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USMLE STEP 1 > Micro AntiMicrobials > Flashcards

Micro AntiMicrobials Flashcards

1
Q

Blocks cell wall synthesis by inhibiting peptidoglycan cross-linking

A

Penicillin, Methicillin, Ampicillin, Piperacillin, Cephalosporins, Aztreonam, Imipenem

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2
Q

Blocks peptidoglycan synthesis

A

Bacitracin, Vancomycin

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3
Q

Inhibits Folic Acid Synthesis (involved in methylation)

A

Sulfonamides, Trimethoprim

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4
Q

Blocks DNA topoisomerase

A

Fluoroquinolones

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5
Q

Blocks mRNA synthesis

A

Rifampin

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6
Q

Damages DNA

A

Metronidazole

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7
Q

Blocks protein synthesis at 50S ribosome

A

Chloramphenicol, Macrolides, Clindamycin, Streptogamins (Quinupristin, dalfopristin), Linezolid

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8
Q

Blocks protein synthesis at 30S ribosome

A

Aminoglycosides, Tetracycline

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9
Q 
Penicillin 
Names? Class? 
MoA
Use? Bactericidal for...
Tox
Resistance
A

G (IV and IM), V (oral). β-lactam Antibiotic
Binds PBP (transpeptidiases) and blocks its cross-linking of peptidoglycan
Gram+, N meningitidis, T pallidum, Syphilis
Bactericidal for Gram+ cocci, Gram+ rods, Gram- cocci, Spirochetes
Hypersensitivity rxn, Hemolytic anemia
β-lactamase cleaves β-lactam ring

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10
Q 
Penicillinase-Resistent Penicillins 
Names 
Spectrum 
MoA
Use
Tox
A

Oxacillin, Nafcillin, Dicloxacillin
Narrow spectrum
Same as penicillin but bulk R group blocks β-lactamase access
S aureus (except MRSA)
Hypersensitivity reaction. Interstitial nephritis

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11
Q 
Aminopenicillins 
Names? Spectrum? 
MoA
Availability 
Use
Tox
Resistance
A

Ampicillin and Amoxicillin. Wide spectrum
Same as penicillin.
AmOxicillin has greater Oral availability
“HELPSS kill Enterococci “
H influenzae, E coli, Listeria, Proteus, Salmonella, Shigella, Enterococci
Hypersensitivity rxn, Ampicillin rash, Pseudomembranous colitis
Penicillinase sensitive. Combine w/ Clavulanic acid to protect against β-lactamase

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12
Q 
Antipseudomonals 
Names
MoA? Spectrum? 
Use
Tox
Resistance
A 
Ticarcillin and Peperacillin 
Same as penicillin. Extended spectrum 
Pseudomonas and Gram- rods
Hypersensitivity rxn
Penicillinase. Use with Clavulanic acid
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13
Q

β-lactamase Inhibitors

A

“CAST”

Clavulanic Acid, Sulbactam, Tazobactam

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14
Q 
Cephalosporins 
MoA
Resistance 
What does it do to bacteria 
What bacteria can in kill? 
Tox
A

β-lactam
Less susceptible to penicillinase
Does not kill “LAME” bugs
Listeria, Atypicals (chlamydia, Mycoplasma, MRSA, Enterococci
Ceftaroline covers MRSA
Hypersensitivity, VitK deficiency. ↑ nephrotoxicity of aminoglycosides

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15
Q

1st gen Cephalosporins
Names
Uses

A

Cefazolin, Cephalexin
Gram+ cocci, Proteus, E coli, Klebsiella
“PEcK”
Cefazolin used prior to surgery to prevent S aureus wound infection

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16
Q

2nd gen Cephalosporins
Names
Uses

A

Cefoxitin, Cefaclor, Cefuroxime
Gram+ cocci, Haemophilus, Enterobacter aerogenes, Neisseria, Proteus, E coli, Klebsiella, Serratia
“HEN PEcKS”

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17
Q

3rd gen Cephalosporins
Names
Uses

A

Ceftriaxone, Cefotaxime, Ceftazidime
Serous Gram- infections resistant to other β-lactam
Ceftriazone: Meningitis and Gonorrhea
Ceftazidime: Pseudomonas

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18
Q

4th gen Cephalosporins
Names
Uses

A

Cefepime

Pseudomonas and Gram+

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19
Q 
Aztreonam 
MoA
Resistance
Use
Tox
A

Monobactam. Prevents peptidoglycan cross-linking by binding PBP3
Resistant to β-lactamase
Gram- rods only. No activity against Gram+ or anaerobes (pseudomonas)
Used for penicillin allergy pts and those with renal insufficiency who cannot tolerate aminoglycosides
Generally nontoxic. Possible GI upset.

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20
Q 
Carbapenems
Names
MoA
Co-administration w/... 
Resistance 
Use
Tox
A

Imipenem, Meropenem, Ertapenem, Doripenem
Broad spectrum β-lactam.
I is coadministered w/ Cilastatin (inhibitor of renal dehydropeptidase I) to ↓ inactivation of drug in renal tubules. M resistent to inactivation
Resistent to β-lactamase
Gram+ cocci, Gram- rods, and anaerobes
Only used when all else fails or life threatening
GI distress, Skin rash, CNS tox (seizures)

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21
Q 
Vancomycin 
MoA
What does it do to bacteria?
Use
Tox
Resistance
A

Inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall precursors
Bactericidal
Gram+ only. Multi-drug resistant organisms: MRSA, enterococci, C diff
“NOT so bad”
Nephrotoxic, Ototoxic, Thrombophlebitis (inflammation of a vein caused by a blood clot), Diffuse flushing - Red Man Syndrome (prevented by pretreatment with antihistamines and slow infusion rate)
Mutation of 2nd D-ala to D-lac

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22
Q

Protein Synthesis inhibitors

A

“Buy AT 30, CCEL (sell) at 50”
30S inhibitors:
Aminoglycosides (bactericidal), Tetracyclines (bacteristatic)
50S inhibitors (bacteristatic):
Chloramphenicol, Clindamycin, Erythromycin (macrolides), Linezolid (variable)

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23
Q 
Aminoglycosides 
Names 
What does it do to bacteria?
MoA
Uptake
A

“Mean GNATS caNNOT kill Anaerobes”
Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin
Bactericidal
Inhibits formation of initiation complex and causes misreading. Blocks translocation
Needs O2 for uptake thus ineffective against anaerobes

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24
Q

Aminoglycosides
Use
Tox
Resistance

A

“Mean GNATS caNNOT kill Anaerobes”
Severe Gram- rods. Synergistic w/ β-lactams. N for bowel surgery
Nephrotoxic (esp w/ cephalosporins), Neuromuscular blockade, Ototoxic (esp w/ loops diuretics), Teratogen
Transferase enzyme that inactivates the drug by acetylation, phosphorylation or adenylation

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25
``` Tetracylcines Names What does it do to bacteria? MoA Elimination Do not take w/ ```
Tetracycline, Doxycycline, Demeclocycline, Minocycline Bacteriostatic Binds 30S and prevents attachment of aminoacyl-tRNA Demeclocycline is an ADH antagonist used to treat SIADH Doxycycline fecally eliminated so it can be given to pts with renal failure Do not take with milk, antaacids, iron b. divalent cations inhibit gut absorption
26
``` Tetracylcines Use Tox Contraindications Resistance ```
Borrelia burgdorferi, M pneumoniae, Rickettsia, and Chlamydia (accumulates in cells so good at killing last 2) GI distress, discoloration of teeth and inhibition of bone growth in children. Photosensitivity Pregnancy ↓ Uptake or ↑ efflux by plasmid encoded pump
27
``` Macrolides Names What does it do to bacteria MoA Use ```
``` Azithromycin, Clarithromycin, Erythromycin Bacteriostatic Blocks translocation ("macroSLIDES"). Binds 23S rRNA of 50S ribosome Atypical pneumonia (Mycoplasma, Chlamydia, Legionella), STDs (Chlamydia), Gram+ cocci (strep in pts allergic to penicillin) ```
28
Macrolides Tox Resistance
"MACRO" Motility issues, Arrhythmia (long QT), acute Cholestatic hepatitis, Rash, eOsinophilia. Increased serum concentration of theophyllines and oral anticoagulants Methylation of 23S rRNA binding site
29
``` Chloramphenicol What does it do to bacteria? MoA Use Tox Resistance ```
Bacteriostatic. Blocks peptidyltransferase at 50S Meningitis (Haemophilus, N meningitidis, Strep pneumoniae) Anemia, Aplastic anemia, Gray baby syndrome (in premies b/c lack of UDP glucuronyl transferase) Plasmid encoded acetyltransferase inactivates drug
30
``` Clindamycin What does it do to bacteria? MoA Use Tox ```
Bacteriostatic. Blocks peptide transfer (transpeptidation) at 50S ribosomal subunit Anaerobes (Bacteroides fragilis, C perfringens) in aspiration pneumonia or lung abscesses. Oral infections with mouth anaerobes "Anaerobes above the diaphragm" Pseudomembranous colitis (C diff overgrowth), Fever, Diarrhea
31
``` Sulfonamides Names What does it do to bacteria? MoA Use Tox Resistance ```
Sulfamethoxazole (SMX), Sulfisoxazole, Sulfadiazine Bacteriostatic PABA antimetabolite inhibits dihydropteroate syntahse Gram+, Gram-, Nocardia, Chlamydia, UTIs Hypersensitivity, Hemolysis (G6PD deficiency), Nephrotoxic (tubulointerstitial nephritis), Photosensitivity, Kernicterus (infants), Displace other drugs from albumin (warfarin) Altered dihydropteronate synthase, ↓ uptake, ↑ PABA synthesis
32
Bacterial DNA, RNA, and Protein Synthesis
PABA + Pteridine --> [Dihydropteroate Synthase] --> Dihydropteroic acid --> Dihydrofolic acid --> [Dihydrofolate reductase] --> THF --> N methylene THF --> Purines (DNA and RNA), Thymidine (DNA), and Methionine (proteins)
33
``` Trimethoprim What does it do to bacteria? MoA Used w/ Use Tox ```
Bacteriostatic Inhibits bacterial DHF reductase Combined with SMX UTIs, Shigella, Salmonella, Pneumocystis jirovecii pneumonia (treatment and prophylaxis) "TMP: Treats Marrow Poorly" Megaloblastic anemia, Leukopenia, Granulocytopenia. May alleviate w/ supplemental folic acid (Leucovorin rescue)
34
``` Fluoroquinolones Names What does it do to bacteria Co-administration MoA Resistance ```
Ciprofloxacin, Norfloxacin, Levofloxacin, Olfoxacin, Sparfloxacin, Moxifloxacin, Gatifloxacin, Enoxacin. Nalidixic acid (quinolone) Bactericidal. Do not take with antacids Inhibits DNA gyrase (topoisomerase II) and topoisomerase IV Chromosome-encoded mutation in DNA gyrase, Plasmid-mediated resistance, efflux pumps
35
Fluoroquinolones Use Tox Contraindications
Gram- rods of Urinary and GI tracts (including Pseudomonas), Neisseria, Some Gram+ organisms "LONES hurt your BONE attachments" GI upset, Super-infections, Skin rashes, Headache, Dizziness. Tendonitis, Tendon rupture, Leg cramps, Myalgias, Long QT Pregnant women, Children (damage to cartilage)
36
``` Metronidazole What does it do to pathogens? MoA Use Tox ```
Bactericidal. Antiprotozoal Free radicals "GET GAP on the METRO" Giardia, Entamoeba, Trichomanas, Gardnerella vaginalis, Anaerobes below the diaphragm (Bacteroides, C diff), H pylori (w/ PPI and Clarithromycin) Disulfiram-like reaction w/ EtOH, Headache, Metallic taste
37
Antimycobacterial Drugs
Tuberculosis Prophylaxis: Isoniazid. Treatment: "RIPE" Rifampin, Isoniazid, Pyrazinamide, Ethambutol M avium-intracellulare Prophylaxis: Azithromycin. Treatment: Azithromycin, Rifampin, Ethambutol, Streptomycin Leprae Treatment: Tuberculoid form w/ Dapsone and Rifampin. Add Clofazimine for Lepromatous form
38
``` Isoniazid Activation MoA Use Tox ```
``` Bacterial catalase-peroxidase (KatG) converts INH into active metabolite ↓ synthesis of mycolic acids TB Neurotoxicity and Hepatotoxicity. Lupus VitB6 prevents neurotoxicity ```
39
Rifampin MoA Use Tox
"4Rs" RNA pol, Revs up P450, Red/Orange fluid, Rapid resistance if used alone Inhibits DNA-dependent RNA pol TB. Delays resistance to dapsone in leprosy. Meningococcal prophylaxis and chemoprophylaxis in contacts of children with Haemophilus influenzae type B Hepatotoxic. Drug interactions (↑ P450). Orange body fluid
40
Pyrazinamide MoA Use Tox
Acidifies intracellular environment TB Hyperuricemia, Hepatotoxic
41
Ethambutol MoA Use Tox
↓ carbohydrate polymerization of mycobacterium cell wall by blocking arabinosyltranferase TB Optic neuropathy (Red-Green Color Blindess)
42
Meningococcal infection prophylaxis
Ciprofloxacin or Rifampin (for children)
43
Gonorrhea prophylaxis
Ceftriaxone
44
Syphilis prophylaxis
Benzathine Penicillin G
45
History of recurrent UTI prophylaxis
TMP-SMX
46
Endocarditis with surgical or dental procedures prophylaxis
Penicillins
47
Pregnant woman carrying GBS prophylaxis
Ampicillin
48
Strep Pharyngitis in child with prior RF prophylaxis
Oral penicillin
49
Post-surgical infection due to S aureus prophylaxis
Cefazolin
50
Gonococcal or Chlamydial conjunctivitis in newborns prophylaxis
Erythromycin ointment
51
HIV prophylaxis for CD4 less than 200
TMP-SMX for Pneumocystis pneumonia | Aerosolized pentamidine used if pt cannot tolerate TMP-SMX but this may not prevent toxoplasmosis
52
HIV prophylaxis for CD4 less than 100
TMP-SMX for Pneumocystis pneumonia and Toxoplasmosis | Aerosolized pentamidine used if pt cannot tolerate TMP-SMX but this may not prevent toxoplasmosis
53
HIV prophylaxis for CD4 less than 50
Azithromycin for Mycobacterium avium complex
54
Treatment of MRSA and VRE (enterococci)?
MRSA: Vancomycin VRE: Linezolid and Streptogramins (quinupristin/dafopristin)
55
``` Amphotericin B MoA Use Route Supplement Tox How to reduce tox? ```
Binds ergosterol forming pores in membrane Cryptococcus (w/ or w/o Flucytosine), Blastomyces, Coccidioides, Histoplasma, Candida, Mucor Intrathecally for fungal meningitis K and Mg to change renal tubule permeability Fever/Chills ("shake and bake"), Hypotension, Nephrotoxic, Arrhythmias, Anemia, IV phlebitis Hydration (for kidneys) and Liposomal form reduces tox
56
Nystatin MoA Use
Binds ergosterol forming pores in membrane | "Swish and swallow" for oral candidiasis (thrush). Topical for diaper rash or vaginal candidiasis
57
``` Azoles Names MoA Use Tox ```
Fluconazole, Ketoconazole, Clotimazole, Miconazole, Itraconazole, Voriconazole Inhibits fungal sterol (ergosterol) synthesis by inhibiting P450 that converts Lanosterol to Ergosterol F for chronic suppression of Crytococcal meningitis in AIDS and Candidal infection of all types I for Blastomyces, Coccidioides, Histoplasma C and M for topical fungal infections Inhibits Testosterone synthesis (gynecomastia), Liver dysfunction
58
Flucytosine MoA Use Tox
Inhibits DNA and RNA synthesis by conversion to 5FU by cytosine daminase Systemic fungal infections (esp miningitis by Cryptococcus) w/ Amphotericin B Bone marrow suppression
59
Caspofungin, Micafungin MoA Use Tox
Inhibits cell wall synthesis by inhibiting β-glucan Invasive aspergillosis, Candida GI upset, Flushing (by histamine release)
60
Terbinafine MoA Use Tox
Inhibits fungal enzyme Squalene Epoxide Dermatophytoses (onychomycosis) LFTs, visual disturbances
61
``` Griseofulvin MoA Where does it accumulate? Use Tox ```
Interferes to MT function disrupting mitosis Oral treatment for superficial infection. Deposits in keratin containing tissues (nails) Inhibits growth of dermatophytes (tinea, ringworm) Teratogenic, Carcinogenic, Confusion, Headaches, ↑ P450 (warfarin metabolism)
62
Antiprotozoan Therapy
Pyrimethamine (toxoplasmosis), Suramin and Melarsoprol (Trypanosoma brucei), Nifurtimox (T cruzi), Sodium Stibogluconate (Leishmaniasis)
63
``` Chloroquine MoA Resistance Use Tox ```
Blocks detoxification of Heme into Hemozoin. Heme accumulates and is toxic to Plasmodia Plasmodial species other than P falciparum Membrane pump that ↓ intracellular concentration Retinopathy
64
Treatment for Plasmodia falciparum
Artemether/lumifantrine or Atovaquone/Proguanil
65
Treatment for life-threatenting malaria
Quinidine (in US), Quinine (Elsewhere), Artisunate
66
Anti-Helminthic Therapy Names MoA
Mebendazole, Pyrantel Pamoate, Ivermectin, Diethylcarbamazine, Praziquantel (for flukes like Schistosoma) Imobilizes helminths
67
Zanamivir, Oseltamivir MoA Use
Inhibits Influenza Neuraminidase decreasing release of progeny Treatment and Prevention of Influenza A and B
68
Ribavirin MoA Use Tox
Inhibits synthesis of Guanine by competitively inhibiting IMP dehydrogenase RSV, HCV (chronic) Hemolytic anemia, Teratogen
69
``` Acyclovir MoA Use Better version? Tox Resistance ```
Guanosine analog that inhibits viral DNA pol by chain termination HSV and VZV. Weak activity against EBV HSV induced mucocutaneous or genital lesions and encephalitis. Prophylaxis for immunocompromised pts No effect on latent HSV or VZV Vanacyclovir has better bioavailability Few toxicities Mutated viral Thymidine kinase
70
Treatment for Herpes Zoster (Shingles)
Famciclovir
71
``` Ganciclovir MoA Use Better version? Tox Resistance ```
Guanosine analog that inhibits viral DNA pol CMV Valganiciclovir is a prodrug with better bioavailability Leukopenia, Neutropenia, Thrombocytopenia, Renal toxicity Mutated CMV DNA pol or lack of viral kinase
72
``` Foscarnet MoA Use Tox Resistance ```
Pyrophosphate analog. Viral DNA pol inhibitor CMV retinitis (when ganciclovir fails), HSV (when acyclovir fails) Nephrotoxic Mutated DNApol
73
``` Cidofovir MoA Use Half life Tox Co-administration ```
Inhibits viral DNA pol CMV retinitis, HSV (when acyclovir fails) Long half-life Nephrtoxic Probenecid and IV saline to reduce toxicity
74
HAART When is it initiated? Regimen
AIDS-defining illness, low CD4 (below 500), High vial load | 2 nucleoside RT inhibitors + 1 non-nucleoside RT inhibitor OR Protease inhibitor OR Integrase inhibitor
75
Protease inhibitors Names MoA Tox
"Navir tease a protease" -navir (Lopi, Ataza, Daru, Fosampre, Saqui, Rito, Indi) Protease cleaves products of HIV mRNA into functional parts Ritonavir can boost other [drug] by inhibiting P450 Hyperglycemia, GI intolerance (nausea, diarrhea), Lipodystrophy Indinavir: Nephropathy and Hematuria
76
``` NRTI Names MoA Activation Uses Tox ```
"Have you DINED with my NUCLEAR family" Tenofovir (TDF), Emtricitabine (FTC), Abacavir (ABC), Lamivudine (3TC), Zidovudine (ZDV, AZT), Didanosine (ddl), Stavudine (d4T) Competitive NT that gets used by RT but has not 3' OH --> early chain termination TDF does not need activation. The rest need to phosphorylated ZDV used as prophylaxis during pregnancy Bone marrow suppression (reversible w/ G-CSF and EPO), Peripheral neuropathy, Lactic Acidosis, Anemia (ZDV)
77
``` NNRTIs Names MoA Activation Tox ```
Nevirapine, Efaverenz, Delavirdine Inhibits RT Does not require phosphorylation Bone marrow suppression (reversible w/ G-CSF and EPO), Peripheral neuropathy, Rash, Anemia (ZDV)
78
Integrase Inhibitors Names MoA Tox
Raltegravir Inhibits HIV genome integration into host cell chromosome Hypercholesterolemia
79
``` Interferons What is it? What produces it? MoA Use Tox ```
Glycoprotein synthesized by virus-infected cells. Blocks replication of both RNA and DNA viruses IFNα: chronic HBV or HCV, Kaposi sarcoma IFNβ: MS IFNγ: NADPH oxidase deficiency Neutropenia, Myopathy
80
Antibiotics to avoid during pregnancy
"SAFe Children Take Really Good Care" Sulfonamides (Kernicterus), Aminoglycosides (Ototoxic), Fluoroquinolones (Cartilage damage), Clarithromycin (Embryotoxic), Tetrocycline (Discolored teeth, inhibition of bone growth), Ribavirin (teratogenic), Griseofulvin (Teratogenic), Chloramphenicol (gray baby)
81
Killed Influenza Vaccine
Generates Abs to H preventing entry of viral particles into the cells

USMLE STEP 1 (25 decks)

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