Antibiotics Flashcards Preview

Pharmacology > Antibiotics > Flashcards

Flashcards in Antibiotics Deck (114):
1

What are the MC and second MC antibiotic MOAs?

#1 = inhibition of cell wall synthesis

#2 = inhibition of protein synthesis

2

Important aerobic gram positive cocci

1) Staphylococci (S. aureus, Coag-negative staph)
2) Streptococci (S. pneumoniae,Group B Strep, Viridans Strep)
3) Enterococci (E. faecalis, E. faecium)

3

Important aerobic gram negative rods

1) E. coli
2) K. pneumoniae
3) Serratia (Enterobacteriaceae)
4) H. influenza
5). P. aeruginosa

4

Important aerobic gram negative cocci

1) Moraxella catarrhalis
2) N. gonorrhoeae
3) N. meningitidis

5

Important atypical respiratory aerobes

1) Legionella spp.
2) Mycoplasma pneumoniae
3) Chlamydia pneumoniae

6

Important anaerobes

1) True anaerobes (gut): Bacteroides fragilis and C. diff
2) Oral anaerobes: Prevotella and Peptostreptococcus

7

MIC

minimum inhibitory concentration

(dilution test to determine microbial sensitivity)

Note: many drugs will not reach their MIC in certain tissues

8

MBC

minimum bactericidal concentration

-cidal = kills bacteria

(dilution test to determine microbial sensitivity)

9

Penicillins MOA

B-Lactam

inhibit cell wall synthesis by binding to penicillin binding proteins (PBPs)

10

How are Penicillins differentiated?

By their side chains

(different penicillins target different bacteria and have different resistance profiles)

11

Penicillins resistance

1) B-lactamases - can cleave beta-lactam ring in center of Penicillins and render them inactive; doesn't affect all penicillins
2) Altered PBPs

12

Natural penicillins

1) Penicillin G (IV)
2) Penicillin VK (PO)

13

Aminopenicillins

1) Amoxicillin
2) Ampicillin
3) Amoxicillin + Clavulanate (Augmentin)

14

Penicillinase-resistance penicillins

1) Methicillin
2) Nafcillin
3) Cloxacillin
4) Dicloxacillin

15

Extended-Spectrum Penicillins

1) Piperacillin
2) Ticarcillin

**These are IV only

16

Natural Penicillins spectrum

1) Gram-positive cocci
2) Neisseria
3) Most oral anaerobes

*Not effective against gram-neg aerobes or beta-lactamase producing organisms

17

What is Penicillins the DOC for?

N. meningitidis
Syphilis

18

Penicillinase-resistance penicillins spectrum

1) Gram-positive cocci (including B-lactamase producers)
2) some Streptococci
3) Oral anaerobes

*Not effective against gram-negative aerobes

19

Penicillinase-resistance penicillins are DOC for

MSSA (methicillin sensitive Staph. aureus)

20

Aminopenicillins MOA

binds to PBPs and inhibits synthesis in bacterial cell wall

21

Aminopenicillins spectrum

1) Some gram negative organisms
2) some gram positive organisms (Strep, Enterococci)
3) oral anaerobes

*Note effective against B-lactamase producing organisms

22

T/F: Aminopenicillins are the DOC for UTIs

FALSE

only use for UTI if you know its caused by enterococci

23

Extended-Spectrum Penicillins

1) Gram negative infx (esp. good again Pseudomonas aeruginosa)
2) Some gram positive (Strep, Staph, Mb Enterococci)
3) Oral anaerobes
4) some true anaerobes

24

Extended-Spectrum Penicillins are indicated for

severe infections

esp. useful for tx Pseudomonas

Broad Spectrum

25

Penicillin + B-lactamase inhibitors

1) Amoxicillin + Clavulonic acid (Augmentin) (PO)
2) Piperacillin + Tazobactam (IV)

26

T/F: Penicillin + B-lactamase inhibitors work very well to treat all anaerobes

TRUE

27

Penicillins ADRs

1) Allergic rxn - anaphylaxis, rash, urticaria, fever
2) Diarrhea
3) Hematologic - anemia, thrombocytopenia
4) Hepatitis (nafcillin, oxacillin)
5) Interstitial nephritis (nafcillin, oxacillin)
6) Seizures
7) Renal failure

28

If pt. have a true Penicillin allergy, there is a 5% cross reactivity with _____________

cephalosporins

29

Amoxicillin + Clavulanate (Augmentin) s/e

-notable GI s/e (diarrhea is very common)

30

What is the most severe cause of antibiotic induced diarrhea?

Pseudomembranous colitis (C. diff colitis)

31

Most penicillins are renally cleared so you have to adjust dosage for renal fn changes. What are the exceptions?

Nafcillin, oxacillin, dicloxacillin

32

What natural product does amoxicillin have a major interaction with?

Acacia

33

Cephalosporins MOA

disturbs cell wall synthesis of bacteria

(B-lactam binds PBPs)

34

T/F: Cephalosporins not, ever cover enterococcus

TRUE

35

*Cephalexin (Keflex)* (PO) and Cafazolin (IV) class

1st generation cephalosporins

36

Cephalexin (Keflex) (PO) and Cafazolin (IV) spectrum

(1st gen)

1) Gram pos = Strep and MSSA
2) Gram neg = some E.coli and Kleb
3) oral anaerobes

37

Cephalexin (Keflex) (PO) and Cafazolin (IV) indications

(1st gen)

UTIs, skin infx, some respiratory infx, surgical prophylaxis

*alternative to penicillins in allergic pt.

38

Cefuroxime, cefotetan, cefoxitin class

2nd generation cephalosporins

(more resistant to beta-lactamase activity than 1st gen)

39

Cefuroxime, cefotetan, cefoxitin spectrum

(2nd gen)

1) Gram pos = Strep, MSSA
2) Gram neg = good coverage
3) Anaerobes = oral and B. fragilis (cefoxitin, cefotetan)

*None are effective against pseudomonas

40

*Ceftriaxone (IV)*, cefotaxime,ceftazidime, cefixime class

3rd generation cephalosporins

41

Ceftriaxone (IV), cefotaxime,ceftazidime, cefixime spectrum

(3rd gen)

1) Gram pos = Strep, MSSA
2) Gram neg = very good; P. aeruginosa (Ceftazidime)
3) oral anaerobes

42

Ceftriaxone (IV), cefotaxime,ceftazidime, cefixime indications

(3rd gen)

-respiratory infx
-serious infx
-some are able to cross BBB

43

Cefuroxime, cefotetan, cefoxitin indications

(2nd gen)

some respiratory (oral)
GI infx (B. fragilis)

44

Cefepime (IV) class

4th generation cephalosporins

45

Cefepime indications

(4th gen)

serious hospital infx

46

Cefepime spectrum

(4th gen)

1) Gram pos = Strep, MSSA
2) Gram neg = Excellent; P. aeruginosa
3) Oral anaerobes

47

What is the only cephalosporin that can tx B. fragilis?

Cefoxitin (2nd gen)

48

Which cephalosporin(s) can tx Pseudomonas?

Ceftazidime (3rd gen)
Cefepime (4th gen)

49

What is the newly approved '5th generation' cephalosporin and what can it tx?

Ceftaroline

Tx: MRSA (the only one), Strep. pneumo, GNR

Does NOT tx pseudomonas

50

Most cephalosporins are renally cleared and doses need to be adjusted for renal function changes. An exception to this is _______

ceftriaxone (3rd gen)

51

Cephalosporin ADRs

1) Allergic - anaphylaxis, rash, urticaria, fever; 3-7% cross resistance with PCN allergy
2) Diarrhea


3) Hematologic - anemia, thrombocytopenia
4) Seizures (high doses)

52

Macrolides MOA

inhibition of bacterial protein synthesis by binding to the 50s subunit

mostly bacteriostatic

53

Macrolides resistance

plasmid mediated changes or inactivation of ribosomal response

54

Erythromycin, Azithromycin, and Clarithromycin class

Macrolides

55

Erythromycin, Azithromycin, and Clarithromycin (i.e. Macrolides) spectrum

1) Gram pos = Strep, pneumococci, Mb MSSA
2) Gram neg = minimal (H. flu)
3) oral anaerobes
4) Atypical respiratory pathogens (legionella, chlamydia, mycoplasma)

56

Which class of antibiotics do well at tx atypical respiratory pathogens such as Legionella sp., Chlamydia pneumoniae, and Mycoplasma pneumonia?

Macrolides**
Tetracyclines
Fluoroquinolones

57

Erythromycin, Azithromycin, and Clarithromycin (macrolides) ADRs

1) GI - N/V, diarrhea (Erythro > clarithro > azithro)
2) Phlebitis (IV erythro)
3) Prolonged QT interval (Erythro > clarithro >> azithro)
4) Hepatotoxicity (erythro)

58

Macrolides have multiple drug interactions because they

inhibit liver CYP3A4

(Erythro >> clarithro >> azithro)

59

Tetracyclines MOA

inhibits protein synthesis by binding to the 30s ribosomal subunit

bacteriostatic

60

Tetracyclines spectrum

1) Gram pos = Strep, MSSA (SSTI)
2) Gram neg = H. flu, rickettsiae; other gram neg often resistant
3) mostly oral anaerobes
4) atypical respiratory pathogens (Legionella, chlamydia, mycoplasma)

61

Tetracyclines ADRs

1) **Photosensitivity
2) nausea and diarrhea
3) **tooth discoloration in children (C/I in children and pregnancy)
4) esophagitis
5) leukocytosis

62

Macrolides natural product interactions

cesium, ephedra, oleander, sida cordifolia

63

Tetracyclines natural product interactions

oleander, hypericum, p-glycoprotein substrates

64

T/F: tetracyclines are more effective when given with calcium supplements or dairy products

FALSE

they should NOT be given with Ca++ or dairy products

65

Sulfonamides (Sulfa Drugs) MOA

inhibits folic acid synthesis via enzyme inhibition

bacteriostatic

66

Sulfamethoxazole with Trimethoprim/Bactrim MOA

synergistically inhibits two steps in folic acid synthesis

67

Sulfamethoxazole with Trimethoprim/Bactrim spectrum

1) Gram pos = Strep, MSSA, CAMRSA
2) Gram neg = most enterobacteriacae
3) Oral anaerobes

68

T/F: Sulfamethoxazole with Trimethoprim/Bactrim can treat community acquired MRSA

TRUE

69

Bactrim ADRs

1) Allergic rxn (sulfonamide moiety) - rash, fever, photosensitivity, urticaria
2) GI effects
3) Neutropenia, thrombocytopenia (folate deficiency)
4) Steven Johnsons Syndrome (rare)

70

Bactrim increases effects of which drug?

warfarin

71

Fluoroquinolones MOA

inhibit bacterial DNA gyrase, inhibiting DNA replication and transcription

***Bactericidal

72

Levofloxacin, Ciprofloxacin, and Moxifloxacin class

Fluoroquinolones

73

Fluoroquinolones spectrum

potent broad-spectrum that can tx most gram neg and some gram pos

1) gram pos = Strep, MSSA (cipro poor)
2) gram neg = majority, P. aerugonisa
3) minimal anaerobes
4) atypical respiratory pathogens (CA pneumonia - legionella, chlamydia, mycoplasma)

74

Fluoroquinolones ADRs

1) GI - nausea
2) CNS - HA, dizziness, insomnia, confusion, seizures; esp. in elderly
3) Cartilage toxicity (C/I children and pregnancy)
4) Prolonged cardia QT interval

75

Levofloxacin (Fluoroquinolone) natural product interactions

1) cesium
2) ephedra
3) grapefruit
4) sida cordifolia
5) sweet orange

76

What are our main anti-anaerobe drugs?

Metronidazole and Clindamycin

77

Metronidazole (Flagyl) MOA

inhibiting nucleic acid synthesis

78

Clindamycin MOA

ribosomal protein synthesis inhibitor

79

Metronidazole (Flagyl) spectrum

ONLY ANAEROBES!

80

Which antibiotic tx C. diff associated diarrhea and intra-abdominal abscess?

Metronidazole (Flagyl)

81

Clindamycin spectrum

1) Gram pos = Step, MSSA, Mb CAMRSA
2) Gram neg = none**
3) Good coverage for anaerobes (o.k. B. fragilis)

82

Metronidazole (Flagyl) ADRs

1) GI - nausea, diarrhea
2) metallic taste
3) "Disulfiram rxn" - flushing, sweating, nausea w/ alcohol; can persist for a few days post drug

83

Clindamycin ADRs

1) GI - Diarrhea, nausea, C. diff

84

Nitrofurantoin (Macrobid) indication

lower UTI

**not for pyelonephritis
*considered safe in pregnancy prior to 38 wks of gestation

85

Nitrofurantoin (Macrobid) MOA

disrupts both DNA and RNA of bacteria which are sensitive to the drug

86

Nitrofurantoin (Macrobid) ADRs

1) GI - N/V, diarrhea
2) fever and chills (LC)
3) pulmonary fibrosis (LC)

87

Gentamicin, Tobramycin, and Amikacin class

Aminoglycosides

88

when would you use aminoglycosides?

severe infections caused by gram negative, pseudomona auerginosa

89

aminoglycosides ADRs

nephrotoxicity and ototoxicity (monitoring required)

only use in hospital severe infx

90

What is the primary drug used to treat MRSA?

IV Vancomycin

91

What is the 'triple antibiotic cream'

Neosporin OTC

Bacitracin + Neomycin + Polymyxin B

92

T/F: Most pharyngitis cases are bacterial

FALSE

90% of cases are viral (however, about 60% of OV result in antibiotic rx)

93

MC bacterial cz of pharyngitis

Group A B-hemolytic streptococci (GABHS)

*S. pyogenes

94

DOC to tx GABHS

penicillin

(if PCN allergy/resistance, tx w/ azithromycin or cephalosporins)

95

What is the leading indication for outpatient antimicrobial use in the U.S.?

otitis media


(25-50% are viral in origin, however, 80% are rx antibiotics)

96

MC bacterial etiologies of otitis media

1) Step. pneumo (~35%)
2) Haemophilus influenzae (~25%)
3) Moraxella catarrhalis (~15%)

97

guidelines state that it is appropriate to observe pt. with otitis media in children 2-12 y/o with non-severe symptoms for ______ hours

48-72 hrs (or start if child worsens)


**70-90% of children have spontaneous resolution with 7-14 days

98

T/F: if child has AOM with otorrhea you should not observe and go right to tx with antibiotics

TRUE

99

DOC for otitis media

#1 Amoxicillin
#2 Amoxicillin-clavulante (2nd line used for more gram neg)

(alternative for PCN allergy or tx failure are Cephalosporins, Macrolides, and Clindamycin)

100

Treatment failure with otitis media is defined as

no improvement after 48-72 hours of initial tx (switch drugs!)

101

T/F: Purulent nasal secretions or sputum do not predict bacterial infection

TRUE

102

____% of sinusitis cases are viral and ____% of sinusitis cases are bacterial

25% viral
75% bacterial

103

What are the MC bacterial cz of sinusitis?

S. pneumoniae, H. influenza, and M. catarrhalis

104

First-line tx for sinusitis

-amoxicillin
-doxycycline
-TMP/SMX

105

Second-line tx for sinusitis

-amoxicillin/clavulanate
-cephalosporins
-azithromycin or clarithromycin

106

MC bacteria involved in community-acquired pneumonia

S. pneumoniae
H. influenzae

107

For pt. with CA pneumonia that were previously healthy have not use of antimicrobials w/in past 3 mo., tx with

- a macrolide (strongly recommended)
- doxycyline (weakly recommended)

*risk of resistance to S. pneumo is high for these drugs

108

MC bacterial cz of uncomplicated cystitis

1) E. coli (75-95% cases)
2) Klebsiella pneumonia
3) Staph. saprophyticus (post-coital UTIs)
4) Enterococcus
5) Strep. agalactiae (group B strep)

109

If Enterococcus is expected as causative organism in uncomplicated cystitis, tx with

Amoxicillin
Ampicillin

(otherwise avoid these drugs)

110

Tx for Gonorrhea

Single dose tx of:
1) Ceftriaxone 250 mg IM x 1

PLUS

2) Azithromycin 1g PO x 1

(fluoroquinolones are no longer used d/t resistance)

111

Tx for Chlamydia trachomatis

1) Doxycycline 100 mg po BID x 7 days

OR

2) Azithromycin 1 g po x1 (used in tx of gonorrhea anyway)

112

Mild-cellulitis is most often d/t

Group A Strep or Staph aureus (MSSA)

113

Cellulitis that is uncomplicated & non-MRSA infx can be tx with

1) Amoxil-clavulanate
2) Dicloxacillin
3) Cephalexin

114

Cellulitis with a suspicion of MRSA infx requires empiric tx with

1) TMP-sulfa
2) Clindamycin
3) Doxycycline