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Antimicrobials Flashcards

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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
5 indications of tetracyclines
- Borrelia burgdorferi - M. pneumonia - Rickettsia - Chlamydia - demeclocyline is also an ADH antagonist and used as a diuretic in SIADH
26
Toxicity of tetracyclines
- discoloration of teeth and inhibition of bone growth in children - C.I. in pregnancy
27
Mechanism of resistance against tetracylines
- decreased uptake or increased efflux via transport pumps | - chemical modification and ribosomal protection
28
MOA of macrolides
- azithromycin, clarithromycin, erythromycin - bacteriostatic - block translocation by binding to the 23S rRNA of the 50S ribosomal subunit
29
Indications for macrolides
- atypical pneumonia - STDs (Chlamydia) - gram positive cocci
30
Toxicity of macrolides
- MACRO - motility issues, arrhythmia, acute cholestatic hepatitis, rash, eosinophilia - increases serum concentrations of theophyllines, oral anticoagulants (warfarin)
31
Mechanism of resistance against macrolides
- methylation of 23S rRNA binding site
32
MOA and indications of chloramphenicol
- MOA: blocks peptidyltransferase at 50S ribosomal subunit, bacteriostatic - indication: meningitis (H. influenza, N. meningitidis, S. pneumoniae)
33
MOA and indications of clindamycin
- 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)
34
MOA of sulfonamides
- PABA antimetabolites inhibit dihydropteroate synthase | - bacteriostatic
35
Mechanism of resistance to sulfonamides
- altered enzyme (bacterial dihydropteroate synthase), decreased uptake, or increased PABA synthesis
36
MOA of trimethoprim
- inhibits bacterial dihydrofolate reductase | - bacteriostatic
37
Toxicity of trimethoprim and what drug can help prevent toxicity
- megaloblastic anemia, leukopenia, and granulocytopenia | - leucovorin is used for folinic acid rescue
38
MOA of fluoroquinolones
- inhibits DNA gyrase (topoisomerase II) and topoisomerase IV - bactericidal - topoisomerase II: more effective in gram negatives - topoisomerase IV: more effective in gram positives
39
Toxicity of fluoroquinolones
- tendon rupture, prolonged QT interval - C.I. during pregnancy - must not be taken with antacids
40
MOA of metronidazole
- forms free radical toxic metabolites in the bacterial cell that damage DNA - bactericidal, antiprotozoal
41
Indications for metronidazole
- GET GAP | - Giardia, Entamoeba, Trichomonas, Gardnerella, Anaerobes (Bacteroides, C. difficile), H. pylori
42
4 drug regimen of TB treatment
- RIPE | - rifampin, isoniazid, pyrazinamide, ethambutol
43
MOA and toxicity of isoniazid
- 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
MOA and toxicity of rifampin
- MOA: inhibits DNA-dependent RNA polymerase | - toxicity: orange colored urine
45
MOA of toxicity of ethambutol
- MOA: decreased carbohydrate polymerization of mycobacterium cell wall by blocking arabinosyltranferase - toxicity: optic neuropathy (red-green colorblindness), decreased visual acuity, and central scotomas
46
Treatment of MRSA and VRE
- MRSA: vancomycin | - VRE: linezolid and streptogramins (quinupristin/dalfopristin)
47
MOA of amphotericin B
- binds ergosteraol and forms membrane pores that allow leakage of electrolytes
48
Indication for nystatin
- oral candidiasis (thrush), diaper rash or vaginal candidiasis
49
MOA of azoles
- inhibit fungal sterol (ergosterol) synthesis by inhibiting the P-450 enzyme that converts lanosterol to ergosterol
50
Indications of azoles
- cryptococcal meningitis in AIDS pts and candidal infections of all types
51
MOA of terbinafine
- inhibits the fungal enzyme squalene epoxidase
52
MOA of griseofulvin
- interferes with microtubule function, disrupts mitosis
53
Indication of nifurtimox
- T. cruzi
54
Indication of chloroquine
- plasmodial species other than P. falciparum
55
Treatment of flukes (trematodes)
- praziquantel
56
MOA and indications of zanamivir and oseltamivir
- MOA: inhibit influenza neuraminidase, decreasing the release of progeny virus - indications: influenza A and B
57
MOA and indications of ribavirin
- MOA: inhibits synthesis of guanine nucleotides by competitively inhibiting IMP dehydrogenase - indications: RSV, chronic hepatitis C
58
MOA of acyclovir
- activated by thymidine kinase and acts as a guanosine analog - preferentially inhibits viral DNA polymerase by chain termination
59
Indications of acyclovir
- HSV and VZV
60
MOA and indication of ganciclovir
- MOA: guanosine analog, preferentially inhibits viral DNA polymerase - indication: CMV
61
MOA and indication of foscarnet
- 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
MOA and indication of cidofovir
- MOA: preferentially inhibits viral DNA polymerase, does not require phosphorylation by viral kinase - indication: CMV retinitis
63
MOA of interferons
- block replication of both RNA and DNA viruses
64
Indications for IFN-alpha, beta and gamma
- IFN-a: chronic HBV and HBC, Kaposi's sarcoma - IFN-b: MS - IFN-g: NADPH oxidase deficiency (chronic granulomatous disease)
65
Cephalosporin that covers MRSA
- ceftaroline
66
Side effects of cephalosporins
- vitamin K deficiency | - increases nephrotoxicity of aminoglycosides
67
Side effects of cloramphenicol
- anemia (dose dependent) - aplastic anemia (dose independent) - gray baby syndrome (in premature infants because they lack liver UDP-glucuronyl transferase)
68
Side effect of clindamycin
- pseudomembranous colitis (C. difficile)
69
Indications for rifampin other than TB
- meningococcal prophylaxis and chemoprophylaxis in contacts of children with H. influenza type B
70
MOA of pyrazinamide
- acidify intracellular environment | - effective in acidic pH of phagolysosomes
71
Treatment of M. avium
- azithromycin, rifampin, ethambutol, and streptomycin
72
Treatment of M. leprae
- dapsone and rifampin for tuberculoid form | - add clofazimine for lepromatous form
73
Prophylaxis against TB
- isoniazid
74
Prophylaxis against M. avium
- azithromycin
75
Prophylaxis for meningococcal infection
- ciprofloxacin (DOC), rifampin for children
76
Prophylaxis for gonorrhea
- ceftriaxone
77
Prophylaxis for syphillis
- benzathine penicillin G
78
Prophylaxis for history of recurrent UTIs
- TMP-SMX
79
Prophylaxis for endocarditis with surgical or dental procedures
- penicillins
80
Prophylaxis for pregnant women carrying group B strep
- ampicillin
81
Prophylaxis for strep pharyngitis in children with prior rheumatic fever
- oral penicillin
82
Prophylaxis for prevention of post-surgical infection due to S. aureus
- cefazolin
83
Prophylaxis for prevention of gonococcal or chlamydial conjunctivitis in newbron
- erythromycin ointment
84
HIV prophylaxis for CD4 < 200
- TMP-SMX to protect against PCP
85
HIV prophylaxis for CD4 < 100
- TMP-SMX to protect against PCP and toxo
86
HIV prophylaxis for CD4 < 50
- azithromycin to protect against M. avium
87
Antifungals that alter membrane function
- amphotericin B and nystatin
88
Antifungals that alter cell wall synthesis
- caspofungin and anidulfungin
89
Antifungals that alter nucleic acid synthesis
- 5-flucytosine
90
Antifungals that alter lanosterol synthesis
- naftifine and terbinafine
91
Antifungals that alter ergosterol synthesis
- "azoles"
92
MOA of flucytosine
- inhibits DNA and RNA biosynthesis by conversion to 5-fluorouracil by cytosine deaminase
93
MOA of caspofungin, micafungin
- inhibits cell wall synthesis by inhibiting synthesis of beta-glucan
94
MOA of chloroquine
- blocks detoxification of heme into hemozoin, heme accumulates and is toxic to plasmodia
95
Indication for pyrimethamine
- toxoplasmosis
96
Indication for suramin and melarsoprol
- T. brucei
97
Indication for sodium stibogluconate
- Lesihmaniasis
98
Indication for praziquantel
- flukes (nematodes) such as Schistosoma
99
Side effect of acyclovir
- nephrotoxicity | - prevent with aggressive hydration
100
Adverse effect of sulfonamides during pregnancy
- kernicterus
101
Adverse effect of aminoglycosides during pregnancy
- ototoxicity
102
Adverse effect of fluoroquinolones during pregnancy
- cartilage damage
103
Adverse effect of clarithromycin during pregnancy
- embryotoxic
104
Adverse effect of tetracyclines during pregnancy
- discolored teeth, inhibition of bone growth
105
Adverse effect of ribavirin during pregnancy
- teratogenic
106
Adverse effect of griseofulvin during pregnancy
- teratogenic
107
Adverse effect of cloramphenicol during pregnancy
- gray baby syndrome
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