Antimicrobials Flashcards

1
Q

What is MIC?

A

Minimum Inhibitor Concentration

The lowest concentration of antibiotic required to prevent growth

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2
Q

What is MBC?

A

Minimum Bacterial concentration

Lowest concentration required to kill bacteria

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3
Q

What is the action for bactericidal antimicrobials

A

Destroys bacterial cell wall

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4
Q

What is the action for bacteriostatic antimicrobials?

A

Stops bacteria from growing stops DNA synthesis of bacteria and halts production of new bacteria

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5
Q

What is the difference between narrow spectrum and broad spectrum antimicrobials?

A

Narrow spectrum kills specific types of bacteria

Broad spectrum kills every type of bacteria

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6
Q

Explain concentration dependent killing of bacteria?

A

Anitibiotic which increase the rate and extent of bacteria killing wih increased concentration

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7
Q

What type of antibiotics are concentration dependent killing antibitics?

A

Aminoglycosides

Fluoroquinolone

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8
Q

Explain time dependent killing of bacteria

A

Greater concentration do not kill vecteria faster. Clinical efficacy is related to the length of time for which high levels of concentration of the antibiotics are maintained

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9
Q

What types of antibiotics are considered time dependent killing antibiotics?

A

Beta lactams
monobactams (aztronam)
Macrolides (erythromycin, clindamycin)

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10
Q

T/F: Continuous infusion of antibiotics has shown to be more effective than intermittent boluses

A

FALSE

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11
Q

Some antibiotics continue to suppress the growth of bacteria after the antibiotc is no longer detectable. What is this known as?

A

Post antibiotic effect PAE

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12
Q

What is the post antibiotic leukocyte effect?

A

After the majority of the bacteria is killed the body can begin to start killing bacteria itself with its own leukocytes

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13
Q

What are the two types of resistance to antimicrobials?

A

Intrinisic - natural resistance to antimicrobial

Acquired - genetic alteration in the bacteria occurs which causes a once effective antimicrobial ineffective

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14
Q

Describe decreased permeability for resistance

A

The porins are altered which inhibits the antibiotic from entering the cell causing resistance to the antibiotic

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15
Q

Describe decreased efflux in antibiotic resistance

A

Cells will actually pump out the antibiotic - importance for macrolides, fluoroquinolones and some beta lactams

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16
Q

Describe inactivation in antibiotic resistance

A

Bacteria forms its own wnzymes which bust open the beta lactams and inactivates them - the enzyme is betalactamases

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17
Q

Which enzyme inactivates beta lactam antimicrobials?

A

Beta lactamase busts open the beta lactams an inactivates them causing resistance

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18
Q

What is an example of target modification in antimicrobial resistance?

A

The bacteria which is suseptable to penicilllin modifies its peniclillin binding proteins which disallow penicillin to bind to its receptors causing resistance to penicillin MRSA is an example

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19
Q

What is a positive reason to use multiple drug therapy?

A

More then 1 drug may be needed to treat infections. Broad spectrum agents may be able to adequately cover multiple organisms with a single agent

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20
Q

What is a negative outcome of muliple drug therapy

A

The unintended bacteria is introduced to antimicrobials and begins to produce antibodies against that antimicrobial leading to future resistance

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21
Q

What is an effective way to prevent resistant strains of organisms during mulidrug therapy?

A

Administer 2 antibiotic with different MOA to prevent resistance

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22
Q

What are the different synergies associated with multidrug therapy

A

Antagonist 1 +1 = 0.5

Indifferent 1 + 1 =1

Inbetween 1 +1 =1.5

Additive 1+1 = 1.5

Synergistic 1 + 1 = 3

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23
Q

Treatment of an infection with an effective therapeutic course of antimicrobial agents is based on what?

A

The right concentration of the right antimicrobial reaching the right site of action for a sufficient period of time to kill or inhibit bacterial growth

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24
Q

What is an antibiogram?

A

Antibiotics are tested against each known bacteria. Antibiograms list the degree of susceptibility and resistnace bacteria has to each antibiotic. Helps to choos the best antibiotic against a specific bacteria

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25
Q

What factos increase a patient risk for a specific type of infection?

A
Impaired host defenses: 
Anatomical neutropenia
aspleenia
malignancy
HIB
immunosuppression
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26
Q

In pregnant women which antibiotic causes acute necrosis of the live, pancreatitis, and possible renal failure and should be avoided?

A

Tetracycline

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27
Q

Which antibitiotic have been deemed safe for pregnancy?

A

Penicillins

Cephalosporins

Erythromycin

Aminoglycosides if necessary

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28
Q

In regards to nosocomial infections, where do most occur in the body?

A

urinary tract
respiratory
blood
Most in the urinary tracct - staph aureus is most common

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29
Q

What devices are highly associated with nosocomial infections

A

Ventilators

Urethral catheters

vascular access catheters

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30
Q

A catheter related infections is defined how

A

At least 1 positive blood culture drawn from both a catheter and a peripheral site

A positive culture drawn through a catheter is nonspecific but a negative culture drawn through a catheter rules out a catheter related infection

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31
Q

What sites of cntral line insertion are associated with the highest rates of infection?

A

Femoral
internal jugular
subclavian

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32
Q

Which antibiotic should first be used to treat catheter related infections?

A

Vancomycin due to the high prevalence of methicillin reistant Staph aureus. Adjust the therapy when the actual offending organism is properly identified

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33
Q

Which antibiotic is probably the best to use for surgical prophylasxis

A

1 st generation cepalosporin such as Cefazolin due to it’s low cost and broad spectrum and low incidence of allergic reactions

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34
Q

Usually, surgical prophylaxis antibiotics should not be continued for how long after surgery

A

No more than 24 hours post op

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35
Q

Describe the Class 1 clean wound?

A

Atraumatic, with no break in sterile technique. The respiratory, GI, and GU tracts are not entered.

No need for prophylactic antibiotic

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36
Q

Describe Class II wound classification

A

Class II Clean Contaminated

Surgery in areas known to harbor bacteria with no spillage of contents

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37
Q

Describe Class III wound classification

A

Cass III Contaminated

Major break in sterile technique with a traumatic wound and gross GI spillage, entrance into biliary or GU tract

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38
Q

Describe Class IV would classification

A

Class IV Dirty infected

Infection exists before surgery. OLd wound with devitalized tissue or perforated viscera

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39
Q

Which wound classification will require at least one dose of antibiotic?

A

Class II and beyond

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40
Q

Which antibiotic are best for UTI’s?

A

Fluoroquinilone
Aminoglycocides
3 rd generation cephalosporins

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41
Q

What is the proper timing of the initation of surgical prophylaxis antibiotics?

A

Antibiotics should be initiated within 1 hour prior to incision or start of procedure when no incision isrequired

Fluoroquinolone or vancomycin may be initiated 2 hour prior to incision or precedure start

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42
Q

Which antibiotic is most recommended for surgical procedures and which antibiotic may be given as an alternative?

A

Cafazolin is most commonly given and Clindamycin is the most common alternative

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43
Q

Which antibiotic is more effective against anaerobes and should be given for aspiration pneumonia?

A

Clindamycin

44
Q

Which bacteria is the leading cause of nosocomial GI infections?

A

C difficile

Clostridium difficile

45
Q

Which form of bacteria can be provoked by the use of antibiotic therapy

A

C. Difficile

46
Q

Diagnosis of C. Difficile is confirmed by the presence of which toxins?

A

Either Enterotoxin A or Cytotoxin B

47
Q

Which antibiotic is the first line of therapy for C. Difficile?

A

Metronidazole (Flagyl)

PO Vancomycin may be used in cases not responding to metronidazole

Diicid - new drug

48
Q

Which antibiotics contain the beta lactam ring and inhibit cell wall synthesis

A

Beta lactams (PCN)
Caphalosporins
Carbapenems
Monobactams

49
Q

How do bacteria form resistance to PCN

A

Bacteria form beta lactamase which is an enzyme that breaks the beta lactam ring and disables the molecule . Bacteria with beta lactamse can resist the effects of beta lactam antibiotics.

50
Q

What are the beta lactamase inhibitors?

A

Subactam
Tazobactam
Clavulanic Acid

Bacteria with beta lactamase attack these inhibitors leaving the beta lactam ring of the true antibiotic intact

51
Q

Which beta lactam can produce Jarisch Herxheimer reaction?

A

A flu like reaction caused by PCN along with GI upset and diarrhea

52
Q

What is the IV form of PCN?

A

PCN G = IV/IM

PO form given without food

53
Q

Amoxicillin is given PO or IV?

A

-PO without regards to food with or wihout food

54
Q

Older generations of betalactams (PCN) are better for gram + or gram - bacteria

A

Older generations are better for gram _ and newer generation are better for gram - bacteria

55
Q

Which penicillins are poor for PO absorption?

A

Oxacillin

Nafcillin

56
Q

Use of Ticarcillin and piperacillin cause what adverse reactions?

A

Prolonged bleeding times
hypokalemia
neutropenia at high doses

57
Q

What is the mechanism of action for cephalosporins

A

Bactericidal

Spectrum of action based on generation 1 - 5

Gram + to Gram -

58
Q

When should first generation Cephalexin and Cefazolin be redosed?

A

Redose after 2 half lives

Cefazolin half life is 4 hours
(Cephalexin half life is 1 hour

59
Q

Which vephalosporin causes diarrhea and biliary sludging and should not be given to kids?

A

Ceftriaxone (Rocephin)

60
Q

Which cephalosporin precipitates with calcium in the same IV line?

A

Ceftriaxon (Rocephin)

61
Q

Which carbapenem has a high risk for seizures?

A

Imipenem

With cilastatin - inhibits dihydropeptidase which is an enzyme that breaks down imipenem

62
Q

Which form of Vancomycin is best given for C. Diff?

A

PO Vancomycin

63
Q

Highest concentration levels for MIC for vancomycin are for what infections?

A

Pneumonia, CNS, infection, seer osteomyelitis

64
Q

What adverse effects are seen with vancomycin?

A
Red man syndrome
nehprotoxicity
otoxicity
thrombocytopenia
All from rapid infusion
65
Q

Vancomycin should be infused at what rate

A

No more than 1 gram / hour

66
Q

What is a good loading dose for vanomycin?

A

30 mg/kg

67
Q

What is the mechanism of action for vancomycin?

A

Disrupts cell wall synthesis, vactericidal

68
Q

Is vancomycin concentration or time dependent?

A

Concentration dependent

69
Q

Which antibiotic causes myelosuppression, anemia leukopenia, pancytopenia, and thrombocytopenia?

A

Linezolid (Zyvox)

Causes accelerated HTN and Fever

70
Q

Which family of antibiotics causes the most GI upset and toxicity?

A

Macrolides

71
Q

Which antibiotic is best for upper and lower respiratory infections?

A

Azithromycin (Zithromax)

72
Q

What effect on the heart may macrolides such as azithromycin have?

A

Prolonged QT

73
Q

Which macrolides are potent inhibitors of CY3A4?

A

Clarithromycin (Biaxin)

Erythromycin

74
Q

Which macrolids is the 2nd choice for gastroporesis

A

Erythromycin

75
Q

Whihc family of antibiotics have many drug interaction including NSAIDS, Warfarin, Antacids, Amiodarone?

A

Fluoroquinolones

76
Q

What CNS effects are seen with fluoroquinolones?

A

Insomnia,

Anxiety altered glucose

77
Q

T/F: Fluoroquinolones may be given to trauma and orth patients

A

False Have a higher risk of post op pain

78
Q

T/F: Fluoroquinolones may be given to children?

A

False

Not for children under 12

Could cause joint damage

79
Q

Which antibiotic is the best drug of choice for GI infections?

A

Cipro

80
Q

Which fluoroquinolone is best for lung infections?

A

Moxifloxacin (avelox?

81
Q

Which antibiotic (Tetracycline) causes permanent tooth discoloration?

A

Doxycycline (vibramycin)

82
Q

At what age should doxycycline not be given to children?

A

After their adult teeth have come in

83
Q

Which tetracycline has high incidences of nausea and vomiting?

A

Tigecycline (Tyfacil)

84
Q

Which family of anitbiotics prolongs neuromuscular blockade?

A

Aminoglycosides - interferes with Ca++ and Mg++ cross bridges between cell membranes

85
Q

Which aminoclycoside has the best gram positive coverage?

A

Gentamycin

86
Q

2 bacteriostatic antibiotics has the same mechanism of actions?

A

bactericidal

87
Q

Which antibiotic is best for dirty surgeries involving the GI tract?

A

Clindamycin (cleocin)

88
Q

Which antibiotic has the highest risk for C. Diff?

A

Clindamycin (Cleocin)

89
Q

What effect does clindamycin have on neuromuscular blockade?

A

Prolongs neuromuscular blockade

90
Q

What effects are seen with metronidazole-coumadin reaction

A

Coumadin levels increase and PT levels are increased

91
Q

Which antibiotic is a CYP 450 inducer and shortens the life of medication using th eCYP system?

A

Rifampin and Rifabutun

92
Q

What side effects will be seen in all body fluids including tears, saliva, and urine when taking rifampin?

A

Will see orange red in color

93
Q

Are beta lactams time dependent or concentration dependent?

A

Beta lactams are time dependent

94
Q

Are aminoglycocides time dependent or concentration dependent

A

Aminoglycosides are concentration dependent

95
Q

Which antibiotics are of the beta lactam confiuration

A
PCN
Cephalosporins
Carbapenems
Monobactams
Beta lactamase inhibitors
96
Q

What is the most common form of resistance in antibiotics?

A

Bacteria cells produce beta lactamase which breaks down the beta lactam ring of the molecule and mades the molecule inactive causeing resistance

97
Q

When is the best time for administration of PCN?

A

1-2 hours before a meal with the exception of amoxicillin

98
Q

Which antimicrobial present the risk of prolonging neuromuscular blockade when paralytics are used?

A

Aminoglycocides
Clindamycin
Tetracycline
Particularly when used with non depolarizing neuromuscular blocking agents

99
Q

Hown may prolonged neuromuscular blockade be treated?

A

Neostigmine and colcium all increase the presence of acetylcholine at the neuromuscular junction

100
Q

Which 3rd generation cephalosporin antimicrobial is best for pseudomonas?

A

Ceftazimide (Fortaz)

101
Q

Which 3rd generation cephalosporin is best for staph coverage?

A

Ceftriaxone (Rocephin)

102
Q

Patients with active seizure should not take which antimicrobial?

A

Carbapenem

Imipenem (Primaxin)

103
Q

Which antibiotics are responsible for prolonging QT intervals?

A

Flurorquinolones - CIPRO , levaquin

Macrolides - erythromycin, azithromycin, clarithromycin

104
Q

Which antibiotic may have the longest half life

A

Azithromycin - 68 hours

105
Q

During pregnancy , which antibiotics should be avoided due to potential for injury to the fetus?

A
Metranidazole
Tetracycline
Fluoroquinolones
Rifampin
Ticarcillin
Trimethoprim
106
Q

Which antibiotic are safe to use during pregnancy?

A

PCN
Cephalosporins
Erythromycin