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Flashcards in Antimicrobials Deck (115):
1

MOA of PCNs

bind PBPs--> inhib. transpeptidation--> inhib. crosslinking of bacterial cell walls

2

Mech. of Resistance for PNCs

penicillinases (B lactamases); structural change in PBP, change in porin structure

3

how do you treat MRSA?

vancomycin

4

how do you treat syphillis?

PCN G or V

5

what are the narrow spectrum PCNs?

PCN G and V
*B lactamase sensitive

6

List the lactams

PCNs, cephalosporins, imipenem, meropenem, aztreonam

7

what are the very narrow spectrum PCNs? what do they treat?

methicillin, nafcillin, oxacillin
staph aureus (not MRSA)
*B lactamase resistant

8

what are the broad spectrum PCNs?

amoxicillin, ampicillin
tx: gram + cocci, not staph, listeria, E. coli, H influenza, borrelia, H. pylori
*B lactamase sensitive

9

what are the extended spectrum PCNs?

ticarcillin, piperacillin, azlocillin
tx: gram neg rods, pseudomonas
*B lactamase sensitive
**synergy with aminoglycosides

10

how are most PCNs excreted?

kidney
*dose reduction in kidney disease

11

What two PCNs are NOT excreted in the kidney?

nafcillin, oxacillin (bile excretion)

12

If a person is allergic to one PCN, can you give them a different one?

NO, assume allergy to all PCNs

13

What is the most unique side effect of PCNs?

Jarish-herxheimer rxn - when tx syphilis

14

What part of a PCN tends to cause hypersensitivity?

sulfur group

15

What is a side effect of methicillin?

interstitial nephritis

16

What is a common side effect of PCNs?

GI distress

17

how do you enhance PCN activity?

add Clavulanic acid or sulbactam
they are B lactamase inhib.

18

what drug increases PCN and cephalosporin concentration?

probenecid

19

What is the MOA of cephalosporins?

same as PCNs: bind PBPs--> inhib. transpeptidation--> inhib. crosslinking of bacterial cell walls
same resistance mech too.

20

first generation cephalosporins

cefazolin
cePHalexin

21

what are first generation cephalosporins used for?

surgical prophylaxis
gram +
E. coli
klebsiella
proteus

22

second generation cephalosporins

cefotetan, cefaclor,
cefuroxime--> crosses BBB

23

What are second generation cephalosporins used for?

gram neg.

24

third gen. cephalosporins

ceftriaxone, cefotaxime, cefdinir, cefixime, cefoperazone

25

what do you use third gen. cephalosporins for?

empirical tx of sepsis and meningitis
NO ACTIVITY AGAINST LAME: listeria, atypicals, MRSA, enterococci

26

How do you treat listeria?

amoxicillin

27

How do you treat atypicals?

macrolides or tetracyclines

28

How do you treat enterococci?

amoxicillin with aminoglycosides

29

4th gen. cephalosporins

cefepime IV only!
-wider spectrum
*B lactamase resistant
**enters CNS

30

What is the mode of excretion for most cephalosporins?

Kidney

31

What cephalosporins are not excreted through the kidney?

cefoperazone, ceftriaxone --> bile

32

Cephalosporin Side Effects

hypersensitivity, GI distress, Disulfiram-like effect

33

What drug should you use if a pt is allergic to cephalosporins?

macrolides (gram+), or aztreonam (gram-)

34

MOA of imipenem and meropenem?

same as PCN but resistant to B lactamases

35

What doe you use imipenem and meropenem for?

gram + cocci, gram - rods, empiric use in nosocomial infections

36

What drug must you give with imipenem? Why?

cilastatin
prevent kidney from metabolizing it too quickly

37

SE of imipenem and meropenem?

GI distress, drug fever, CNS
**1/2 of pts have seizures with imipenem

38

MOA for aztreonam? Use? SE?

same as PCNs + B lactamase RESISTANT
ONLY IV
use: gram neg. rods
**no cross allergenicity with cephalosporins and PCNs

39

MOA vancomycin

binds d-ala-d-ala muramyl pentapeptide--> blocks transglycosylation--> prevents elongation of peptidoglycan cell wall

40

What do you use vancomycin for?

MRSA
enterococci
c. diff

41

What is the first line tx for C. difficile?

metronidazole

42

What are VRSA and VRE microbes? how do they develop resistance?

vancomycin resistant staph aureus
vancomycin resistant enterococci
*change in muramyl pentapeptide target to d-lactate

43

how do you treat VRSA and VRE?

linezolid and streptogramins

44

How is vancomycin delivered?

IV
orally only for colitis

45

SE of vancomycin?

Red man syndrome (histamine induced vasodilation)
ototoxicity
nephrotoxicity

46

MOA of aminoglycosides

inhibits initiation of protein synthesis (30S subunit)--> BACTERIOSTATIC
can also cause misreading of genetic code-> BACTERIOCIDAL

47

Name the aminoglycosides

gentamycin, tobramycin, amikacin, streptomycin

48

What do you use aminoglycosides for?

TB, bubonic plague, tularemia
gram neg rods: pseudomonas
CANT BE USED ON ANAEROBES

49

Excretion of aminoglycosides?

water soluble--> KIDNEY

50

Side effect of aminoglycosides?

nephrotoxicity, ototoxicity, neuromuscular blockade

51

What is neomycin and what is it known for?

aminoglycoside in neosporin, known for contact dermatitis (hypersensitivity)

52

How are aminoglycosides given?

1xday dosing: bacteriocidal so only need a spike once a day
decreases SE

53

aminoglycosides resistance?

conjugating enzymes--> eliminates it too fast to be effective

54

MOA of chloramphenicol?

inhibits peptides transferase (50S)
bacteriostatic

55

What is chloramphenicol used for?

backup for salmonella, b. fragillis, rickettsia, bacterial meningitis

56

Where is chloramphenicol broken down?

LIVER; does reduction in liver dysfunction and in neonates
INHIBITS CYP450

57

SE of chloramphenicol?

dose dependent bone marrow suppression (hypersensitivity), grey baby syndrome and kernicterus

58

Resistance of chloramphenicol?

changes in peptidyl transferase

59

Macrolides MOA?

inhibit translocation (50S)
**inhib. CYP450

60

Names of Macrolides?

erythromycin, azithromycin, clarithromycin, clindamycin

61

What are the Macrolides used for?

gram pos. cocci: staph aureus and anaerobes
also goes into bones for osteomyelitis
atypicals (chlamydia, mycoplasma, ureaplasma)
legionella
campylobacter
mycobacteria avium-intracellular

62

SE of Macrolides?

GI distress, reversible deafness

63

how do you treat macrolide resistant s. pneumo?

telithromycin

64

Macrolides resistance?

methylation of rRNA by methyltransferase of bug--> unable to recognize binding site

65

Tetracylines MOA?

inhibits elongation (30S)
bacteriostatic

66

What abx cannot be used in pregnant women?What do you use tetracyclines for?

aminoglycosides, fluoroquinolones, sulfonamides, tetracylcines

67

What do you use tetracyclines for?

chlamydia, mycoplasma, H. pylori, rickettsia, borrelia burgdorferi, brucella, vibrio, treponema

68

name the tetracyclines

doxycycline, minocycline, demeclocycline

69

what do you use doxycycline for?

prostatitis

70

what do you use minocycline for?

gingivitis

71

what do you use demeclocycline for?

SIADH (blocks ADH receptors)

72

SE of tetracyclines

tooth enamel dysphagia, decreased bone growth, phototoxicity, GI distress, superinfection with candidiasis, vestibular dysfunction

73

tetracycline resistance

pumps drugs out of cells

74

excretion of tetracyclines

most through kidneys, doxycyline goes through liver

75

What is unique about the tetracyclines in regard to divalent cations?

they are chelators
so they shouldn't be taken with food or with vitamins

76

streptogramins moa?

inhibit elongation 50S by blocking acceptor site and decreases release of completed peptide

77

what are the streptogramins?

quinipristin and dalfopristin

78

What do you use streptogramins for?

VRE and VRSA

79

Linezolid MOA?

inhibits initiation (50S)

80

What do you use Linezolid for?

VRE, VRSA, drug resistant pneumococci

81

SE of Linezolid?

bone marrow suppression

82

Fluoroquinolones MOA?

inhib. NA synthesis by inhib. topoisomerase 2 and 4 (DNA gyrase)

83

Name the Fluoroquinolones?

norfloxacin, ciprofloxacin, ofloxacin

84

What do you use Fluoroquinolones for?

UTI, STD (chlamydia, gonorrhea), skin and soft tissue infection with gram neg., shigella, salmonella, E. coli, campylobacter, drug resistant pneumo

85

Why do you have to take Fluoroquinolones without food?

it binds to iron and calcium which inhibits its absorption

86

Excretion of Fluoroquinolones

kidney

87

SE of Fluoroquinolones

tendonitis, tendon rupture, phototoxicity, rash, CNS effects (increase QT interval, Seizures with IV), contraindicated in kids and preg

88

MOA of sulfonamides?

inhib. dihydropteroate synthetase (indirectly inhib. NA synth.)

89

SE of sulfonamides?

hypersensitivity, Stevens-Johnson syndrome (aka exfoliating dermatitis), hemolysis in G6PD deficiency, phototoxicity

90

MOA of trimethoprim and pyrimethamine?

inhib. dihydrofolate reductase (also in humas) - indirectly inhib NA synth.

91

How does trimethoprim and pyrimethamine have anti-neoplastic activity?

because its inhib. dihydrofolate reductase, which is in the microbe and human!

92

SE of trimethoprim and pyrimethamine?

bone marrow suppression
*worrisome because it is used for tx in HIV pts and can worsen leukoplakia

93

What is trimethoprim-sulfamethoxazole used for?

nocardia, listeria, gram neg. and gram pos., pneumocystis jiroveci (prophylaxis in HIV)

94

Pyrimethamine-sulfadiazine use?

toxoplasma gondii (prophylaxis in HIV)

95

Metabolism of trimethoprim and pyrimethamine?

acetylation by liver, excreted in kidney--> can cause kidney stones because its conjugate is less water soluble

96

Why do trimethoprim and pyrimethamine cause drug interactions?

high protein binding, causes kernicterus in neonates

97

Metronidazole MOA?

produces free radicals, bactericidal

98

What is Metronidazole used for?

drug of choice for giardia, trich, entamoeba, C. diff, gardernella, H. pylori

99

SE of Metronidazole?

metallic taste!
disulfiram-like effect

100

What combos are usually used for H. pylori?

BMT= bismuth + metronidazole + tetracycline OR
clarithromycin + amoxicillin + omeprazole

101

Antitubercular drugs

isoniazid, rifampin, ethambutol, pyrazinamide, streptomycin

102

How do you prevent resistance in antitubercular drugs?

combination therapy

103

isoniazid MOA?

cell wall synth inhib. - mycolic acid synth.

104

isoniazid is a prodrug, what allows it to become activated?

conversion by catalase

105

isoniazid resistance?

if the microbe is missing the catalase gene

106

isoniazid use?

mycobacterium only

107

SE of isoniazid?

hepatitis, peripheral neuritis, sideroblastic anemia (B6 def., increased iron), SLE, hemolysis in G6PD def.

108

Rifampin MOA?

inhib. DNA dependent RNA polymerase (transcription)

109

SE of Rifampin?

hepatitis, induction of P450, red-orange metabolites in urine, saliva, tears

110

Ethambutol MOA?

inhib. cell wall synth. by blocking arabingalactan

111

SE of Ethambutol?

dose dependent optic neuritis --> loss of color vision

112

Pyrazinamide MOA?

UNKOWN, prodrug

113

SE of Pyrazinamide?

hepatitis, hyperuricemia

114

Streptomycin MOA?

inihib protein synthesis

115

SE of Streptomycin?

deafness, vestibular dysfunction, nephrotoxicity, neuromuscular blockade vie decreased ach release