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Flashcards in Antimicrobial Therapy Deck (105):
1

Antimicrobial therapy 

folic acid synthesis 

  • Sulfonamides 
  • Trimethoprim 

2

Antimicrobial therapy 

DNA Topoisomerases 

  • Fluoroquinolones
  • Quinolone 

3

Antimicrobial therapy 

damages DNA

Metronidazole

4

Antimicrobial therapy 

mRNA synthesis 

Rifampin

5

Antimicrobial therapy 

protein synthesis (50S)

  • Chloramphenicol
  • Clindamycin
  • Linezolid 
  • Macrolides
  • Streptogramins 

6

Antimicrobial therapy 

protein synthesis (30S)

  • Aminoglycosides
  • Tetracyclines

7

Antimicrobial therapy 

cell wall synthesis (peptidoglycan cross linking) 

  • penicillinase-sensitive penicillins
  • penicillinase-resistant penicillins
  • antipseudomonals
  • cephalosporins
  • carbapenems 
  • monobactams 

8

Antimicrobial therapy 

cell wall synthesis (peptidoglycan synthesis) 

Glycopeptides

9

Penicillin G, V

administration 

  • prototype ß-lactam antibiotics 
  • penicillin G - IV & IM
  • penicillin V - oral 

10

Penicillin G, V

mechanism 

  • bind PBPs (transpeptidases)
  • block transpeptidase cross-linking of peptidoglycan 
  • activate autolytic enzymes 

11

Penicillin G, V

clinical use 

penicillinase 

  • gram (+) organisms 
    • S. pneumoniae, S. pyogenes, Actinomyces
  • N. meningitidis, T. pallidum 
  • bactericidal: gram (+) cocci, gram (+) rods, gram (-) cocci, spirochetes 
  • penicillinase sensitive 

 

12

Penicillin G, V

toxicity 

  • hypersensitivity rxns 
  • hemolytic anemia 

13

Penicillin G, V

resistance 

penicillinase in bacteria cleaves ß-lactam ring

type of ß-lactamase 

14

Ampicillin, amoxicillin 

mechanism 

  • same as penicillin
  • wider spectrum
  • penicillinase sensitive 
  • combine w/ clavulanic acid to protect against ß-lactamase 

15

Ampicillin, amoxicillin 

clinical use 

HELPSS kill enterococci 

  • extended-spectrum penicillin 
  • Haemophilus influenzae 
  • E. coli 
  • Listeria monocytogenes
  • Proteus mirabilis 
  • Salmonella 
  • Shigella 
  • enterococci 

16

Ampicillin, amoxicillin 

toxicity 

  • hypersensitivity rxns
  • rash
  • psuedomembranous colitis 

17

Ampicillin, amoxicillin 

resistance 

  • penicillinase in bacteria cleaves ß-lactam ring
  • ß-lactamase 

18

Oxacillin, nafcillin, dicloxacillin 

mechanism 

  • same as penicillin 
  • narrow spectrum
  • penicillinase resistant 
    • bulky R group 
    • blocks access of ß-lactamase to ß-lactam ring 

19

Oxacillin, nafcillin, dicloxacillin

clinical use 

S. aureus (except MRSA)

20

Oxacillin, nafcillin, dicloxacillin 

toxicity 

  • hypersensitivity rxns 
  • interstitial nephritis 

21

Ticarcillin, piperacillin 

mechanism 

  • same as penicillin
  • extended spectrum 

22

Ticarcillin, piperacillin

clinical use 

  • Pseudomonas spp. 
  • gram-negative rods 
  • susceptible to penicillinase 
  • use w/ ß-lactamase inhibitors 

23

Ticarcillin, piperacillin 

toxicity 

hypersensitivity rxns

24

ß-lactamase inhibitors 

CAST

  • Clavulanic Acid 
  • Sulbactam
  • Tazobactam

25

Cephalosporins 

mechanism 

  • ß-lactams
  • inhibit cell wall synthesis 
  • less susceptible to penicillinases 
  • bactericidal 

26

1st generation cephalosporins 

cefazolin, cephalexin 

  • gram (+) cocci 
  • PEcK
    • Proteus mirabilis
    • E. coli 
    • Klebsiella 

27

_______ used prior to surgery to prevent S. aureus wound infections. 

Cefazolin 

28

2nd generation cephalosporins 

cefoxitin, cefaclor, cefuroxime 

  • gram (+) cocci 
  • HEN PEcKS
    • Haemophilus influenzae
    • Enterobacter aerogenes
    • Neisseria spp. 
    • Proteus mirabilis 
    • E. coli 
    • Klebsiella pneumoniae 
    • Serratia marcescens 

29

3rd generation cephalosporins 

ceftriaxone, cefotaxime, ceftazidime 

  • serious gram (-) infections resistant to other ß-lactams 
  • Ceftriaxone - meningitis & gonorrhea
  • Ceftazidime - Psuedomonas 

30

4th generation cephalosporins 

cefepime

  • increased activity against Pseudomonas & gram (+) organisms 

31

5th generation cephalosporins 

ceftaroline 

  • broad gram (+) & gram (-) organism coverage 
  • MRSA, not Pseudomonas 

32

Cephalosporins 

toxicity 

  • hypersensitivity rxns 
  • vitamin K deficiency 
  • low cross-reactivity w/ penicillins 
  • increased nephrotoxicity of aminoglycosides 

33

Aztreonam 

mechanism 

  • monobactam
  • resistant to ß-lactamases
  • prevents peptidoglycan cross-linking
    • binds PBP
  • synergistic w/ aminoglycosides 
  • no cross-allergy w/ penicillins 

34

Aztreonam 

clinical use 

  • gram (-) rods only 
  • penicillin-allergic patients 
  • patients w/ renal insufficiency who can't tolerate aminoglycosides 

35

Aztreonam toxicity 

  • usually non-toxic 
  • occasional GI upset 

36

Carbapenems 

  • Imipenem
  • Meropenem 
  • Ertapenem
  • Doripenem 

37

Carbapenems 

mechanism 

Imipenem

  • broad-spectrum, ß-lactamase resistant 
  • admin w/ cilastatin 
    • inhibitor of renal dehydropeptidase I
    • decreased inactivation of drug in renal tubules 

38

Carbapenems

clinical use

  • gram (+) cocci, gram (-) rods, anaerobes 
  • wide spectrum
  • life-threatening infections or when other drugs have failed 
  • Meropenam has decreased risk of seizures

39

Carbapenems 

toxicity 

  • GI distress
  • skin rash
  • CNS toxicity (seizures)

40

Vancomycin 

mechanism 

  • inhibits cell wall peptidoglycan formation 
  • binds D-ala-D-ala 
  • bactericidal 

41

Vancomycin 

clinical use 

  • gram (+) only 
  • serious, multidrug-resistant organisms
  • MRSA, enterococci, C. difficile 

42

Vancomycin 

toxicity 

NOT trouble-free

  • Nephrotoxicity 
  • Ototoxicity 
  • Thrombophlebitis 
  • diffuse flushing
  • red man syndrome 

43

Vancomycin

resistance

  • aa modification of D-ala-D-ala to D-ala-D-lac 

44

Protein synthesis inhibitors 

  • 30S inhibitors
  • 50S inhibitors 

Buy AT 30, CCEL (sell) at 50

  • 30S inhibitors
    • Aminoglycosides 
    • Tetracyclines
  • 50S inhibitors 
    • Chloramphenicol, Clindamycin 
    • Erythromycin (macrolides)
    • Linezolid 

45

Aminoglycosides 

GNATS

  • Gentamicin
  • Neomycin
  • Amikacin
  • Tobramycin
  • Streptomycin

46

Aminoglycosides 

mechanism 

  • bactericidal 
  • inhibits formation of initiation complex 
  • misreading of mRNA
  • blocks translocation 
  • requires O2 (aerobes)

47

Aminoglycosides 

clinical use 

  • severe gram (-) rod infections 
  • synergistic w/ ß-lactam antibiotics 

48

________ for bowel surgery. 

Neomycin

49

Aminoglycosides 

toxicity 

NNOT

  • Nephrotoxicity 
  • Neuromuscular blockade 
  • Ototoxicity 
  • Teratogen 

50

Aminoglycosides

resistance 

  • bacterial transferase enzymes inactivate drug
    • acetylation
    • phosphorylation
    • adenylation

51

Tetracyclines

 

  • Tetracycline
  • Doxycycline
  • Minocycline 

52

Tetracyclines

mechanism 

  • bacteriostatic 
  • binds 30S & prevents attachment of aminoacyl tRNA
  • limited CNS penetration 

53

________ is fecally eliminated & can be used in patients w/ renal failure. 

Doxycycline

54

Do not take tetracyclines w/ ______, _____, or ____-containing preparations b/c divalent cations inhibit its absorption in the gut. 

  • milk (Ca2+)
  • antacids (Ca2+, Mg2+)
  • iron

55

Tetracyclines

clinical use 

  • Borrelia burgdorferi 
  • M. pneumoniae 
  • Rickettsia & Chlamydia (intracellular) 
  • treats acne 

56

Tetracyclines 

toxicity 

  • GI distress
  • discoloration of teeth & inhibition of bone growth 
    • children 
  • photosensitivity 
  • contraindicated in pregnancy 

57

Tetracyclines 

resistance 

decreased uptake or increased efflux out of bacterial cells by plasmid-encoded transport pumps 

58

Macrolides

  • Azithromycin
  • Clarithromycin
  • Erythromycin 

59

Macrolides 

mechanism 

  • inhibit protein synthesis
  • block translocation 
  • bind 23S rRNA of 50S ribosomal subunit 
  • bacteriostatic 

60

Macrolides

clinical use 

  • atypical pneumonias 
    • Mycoplasma
    • Chlamydia 
    • Legionella 
  • STDs
    • Chlamydia 
  • gram (+) cocci 
    • Strep in patients allergic to penicillin 

61

Macrolides 

toxicity 

MACRO

  • GI Motility issues
  • Arrhythmia (prolonged QT)
  • acute Cholestatic hepatitis
  • Rash
  • eOsinophilia 
  • Increases serum conc of theophyllines, oral anticoagulants 

62

Macrolides

resistance 

methylation of 23S rRNA-binding site 

63

Chloramphenicol 

mechanism 

blocks peptidyltransferase at 50S ribosomal subunit

64

Chloramphenicol 

clinical use 

  • meningitis 
    • Haemophilus influenzae 
    • Neisseria meningitidis 
    • Streptococcus pneumoniae 
  • rocky mountain spotted fever
    • Rickettsia rickettsii 
  • limited use due to toxicity (but low cost)

65

Chloramphenicol 

toxicity 

  • anemia (dose dependent)
  • aplastic anemia (dose independent)
  • gray baby syndrome 
    • premature infants
    • lack liver UDP-glucuronyl transferase

66

Chloramphenicol 

resistance 

plasmid-encoded acetyltransferase inactivates the drug 

67

Clindamycin

mechanism 

blocks peptide transfer (translocation) at 50S ribosomal subunit 

 

68

Clindamycin

clinical use 

  • anaerobic infections (Bacteroides, Clostridium perfringens) in...
    • aspiration pneumonia 
    • lung abscesses
    • oral infections 
  • invasive group A strep infection 

69

______ treats anaerobes above the diaphragm. 

______ treats anaerobes below the diaphragm. 

Clindamycin

Metronidazole

70

Clindamycin 

toxicity 

  • Pseudomembranous colitis (C. diff overgrowth)
  • fever
  • diarrhea

71

Sulfonamides 

  • sulfamethoxazole (SMX)
  • sulfisoxazole 
  • sulfadiazine 

72

Sulfonamides 

mechanism 

  • inhibit folate synthesis 
  • PABA antimetabolites inhibit dihydropteroate synthase 
  • bacteriostatic 

A image thumb
73

Sulfonamides 

clinical use 

  • gram (+)
  • gram (-)
  • Nocardia
  • Chlamydia
  • triple sulfas or SMX for simple UTI 

74

Sulfonamides

toxicity 

  • hypersensitivity rxns 
  • hemolysis if G6PD deficient 
  • nephrotoxicity (tubulointerstitial nephritis)
  • photosensitivity 
  • kernicterus in infants 
  • displace other drugs from albumin (warfarin)

75

Sulfonamides

resistance 

  • altered enzyme (bacterial dihydropteroate synthase)
  • decreased uptake 
  • increased PABA synthesis 

76

Trimethoprim

mechanism 

inhibits bacterial DHFR

bacteriostatic 

77

Trimethoprim 

clinical use 

  • combination w/ sulfonamides (TMP-SMX)
  • sequential blockade of folate synthesis
  • combination used for UTIs, Shigella, Salmonella, PCP pneumonia treatment & prophylaxis, toxoplasmosis prophylaxis 

78

Trimethoprim 

toxicity 

  • megaloblastic anemia 
  • leukopenia 
  • granulocytopenia 

79

Fluoroquinolones

 

  • ciprofloxacin
  • norfloxacin
  • levofloxacin
  • ofloxacin
  • sparfloxacin
  • moxifloxacin
  • gemifloxacin
  • enoxacin
  • nalidixic acid (quinolone)

80

Fluoroquinolones 

mechanism 

  • inhibit DNA gyrase (topoisomerase II) & topoisomerase IV
  • bactericidal must NOT be taken w/ antiacids 

81

Fluoroquinolones

clinical use 

  • gram (-) rods of urinary & GI tracts 
    • includes Pseudomonas 
  • Neisseria 
  • some gram (+)

82

Fluoroquinolones 

toxicity 

  • GI upset
  • superinfections
  • skin rashes
  • headache 
  • dizziness 
  • less common: tendonitis, tendon rupture, leg cramps, myalgias 
  • contraindicated in pregnant women, nursing mothers, children <18 YO --> possible damage to cartilage
  • prolonged QT interval 
  • tendon rupture in >60 YO & patients taking prednisone 

83

Fluoroquinolones

resistance 

  • chromosome-encoded mutation in DNA gyrase
  • plasmid-mediated resistance
  • efflux pumps 

84

Metronidazole

mechanism 

  • free radical toxic metabolites in bacterial cell that damage DNA 
  • bactericidal 
  • antiprotozoal 

85

Metronidazole

clinical use 

GET GAP 

  • Giardia
  • Entamoeba
  • Trichomonas 
  • Gardnerella vaginalis 
  • Anaerobes (Bacteroides, C. difficile)
  • H. Pylori (triple therapy)
    • metronidazole + PPI + clarithromycin

86

Metronidazole 

toxicity 

  • disulfiram-like rxn w/ alcohol 
    • severe flushing 
    • tachycardia
    • hypotension 
  • headache
  • metallic taste

87

Antimycobacterial drugs 

  • M. tuberculosis
  • M. avium-intracellulare 
  • M. leprae 

  • M. tuberculosis
    • Prophylaxis: Isoniazid 
    • Treatment: RIPE
      • Rifampin
      • Isoniazid
      • Pyrazinamide
      • Ethambutol 
  • M. avium-intracellulare 
    • Prophylaxis: azithromycin, rifabutin
    • Treatment: azithromycin/clarithromycin + ethambutol 
  • M. leprae
    • Prophylaxis: N/A
    • Treatment: dapson & rifampin (T); + clofazimine (L)

88

Isoniazid 

mechanism 

  • decreases synthesis of mycolic acids 
  • bacterial catalase-peroxidase needed to convert to active metabolite 

89

Isoniazid 

toxicity  

INH Injures Neurons & Hepatocytes

  • neurotoxicity 
  • hepatotoxicity 
  • pyridoxine (vit B6) can prevent neurotoxicity, lupus 

90

Rifamycins

 

  • Rifampin
  • Rifabutin 

91

4 R's of Rifampin 

Rifampin ramps up CYP450, but rifabutin does not 

  • RNA polymerase inhibitor 
  • Ramps up microsomal CYP450
  • Red/orange body fluids 
  • Rapid resistance if used alone 

92

Rifamycins

_____ favored over _____ in patients w/ HIV infection due to less CYP450 stimulation. 

rifabutin

rifampin

93

Pyrazinamide 

mechanism 

  • uncertain
  • thought to acidify intracellular environment 
  • conversion to pyrazinoic acid 
  • effective in acidic pH of phagolysosomes (TB engulfed by macrophages)

94

Pyrazinamide 

clinical use

toxicity 

  • Mycobacterium tuberculosis 
  • Hyperuricemia, hepatotoxicity 

95

Ethambutol 

mechanism 

decreases carb polymerization of mycobacterium cell wall by blocking arabinosyltransferase 

96

Ethambutol

clinical use

toxicity 

  • Mycobacterium tuberculosis 
  • Optic neuropathy (red-green color blindness)

97

antimicrobial prophylaxis

endocarditis w/ surgical or dental procedures

penicillins

98

antimicrobial prophylaxis 

gonorrhea 

ceftriaxone 

99

antimicrobial prophylaxis 

history of recurrent UTIs

TMP-SMX

100

antimicrobial prophylaxis 

meningococcal infection 

ciprofloxacin 

rifampin (children)

101

antimicrobial prophylaxis 

pregnant woman carrying group B strep

ampicillin

102

antimicrobial prophylaxis 

prevention of gonococcal or chlamydial conjunctivitis of the newborn 

erythromycin ointment 

103

antimicrobial prophylaxis 

prevention of postsurgical infection due to S. aureus 

cefazolin 

104

antimicrobial prophylaxis 

prophylaxis of strep pharyngitis in child w/ prior rheumatic fever 

oral penicillin 

105

antimicrobial prophylaxis 

syphilis 

benzathine penicillin G