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Flashcards in Antibiotics Deck (134):
1

Drugs with highest risk of CDAD

clindamycin, ampicillin, cephalosporins and fluoroquinolones

2

Drugs to treat CDAD

metronidazole or vancomycin

3

What should you use to treat UTI empirically

co-trimoxazol

4

How are most antibiotics cleared

excretion by the kidney, consideration for young and elderly

5

antibiotics cleared by the kidney (7)

aminoglycosides, vancomycin, cephalosporins, sulfonamides/trimethoprim, extended spectrum penicillins, carbapenems, ethambutol

6

antibiotics cleared by the liver (7)

Clindamycin, macrolides, chloramphenicol, tetracyclines, metronidazole, isoniazid, rifampin

7

Which drugs are class D for birth defects

aminoglycosides and tetracyclins

8

antibiotics with placental and breast milk transfer

1) aminoglycoside ototoxicity during fetal development
2) sulfonamide induced kernicterus in nursing infants

9

Most common sources of antibiotic allergy (4)

beta lactams (penicillin), sulfonamides, trimethoprim, and erythromycin

10

What is the most important difference between gram+ and gram- bacterial

gram negative bacteria have an outermembrane which makes them more difficult to penetrate with antibiotics

11

What is the main MOA of penicillin

irreversible inhibition of transpeptidases

12

structure of penicillins

Beta-lactam ring fused to a 5-member thiazolidine

13

Main mechanisms of penicillin resistance (3)

1. Inability to penetrate G- outermembrane
2. Acquired mutations in PBPs that lower affinity for B-lactam
3. Beta-lactamases

14

What are the standard, narrow-spectrum penicillins?

Penicillin G, penicillin V

15

Which standard, narrow-spectrum penicillin is orally effective?

Penicillin V

16

What is the DOC for syphilis?

Penicillin G,V

17

What are the penicillinase-resistant penicillins

Nafcillin

18

What are the aminopenicillins?

amoxicillin

19

What unique property do aminopenicillins have?

Positive charge that makes them effective against G-

20

Antipseudomonal penicillins

ticarcillin, piperacillin

21

Which penicillins are prescribed with Beta-lactamases

Amoxicillin, ticarcillin, piperacillin

22

Repository prep of penicillin and what it is used for

Pen G benzathine, syphilis and rheumatic fever

23

What is a Jarisch-Herxheimer reaction

rash, fever, flushing after shot due to death of pathogen, typically syphilis

24

What is a side effect specific to ticarcillin

sodium overload can be a problem in CHF

25

What is SJS

Steven Johnson's syndrome is a separation of the dermis from the epidermis covering less than 10% of the body. If it covers more it is called toxic epidermal necrolysis (TEN).

26

What are the first generation cephalosporins

cefazolin

27

First generation cephalosporins have which features (3)

1) high activity against G+ MSSA and strep
2) Alternative to penicillin when mild allergy exist
3) Prophylaxis before surgery

28

What are the second generation cephalosporins

cefoxitin

29

Second generation cephalosporins have which features (3)

1) Better G- than 1st gen
2) Little CNS penetration
3) Largely replaced by gen 3

30

What are the third generation cephalosporins

ceftriaxone

31

Third generation cephalosporins

ceftriaxone

32

Third generation cephalosporins have which features (4)

1) higher activity against G-
2) CNS penetration
3) Most widely used
4) meningitis, gonorrhea, empiric chlamydia

33

Fourth generation cephalosporins

cefepime

34

Fourth generation cephalosporins have which features (3)

1) highly resistant to beta-lactamases
2) good CNS penetration
3) treatment of hospitalized patients when resistance is suspected

35

What is special about 5th gen cephalosporins

acitivity against MRSA

36

What are the carbapenems

imipenum, cilastatin

37

What are the important features of carbapenems

1) Beta-lactam
2) broad spectrum
3) Highly resistant to beta-lactamases
4) only given parenterally

38

What is a unique toxicity of imipenem?

seizures

39

What are the monobactams

aztreonam

40

What is the structure of monobactams

contains beta-lactam ring, but not fused with a second ring. Is not an allergen like penicillin

41

What are the features of monobactams (4)

1) only active against G- bacteria including pseudomonas
2) Given IV, reduced in renal insufficiency
3) resistant to most beta-lactamases
4) Safe for patients with penicillin allergy

42

What are the glycopeptides

vancomycin

43

What are glycopeptides used for

Generally serious infections with G+ bacteria
Parenteral- sepsis or endocarditis caused by MRSA or sensitive enterococci
In combination with 3rd gen cephalosporins for meningitis
Oral for CDAD if metronidazole is ineffective
Alternative to penicillin

44

Route of administration for glycopeptides

IV for systemic and viral infections
orally to treat GI infections

45

What are the adverse reactions to glycopeptides (3)

1) Ototoxic
2) red man syndrome (histamine reaction)
3) Thrombophlebitis

46

Which cell wall synthesis inhibitor is commonly used for UTI with G- bacteria

Fosfomycin

47

What is the MOA of fosfomycin

inhibits production of murein monomers by inhibiting enolpyruvate transferase

48

What is unique about fosfomycin that allows it to treat G- bacteria

It enters through a transporter, but mutations confer resistance

49

Which cell wall synthesis inhibitor is a component of Neosporin

Bacitracin

50

Why is bacitracin only effective against G+ bacteria

It works inside the bacteria to inhibit bactoprenol dephosphorylation, it cannot penetrate G- outer membrane

51

Which classes of cell wall inhibitors work inside or outside the bacterial cell

inside- fosfomycin and bacitracin
outside- vancomycin and beta lactams

52

What are the classes of beta-lactams (4)

Penicillins, cephalosporins, carbapenems, and monbactams

53

What are the sizes of the mammalian and bacterial ribosomes and their subunits

Bacterial 70S, 30S and 50S
Mammalian 80S, 40S and 60S

54

What is the structure of aminoglycosides and what are the consequences?

2 or more amino sugars connected by glycoside linkages. Large bulky, cationic, hydrophilic structure. Does not cross membranes attracted to negative LPS

55

What are the aminoglycosides (4)

gentamicin, amikacin, streptomycin, neomycin

56

How do aminoglycosides get into bacteria

Concentration dependent, passive diffusion through porins, active transport across membrane is O2 dependent. only effective against aerobes. Can be synergistic with cell wall inhibitors

57

Aminoglycosides MOA (3)

Binding to 30S
1) inhibits formation of initiation complex
2) misreading of mRNA
3) blockade of translocation
Note: has post antibiotic effect

58

Therapeutic considerations for aminoglycosides

Narrow spectrum, diminished therapeutic resistance

59

Aminoglycoside used as second line drug for TB

Streptomycin

60

aminoglycoside used in hospitals where resistance is common due to susceptibility to inactivation

Amikacin

61

Aminoglycoside in neosporin effective against G- bacteria

neomycin

62

What are the two Ototoxic antibiotic classes

aminoglycosides and glycopeptides (vancomycin)

63

What are the adverse reactions to aminoglycosides (3) and what is a way to avoid them

1) ototoxicity
2) nephrotoxicity (mostly bad due to reduced clearance)
3) Neuromuscular blockade with high doses, respiratory paralysis
Can administer once daily in large dose

64

Tetracyclines (3)

tetracycline, tigecycline, doxycycline

65

Which two antibiotic classes bind to the 30S ribosomal subunit

tetracyclines and aminoglycosides

66

How are tetracyclines transported into the bacterial cell

active transport system only present in bacterial cells

67

Administration of tetracyclines

Orally (except tigecycline), do not administer with dairy widely distributed

68

Therapeutic profile of tetracyclines

broad spectrum antibiotics, rickettsial infections, peridontal disease, acne, prophylaxix of malaria

69

Adverse reactions of tetracyclines (6)

1) GI irritation
2) Deposition in bone and teeth, staining
3) renal toxicity, especially if outdated
4) superinfection
5) hepatotoxicity at high doses, esp in preg women
6) photosensitivity

70

Macrolydes (2)

erythromycin, azithromycin

71

MOA of macrolydes

binds to 50S inhibits translocation

72

Resistance to macrolydes

plasma-encoded methylation of 50S

73

Adverse reactions to macrolydes

Generally very safe
1) GI irritation is most common, increases motility
2) Cholestatic hepatitis
3) Prolonged Q-T interval

74

What is the prototype oxizolidinone?

linezolid

75

What is the MOA of oxizolidinones

binding to 23S of the 50S subunit, blocks formation of initiation complex. Bacteriostatic

76

What are the Streptogramins?

quinupristin-dalfopristin

77

What are the therapeutic uses of oxizolidines

MDR G+ pathogens when other agents are not available, due to negative effects like anemia and neuropathy. Have to do blood counts weekly

78

What is the MOA of streptogramins?

inhibits Dalfopristin directly inhibits peptidyl transferase center of the 23S rRNA (50S)
Quinupristin binds at the same site as the macrolides
A 30:70 fixed dose combination is bactericidal

79

What is the fluoroquinolones prototype drug

ciproflaxin

80

What is the structure of fluoroquinolones

fluorinated derivatives of the quinolone, nalidixic acid

81

MOA of fluoroquinolones

Inhibits one of the two topoisomerase II enzymes. Bactericidal

82

Pharmacokinetics of fluoroquinolones

orally available and widely distributed, cleared renally

83

What is the unique side effect of fluoroquinolones?

Tendon rupture, do not give to patients <18

84

What are the therapeutic uses of fluoroquinolones (3)

1) Widely used for urogenital, respiratory and GI infections Aerobic G-
2) Prophylaxis for anthrax
3) Respiratory fluoroquinolones

85

Which protein synthesis inhibitor is associated with CDAD?

Clindamycin presents in up to 5% patients and may develop weeks after drug withdrawl

86

What other drug class has a similar mechanism to clindamycin?

macrolides

87

What type of bacteria is clindamycin used to treat

most anaerobic and G+ aerobes

88

Which drug is cheap and effective against a broad spectrum, but not commonly used in the developed world due to toxicities

Chloramphenicol

89

Chloramphenicol's MOA

binds to peptidyl transferase center of 50S, prevents attachment of incoming tRNA to A-site

90

What is one condition where chloramphenicol is still used

bacterial meningitis

91

What are the main adverse reactions of chloramphenicol (3)

1) gray baby syndrome
2) bone marrow suppresion
3) aplastic anemia

92

What are oxizolindones primarily used for therapeutically

MDR G+ bacteria, only when others are not effective

93

Adverse reactions to oxizolindones

Reversible myelosuppression, blood counts weekly
Neuropathy

94

What drug interaction does linezolid have

MAOIs and SSRIs, serotonin syndrome

95

What organisms is quinupristin-dalfopristin affective against

G+, G- activity limited

96

Adverse reactions to quinupristin-dalfopristin

hyperbilirubinemia (jaundice)
arthralgia /myalgia (joint and muscle pain)
Inhibits CYP3A4

97

Which protein synthesis inhibitors are bacteriocidal

aminoglycosides and quinupristin/dalfopristin

98

What are the major resistance mechanisms to protein synthesis inhibitors

decreased uptake or efflux
bacterial enzymes that inactivate the drug

99

Major side effects from protein synthesis inhibitors
1) ototoxicity
2) tooth discoloration
3) CDAD
4) aplastic anemia

1) aminoglycosides
2) tetracyclines
3) Clindamycin
4) chloramphenicol

100

Protein synthesis that bind the 50S and 30S subunits

50S- macrolides and miscellaneous
30S- aminoglycosides and tetracyclins

101

What are the adverse reactions associated with fluoroquinolones

1) tendon rupture
2) confusion, visual disturbances in elderly
3) prolong Q-T interval,
4) CDAD

102

What drug interactions do fluoroquinolones have

increase theophylline and warfarin
oral absorption reduced if taken with multivalent cations

103

What is the drug of choice to treat CDAD

Metronidazole

104

What is the MOA of metronidazole

Initiates strand breaks and loss of helical structure, cannot be metabolized by human cells

105

Therapeutic uses of metronidazole (5)

1) anaerobic bacterial infections
2) bacterial vaginosis
3) CDAD
4) with tetracycline and bismuth subsalicylate for H.pylori in peptic ulcer disease
5) antiparasitic agent

106

Adverse reactions to metronidazole

headache, GI, metallic taste, dark brown urine

107

Drug interactions with metronidazole

disulfiram-like reaction with ethanol
inhibits metabolism of warfarin-bleeding

108

Sulfonamine prototype

sulfamethoxazole

109

Sulfonamine MOA

Structural analog of PABA, bacteriostatic

110

Resistance mechanisms to sulfonamine

1) synthesis of PABA to overcome inhibition
2) mutation in dihydropteroate synthase
3) decreased uptake

111

Therapeutic uses of sulfonamides

Broad specturm against G-/G+
diminished due to development of resistance and safer alternatives
Mostly in combination with trimethoprim

112

Adverse reactions to sulfonamides

1) kernicterus
2) hypersensitivity- Stevens-Johnson syndrome
3) Hemolytic anemia

113

What are the 2 types of folic acid inhibitors

sulfonamides, trimethoprim (TMP)

114

What is the MOA of trimethoprim

inhibits dihydrofolate reductase (DHFR)

115

Resistance to Trimethoprim

1) increased synthesis of DHFR
2) mutated DHFR
3) reduced uptake

116

Adverse reactions to trimethoprim

Bone marrow suppression in folate deficient patients
Fatal fetal malformations in experimental animals

117

What is co-trimoxazole

Fixed-dose combination of trimethoprim and sulfamethoxazole that has a synergistic bactericidal effect due to inhibition of sequential steps of folate biosynthesis.

118

Therapeutic uses of co-trimoxazole (5)

1) UTI, chronic and recurrent
2) oportunistic pneumonia
3) ear infections
4) MSSA + MRSA
5) Shigellosis (diarrhea)

119

What is the third line drug for CDAD

Fidoxomicin after metronidozol and vancomycin.

120

What features does fidoxomicin have relative to other treatments for CDAD

minimally disruptive to normal GI flora and lowers risk of recurrence.

121

What Nucleic acid synthesis inhibitor is a pro-drug

Metronidazol causes DNA strand breaks in anaerobic bacteria

122

Which drug class inhibits bacterial DNA gyrase

Fluoroquinolones

123

Which drugs inhibit bacterial RNA polymerase

Fidoxamicin and rifampin

124

Major side effects of nucleic acid synthesis inhibitors and their causative agents

1) tendon rupture- fluoroquinolones
2) kernicterus, hemolytic anemia- sulfonamides
3) Myelosuppression- SMX and TMP

125

What is the prototype Lipopeptide

daptomycin

126

What is the MOA of lipopeptides

Calcium dependent insertion of lipophilic tail into plasma membrane forms an ion-permeable channel that permits efflux of intracellular K+

127

Therapeutic uses for daptomycin

administered IV, complicated skin, bacteremia and right-sided endocarditis with resistant microbes

128

Adverse reactions to daptomycin

myopathy

129

What are the polymyxins?

colistin, polymyxin B

130

MOA of polymyxins

Binds to neg charged LPS in G- bacteria , disrupts plasma membranes

131

What are the two formulations of colistin?

Colistin sulfate (cationic)- oral and GI
Colistimethate (anionic)- parenteral use, prodrug

132

What are the therapeutic uses of colistimethate

treatment of last resort for serious MDR G- infections

133

Colistin sulfate therapeutic uses

topical for infection of skin, mucous membranes, eye, ear

134

What are the side effects of colistin

reversible nephrotoxicity and neurotoxicity