIDENCE OF C. DIFF ASSOCIATED DIARRHEA vs. other abx.
Hepatotoxicity
115
What special considerations regarding food are made when taking Clindamycin?
Admin w/ food decreases GI upset
| Admin w/ full glass of water dec. esophageal ulceration
116
Linezolid: MC use?
MRSA or Vanco resistant E. faecium-Very very expensive and second choice to Vanco
117
What meds must you closely monitor levels of when giving a Linezolid with them?
SSRI's.
118
Benefits and drawbacks to prescribing Linezolid?
It is extremely effective (99.5%) against staph aureus, has great pulm penetration. Oral formulation is 100% bioavailable (Vanco is not available PO).
Drawbacks: Risk of optic neuropathy, Thrombocytopenia, although oral form is available it is very expensive and not always covered by insurance.
119
MOA aminoglycosides?
inhibits protein synthesis by binding to the 30S ribosomal subunit.
120
What medications are Aminoglycoside?
```
Gentamincin-IV
Tobramycin-IV
Amikacin-IV
Streptomycin-IV (rarely used)
Neomycin-topical (PO prep for bowel surgery, and hepatic encephalopathy)
Kanamycin-topical only
```
121
What bacteria do Gentamicin, Tobramycin, and amikacin cover?
| MC uses?
Gram pos: staph aureus
Gram neg: bacilli coverage
Rarely uses alone esp. with gram pos
(synergistic with PCN or Vanco for bacterial endocarditis)
122
ADE of aminoglycosides?
Ototoxicity, Nephrotoxicity: monitor renal function and serum drug concentrations every few days.
123
What are the benefits of extended interval dosing?
```
Probable reduced nephrotoxicity
Decreased lab monitoring
No risk of sub-therapeutic peak level
Decreased-pharm and nursing times
Easier for home care doses
```
124
What is the MOA for sulfonamides?
Competitive antagonist of para-aminobenzoic acid (PABA) which prevents formation of folic acid (folic acid is necessary for amino acid production)
125
What medications are Sulfonamides?
Sulfisoxazole
| Sulfamethoxazole/trimethoprim (Bactrim)
126
What bacteria do sulfonamides cover?
| MC use?
Gram positive: staph, S. pneumo
Gram neg: E coli
Atypicals: Chlamydia
MC use:
Sulfamethazole-trimethoprim IS FIRST LINE for CA-MRSA, PCP tx and prophylaxis
127
ADE sulfonamides?
```
Photosensitivity
N/V/D
Derm-rash, SJS, TENS
Hemolytic anemia
"sulfa allergies" are common
```
128
Special instructions for pt's taking sulfonamides?
Admin-Instruct pt to drink plenty of fluids
129
DI for sulfa meds:
numerous, Warfarin can increase INR
| Methotrexate, phenytoin, digoxin
130
MOA fluoroquinolones
Inhibit bacterial topoisomerase II (DNA gyrase) and IV thereby blicking DNA synthesis
131
What medications are Fluoroquinolones?
```
Ciprofloxacin
Ofloxacin
Norfloxacin
Levofloxacin
Moxifloxacin
```
132
What do Cipro, Oflo, and Norfloxacin cover?
| MC use?
Gram neg: Enterobacteriaceae, H. Flu,
Pseudomonas (CIPRO ONLY)
Complicated and uncomplicated UTI's
133
What do Levo, Moxifloxacin and ophthalmic Gatifloxacin cover?
MC Use?
Gram positive: Strep pneumo (Including PRSP)
Gram negative: Enterbacteriaceae, H. flu, M. catarrhalis, Pseudomonas(levofloxacin)
Similar to second gen plus CAP and UTI
Moxifloxacin is not used to tx UTI
134
ADE Fluoroquinolones
```
N/V/D/C
Photosensitivity
Hepatotoxicity
Hypoglycemia/hyperglycemia
QT Prolongation
```
135
Black box warning fluoroquinolones
Tendonitis or tendon rupture-higher risk in elderly, renal insuff., and concurrent steroid use.
136
What are the indications for use of fluoroquinolone in pregnant females?
C and NOT recommended when breast feeding!!
137
Administration of fluoroquinolones:
asorption reduced when administered with magnesium, calcium, aluminum, iron, zinc-separate by at least 2 hours.
138
DI of fluoroquinolones
Increases INR when given with Warfarin (monitor closely)
| Avoid use with other meds that prolong QT interval-Cipro least likely, Moxi most likely.
139
Metronidazole spectrum of activity
Protozoa and anaerobes-Bacteriodes group. C. diff
140
common use for Metronidazole
Intrabd infection, gyencologic infectsion, pseudomembranous colitis caused by C. diff
FIRST LINE FOR C. DIFF!!!
141
ADE metronidazole
Gi-N/V, xerostomia, anorexia, abd pain
| CNS-Peripheral neuropathy, seizures, encephalopathy, - must discontinue
142
Admin of metronidazole
Extended release-admin on empty stomach at least 1 hour before or 2 hours after meals
143
DI metronidazole?
Ethanol-avoid alcohol during and 3 days after
Increase INR when on Warfarin
May increase concentrations of Phenytoin
144
Nitrofurantoin MC use?
UTI-VERY good option for UTI- 96% E.coli susceptible with nitro vs. 87% with bactrim
145
When is it not OK to use Nitrofurantoin?
CrCl less than 60mL/min (not good for use in elderly pt's)
146
Admin of nitrofurantoin?
Food or milk may enhance GI tolerance
147
ADE Nitrofurantoin?
GI: N/V
| Serious AE with long term tx-hepatotoxicity, and pulmonary toxicity-avoid in elderly
148
DI Nitrofurantoin?
Probenecid increases serum conc.
149
T/F pt's who are allergic to PCN are thought to have a 15% chance of also being allergic to cephalosporin?
F - only about a 3-7% chance. Cephalosporins should be considered second line unless the pt has anaphylaxis to the PCN.
150
```
Which of the following fluoroquinolones does not require dose adjustment for renal insufficency?
A. Moxifloxacin
B. Levofloxacin
C. Ciprofloxacin
D. Norfloxacin
```
A-Moxifloxacin
151
List the commonly used ABX that DO NOT require renal dosage adjustments:
```
Ceftriaxon
Metronidazole
Clindamycin
Nafcillin/oxacillin/dicloxacillin
Azithromycin
Doxycycline
Moxifloxacin
```
152
How many drugs are needed to tx. and prevent resistant strains of TB.
A minimum of 2 drugs , usually 3/4 must be used simultaneously to prevent resistance in TB
153
How long is the tx duration at minimum for TB tx.?
6mos minimun, up t 2-3 years for multi drug resistant TB (MDR TB)
154
What are the two drugs that are the preferred first line agents for TB?
Isoniazid
| Rifampin
155
What is the typical 4 drug regiment - with time line for TB tx?
Isoniazid-6mos
Rifamipin-6mos
Ethambutol-first 2 mos.
Pyrazainamide-first 2 mos.
156
MOA Isoniazid IV and PO?
Inhibit biosynthesis of mycolic acid-a necessary component of cell wall
157
Administration and synergistic medication for Isoniazid?
Administer with Pyridoxine 10-50mg / day to minimize adverse CNS effects
158
Spectrum of activity for isoniazid?
mycobacterium
159
ADE for Isoniazid?
CNS-peripheral neuropathy if not given with pyridoxine
Hepatitis
GI distress, xerostomia, hyperglycemia, metabolic acidosis, urine retetnion,
160
DI isoniazid?
Separate admin from antacids by 1 hour
INH may increase conc. of benzodiazepines, carbamepazine, and phenytoin
INH inhibits monoamine oxidase so use avoid co-admin wit other MAO inhibitors
161
MOA Rifampin IV and PO?
Inhibits RNA synthesis by binding to beta subunit of RNA polymerase
162
Spectrum of activity for Rifampin?
Gram neg and gram pos cocci, mycobacteria, chlamydia-resistance develops quickly-not to be used as mono therapy.
163
Uses for rifampin?
TB tx and prophylaxis, leprosy, MRSA, MSSA, eliminates meningococcal carriage, prophylaxis of H. flu type B.
164
ADE rifampin?
Change body fluid color-tears, sweat, urine
GI: NVD
Flu like symptoms-fever, chills, myalgia
Renal-interstitial nephritis, glomerulonephritis, nephrotic syndrome
165
DI rifampin?
Inducer of CYP 450 enzymes-significant DI's
| has been shown to decrease effectiveness of oral contraceptives!!!
166
ADE Ethambutol
```
Optic neuritis
Pulm infiltrates
Hepatotoxicity
GI: N/V/D
Not many DI's-separate from aluminum by 4 hours
```
167
spectrum of activity for Pyranzinamide?
Active Vs. only mycobacterium tuberculosis
168
ADE for Pyranzinamide?
Hepatotoxicity
Arthralgia (gout)
Hypersensitivity
