Antibacterials I Flashcards Preview

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Flashcards in Antibacterials I Deck (102)
1

transported into the cell by an energy-requiring aerobic process (does not occuranaerobically)
• bind to several ribosomal sites, usually at 30S/50S interface; stops initiation, causes
premature release of ribosome from mRNA, and mRNA misreading
• post-antibiotic effect
• concentration-dependent killing

Aminoglycosides

2

aminoglycoside mechanism

binds to several 30S/50S interfce to stop initiation and causes premature release of ribosome from mRNA and mRNA mistreading

3

How do bacteria resist aminoglycosides?

enzymatic modification of the aminoglycosides

4

more effective against gram-neg. than gram-pos.
• poor activity against anaerobes
• primarily for gram-neg. ‘aerobic’ bacilli, incl. Enterobacteriaceae and Pseudomonas
aeruginosa

Aminoglycosides

5

aminoglycosides are better for gram negative or positive
for anaerobes or aerobes

gram negative
aerobes

6

due to toxicity, use restricted to serious infections in which other agents are unsuitable
• often used in conjunction with other agents (e.g. β-lactams)---- streptomycin

aminoglycosides

7

Gentamicin, tobramycin and amikacin are examples of

aminoglycosides

8

which aminoglycoside is most resistant to bacterial inactivation

amikacin

9

What four bacteria do aminoglycosides work great for

P.aeruginoa, Klebsiella, Enterobacter, Serratia

10

P.aeruginoa, Klebsiella, Enterobacter, Serratia are all suspeptible to what class of drugs

aminoglycosides used with B-lactams

11

How are aminoglycoside metabolized?

glomerular filtration

12

Adverse rxn of aminoglycosides

nephrotoxic and ototoxic and is related to dose and duration of therapy. less common is neuromuscular blockade

13

How are aminoglycosides administered?

IV or IM with poor penetration to CSF
*serious infection~~ combined with other antibiotics

14

MEch of Tetracyclines

transported into cell via carrier... binds to 30S ribosomal to stop attachment of aminoacly-tRNA to acceptor site
bacteriostatic

15

transported into cell via carrier... binds to 30S ribosomal to stop attachment of aminoacly-tRNA to acceptor site
bacteriostatic

tetracyclines

16

Modern tetracyclines such as _____ and ______ have longer 1/2 lives and are more lipophilic

minocycline and doxycycline

17

How does bacteria devo resistance to tetracyclines

increased transport of drug out of cells... resistant to one tetracylcine, likely resistant to all of them

18

Tetracyclines are no longer used bc

increased resistance

19

Preferred agents for rickettsia and chylamydia

Tetracyclines

20

Preferred agent for Mycoplasma and ureplasma and Borrelia (or lymes)

tetracyclines

21

alternative drug for syphilis and gonorrhea

tetracyclines

22

What can tetracyclines be used for

Rickettsia
Chylamydia
Mycoplasma and Ureaplasma
Borrelia
alt for gonorrhea and syphilis

23

You shouldn't used antacids with tetracycline because

the Ca++ in them will bind to tetracyclines and inhibit absorption

24

Adverse rxns to tetracyclines

GI disturbance, pseudomembranous enterocolitis, Candida superinfection, photosensitive, teeth discoloration, DONT USE IF PREGNANT

25

Tigecycline mech

binds to 30S and blocks aminoacyle-tRNA as well as other unique sites in ribosomes

26

This tetracycline doesn't have cross resistance with other antiBacts including tetracyclines

Tigecycline

27

Uses of Tigecycline by SITE

skin/skin strucutre infections
complicated intrabdominal infections
Community acquired pneumonia (CAP)

28

What pathogens are Tigecycline effective for

E.coli, Klebsiella, enterobacter but NOT psuedonomas
Staph (both MSSA and MRSA)
Bacteriodes
Clostridium perfringes
CAP: S. pneumoniae, Haemophilus

29

Drug to tx E.coli, Klebsiella, enterobacter but NOT psuedonomas

Tigecycline

30

Drug that can tx bacteriodes and Clostridium perfringes

Tigecycline

31

Tetracycline that can take care of both MSSA and MRSA

Tigecycline

32

Adverse affects of Tigecycilne

nausea and vomit and cant use with antacids

33

interferes with binding of aminoacyl-tRNA to 50S subunit and inhibits peptide bond
formation (blocks peptidyl transferase)

Chloramphenicol

34

Mech of Cloramphenicol

fucks with binding of amino-tRNA to 50s and inhibits peptide bond formaiton

35

administration of tigecycline

iv only

36

alternative for Pen G sensitive syphilis and uncomplicated gonhorea

Doxycycline and minocycline

37

Tricycline least sensitive for Ca++ antiacids

Doxycycline

38

most lipophilic tetracycline thats used prophylactictly for N. Meningitis

Minocycline

39

1/2 life of minocycline

11-26 hours

40

1/2 for doxycycline

24 hours

41

Uses of Chloramphenicol

broad spectrum but VERY serious side effects

42

Major used of Chloramphenicol

alternative tx of meningitis in B lactam allergic pts
brain abscesses
severe slamonella infections

43

Drug of choice for rickettsia in children

doxycycline

44

Used to tx chronic granulomatois, bacterial ophthalmic issues

Chloramphenicol

45

Chloramphenicol is toxic because

Bone marrow depression (most common effect and limits its use to life-threatening
infections); can progress to a fatal aplastic anemia

46

Bone marrow depression (most common effect and limits its use to life-threatening
infections); can progress to a fatal aplastic anemia

Chloramphenicol

47

What causes Grey baby syndrome

high level of unmetabolized Chloramphenicol

48

Adverse affects of chloramphenicol

Grey baby/aplastic anemia/ optic neuritis/ enterocolitis
~~ binds to mitochondrial 70S

49

3 key macrolides

Azithromycin, Clarithromycin, Erythromycin

50

Mech of macrolides

bind to 50S and block protein synthesis by blocking translocation

51

Macrolides are bacteriostatic or bacteriacidal

bacteriostatic

52

Bacteria devo resistance to chloramphenicol via:

CAT: acetylated by bacteria

53

When is the activity of macrolides reduced

when pH is below 7

54

Resistance to macrolides

they methylate the 23S of teh 50S and inhibit binding or drug efflux

55

Macrolide for gram-pos.
→ e.g. Streptococcus, only some Staphylococcus (MSSA)

Erythromycin

56

Uses of Erythromycin

gram +streptococcus and some staph

57

Macrolide for Chlamydia, mycoplasma, Legionella and Bordetela

Erythromycin

58

What bacteria does Erythormycin tx

Chlamydia, mycoplasma, Legionella and Bordetela

59

Toxicity of Erythromycin

inhibits CYP3A4, increase risk of arrhthymias and cardiac arrest and nausea

60

What macrolide inhibits CYP3A4

Erythromycin

61

alternative to erythromycin for treatment of: pharyngitis, respiratory infections

Clarithromycin

62

Clarithromycin tx the same bacteria as Erythromycin as well as

H. influenza, Moraxella, penicillin-resistant Strep.pneumoniae, Helicobacter pylori

63

Tx H. influenza, Moraxella, penicillin-resistant Strep.pneumoniae, Helicobacter pylori

Clarithromycin

64

Macrolide to tx atypical mycobacterial infections

Clarithromycin

65

Adverse rxn of Clarithromycin

less GI issues then Erythro but INCREASED cardiovascular risk (longer QT interval)

66

less GI issues then Erythro but INCREASED cardiovascular risk (longer QT interval)

Clarithromycin

67

Macrolide for respiratory infections such as S.penumonai, H.influenza, mycoplasm

Azithromycin

68

Used to be 1st line for chlamydia and N. gonorrheoae

Azithromycin
for gonorrhea, use ceftriaxone + azithromycin

69

Is Azithromycin used for Helicobacter?

NOPE

70

Adverse rxn of azithromycin

less GI then erythromycin, fewer drug interations and slight QT prolonged

71

which macrolide has long 1/2 of 3 days and is more acid stable

azithromycin

72

Mech of Clindamycin

binds to 50S ribosomal subunit,
blocks translocation along ribosomes

73

Uses of Clindamycin

most gram-pos. cocci and many anaerobes incl. Bacteroides fragilis

74

most gram-pos. cocci and many anaerobes incl. Bacteroides fragilis

Clindamycin

75

What do we NOT use Clindamycin for?

hospital aquired MRSA

76

What limits our use of Clindamycin

serious colitis

77

Adverse rnxs of Clindamycin

Antibiotic associated enterocolitis
GI and diarrhea
hepatotoxic

78

Mech of Linezolid

interferes with protein synthesis: binds to 50S ribosomal subunit, interfering with formation of 70S initiation complex

79

Uses of Linezolid

VRE
MRSA and MSSA
Group A and B strep
S. pneumonia (even if its multidrug resistant)

80

What can treat all of these
VRE
MRSA and MSSA
Group A and B strep
S. pneumonia (even if its multidrug resistant)

Linezolid

81

Linezolid is _______ for staph and enterooccus

Bacteriostatic

82

This drug is a non-selective inhibitor of MAO

Linezolid

83

Sides of Linezolid

non-selective inhibitor of MAO (many possible drug interactions, avoid foods with
tyramine), bone marrow suppresion, superinfection, enterocolitis

84

inhibit folate synthesis in bacteria by competitive inhibition of dihydropteroate synthase

Sulfonamides

85

______ is necessary co-factor for key rxns in all cells and bacteria make their own

folate

86

humans are different from bacteria in regards to folate bc

we get it from diet, they make it, thus its a good target for therapies

87

Sulfonamides work by:

inhibiting folate synthesis in bacteria... done via competitive inhibition of dihydropteroate synthase

88

Main uses of sulfonamides

UTI

89

most common: sulfamethoxazole given with trimethoprim is used for

urinary tract infections
bacillary dysentery (Shigella) typhoid fever (Salmonella typhi)

90

Used to tx
UTIs
Bacillary dynsteary or Shigella
typhoid fever

Sulfamethoxazole + trimethoprim

91

Used to tx burn pts

silver sulfadiazine

92

Two sulfonamide drugs

sulfamethoxazole
silver sulfadiazine

93

Adverse rxns of sulfonamides

CYP2C9 inhibitors
renal damage dt cystalluria, rashes or hypersensitive

94

CYP2C9 inhibitors
renal damage dt cystalluria, rashes or hypersensitive

sulfonamides

95

inhibits folate synthesis in bacteria by competitively inhibiting dihydrofolate
reductase

Trimethoprim

96

Trimpethoprim mechanism

inhibits folate synthesis by competitively inhibiting dihyrofolate reductase

97

How is trimethoprim more specific for bacteria then humans

while humans have dihydrofolate reductase, it is 100,000-fold less sensitive to trimethoprim than is the bacterial enzyme

98

Adverse rxn to trimethoprim

nausea, vomiting, diarrhea, rashes
• eosinophilia, neutropenia, bone marrow suppression
inhibits CYP2C9, causing increased levels of warfarin, etc.

99

most often in conjunction with sulfamethoxazole to have bactericidal affects

Trimethoprim

100

urinary infections (Enterobacteriaceae and coagulase-negative Staphylococcus)
• upper respiratory tract and ear infections (H. influenzae, Moraxella, S. pneumoniae)
• also for Pneumocystis jiroveci (carinii), Salmonella, Shigella,

Trimethoprim

101

Drug choice based on

susceptibility of the pathogen site of infection, drug penetration emergence of resistance superinfection with another organism

102

Four categories of antibacterials use

1. Prophylactic
2. Empiric
3. Pathogen-directed
4. Susceptibility-guided