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USMLE Step 1 > Microbiology--Pharmacology > Flashcards

Microbiology--Pharmacology Flashcards

1
Q

Penicillin G ,V use

A

G+ organisms: S pneumoniae, S pyogenes, Actinomyces, Also used for N meningitidis, T pallidum

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2
Q

Ampicillin, amoxicillin use

A

H flu, E coli, Listeria, Proteus, Salmonella, Shigella

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3
Q

Oxacillin, nafcillin, dicloxacillin

A

S aureus–has bulky R group to prevent penicillinase breakdown

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4
Q

antibiotic that can cause pseudomembranous colitis

A

ampicillin, amoxicillin

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5
Q

Ticarcillin, piperacillin

A

antipseudomonals–use with B lactamase inhibitors like tazobactam

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6
Q

what are organisms typically not covered by cephalosporins?

A

LAME: listeria, atypicals (chlamydia, mycoplasma), MRSA, Enterococci

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7
Q

1st generation cephalosporin

A

cefazolin, cephalexin–gram+ and PEcK: proteus, e coli, Klebsiella

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8
Q

2nd generation cephalosporin

A

cefoxitin, cefaclor, cefuroxime–gram +, and HEN PEcKS: h flu, enterobacter, Neisseria spp, Proteus, E coli, Klebsiella, Serratia

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9
Q

3rd generation cephalosporin

A

ceftriaxone, cefotaxime, ceftazidime; use ceftriaxone in meningitis and gonorrhea; use ceftazidime in pseudomonas

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10
Q

4th generation cephalosporin

A

cefepime–increased activity against pseudomonas and G+ organisms

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11
Q

5th generation cephalosporin

A

ceftaroline–broad gram+ and - coverage including MRSA, but does NOT cover pseudomonas

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12
Q

toxicities of cephalosporins?

A

vit K deficiency; low cross reactivity with penicillis; greater nephrotoxicity than aminoglycosides

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13
Q

what is a monobactam?

A

aztreonam–prevents peptidoglycan cross linking by binding to PBP3. Synergistic w/ aminoglycosides; no cross reactivity with penicillin

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14
Q

aztreonam uses?

A

gram - only; no activity against g+ or anaerobes; use in penicillin allergics or renal failure patients who can’t tolerate aminoglycosides

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15
Q

What is imipenem always administered with?

A

cilastatin–inhibitor of renal dehydropeptidase I

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16
Q

Which carbapenem is stable to dehydropeptidase I

A

meropenem

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17
Q

carbapenem tox?

A

GI distress, skin rash, CNS toxicity (seizures)–last resort bug

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18
Q

Vancomycin MoA?

A

inhibits cell wall peptidoglycan formation by binding D-ala Dala portion of cell wall precursors; resistance forms when AA modified to DalaDlac

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19
Q

Vancoymcin use?

A

only for G+, MRSA, enterococci, C diff

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20
Q

Vancomycin tox?

A

NOT; nephrotoxicity, ototoxicity, thrombophlebitis, diffuse flusing (red man syndrome)–prevent with antihistamines and slow infusion rate

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21
Q

Which antibacterial protein synthesis inhibitors target which ribosome?

A

buy AT 30; CCEL at 50: 30S: aminoglycosides, tetracyclines; 50S: chloramphenicol, clindamycin, erythromycin (macrolides), linezolid

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22
Q

What are some aminoglycosides?

A

Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin

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23
Q

aminoglycoside MoA:

A

30S: inhibit formation of initiation complex and cause misreading of mRNA; also blocks translocation; requires O2 for uptake so ineffective against anaerobes

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24
Q

aminoglycoside use?

A

severe gram negative rod infections; synergistic with B lactam anbx; neomycin for bowel surgery;

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25
aminoglycoside resistance?
transferase enzymes inactive the drug by acetylation, phophorylation or adenylation
26
Tetracycline MoA?
bind to 30S and prevent attachment of aminoacyl tRNA; limited CNS penetration; doxycycline eliminated by gut and can use in renal failure patients; do not take with milk, antacids, or iron containing preps because divalent cations inhibit gut absorption
27
Tetracycline use?
borrelia, mycoplasma, rickettsia, Chlamydia--drug can accumulate intracellularly
28
Tetracycline resistance?
decreased uptake or increased efflux out of bacterial cells by plasmid encoded transport pumps
29
Macrolides MoA?
Inhibit protein synthesis by blocking translocation; binds to 23S rRNA of 50S ribosomal subunit
30
Macrolide toxicity?
MACRO: GI motility issues, arrhythmia (prolonged QT), acute cholestatic hepatitis, rash, eosinophilia; increases serum concetrations of theophylines, oral anticoagulants
31
Macrolide resistance?
methylation of 23S rRNA-binding site prevents drug binding
32
Chloramphenicol MoA?
blocks peptidyltransferase at 50S ribosomal subunit
33
Chloamphenicol tox?
anemia, aplastic anemia, gray baby syndrome (lack liver UDP-glucuronyl transferase)
34
Chloramphenicol resistance?
plasmid encoded acetyltransferase inactivates the drug
35
Clindamycin MoA?
blocks peptide transfer (translocation) at 50S ribosomal subunit,
36
Sulfonamide MoA?
inhibit folate synthesis, PABA antimetabolites inhibit DHF synthase
37
Sulfonamides, trimethoprim, pyrimethamine affect the THF pathway at which enzymes?
Sulfonamides: Dihydropterate synthase; Trimethoprim/pyramethamine: dihydrofolate reductase
38
Sulfonamide tox?
hemolysis if G6PD deficient; tubulointerstitial nephritis; photosensitivity; kernicterus in infants; displaces other drugs from albumin (like warfarin)
39
trimethoprim MoA?
inhibits DHF reductase
40
TMP tox?
TMP: treats marrow poorly: megaloblastic anemia, leukopenia, granulocytopenia (can alleviate with folinic acid (leucovorin))
41
Fluoroquinolones (-floxacins)
inhibit DNA gyrase (topoisomerase II) and topoisomerase IV; do NOT take with antacids
42
fluoroquinolone tox?
tendonitis/tendon rupture/leg cramps/myalgias, contraindicated in pregnant women, nursing mothers, children < 18 over concerns for cartilage damage, can cause prolonged QT,
43
fluoroquinolone resistance?
chromosome encoded mutation in DNA gyrase, plasmid mediated, efflux pumps
44
Metronidazole MoA? Tox?
forms free radical toxic metabolites in the bacterial cell that damage DNA; disulfiram like reaction with alcohol; headache; metallic taste
45
Isoniazid MoA?
decreases synthesis of mycolic acids, bacterial catalase peroxidase (KatG) needed to convert INH to active metabolite
46
Isoniazid Tx?
Neurotoxicity; hepatotoxicity; B6 can prevent neurotoxicity and lupus
47
Rifampin, rifabutin MoA
inhibits DNA dependent RNA polymerase
48
Rifabutin is favored in patients w/ HIV over Rifampin why?
Rifampin ramps up CYP450; rifabutin does not
49
Pyrazinamide tox?
hyperuricemia, hepatotoxicity
50
Ethambutol MoA?
decreases carbohydrate polymerization of mycobacterium cell wall by blocking arabinosyltransferase
51
Ethambutol tox?
optic neuropathy--can cause red green color blindness
52
Prophylaxis: endocarditis with surgical or dental procedures
Penicillins
53
Prophylaxis: gonorrhea
ceftriaxone
54
Prophylaxis history of recurrent UTIs
TMP SMX
55
Prophylaxis meningococcal infx
Ciprofloxacin (rifampin for child)
56
Prophylaxis Pregnant women carrying group B strep
Ampicillin
57
Prophylaxis Prevention of gonococcal or chlamydial conjunctivitis in newborn
Erythromycin ointment
58
Prevention of postsurgical infection due to S aureus
Cefazolin
59
Prophylaxis strep pharyngitis in child with prior rheumatic fever
oral penicillin
60
prophylaxis in HIV patients with CD4 counts < 200, <50
<50 azithromycin for MAC; use pentamidine if TMPSMX cannot be tolerated
61
serotonin syndrome anbx
linezolid--inhibits 50S
62
Amphotericin B MOA?
binds ergosterol and forms membrane pores that allow electrolyte leakage
63
what supplements must be given with amphotericin B?
supplement K and Mg because of altered renal tubule permeability
64
amphotericin tox?
fevers/chills, hypotension, nephrotoxicity, arrhythmias, anemia, IV phelbitis, hydration decreases renal damage; liposomal forms can decrease toxicity
65
Nystatin MoA?
binds ergosterol--pores; only topical because so toxic
66
Azoles MoA?
inhibit fungal sterol (ergosterol) synthesis by inhibiting CYP450 enymes that convers lanosterol to ergosterol
67
chronic supression of cryptococcal meningitis in AIDS and candida infx of all types
fluconazole
68
blastomyces, coccidiodes, histoplasma
itraconazole
69
topical fungal infx
clotrimazole and miconazole
70
azole tox?
testosterone synthesis inhibitor (esp ketoconazole), liver (inhibits CYP450)
71
Flucytosine moA? tox
converted to 5-FU via cytosine deaminase to inhibit DNA and RNA biosynthesis; bone marrow supression
72
Caspofungin, micafungin, anidulafungin MoA? Tox?
inhibits cell wall synthesis by inhibiting synthesis of B glucan; GI upset/flushing via histamine release
73
Terbinafine MoA? tox?
inhibits funal enzyme squalene epoxidase (squalen to squalene epoxide); use for skin funal infections esp finger/toe nails; GI upset/HA/liver tox/taste disturbance
74
Griseofulvin moA? Tox?
interferes with microtubule function to disrupt mitosis; teratogenic/carcinogenic/confusion/H/A; increases p450 and warfarin metabolism
75
Chloroquine moA?
block detoxification of heme into hemazoin; heme accumulates and kills plasmodia; do not use for falciparum
76
chloroquine resistance?
efflux pump
77
falciparum treatment?
artemether/lumefantrine, atovaquone/proguanil
78
Zanamivir, oseltamivir moa?
neuraminidase inhibitor, prevent release of progeny virus; used for flu A/B
79
ribavirin moa? tox?
inhibits synthesis of guanine nucelotides by competitively inhibiting IMP dehydrogenase; RSV/chronic hep C; hemolytic anemia, severe teratogen
80
acyclovir, famciclovir, valacyclovir moa? Tox?
guanosine analog that requires phosphorylation by thymidine kinase; used for HSV/VZV; crystalline nephropathy and ARF if not adequately hydrated
81
Ganciclovir moa? Tox?
5' monophosphate formed by CMV viral kinase. Guanosine analog; use for CMV; leukopenia/neutropenia/thrombocytopenia/renal toxicity
82
Foscarnet moa? Tox?
viral DNA Polymerase inhibitor that binds to pyrophosphate binding side of enzyme; does not need activation by viral kinase; nephrotoxicity
83
used in CMV retinitis when gancyclovir fails, used in acycolvir resistant HSV
foscarnet
84
cidofovir moa, tox?
preferentially inhibits viral DNA polymerase; no need for kinase activation; nephrotoxicity, administer with probenecid and IV saline to decrease toxicity
85
when to initiate HAART?
aids defining illness, CD4 < 500; high viral load: 2NRTIs and 1 NNRTI/1 protease inhibitor/1 integrase inhibitor
86
-navir HIV drug MoA?
protease inhibitors; prevent maturation of new virus;
87
whats special about ritonavir?
can boost other drug concentrations by inhibiting P450
88
-navir tox?
hyperglycemia, GI intolerance, lipodystrophy, thrombocytopenia
89
tox of indinavir?
nephropathy, hematuria
90
NRTIs moa?
competitively inhibit nucleotide binding to reverse transcriptase and terminate DNA synthesis (lack 3' OH group)
91
Tenofovir
nucleotide; all others are nucleosides that need to be phosphorylated to be active
92
NRTI tox?
bone marrow supression (give GCSF and EPO); peripheral neuropathy; lactic acidosis (nucleosides)
93
NRTI that can cause anemia
zidovudine; used in general phrophylaxis and during pregnancy
94
NRTI that causes pancreatitis
didanosine
95
NNRTI that causes vivid dreams/CNS symptoms
efavirenz
96
NNRTI tox
rash and heptotoxicity--do not use delavirdine or efavirenz in pregnancy
97
Raltegravir
integrase inhibitor; reversibly inhibits HIV integrase; hypercholesterolemia
98
Enfuvirtide
fusion inhibit; binds gp41; inhibits viral entry
99
Maraviroc
binds CCR-5 on surface of T cells/monocytes inhibiting interaction with gp120 on HIV
100
IFN-alpha
chronic hep B/C, kaposi, hairy cell leukemia, condyloma acuminatum, renal cell carcinoma, malignant melanoma
101
IFN-beta
multiple sclerosis
102
IFN gamma
chronic granulomatous disease
103
IFN tox?
neutropenia, myopathy
104
vitamin A can improve which infection?
measles

USMLE Step 1 (36 decks)

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