Antimicrobials Flashcards

1
Q

MOA of penicillin

A
  • bind penicillin binding proteins (transpeptidases) and block transpeptidase cross-linking of peptidoglycan
  • activate autolytic enzymes
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2
Q

Penicillinase resistant penicillins

A
  • Oxacillin, nafcillin, dicloxacillin

- use for S. aureus (except MRSA)

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3
Q

Aminopenicillins

A
  • Ampicillin, amoxicillin

- combine with clavulanic acid to protect against beta-lactamase

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4
Q

Beta lactam antipesudomonals

A
  • Ticarcillin, piperacillin
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5
Q

Beta-lactamase inhibitors

A
  • CAST

- Clavulanic Acid, Sulbactam, Tazobactam

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6
Q

MOA of cephalosporins

A
  • beta lactams that inhibit cell wall synthesis but are LESS susceptible to penicillinases
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7
Q

Organisms not covered by cephalosporins

A
  • LAME

- Listeria, Atypicals (Chlamydia, Mycoplasma), MRSA, and Enterococci

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8
Q

Indications for 1st generation cephalosporins (cefazolin, cephalexin)

A
  • gram positive cocci and PEcK
  • Proteus, E. coli, Klebsiella
  • cefazolin used prior to surgery to prevent S. aureus infections
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9
Q

Indications for 2nd generation cephalosporins (cefoxitin, cefaclor, cefuroxime)

A
  • gram positive cocci and HEN PEcKS

- Haemophilius, Enterobacter, Neisseria, Proteus, E. coli, Klebsiella, Serratia

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10
Q

Indications for 3rd generation cephalosporins (ceftriaxone, cefotaxime, ceftazidime)

A
  • serious gram negative infections resistant to other beta-lactams
  • ceftriaxone: meningitis and gonorrhea
  • ceftazidine: pseudomonas
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11
Q

Indications for 4th generation cephalosporins (cefepime)

A
  • increased activity against pseudomonas and gram positive organisms
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12
Q

MOA of aztreonam

A
  • monobactam resistant to beta-lactamases
  • prevents peptidoglycan cross-linking by binding to PBP3
  • synergistic with aminogycosides
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13
Q

Indications for aztreonam

A
  • gram negative rods only
  • penicillin allergic pts.
  • pts. with renal insufficiency who cannot tolerate aminoglycosides
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14
Q

MOA of imipenem/cilastatin

A
  • beta-lactamse resistant carbapenem

- always given with cilastatin (inhibitor of renal dehydropeptidase I) to decrease inactivation of drug in renal tubules

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15
Q

MOA of vancomycin

A
  • inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall precursors
  • Bactericidal
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16
Q

Indications for vancomycin

A
  • gram positive only: MRSA, enterococci, and C. difficile
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17
Q

Toxicity of vancomycin

A
  • nephrotoxicity, ototoxicity, thrombophlebitis

- Red Man Syndrome: diffuse flushing (can be prevented by pretreatment with antihistamines and slow infusion rate)

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18
Q

Resistance to vancomycin

A
  • amino acid change of D-ala D-ala to D-ala D-lac
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19
Q

Protein synthesis inhibitors

A
  • Buy AT 30, CCEL at 50
  • 30S inhibitors: aminoglycosides (bactericidal) and tetracyclines (bacteriostatic)
  • 50S inhibitors: chloramphenicol, clindamycin (bacteriostatic), erythromycin (macrolide, bacteriostatic), and linezolid (variable)
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20
Q

MOA of aminoglycosides

A
  • gentamicin, neomycin, amikacin, tobramycin, streptomycin
  • bactericidal
  • inhibit formation of initiation complex and cause misreading of mRNA
  • also block translocation
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21
Q

Indications for aminoglycosides

A
  • severe gram negative rod infections
  • synergistic with beta-lactams
  • ineffective against anaerobes because they require O2 for uptake
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22
Q

Toxicity of aminoglycosides

A
  • nephrotoxicity (esp. when used with cephalosporins)
  • ototoxicity (esp. when used with loop diuretics)
  • neuromuscular blockade
  • teratogen
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23
Q

Mechanism of resistance against aminoglycosides

A
  • transferase enzymes that inactivate the drug by acetylation, phosphorylation or adenylation
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24
Q

MOA of tetracyclines

A
  • tetracycline, doxycycline, demeclocycline, minocycline
  • bacteriostatic
  • bind to 30S and prevent attachment of aminoacyl-tRNA
  • divalent cations inhibit its absorption in the gut (don’t take with milk, antacids, or iron-containing solutions)
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25
Q

5 indications of tetracyclines

A
  • Borrelia burgdorferi
  • M. pneumonia
  • Rickettsia
  • Chlamydia
  • demeclocyline is also an ADH antagonist and used as a diuretic in SIADH
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26
Q

Toxicity of tetracyclines

A
  • discoloration of teeth and inhibition of bone growth in children
  • C.I. in pregnancy
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27
Q

Mechanism of resistance against tetracylines

A
  • decreased uptake or increased efflux via transport pumps

- chemical modification and ribosomal protection

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28
Q

MOA of macrolides

A
  • azithromycin, clarithromycin, erythromycin
  • bacteriostatic
  • block translocation by binding to the 23S rRNA of the 50S ribosomal subunit
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29
Q

Indications for macrolides

A
  • atypical pneumonia
  • STDs (Chlamydia)
  • gram positive cocci
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30
Q

Toxicity of macrolides

A
  • MACRO
  • motility issues, arrhythmia, acute cholestatic hepatitis, rash, eosinophilia
  • increases serum concentrations of theophyllines, oral anticoagulants (warfarin)
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31
Q

Mechanism of resistance against macrolides

A
  • methylation of 23S rRNA binding site
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32
Q

MOA and indications of chloramphenicol

A
  • MOA: blocks peptidyltransferase at 50S ribosomal subunit, bacteriostatic
  • indication: meningitis (H. influenza, N. meningitidis, S. pneumoniae)
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33
Q

MOA and indications of clindamycin

A
  • MOA: blocks peptide transfer (transpeptidation) at 50S ribosomal subunit, bacteriostatic
  • indication: anaerobic infections (above the diaphragm compared to metronidazole which treats anaerobic infections below the diaphragm)
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34
Q

MOA of sulfonamides

A
  • PABA antimetabolites inhibit dihydropteroate synthase

- bacteriostatic

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35
Q

Mechanism of resistance to sulfonamides

A
  • altered enzyme (bacterial dihydropteroate synthase), decreased uptake, or increased PABA synthesis
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36
Q

MOA of trimethoprim

A
  • inhibits bacterial dihydrofolate reductase

- bacteriostatic

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37
Q

Toxicity of trimethoprim and what drug can help prevent toxicity

A
  • megaloblastic anemia, leukopenia, and granulocytopenia

- leucovorin is used for folinic acid rescue

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38
Q

MOA of fluoroquinolones

A
  • inhibits DNA gyrase (topoisomerase II) and topoisomerase IV
  • bactericidal
  • topoisomerase II: more effective in gram negatives
  • topoisomerase IV: more effective in gram positives
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39
Q

Toxicity of fluoroquinolones

A
  • tendon rupture, prolonged QT interval
  • C.I. during pregnancy
  • must not be taken with antacids
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40
Q

MOA of metronidazole

A
  • forms free radical toxic metabolites in the bacterial cell that damage DNA
  • bactericidal, antiprotozoal
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41
Q

Indications for metronidazole

A
  • GET GAP

- Giardia, Entamoeba, Trichomonas, Gardnerella, Anaerobes (Bacteroides, C. difficile), H. pylori

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42
Q

4 drug regimen of TB treatment

A
  • RIPE

- rifampin, isoniazid, pyrazinamide, ethambutol

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43
Q

MOA and toxicity of isoniazid

A
  • MOA: decreased synthesis of mycolic acid, requires catalase peroxidase (KatG) to convert to active metabolite
  • toxicity; neurotoxicity, hepatotoxicity
  • Pyridoxine (vit. B6) can prevent neurotoxicity
44
Q

MOA and toxicity of rifampin

A
  • MOA: inhibits DNA-dependent RNA polymerase

- toxicity: orange colored urine

45
Q

MOA of toxicity of ethambutol

A
  • MOA: decreased carbohydrate polymerization of mycobacterium cell wall by blocking arabinosyltranferase
  • toxicity: optic neuropathy (red-green colorblindness), decreased visual acuity, and central scotomas
46
Q

Treatment of MRSA and VRE

A
  • MRSA: vancomycin

- VRE: linezolid and streptogramins (quinupristin/dalfopristin)

47
Q

MOA of amphotericin B

A
  • binds ergosteraol and forms membrane pores that allow leakage of electrolytes
48
Q

Indication for nystatin

A
  • oral candidiasis (thrush), diaper rash or vaginal candidiasis
49
Q

MOA of azoles

A
  • inhibit fungal sterol (ergosterol) synthesis by inhibiting the P-450 enzyme that converts lanosterol to ergosterol
50
Q

Indications of azoles

A
  • cryptococcal meningitis in AIDS pts and candidal infections of all types
51
Q

MOA of terbinafine

A
  • inhibits the fungal enzyme squalene epoxidase
52
Q

MOA of griseofulvin

A
  • interferes with microtubule function, disrupts mitosis
53
Q

Indication of nifurtimox

A
  • T. cruzi
54
Q

Indication of chloroquine

A
  • plasmodial species other than P. falciparum
55
Q

Treatment of flukes (trematodes)

A
  • praziquantel
56
Q

MOA and indications of zanamivir and oseltamivir

A
  • MOA: inhibit influenza neuraminidase, decreasing the release of progeny virus
  • indications: influenza A and B
57
Q

MOA and indications of ribavirin

A
  • MOA: inhibits synthesis of guanine nucleotides by competitively inhibiting IMP dehydrogenase
  • indications: RSV, chronic hepatitis C
58
Q

MOA of acyclovir

A
  • activated by thymidine kinase and acts as a guanosine analog
  • preferentially inhibits viral DNA polymerase by chain termination
59
Q

Indications of acyclovir

A
  • HSV and VZV
60
Q

MOA and indication of ganciclovir

A
  • MOA: guanosine analog, preferentially inhibits viral DNA polymerase
  • indication: CMV
61
Q

MOA and indication of foscarnet

A
  • MOA: viral DNA polymerase inhibitor that binds to the pyrophosphate binding site of the enzyme, does not require activation by viral kinase
  • indication: CMV retinitis
62
Q

MOA and indication of cidofovir

A
  • MOA: preferentially inhibits viral DNA polymerase, does not require phosphorylation by viral kinase
  • indication: CMV retinitis
63
Q

MOA of interferons

A
  • block replication of both RNA and DNA viruses
64
Q

Indications for IFN-alpha, beta and gamma

A
  • IFN-a: chronic HBV and HBC, Kaposi’s sarcoma
  • IFN-b: MS
  • IFN-g: NADPH oxidase deficiency (chronic granulomatous disease)
65
Q

Cephalosporin that covers MRSA

A
  • ceftaroline
66
Q

Side effects of cephalosporins

A
  • vitamin K deficiency

- increases nephrotoxicity of aminoglycosides

67
Q

Side effects of cloramphenicol

A
  • anemia (dose dependent)
  • aplastic anemia (dose independent)
  • gray baby syndrome (in premature infants because they lack liver UDP-glucuronyl transferase)
68
Q

Side effect of clindamycin

A
  • pseudomembranous colitis (C. difficile)
69
Q

Indications for rifampin other than TB

A
  • meningococcal prophylaxis and chemoprophylaxis in contacts of children with H. influenza type B
70
Q

MOA of pyrazinamide

A
  • acidify intracellular environment

- effective in acidic pH of phagolysosomes

71
Q

Treatment of M. avium

A
  • azithromycin, rifampin, ethambutol, and streptomycin
72
Q

Treatment of M. leprae

A
  • dapsone and rifampin for tuberculoid form

- add clofazimine for lepromatous form

73
Q

Prophylaxis against TB

A
  • isoniazid
74
Q

Prophylaxis against M. avium

A
  • azithromycin
75
Q

Prophylaxis for meningococcal infection

A
  • ciprofloxacin (DOC), rifampin for children
76
Q

Prophylaxis for gonorrhea

A
  • ceftriaxone
77
Q

Prophylaxis for syphillis

A
  • benzathine penicillin G
78
Q

Prophylaxis for history of recurrent UTIs

A
  • TMP-SMX
79
Q

Prophylaxis for endocarditis with surgical or dental procedures

A
  • penicillins
80
Q

Prophylaxis for pregnant women carrying group B strep

A
  • ampicillin
81
Q

Prophylaxis for strep pharyngitis in children with prior rheumatic fever

A
  • oral penicillin
82
Q

Prophylaxis for prevention of post-surgical infection due to S. aureus

A
  • cefazolin
83
Q

Prophylaxis for prevention of gonococcal or chlamydial conjunctivitis in newbron

A
  • erythromycin ointment
84
Q

HIV prophylaxis for CD4 < 200

A
  • TMP-SMX to protect against PCP
85
Q

HIV prophylaxis for CD4 < 100

A
  • TMP-SMX to protect against PCP and toxo
86
Q

HIV prophylaxis for CD4 < 50

A
  • azithromycin to protect against M. avium
87
Q

Antifungals that alter membrane function

A
  • amphotericin B and nystatin
88
Q

Antifungals that alter cell wall synthesis

A
  • caspofungin and anidulfungin
89
Q

Antifungals that alter nucleic acid synthesis

A
  • 5-flucytosine
90
Q

Antifungals that alter lanosterol synthesis

A
  • naftifine and terbinafine
91
Q

Antifungals that alter ergosterol synthesis

A
  • “azoles”
92
Q

MOA of flucytosine

A
  • inhibits DNA and RNA biosynthesis by conversion to 5-fluorouracil by cytosine deaminase
93
Q

MOA of caspofungin, micafungin

A
  • inhibits cell wall synthesis by inhibiting synthesis of beta-glucan
94
Q

MOA of chloroquine

A
  • blocks detoxification of heme into hemozoin, heme accumulates and is toxic to plasmodia
95
Q

Indication for pyrimethamine

A
  • toxoplasmosis
96
Q

Indication for suramin and melarsoprol

A
  • T. brucei
97
Q

Indication for sodium stibogluconate

A
  • Lesihmaniasis
98
Q

Indication for praziquantel

A
  • flukes (nematodes) such as Schistosoma
99
Q

Side effect of acyclovir

A
  • nephrotoxicity

- prevent with aggressive hydration

100
Q

Adverse effect of sulfonamides during pregnancy

A
  • kernicterus
101
Q

Adverse effect of aminoglycosides during pregnancy

A
  • ototoxicity
102
Q

Adverse effect of fluoroquinolones during pregnancy

A
  • cartilage damage
103
Q

Adverse effect of clarithromycin during pregnancy

A
  • embryotoxic
104
Q

Adverse effect of tetracyclines during pregnancy

A
  • discolored teeth, inhibition of bone growth
105
Q

Adverse effect of ribavirin during pregnancy

A
  • teratogenic
106
Q

Adverse effect of griseofulvin during pregnancy

A
  • teratogenic
107
Q

Adverse effect of cloramphenicol during pregnancy

A
  • gray baby syndrome