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USMLE Step 1-2015 > Antimicrobials > Flashcards

Antimicrobials Flashcards

1
Q

Ampicillin/amoxicillin use

A

Extended spectrum penicillin (HHELPSS kill enterococci)

H. influenzae, H pylori, E coli, Listeria monocytogenes, proteus mirabilis, Salmonella, Shigella, enterococci

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2
Q

Methicillin similar drugs

A

Dicloxacillin, nafcillin, oxacillin

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3
Q

Reason methicillin is penicillinase resistant

A

Bulky R group blocks access of B-lactamse to B-lactam ring

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4
Q

In addition to hypersensitivity rxn., specific side effect for penicillin, aminopenicillin, penicillinase-resistant penicillin

A

Penicillin-hemolytic anemia
Aminopenicillin-Skin rash (not allerg), pseudomembranous colitis
Penicillinase-resistant penicillins-interstitial nephritis

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5
Q

B-lactamase inhibitors

A

Clavulinic Acid, Sulbactam, Tazobactam (CAST)

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6
Q

What can monobactams only be used for?

A

Gram negative rods only

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7
Q

What are imipenems given with?

A

Cilastatin (inhibitor of renal dehydropeptidase I)–>decrease inactivation of drug in renal tubules

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8
Q

Mechanism of resistance in cephalosporins

A

Structural changes in penicillin binding proteins (transpeptidases)

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9
Q

Organisms not covered by cephalosporins?

A

LAME: Listeria, Atypicals (Chlamydia, Mycoplasma), MRSA, Enterococci. Exception: ceftaroline covers MRSA

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10
Q

MOA that 3rd generation have better activity on gram - than 1st/2nd generation?

A

similar to penicillins, 1st and 2nd generation are suceptible to b-lactamase inhibition. 3rd generation include gram - because of combination of chemical groups around b-lactam ring that prevent b-lactamase access

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11
Q

Ceftriaxone use?

A

meningitis, gonorrhea, disseminated lyme disease

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12
Q

Ceftazidime use?

A

Peudomonas

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13
Q

How to prevent red man syndrome with vanco

A

Pretreatment with antihistamines

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14
Q

Complication of vancomycin

A

NOT trouble free (Nephrotoxicity, Ototoxicity, Thrombophlebitis)

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15
Q

Cephalosporins increase nephrotoxicity of what?

A

Aminoglycosides

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16
Q

30 S inhibitors

A

Aminoglycosides (bactericidal)
Tetracyclines (bacteriostatic)

Buy AT 30

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17
Q

50 S inhibitors

A

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

CCEL at 50

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18
Q

Prevention of initiation complex formation/misreading of mRNA?

A

Aminoglycosides

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19
Q

Prevention of peptidyl transferase

A

Chloramphenicol

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20
Q

Prevention of translocation

A

Macrolides (erythromycin), Clindamycin

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21
Q

Prevention of A-site tRNA binding

A

Tetracyclines

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22
Q

Aminoglycosides and toxicity

A

Gentamiacin, Neomycin, Amikacin, Tobramycin, Streptomycin (GNATS)

Nephrotoxicity, Neuromuscular blockade, Ototoicity (especially when used with loop diurectis), Teratogen

Mean (“aminoglycoside”) GNATS caNNOT kill anaerobes

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23
Q

Aminoglycosides mechanism of resistance

A

Bacterial transferase enzymes inactivate the drug by acetylation, phosphorylation, and adenylation

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24
Q

What prevents tetracycline absorption?

A

Divalent cations (milk antacids or iron containing preparations)

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25
Mechanism of resistance of tetracyclines
decrease uptake or increase efflux out of bacterial cells by plasmid encoded transport pumps
26
why does chloramphenicol cause gray baby syndrome?
Premature infants lack udp-glucuronyl transferase which is enzyme necessary in liver for metabolism of chloramphenicol
27
Anaerobic infection treatment above diaphragm vs anaerboic infection treatment below diaphragm
Above-clindamycin | Below-metronitazole
28
Mechanism of resistance of Linezolid
Point mutation of ribosomal RNA
29
Macrolide mechanism of resistance
Methylation of 23s rRNA binding site preventing binding of drug
30
Toxicity of MACROlides
GI MOtility issues, Arrhythmia caused by prolonged QT interval, acute Cholestatic hepatitis, Rash, eOsinophilia
31
Sulfonamides inhibit what and what is MOA
Sulfonamides inhibit dihydropteroate synthase by acting as a PABA analog where high levels inhibit dihydropteroate synthase
32
Trimethoprim toxicity
Marrow problems (megoloblastic anemia, leukopenia, granulocytopenia). May be alleviated with supplemental folinic acid
33
Mechanism of resistance of sulfonamides
Altered enzyme (bacterial dihydropteroate synthase), decrease uptake, or increase PABA synthesis
34
Mechanism of resistance in fluoroquinolones
Chromosome encoded mutation in DNA gyrase, plasmid-mediated resistance, efflux pumps
35
Lipopeptide that disrupts cell membrane of grampositive cocci by causing depolarization of bacterial cell membrane and inhibiting DNA, RNA, and protein synthesis
Daptomycin
36
Metranidazole MOA?
Forms toxic free metabolistes in the bacterial cell that damage DNA
37
Metranidazole treatment?
GET GAP. Garderealla, Entamoeba, Trichomonas, Giardia, Anaerobes (Bacteriodes, C. Difficile), H. Pylori (PPI)
38
Metranidazole toxicity?
Disulfiram like reaction (severe flushing, tachycardia, hypotension)
39
M tuberculosis prophylaxis
Isoniazid
40
M tuberculosis treatment
Rifampin, Isoniazid, Pyrazinamid, Ethambutol (RIPE for treatment)
41
M avium-intracellulare prophylaxis
Azithromycin, rifabutin
42
M leprae prophylaxis
N/A
43
M avium-interacellulare treatment
More drug resistant than M. tuberculosis. Azithromycin or clarithromycin + ethambutol. Can add rifabutin or ciprofloxacin
44
M. leprae treatment
Long-term treatment with dapsone and rifampin for tuberculoid form. Add clofazimine for lepromatous form
45
Mechanism of resistance in rifamycins
Mutations reduce drug binding to RNA polymerase and monotherapy rapidly leads to resistance (through spontaneous genetic mutations in bacterial DNA-dependent RNA polymerase)
46
What would prevent isoniazid activation?
Mycobacterial catalase peroxidase
47
Treatment for high risk of endocarditis and undergoing surgical/dental procedure
Amoxicillin
48
Treatment of exposure to gonorrhea
Ceftriaxone
49
Treatment of history of recurrent UTI
TMP-SMX
50
Treatment of exposure to meningococcal infections
Ceftriaxone, ciprofloxacin, or rifampin
51
Treatment of pregnant woman carrying group B strep
Penicillin G
52
Prevention of gonococal conjunctivities in newboarn
Erythromycin ointment
53
Prevention of postsurgical infection due to S. auereus
Cefazolin
54
Prophylaxis of strep pharyngitis in child with prior rheumatic fever
Benzathing penicillin G or oral penicillin V
55
Exposure to syphillis
Benzathine penacillin G
56
MOA pyrazinamide
Prodrug converted to pyrazinoic acid (requires acidic environment as present within macrophage phagolysososme to exert antimicrobial effects)
57
Prophylaxis in HIV patients
TMP-SMX for pneumocystis pneumonia
58
Prophylaxis in HIV patients
TMP-SMX for pneumocystis pneumonia
59
CD4
Azithromycin or clindamycin for mycobacterium avium complex
60
MRSA treatment options
Vancomycin, ceftaroline, linezolid, daptomycin, tigecycline
61
VRE treatment options
linezolid and streptogramins
62
Multidrug resistant P aeruginosa/acinetobacter baumannii
Polymyxins B and E (colistin)
63
What should amphotericin be supplemented with and why?
K+/Mg2+-->severe electrolyte abormalities due to increase distal tubular membrane permeability can be at risk for arrhythmias
64
Oseltamivir and zamamivir inhibit what?
Influenza neuraminadase
65
Cidofovir should be coadministered with what to avoid toxicity?
Probenecid + IV saline
66
Only NRTI that does not need to be phosphorylated to be active
Tenofovir
67
Side effect pancreatitis in HIV therapy
didanosine
68
Side effect anemia in HIV therapy
ZDV
69
Side effect nephropathy/nephrolithiasis in HIV therapy
indinavir
70
Common side effect of all NNRTI
Rash and hepatotoxicity
71
HIV drug with vivid dreams and CNS symptoms
Efavirenz
72
Enfuviritide MOA
Binds gp41 preventing viral entry
73
Maraviroc MOA
Binds CCR5 on surface of T cells/monocytes, inhibiting interaction with gp120
74
Antibiotics to avoid in pregnancy
Sulfonamides (kernicterus), Aminoglycosides (ototoxicity), Fluoroquinolones (cartilage damage), clarithromycin (embryotoxin), tetracyclines (discolored teeth, inhibition of bone growth), ribavirin (antiviral-teratogenic), griseofulvin (antifungal0teratogenic), chlromphenicol (gray baby syndrome) SAFe Children Take Really Good Care

USMLE Step 1-2015 (18 decks)

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