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Flashcards in Antimicrobials Deck (106)
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1

What is MIC?

Minimum Inhibitor Concentration

The lowest concentration of antibiotic required to prevent growth

2

What is MBC?

Minimum Bacterial concentration

Lowest concentration required to kill bacteria

3

What is the action for bactericidal antimicrobials

Destroys bacterial cell wall

4

What is the action for bacteriostatic antimicrobials?

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

5

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

Narrow spectrum kills specific types of bacteria

Broad spectrum kills every type of bacteria

6

Explain concentration dependent killing of bacteria?

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

7

What type of antibiotics are concentration dependent killing antibitics?

Aminoglycosides
Fluoroquinolone

8

Explain time dependent killing of bacteria

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

9

What types of antibiotics are considered time dependent killing antibiotics?

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

10

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

FALSE

11

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

Post antibiotic effect PAE

12

What is the post antibiotic leukocyte effect?

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

13

What are the two types of resistance to antimicrobials?

Intrinisic - natural resistance to antimicrobial

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

14

Describe decreased permeability for resistance

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

15

Describe decreased efflux in antibiotic resistance

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

16

Describe inactivation in antibiotic resistance

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

17

Which enzyme inactivates beta lactam antimicrobials?

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

18

What is an example of target modification in antimicrobial resistance?

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

19

What is a positive reason to use multiple drug therapy?

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

20

What is a negative outcome of muliple drug therapy

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

21

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

Administer 2 antibiotic with different MOA to prevent resistance

22

What are the different synergies associated with multidrug therapy

Antagonist 1 +1 = 0.5

Indifferent 1 + 1 =1

Inbetween 1 +1 =1.5

Additive 1+1 = 1.5

Synergistic 1 + 1 = 3

23

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

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

24

What is an antibiogram?

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

25

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

Impaired host defenses:
Anatomical neutropenia
aspleenia
malignancy
HIB
immunosuppression

26

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

Tetracycline

27

Which antibitiotic have been deemed safe for pregnancy?

Penicillins

Cephalosporins

Erythromycin

Aminoglycosides if necessary

28

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

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

29

What devices are highly associated with nosocomial infections

Ventilators

Urethral catheters

vascular access catheters

30

A catheter related infections is defined how

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

31

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

Femoral
internal jugular
subclavian

32

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

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

33

Which antibiotic is probably the best to use for surgical prophylasxis

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

34

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

No more than 24 hours post op

35

Describe the Class 1 clean wound?

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

No need for prophylactic antibiotic

36

Describe Class II wound classification

Class II Clean Contaminated

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

37

Describe Class III wound classification

Cass III Contaminated

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

38

Describe Class IV would classification

Class IV Dirty infected

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

39

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

Class II and beyond

40

Which antibiotic are best for UTI's?

Fluoroquinilone
Aminoglycocides
3 rd generation cephalosporins

41

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

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

42

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

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

43

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

Clindamycin

44

Which bacteria is the leading cause of nosocomial GI infections?

C difficile

Clostridium difficile

45

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

C. Difficile

46

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

Either Enterotoxin A or Cytotoxin B

47

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

Metronidazole (Flagyl)

PO Vancomycin may be used in cases not responding to metronidazole

Diicid - new drug

48

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

Beta lactams (PCN)
Caphalosporins
Carbapenems
Monobactams

49

How do bacteria form resistance to PCN

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

What are the beta lactamase inhibitors?

Subactam
Tazobactam
Clavulanic Acid

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

51

Which beta lactam can produce Jarisch Herxheimer reaction?

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

52

What is the IV form of PCN?

PCN G = IV/IM

PO form given without food

53

Amoxicillin is given PO or IV?

-PO without regards to food with or wihout food

54

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

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

55

Which penicillins are poor for PO absorption?

Oxacillin

Nafcillin

56

Use of Ticarcillin and piperacillin cause what adverse reactions?

Prolonged bleeding times
hypokalemia
neutropenia at high doses

57

What is the mechanism of action for cephalosporins

Bactericidal

Spectrum of action based on generation 1 - 5

Gram + to Gram -

58

When should first generation Cephalexin and Cefazolin be redosed?

Redose after 2 half lives

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

59

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

Ceftriaxone (Rocephin)

60

Which cephalosporin precipitates with calcium in the same IV line?

Ceftriaxon (Rocephin)

61

Which carbapenem has a high risk for seizures?

Imipenem

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

62

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

PO Vancomycin

63

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

Pneumonia, CNS, infection, seer osteomyelitis

64

What adverse effects are seen with vancomycin?

Red man syndrome
nehprotoxicity
otoxicity
thrombocytopenia
All from rapid infusion

65

Vancomycin should be infused at what rate

No more than 1 gram / hour

66

What is a good loading dose for vanomycin?

30 mg/kg

67

What is the mechanism of action for vancomycin?

Disrupts cell wall synthesis, vactericidal

68

Is vancomycin concentration or time dependent?

Concentration dependent

69

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

Linezolid (Zyvox)

Causes accelerated HTN and Fever

70

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

Macrolides

71

Which antibiotic is best for upper and lower respiratory infections?

Azithromycin (Zithromax)

72

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

Prolonged QT

73

Which macrolides are potent inhibitors of CY3A4?

Clarithromycin (Biaxin)

Erythromycin

74

Which macrolids is the 2nd choice for gastroporesis

Erythromycin

75

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

Fluoroquinolones

76

What CNS effects are seen with fluoroquinolones?

Insomnia,
Anxiety altered glucose

77

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

False Have a higher risk of post op pain

78

T/F: Fluoroquinolones may be given to children?

False

Not for children under 12

Could cause joint damage

79

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

Cipro

80

Which fluoroquinolone is best for lung infections?

Moxifloxacin (avelox?

81

Which antibiotic (Tetracycline) causes permanent tooth discoloration?

Doxycycline (vibramycin)

82

At what age should doxycycline not be given to children?

After their adult teeth have come in

83

Which tetracycline has high incidences of nausea and vomiting?

Tigecycline (Tyfacil)

84

Which family of anitbiotics prolongs neuromuscular blockade?

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

85

Which aminoclycoside has the best gram positive coverage?

Gentamycin

86

2 bacteriostatic antibiotics has the same mechanism of actions?

bactericidal

87

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

Clindamycin (cleocin)

88

Which antibiotic has the highest risk for C. Diff?

Clindamycin (Cleocin)

89

What effect does clindamycin have on neuromuscular blockade?

Prolongs neuromuscular blockade

90

What effects are seen with metronidazole-coumadin reaction

Coumadin levels increase and PT levels are increased

91

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

Rifampin and Rifabutun

92

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

Will see orange red in color

93

Are beta lactams time dependent or concentration dependent?

Beta lactams are time dependent

94

Are aminoglycocides time dependent or concentration dependent

Aminoglycosides are concentration dependent

95

Which antibiotics are of the beta lactam confiuration

PCN
Cephalosporins
Carbapenems
Monobactams
Beta lactamase inhibitors

96

What is the most common form of resistance in antibiotics?

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

97

When is the best time for administration of PCN?

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

98

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

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

99

Hown may prolonged neuromuscular blockade be treated?

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

100

Which 3rd generation cephalosporin antimicrobial is best for pseudomonas?

Ceftazimide (Fortaz)

101

Which 3rd generation cephalosporin is best for staph coverage?

Ceftriaxone (Rocephin)

102

Patients with active seizure should not take which antimicrobial?

Carbapenem
Imipenem (Primaxin)

103

Which antibiotics are responsible for prolonging QT intervals?

Flurorquinolones - CIPRO , levaquin
Macrolides - erythromycin, azithromycin, clarithromycin

104

Which antibiotic may have the longest half life

Azithromycin - 68 hours

105

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

Metranidazole
Tetracycline
Fluoroquinolones
Rifampin
Ticarcillin
Trimethoprim

106

Which antibiotic are safe to use during pregnancy?

PCN
Cephalosporins
Erythromycin