Microbiology--Pharmacology Flashcards Preview

USMLE Step 1 > Microbiology--Pharmacology > Flashcards

Flashcards in Microbiology--Pharmacology Deck (104):
1

Penicillin G ,V use

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

2

Ampicillin, amoxicillin use

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

3

Oxacillin, nafcillin, dicloxacillin

S aureus--has bulky R group to prevent penicillinase breakdown

4

antibiotic that can cause pseudomembranous colitis

ampicillin, amoxicillin

5

Ticarcillin, piperacillin

antipseudomonals--use with B lactamase inhibitors like tazobactam

6

what are organisms typically not covered by cephalosporins?

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

7

1st generation cephalosporin

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

8

2nd generation cephalosporin

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

9

3rd generation cephalosporin

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

10

4th generation cephalosporin

cefepime--increased activity against pseudomonas and G+ organisms

11

5th generation cephalosporin

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

12

toxicities of cephalosporins?

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

13

what is a monobactam?

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

14

aztreonam uses?

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

15

What is imipenem always administered with?

cilastatin--inhibitor of renal dehydropeptidase I

16

Which carbapenem is stable to dehydropeptidase I

meropenem

17

carbapenem tox?

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

18

Vancomycin MoA?

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

19

Vancoymcin use?

only for G+, MRSA, enterococci, C diff

20

Vancomycin tox?

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

21

Which antibacterial protein synthesis inhibitors target which ribosome?

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

22

What are some aminoglycosides?

Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin

23

aminoglycoside MoA:

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

24

aminoglycoside use?

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

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