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Flashcards in Antimicrobials - First Aid Deck (198):
1

Penicillin G and V (prototype Beta-lactams) MOA

Bind penicillin-binding proteins to block transpeptidase cross-linking of peptidoglycan.

They also activate autolytic enzymes.

2

Penicillin G and V Use

-mostly for gram-positive organisms
-also for N. meningitidis and T. pallidum

3

Penicillin G, V are bactericidal for...

gram-positive cocci and rods, gram-negative cocci and spirochetes.

4

Toxicity of Penicillin G, V

HSRs and hemolytic anemia

5

Resistance to Penicillin G, V

penicillinase in bacteria (a type of beta-lactamase) cleaves the beta-lactam ring

6

Ampicillin/Amoxicillin MOA

same as penicillin

7

Ampicillin/Amoxicillin Use

extended spectrum penicillins
-H. influenzae
-E. coli
-Listeria
-Proteus
-Salmonella
-Shigella
-enterococci

8

Ampicillin/Amoxicillin Toxicity

-HSRs
-rash
-pseudomembranous colitis

9

Ampicillin/Amoxicillin Resistance

-penicillinase

10

Oxacillin, Nafcillin, Dicloxacillin MOA

same as penicillin; penicillinase resistant because bulky R group blocks access of beta-lactamase

11

Oxacillin, Nafcillin, Dicloxacillin Use

S. aureus (narrow spectrum)

12

Oxacillin, Nafcillin, Dicloxacillin Toxicity

HSRs, interstitial nephritis

13

MRSA is resistant because of....

altered PBP target site.

14

Ticarcillin, Piperacillin MOA

same as penicillin

15

Ticarcillin, Piperacillin Use

extended spectrum; Pseudomonas and gram-negative rods

16

Beta-lactamse inhibitors are often...

added to penicillin antibiotics to protect the antibiotic from destruction by beta-lactamase.

(Clavulanic Acid, Sulbactam, Tazobactam)

17

Cephalosporins MOA

Beta-lactam drugs that inhibit cell wall synthesis but are less suceptible to penicillinases; bactericidal

18

Organisms typically not covered by cephalosporins are...

LAME:
-Listeria
-Atypicals
-MRSA
-Enterococci

(Exception: ceftaroline covers MRSA)

19

1st generation Cephalosporins Use

Cefazolin, Cephalexin
-gram positive cocci
-Proteus
-E. coli
-Klebsiella

20

Cefazolin is used prior to...

surgery to prevent S. aureus wound infections.

21

2nd generation Cephalosposrins Use

Cefoxitin, Cefaclor, Cefuroxime
-gram positive cocci
-H. influenza
-Enterobacter
-Neisseria
-Proteus
-E. coli
-Klebsiella
-Serratia

22

3rd genreation Cephalosporins Use

Ceftriaxone, Cefotaxime, Ceftazidime
-serious gram negative infections resistant to other beta-lactams
(Ceftriaxone for Neisseria and Ceftazidime for Pseudomonas)

23

4th generation Cephalosporins Use

Cefepime
-increased activity against pseudomonas and gram-positives

24

5th generation Cephalosporins Use

Ceftaroline
-broad gram positive and negative coverage
-including MRSA
-does NOT cover pseudomonas

25

Cephalosporins toxicity

-HSRs
-vitamin K deficiency
-increased nephrotoxicity of aminoglycosides

26

Aztreonam MOA

a monobactam; resistant to beta-lactamases; prevents peptidoglycan cross-linking by binding to PBP3

27

Aztreonam Use

gram-negative rods only; for penicillin allergic pts and those with renal insufficiency who cannot tolerate aminoglycosides

28

Carbapenems (4)

1. Imipenem
2. Meropenem
3. Ertapenem
4. Doripenem

29

Carpabenem (Imipenem) MOA

broad-spectrum, beta-lactamase reistant; always admisistered with Cilastatin (inhibitor of renal dehydropeptidase I) to decrease inactivation of the drug in the renal tubules

30

Clinical use of carbapenems

-gram positive cocci
-gram negative rods
-anaerobes

31

Toxicity

GI distress, rash, CNS toxicity (seizures) - limits use

(Meropenem has decreased risk of seizures)

32

Vancomycin MOA

inhibits cell wall peptidoglycan formation by binding D-ala-D-ala portion of cell wall precurors; bactericidal

33

Use of Vancomycin

gram positive only (serious, multidrug resistant organisms including MRSA, enterococci and C. diff)

34

Toxicity of Vancomycin

-Red Man Syndrome
-Nephrotoxicity
-Ototoxicity
-Thrombophlebitis

35

Mechanism of resistance to Vancomycin

-amino acid modification of D-ala-D-ala to D-ala-D-lac

36

Protein synthesis inhibitors specifically target...

the smaller bacterial ribosome (70S (30S+50S)) leaving the human ribosome (80S) unaffected.

37

30S Inhibitors

Aminoglycosides (bactericidal)
Tetracyclines (bacteriostatic)

38

50S Inhibitors

Chloramphenicol, Clindamycin (bacteriostatic)
Erythromycin (macrolides - bacteriostatic)
Linezolid

39

Aminoglycosides (5)

1. Gentamicin
2. Neomycin
3. Amikacin
4. Tobramycin
5. Streptomycin

40

Aminoglycosides MOA

inhibit formation of initiation complex and cause misreading of mRNA; also block translocation

41

Aminoglycosides are ineffective against...

anaerobes bc they require O2 for uptake.

42

Aminoglycosides Use

-severe gram-negative rod infections
-neomycin for bowel surgery

43

Aminoglycosides Toxicity

-Nephrotoxicity (esp. with cephalosporins)
-Neuromuscular blockade
-Ototoxicity (esp. with loop diuretics)
-Teratogen

44

Aminoglycosides resistance

bacterial transferase enyzmes inactivate the drug by acetylation, phosphorylation or adenylation

45

Tetracyclines (3)

1. Tetracycline
2. Doxycycline
3. Minocycline

46

MOA of Tetracyclines

bind to 30S and prevent attachment of aminoacyl-tRNA

47

Doxycycline is eliminated...

fecally and can be used in pts with renal failure.

48

Tetracyclines should not be taken with...

milk, antacids or iron-containing preps because divalent cations inhibit its absorption in the gut.

49

Clinical use of tetracyclines

-Borrelia
-M. pneumoniae
-Rickettsia and Chlamydia (bc it can accumulate intracellularly)

50

Toxicity of Tetracycline

-GI
-discoloration of teeth-
-inhibition of bone growth
-photosensitivity

(contraindicated in pregnancy)

51

Resistance to Tetracycline

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

52

Macrolides (3)

1. Azithromycin
2. Clarithromycine
3. Erythromycine

53

Macrolides MOA

inhibit protein synthesis by blocking translocation; binds to the 23S rRNA of the 50S ribosomal subunit

54

Macrolides Use

-atypical pneumonias
-STDs (Chlamydia)
-gram-positive cocci (strep infxns in pts allergic to penicillin)

55

Toxicity of Macrolides

-GI motility issues
-Arrhythmia (prolonged QT)
-acute cholestatic hepatitis
-rash
-eosinophilia

56

Macrolides increase the concentration of...

theophyllines and oral anticoagulants.

57

Resistance to Macrolides

methylation of 23S rRNA binding site prevents binding of drug

58

Chloramphenicol Mechanism

blocks peptidyltransferase at 50S ribosomal subunit; bacteriostatic

59

Chloramphenicol Use

Meningitis
Rocky Mountain Spotted Fever

60

Toxicity of Chloramphenicol

-anemia (dose dependent)
-aplastic anemia (dose independent)
-gray baby syndrome

61

Chloramphenicol causes gray baby syndrome in premature infants because...

they lack liver UDP-glucuronyl transferase.

62

Chloramphenicol resistance

plasmid-encoded acetyltransferase inactivates the drug

63

Clindamycin MOA

blocks peptide transfer (translocation) at 50S ribosomal subunit; bacteriostatic

64

Clindamycin Use

-anaerobic infxns (Bacteroides, C. perfringens) in aspiration pneumonia
-lung abscesses
-oral infxns
-Group A Strep

65

Clindamycin Toxicity

-pseudomembranous colitis
-fever
-diarrhea

66

Treat anaerobes above the diaphragm with...

Clindamycin and below the diaphragm with Metronidazole.

67

Sulfonamides (3)

1. Sulfamethoxazole (SMX)
2. Sulfisoxazole
3. Sulfadiazine

68

Sulfonamides MOA

-inhibits folate synthesis
-para-aminobenzoic acid (PABA) antimetabolites inhibit dihydropteroate synthase; bacteriostatic

69

Sulfonamides Use

-gram positive
-gram negative
-Nocardia
-Chlamydia
-simple UTI

70

Toxicity of Sulfonamides

-HSRs
-hemolysis if G6PD deficient
-tubulointerstitial nephritis
-photosensitivity
-kernicterus in infants
-displaces other drugs from albumin (warfarin)

71

Resistance to Sulfonamides

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

72

Trimethoprim MOA

inhibits bacterial dihydrofolate reductase; bacteriostatic

73

Trimethoprim Use

in combo with sulfonamides causing sequential block of folate synthesis; UTIs, Shigella, Salmonella, Pneumocystis jirovecii, pneumonia tx/prophylasis, toxoplasmosis prophylaxis

74

Trimethoprim Toxicity

-megaloblastic anemia
-leukopenia
-granulocytopenia

75

Fluoroquinolones (9)

1. Ciprofloxacin
2. Norofloxacin
3. Levofloxacin
4. Ofloxacin
5. Sparfloxacin
6. Moxifloxacin
7. Gemifloxacin
8. Enoxacin
10. Nalidixic Acid (a quinolone)

76

MOA of Fluoroquinolones

inhibit DNA gyrase (topoisomerase II) and topoisomerase IV; bactericidal

77

Use of Fluoroquinolones

gram-negative rods of urinary and GI tracts (including pseudomonas), Neisseria

78

Fluoroquinolones Toxicity

-superinfections
-tendonitis
-tendon rupture (in people over 60 and people taking prednisone)
-leg cramps
-QT prolonagation

79

Fluoroquinolones are contraindicated in...

pregnant women, nursing mothers, and children under 18 due to risk of cartilage defect.

80

Resistance to Fluoroquinolones

chromosome-encoded mutation in DNA gyrase, plasma-mediated reissitance, efflux pumps

81

Metronidazole MOA

forms free radical toxic metabolites in the bacterial cell taht damage DNA; bactericidal; antiprotozoal

82

Metronidazole Use

Giardia
Entamoeba
Trichomonas
Gardnerella
Anaerobes
H. pylori (w/ a proton pump inhibitor and clarithromycin)

83

Metronidazole Toxicity

Disulfiram like rxn (flushing, tachycardia, hyoptension)

84

Mycobacterium tuberculosis prophylaxis

Isoniazid

85

Mycobacterium tuberculosis treatment

Rifampin
Isoniazid
Pyrazinamide
Ethambutol

86

Mycobacterium avium-intracellulare prophylaxis

Azithromycin
Rifabutin

87

Mycobacterium avium-intracellulare treatment

-more drug resistant than M. tuberculosis
-Azithromycin or Clarithromycin + Ethambutol

88

Mycobacterium leprae treatment

long-term treatment with dapsone and rifampin for tuberculoid form; add clofazimine for lepromatous form

89

Isoniazid MOA

decreased synthesis of mycolic acids; bacterial catalase-peroxidase needed to convert INH to the active metabolite

90

Isoniazid Use

M. tuberculosis

91

Toxicity of Isoniazid

-neurotoxicity, hepatotoxicity
(B6 can prevent the neurotoxicity)

92

Rifampin, Rifabutin MOA

inhibits DNA-dependent RNA polymerase

93

Use of Rifampin, Rifabutin Use

M. tuberculosis; delays resistance to dapsone when used for leprosy; used for meningococcal prophylaxis and prophylaxis in contacts of kids w/ Hib

94

Toxicity of Rifampin, Rifabutin

-orange body fluids
-hepatotoxicity/drug interaction
(Rifabutin favored in pts with HIV due to less CYP450 stimulation.)

95

Pyrazinamide MOA

thought to acidify intracellular environment via conversion to pyrazinoic acid; effective in acidic pH of phagolysosomes where TB engulfed by macrophages is found

96

Pyrazinamide Use

M. tuberculosis

97

Toxicity of Pyrazinamide

Hyperuricemia, hepatotoxicity

98

Ethambutol MOA

decreased carbohydrate polymerization of mycobacterium cell wall by blocking arabinosyltransferase

99

Ethambutol Use

M. tuberculosis

100

Ethambutol toxicity

optic neuropathy (red-green color blindness)

101

Prophylaxis for endocarditis with surgical or dental procedures

Penicillins

102

Prophylaxis for gonorrhea

Ceftriaxone

103

Prophylaxis for recurrent UTIs

TMP-SMX

104

Prophylaxis for meningococcal infxn

Ciprofloxacin
(Rifampin for children)

105

Prophylaxis for pregnant women carrying group B strep

Ampicillin

106

Prevention of gonococcal or chlamydial conjunctivitis in the newborn

erythromycin ointment

107

Prevention of postsurgical infxn due to S. aureus

Cefazolin

108

Prophylaxis of strep pharyngitis in a child with prior rheumatic fever

oral penicillin

109

Prophylaxis for syphilis

benzathine penicillin G

110

Prophylaxis of Pneumocystis pneumonia in HIV pts with CD4<200

TMP-SMX

111

Prophylaxis of Pneumocystis pneumonia and toxoplasmosis in HIV pts with CD4 < 100

TMP-SMX

112

Prophylaxis of M. avium in HIV pts with CD4 < 50

Azithromycin

113

MRSA treatments

-vancomycin
-daptomycin
-linezolid (can cause serotonin syndrome)
-tigecycline
-ceftaroline

114

VRE treatments

-linezolid
-streptogramins (quinupristin/dalfopristin)

115

Amphotericin B MOA

binds ergosterol (unique to fungi); forms membrane pores that allows leakage of electrolytes

116

Amphotericin B Use

-Cryptococcus
-Blastomyces
-Coccidioides
-Histoplasma
-Candida
-Mucor

(give supplemental K+ and Mg2+ bc of altered renal tubule permeability)

117

Amphotericin B toxicity

-fevers/chills
-nephrotoxicity
-arrhythmias
-anemia
-IV phlebitis

118

Nystatin MOA

same as amphotericin B; topical form only!

119

Nystatin Use

"swish and swallow" for oral candidiasis; topical for diaper rash or vaginal candidiasis

120

Azoles (6)

1. Fluconazole
2. Ketoconazole
3. Clotrimazole
4. Miconazole
5. Itraconazole
6. Voriconazole

121

Azoles MOA

inhibit fungal sterol synthesis by inhibiting the CYP450 that converts lanosterol to ergosterol

122

Azoles Use

local/less serious systemic mycoses
-Fluconazole for chronic suppression of cryptococcal meningitis in AIDS pts and candidal infections of all types
-Itraconazole for Blasto, Cocci, and Histo
-Clotrimazole/Miconazole for topical fungal infxns

123

Azoles toxicity

-testosterone synthesis inhibition (gyencomastia, esp. w/ ketoconazole), liver dysfunction (inhibits CYP450)

124

Flucytosine MOA

inhibits DNA and RNA biosynthesis by conversion to 5-FU by cytosine deaminase

125

Use of Flucytosine

systemic funcgal infections (esp. meningitis caused by Crypto) in combo w/ amphotericin B

126

Toxicity of flucytosine

bone marrow suppression

127

Echinocandins (3)

1. Caspofungin
2. Micafungin
3. Anidulafungin

128

Echinocandins MOA

inhibits cell wall synthesis by inhibiting synthesis of beta-glucan

129

Use of Echinocandins

invasive aspergillosis, Candida

130

Terbinafine MOA

inhibits the fungal enzyme squalene epoxidase

131

Terbinafine Use

dermatophytoses (esp onychomycosis)

132

Griseofulvin MOA

interferes w/ microtubule fxn; disrupts mitosis; deposits keratin-containing tissues

133

Use of Griseofulvin

oral treatment of superficial infections; inhibits growth of dermatophytes (tinea, ringworm)

134

Griseofulvin toxicity

teratogenic, carcinogenic, confusion, headaches, increased P450 and warfarin metabolism

135

Toxoplasmosis tx

pyrimethamine

136

Trypanosoma brucei tx

Suramin and Meelarsoprol

137

T. cruzi tx

Nifurtimox

138

Leishmaniasis tx

Sodium Stibogluconate

139

Chloroquine MOA

blocks detoxification of heme into hemozoin; heme accumulates and is toxic to plasmodia

140

Chloroquine Use

treatment of plasmodial species other than P. falciparum (resistance to P. falciparum due to membrane pump that decreases intracellular concentration of the drug)

141

Treat P. falciparum with...

artemether/lumefantrine or atovaquone/proguanil.

142

For life-threatening malaria, use...

quinidine or artesunate.

143

Toxicity of chloroquine

retinopathy
pruritis

144

Antihelminthic therapy (5)

1. Mebendazole
2. Pyrantel pamoate
3. Ivermectin
4. Diethylcarbamazine
5. Praziquantel

(immobilize helminths)

145

Treatment for flukes (trematodes) such as Schistosoma

Praziquantel

146

Zanamivir, Oseltamivir MOA

inhibit influenza neuraminidase leading to decreased release of progeny virus

147

Zanamivir, Oseltamivir Use

treatment/prevention of influenza A and B

148

Ribavirin MOA

inhibits synthesis of guanine nucleotides by competitively inhibiting inosine monophosphate dehydrogenase

149

Ribavirin Use

RSV, chronic hep C

150

Ribavirin toxicity

-hemolytic anemia
-severe teratogen

151

Acyclovir, Famciclovir, Valacyclovir MOA

guanosine analog; triphosphate formed by cellular enzymes; preferentially inhibits DNA polymerase by chain termination

152

Acyclovir, Famciclovir and Valacyclovir have few adverse effects because...

they are monophosphorylated by HSV/VZV thymidine kinase and not phosphorylated in uninfected cells.

153

Use of Acyclovir, Famciclovir and Valacyclovir

HSV and VZV
-HSV induced mucocutaneous/genital lesions and encephalitis
-prophylaxis in immunocompromised
-

154

Acyclovir, Famciclovir and Valacyclovir have no effect on..

latent forms of HSV and VZV.

155

Toxicity of Acyclovir, Famciclovir and Valacyclovir

obstructive crystalline nephropathy and acute renal failure

156

Mechanism of resistance to Acyclovir, Famciclovir and Valacyclovir

mutated viral thymidine kinase

157

Ganciclovir MOA

5' monophosphate formed by a CMV viral kinase; guanosine analog; triphosphate formed by cellular kinases; preferentially inhibits viral DNA polymerase

158

Use of Ganciclovir

CMV, esp. in immunocompromised pts

159

Toxicity of Ganciclovir

leukopenia, neutropenia, thrombocytopenia, renal toxicity

160

Resistance to Ganciclovir

mutated CMV DNA polymerase or lack of viral kinase

161

Foscarnet MOA

viral DNA polymerase inhibitor that binds to the pyrophosphate-binding site of the enzyme; does not require activation by viral kinase

162

Foscarnet Use

CMV retinitis in immunocompromised pts when ganciclovir fails; acyclovir resistant HSV

163

Toxicity of Foscarnet

Nephrotoxicity

164

Resistance to Foscarnet

mutated DNA polymerase

165

Cidofovir MOA

preferentially inhibits viral DNA polymerase; does not require phosphorylation by viral kinase

166

Use of Cidofovir

CMV retinitis in immunocompromised pts; acyclovir-resistant HSV

167

Toxicity of Cidofovir

nephrotoxicity (administer with probenecid and IV saline to decrease toxicity)

168

Highly Active Antiretroviral Therapy (HAART) is initiated when...

pts present with an AIDs defining illness, low CD4 cell counts (<500), or a high viral load.

169

HAART regimen consists of..

3 drugs to preven resistance:
-2 nucleoside reverse transcriptase inhibitors
-1 non-nucleoside reverse transcriptase inhibitor OR 1 protease inhibitor OR 1 integrase inhibitor

170

Protease Inhibitors (7)

1. Atazanavir
2. Darunavir
3. Fosamprenavir
4. Indinavir
5. Lopinavir
6. Ritonavir
7. Saquinavir

(Navir tease a protease)

171

The assembly of HIV virions depends on...

HIV-1 protease (pol gene) which cleaves the polypeptide products of HIV mRNA into their functional parts. Thus, protease inhibitors prevent maturation of new viruses.

172

Ritonavir can boost...

other drug concentrations by inhibiting CYP450.

173

Toxicity of protease inhibitors

hyperglycemia, lipodystrophy, nephropathy, hematuria

174

NRTIs (nucleoside reverse transcriptase inhibitors) (7)

1. Abacavir
2. Didanosine
3. Emtricitabine
4. Lamivudine
5. Stavudine
6. Tenofovir
7. Zidovudine

(Have you dined (vudine) w/ my nuclear (nucleoside) family?)

175

NRTIs MOA

competitively inhibit nucleotide binding to reverse transcriptase and terminate the DNA chain

176

NRTIs need to be...

phosphorylated to be active (except for tenofovir which is a nucleotide).

177

Zidovudine is used for...

general prophylaxis and during pregnancy to decrease risk of fetal transmission.

178

Toxicity of NRTIs

bone marrow suppression (give G-CSF and EPO), neuropathy, lactic acidosis, anemia (ZDV), pancreatitis (didanosine)

179

NNRTIs (non-nucleoside reverse transcriptase inhibitors) (3)

1. Efavirenz
2. Nevirapine
3. Delavirdine

180

NNRTIs MOA

bind to reverse transcriptase at a site different from NRTIs; do not require phosphorylation for activation

181

Toxicity of NNRTIs

-rash, hepatotoxicity
-vivid dreams and CNS symptoms (Efavirenz)

182

Delavirdine and Efavirenz are contraindicated in...

pregnancy.

183

Raltegravir MOA

inhibits HIV genome integration into host cell chromosome by reversibly inhibiting HIV integrase

184

Raltegravir Toxicity

hypercholesterolemia

185

Fusion inhibitors

Enfuvirtide
Maraviroc

186

Enfuvirtide MOA

binds gp41, inhibiting viral entry

187

Maraviroc MOA

binds CCR-5 on surface of T cells/monocytes inhibiting interaction with gp120

188

Interferons MOA

glycoproteins normally synthesized by virus-infected cells, exhibiting a wide range of antiviral and antitumoral properties

189

Use of INF-alpha

chronic Hep B/C, Kaposi sarcoma, hairy cell leukemia, condyloma acuminatum, RCC and malignant melanoma

190

Use of IFN-beta

MS

191

Use of IFN-gamma

CGD

192

Toxicity of interferons

neutropenia
myopathy

193

Antibiotics to avoid in pregnancy

SAFe Children Take Really Good Care
Sulfonamides
Aminoglycosides
Fluoroquinolones
Clarithromycin
Tetracyclines
Ribavirin
Griseofulvin
Chloramphenicol

194

Sulfonamides teratogenecity

Kernicterus

195

Aminoglycosides teratogenecity

ototoxicity

196

Fluoroquinolones teratogenecity

cartilage damage

197

Clarithromycin teratogenecity

embryotoxic

198

Tetracyclines teratogenecity

discolored teeth, inhibition of bone growth