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USMLE Step 1-2015 > Antimicrobials > Flashcards

Antimicrobials Flashcards

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USMLE® Step 1 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
Q

Mechanism of resistance of tetracyclines

A

decrease uptake or increase efflux out of bacterial cells by plasmid encoded transport pumps

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26
Q

why does chloramphenicol cause gray baby syndrome?

A

Premature infants lack udp-glucuronyl transferase which is enzyme necessary in liver for metabolism of chloramphenicol

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27
Q

Anaerobic infection treatment above diaphragm vs anaerboic infection treatment below diaphragm

A

Above-clindamycin

Below-metronitazole

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28
Q

Mechanism of resistance of Linezolid

A

Point mutation of ribosomal RNA

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29
Q

Macrolide mechanism of resistance

A

Methylation of 23s rRNA binding site preventing binding of drug

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30
Q

Toxicity of MACROlides

A

GI MOtility issues, Arrhythmia caused by prolonged QT interval, acute Cholestatic hepatitis, Rash, eOsinophilia

31
Q

Sulfonamides inhibit what and what is MOA

A

Sulfonamides inhibit dihydropteroate synthase by acting as a PABA analog where high levels inhibit dihydropteroate synthase

32
Q

Trimethoprim toxicity

A

Marrow problems (megoloblastic anemia, leukopenia, granulocytopenia). May be alleviated with supplemental folinic acid

33
Q

Mechanism of resistance of sulfonamides

A

Altered enzyme (bacterial dihydropteroate synthase), decrease uptake, or increase PABA synthesis

34
Q

Mechanism of resistance in fluoroquinolones

A

Chromosome encoded mutation in DNA gyrase, plasmid-mediated resistance, efflux pumps

35
Q

Lipopeptide that disrupts cell membrane of grampositive cocci by causing depolarization of bacterial cell membrane and inhibiting DNA, RNA, and protein synthesis

A

Daptomycin

36
Q

Metranidazole MOA?

A

Forms toxic free metabolistes in the bacterial cell that damage DNA

37
Q

Metranidazole treatment?

A

GET GAP. Garderealla, Entamoeba, Trichomonas, Giardia, Anaerobes (Bacteriodes, C. Difficile), H. Pylori (PPI)

38
Q

Metranidazole toxicity?

A

Disulfiram like reaction (severe flushing, tachycardia, hypotension)

39
Q

M tuberculosis prophylaxis

A

Isoniazid

40
Q

M tuberculosis treatment

A

Rifampin, Isoniazid, Pyrazinamid, Ethambutol (RIPE for treatment)

41
Q

M avium-intracellulare prophylaxis

A

Azithromycin, rifabutin

42
Q

M leprae prophylaxis

A

N/A

43
Q

M avium-interacellulare treatment

A

More drug resistant than M. tuberculosis. Azithromycin or clarithromycin + ethambutol. Can add rifabutin or ciprofloxacin

44
Q

M. leprae treatment

A

Long-term treatment with dapsone and rifampin for tuberculoid form. Add clofazimine for lepromatous form

45
Q

Mechanism of resistance in rifamycins

A

Mutations reduce drug binding to RNA polymerase and monotherapy rapidly leads to resistance (through spontaneous genetic mutations in bacterial DNA-dependent RNA polymerase)

46
Q

What would prevent isoniazid activation?

A

Mycobacterial catalase peroxidase

47
Q

Treatment for high risk of endocarditis and undergoing surgical/dental procedure

A

Amoxicillin

48
Q

Treatment of exposure to gonorrhea

A

Ceftriaxone

49
Q

Treatment of history of recurrent UTI

A

TMP-SMX

50
Q

Treatment of exposure to meningococcal infections

A

Ceftriaxone, ciprofloxacin, or rifampin

51
Q

Treatment of pregnant woman carrying group B strep

A

Penicillin G

52
Q

Prevention of gonococal conjunctivities in newboarn

A

Erythromycin ointment

53
Q

Prevention of postsurgical infection due to S. auereus

A

Cefazolin

54
Q

Prophylaxis of strep pharyngitis in child with prior rheumatic fever

A

Benzathing penicillin G or oral penicillin V

55
Q

Exposure to syphillis

A

Benzathine penacillin G

56
Q

MOA pyrazinamide

A

Prodrug converted to pyrazinoic acid (requires acidic environment as present within macrophage phagolysososme to exert antimicrobial effects)

57
Q

Prophylaxis in HIV patients

A

TMP-SMX for pneumocystis pneumonia

58
Q

Prophylaxis in HIV patients

A

TMP-SMX for pneumocystis pneumonia

59
Q

CD4

A

Azithromycin or clindamycin for mycobacterium avium complex

60
Q

MRSA treatment options

A

Vancomycin, ceftaroline, linezolid, daptomycin, tigecycline

61
Q

VRE treatment options

A

linezolid and streptogramins

62
Q

Multidrug resistant P aeruginosa/acinetobacter baumannii

A

Polymyxins B and E (colistin)

63
Q

What should amphotericin be supplemented with and why?

A

K+/Mg2+–>severe electrolyte abormalities due to increase distal tubular membrane permeability can be at risk for arrhythmias

64
Q

Oseltamivir and zamamivir inhibit what?

A

Influenza neuraminadase

65
Q

Cidofovir should be coadministered with what to avoid toxicity?

A

Probenecid + IV saline

66
Q

Only NRTI that does not need to be phosphorylated to be active

A

Tenofovir

67
Q

Side effect pancreatitis in HIV therapy

A

didanosine

68
Q

Side effect anemia in HIV therapy

A

ZDV

69
Q

Side effect nephropathy/nephrolithiasis in HIV therapy

A

indinavir

70
Q

Common side effect of all NNRTI

A

Rash and hepatotoxicity

71
Q

HIV drug with vivid dreams and CNS symptoms

A

Efavirenz

72
Q

Enfuviritide MOA

A

Binds gp41 preventing viral entry

73
Q

Maraviroc MOA

A

Binds CCR5 on surface of T cells/monocytes, inhibiting interaction with gp120

74
Q

Antibiotics to avoid in pregnancy

A

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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