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Microbiology Flashcards

1
Q

MOA penicillin G and V

A
  1. Prototype Beta lactam Abx
    - Binds pencillin binding proteins known as transpeptidase and blocks cross linking of peptidogylcans. Activates autolytic enzymes
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2
Q

What is penicillin used to treat?

A
  1. think Gram Positive
  2. N Meningitidis
  3. Syphilis
    - it’s cidial for all of the above
    - it is also pencillinase sensitive
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3
Q

ADE of penicillin

A

HSR rxn, hemolytic anemia

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4
Q

MOA of ampicillin and amoxicillin

A

same as penicillin but can wider spectrum use.

  • Amoxicillin has better oral bioavailability than ampicillin
  • sensitive to penicillinase
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5
Q

What can you combine w/ ampicillin and amoxicillin to fight beta lactamases?

A

clavulanic acid

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6
Q

What are ampicillin and amoxicillin used to treat?

A
  1. Extended spectrum penicillin - H influenza, E. Coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, Shigella, enterococci
    - thinks HELPSS kill enterococci
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7
Q

ADE of ampicillin and amoxicillin

A

HSR rxn, rash, pseudomembranous colitis

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8
Q

MOA of oxacillin, nafcillin, and dicloxacillin

A

Same as penicillin but narrower spectrum.

- Have a bulky R group that block access of Beta lactamase to beta lactam ring

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9
Q

uses for oxacillin, nafcillin, and dicloaxcillin

A

S Aureus (except MRSA - resistant b/c of altered penicillin binding protein target site)

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10
Q

ADE of oxacillin, nafcillin, and dicloaxcillin

A

HSR rxn and intersitital nephritis

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11
Q

MOA of antipseudomonals penicillins (ticarcillin and piperacillin)

A

same as penicillin, extended spectrum

- use w/ Beta lactamase inhibitors to treat Pseudomonas and gram negative rods

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12
Q

ADE of antipseudomonal penicillin

A

HSR rxn

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13
Q

What are you beta lactamase inhibitors?

A

clavulanic acid, sulbactam, taxobactam,

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14
Q

MOA of cephalosporins

A

Beta lactam drugs that inhibit cell wall synthesis but are less susceptible to penicillinases
- cidial

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15
Q

What organisms aren’t typically covered by cephalosporins?

A

think LAME

  1. Listeria
  2. Atypical - chylamidia, mycoplasma
  3. MRSA - (exception - ceftaroline)
  4. Enterococci
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16
Q

What are the 1st gen cephalosporins and what do they treat?

A

Cefazolin and cephalexin
- gram positive cocci
PEcK: Proteus, E. coli, Klebsiella

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17
Q

When is cefazolin used?

A

before surgery to prevent S aureus wound infxns

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18
Q

What are teh 2nd gen cephalosporin and what do they treat?

A

Cefoxitin, cefaclor, cefuroxime
- gram positive cocci
HEN PEcKS : H flu, Enterobacter, Neisseria, Proteus, E. Coli, Klebsiella, Serratia

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19
Q

What are your 3rd gen cephalosporins and what do they treat?

A

Ceftriaxone, cefoxtaxime, ceftaxidine

  • serious gram negative infections resistant to other beta lactams
    1. ceftriaxone - meningitis and gonorrhea
    2. ceftaxidime - Pseudomonas
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20
Q

What are your 4th gen cephalosporins and what do they treat?

A

Cefepime : increased activity against Pseudomonas and gram positive organisms

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21
Q

What are your 5th gen cephalosporins and what do they treat?

A

Ceftaroline

  • broad gram positive and gram negative coverage
  • MRSA but NOT Pseudomonas
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22
Q

ADE of Cephalosporins

A
  1. HSR Rxn
  2. Vit K deficiency
  3. Low cross reactivity w/ penicillins
  4. increased aminoglycosides mediated kidney toxicity
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23
Q

MOA of Aztreonam

A

monobactam, resistant to Beta lactamases

  • prevents peptidoglycan cross linking by binding to penicillin binding protein
  • syngergistic w/ aminoglycoside
  • no cross allergenicity w/ penicillin
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24
Q

Uses of aztreonam

A

Gram negative rods only

- for penicillin allergic pts and those w/ renal insufficiency who can’t tolerate aminoglycosides

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25
Q

MOA of carbapenems

A

Broad spectrum
Beta lactamase resistant
Always given w/ cilstatin

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26
Q

What is cilastatin?

A

inhibits renal dephydropeptidase I to decrease inactivation of drug in renal tubules

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27
Q

Uses for carbapenems?

A
  1. gram positive cocci
  2. gram negative rods
  3. anerobes
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28
Q

What is special about Meropenem?

A
  • decreased risk of seizures

- stable to dephydropeptidase I in kidney

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29
Q

ADE of carbapenems?

A

GI distress
Skin rash
CNS toxicity (seizures) at very high plasma levels

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30
Q

MOA of vancomycin

A

inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall precursors
- cidial

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31
Q

Vancomycin uses

A

Gram positives only, multidrug resistant organism, MRSA, enterococci, and Clostridium difficile

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32
Q

ADE of vancomycin

A
  1. renal toxicity
  2. otoxocitiy
  3. Thrombrophlebitis
  4. diffuse flushing - red man syndrome ( can be prevented w/ pretreatment w/ antihistamine and slow infusion rate)
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33
Q

Mechanism of resistance against vancomycin

A

Modification of D-ala D-ala to D-ala D-lac

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34
Q

MOA of Aminoglycosides

A
  1. cidial
  2. inhibits formation of initation complex and causes misreading of mRNA. Also blocks translocation
    - Needs O2 for uptake therefore ineffective against anaerobes
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35
Q

What are your aminoglycosides

A

Gentamicin, neomycin, amikacin, tobramycin, streptomycin

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36
Q

When are aminoglycosides used?

A

Severe gram negative rod infxns

  • syngergistic w/ beta lactam Abx.
  • use Neomycin for bowel surgery
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37
Q

ADE for Aminoglycosides

A
  1. renal toxicity esp w/ cephalosporins
  2. Neuromuscular blockade
  3. ototoxicity esp w/ loop diuretics
  4. teratogen
38
Q

Mechanism of resistance for aminoglycosides

A

bacterial transferase enzyme inactivates the drug by acetylation, phosphorylation, or adenylation

39
Q

MOA of tetracycline

A
  1. static
  2. Binds 30S and prevents attachement of aminoacyl-tRNA
  3. limited CNS penetration
40
Q

What tetracycline can be used in pts w/ renal failure?

A

Doxycycline b/c it is fecally eliminated

41
Q

What are some cautions of tetracyclines?

A

don’t take w/ milk (Ca2+) and antacids or Fe containing preparations b/c divalent cations inhibit its absorption in the gut

42
Q

uses for tetracycline

A
  1. Borrelia - Lyme dz
  2. Mycoplasma pneumonia
  3. Rickettsia and Chlamydia - b/c drug accumulates intracellularly
  4. Also used to treat acne
43
Q

ADE of tetracycline

A
  1. GI distress
  2. discoloration of teeth and inhibition of bone growth in kids
  3. photosensitivity
  4. Contraindicated in pregnancy
44
Q

What is the mechanism of resistance for tetracyclines?

A

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

45
Q

MOA of Macrolides

A

inhibit protein synthesis by blocking translations

  • binds to 23S rRNA of the 50S subunit
  • static
46
Q

When are macrolides used?

A
  1. Atypical pneumonia - mycoplasma, legionella, chlamydia
  2. STDs- chlamydia
  3. gram positive cocci - streptococcal infxns in pts allergic to penicillin
47
Q

ADE of macrolides?

A
  1. GI motility issues
  2. Arrhythmia b/c of prolonged QT
  3. acute cholestatic hepatitis
  4. Rash
  5. Esoinophilia
    - Can increase serum levels of theophyllines and oral anticoagulants
48
Q

Mechanism of resistance for macrolides?

A

methylation of 23s rRNA binding site prevents binding of drug

49
Q

MOA of chloramphenicol

A

blocks peptidyltransferase at 50S subunit

- static

50
Q

When is chloramphenicol used?

A

meningitis (H flu, Nesseria, Strep pneumonia) and RMSF

51
Q

ADE of chloramphenicol

A
  1. dose dependent anemia
  2. Aplastic anemia
  3. Gray baby syndrome - b/c premies back UDP-glucuronyl transferase
52
Q

Mechanism of resistance for chloramphenicol

A

plasmid encoded acetyltransferase inactivates the drug

53
Q

MOA of Clindamycin

A

blocks peptide transfer (translocation) at 50S subunit

- static

54
Q

When is clindamycin used?

A
  1. Anerobic infxn - Bacteroides species, Clostridium perfringens in aspiration pneumonia, lung abscesses, and oral infxns
  2. effective against Group A strep infxn - pyogenes
    * treats anerobes about the diaphragm
55
Q

ADE of clindamycin

A

Pseudomembranous colitis, fever, diarrhea

56
Q

MOA of Sulfonamides

A

Inhibits folate synthesis

  • PABA antimetabolite that inhibits diphydropterorate synthase
  • static
57
Q

When are sulfonamides used?

A
  1. Gram positive
  2. gram negative
  3. Nocardia
  4. Chlamydia
    Simple UTI
58
Q

ADE of sulfonamides

A
  1. HSR rxn
  2. Hemolysis if G6PD deficient
  3. Renal toxicity (tubulointerstitial nephritis)
  4. Photosensitivity
  5. Kernicterus in infants
  6. displaces other drugs from albumin eg warfarin
59
Q

Mechanism of resistance of sulfonamides

A

altered enzymes, decreased uptake, increased PABA synthesis

60
Q

MOA of Trimethoprim

A

inhibits bacterial DHF reductase

- static

61
Q

When is trimethoprim used?

A
  1. combo w/ sulfonamides - causing sequential folate synthesis blockade. UTI, Shigella, Salmonella, PCP, toxoplasmosis prophylaxis
62
Q

ADE of trimethoprim

A

Megaloblastic anemia, leukopenia, granulocytopenia

- may alleviate w/ supplemental folinic acid

63
Q

MOA Fluoroquinolones

A

inhibits DNA gyrase (topoisomerase II) and topo IV

  • cidial
  • MUST NOT BE TAKEN W/ antacids
64
Q

When are fluroquinolones used?

A

gram negative rods of urinary and GI tracts

Neisseria, some gram positive

65
Q

ADE of fluoroquinolone

A
  1. GI upset
  2. Superinfxns
  3. skin rashes
  4. Headache, dizziness
  5. Tendonitis, tendon rupture, leg cramps, myalgias
  6. QT prolongation
66
Q

What are fluoroquinolones contraindicated in pregnancy, nursing mothers, and kids less than 18?

A

possible damage to cartilage

67
Q

Mechanism of resistance to fluoroquinolones

A

Chromosome encoded mutation in DNA gyrase, plasmid mediated resistance, efflux pump

68
Q

MOA of metronidazole

A

forms free radical toxic metabolites in bacterial cell that damages DNA
- bactericidal and antiprotozoal

69
Q

When is metronidazole used?

A

GET GAP

Giardia, Entamoeba, Trichomonas, Gardnerella, Anaerobes, H Pylori w/ PPI and clarithomycin

70
Q

ADE of metronidazole

A
  1. disulfiram like rxn - severe flushing, tachycardia, hypotension w/ alcohol
  2. HA
  3. metallic taste
71
Q

What are your drugs for prophylaxis of the following?

  1. M Tuberculosis
  2. M. avium - intracellulare
  3. M leprae -
A
  1. INH
  2. Azithromycin, rifabutin
  3. n/a
72
Q

What are the treatments for the following?

  1. M tuberculosis
  2. M. avium - intracellulare
  3. M leprae
A
  1. RIPE
  2. Azithromycin or clarithomycin + ethambutol. Can add rifabutin or ciprofloxacin
  3. Long term treatment w/ dapsone and rifampin for tuberculoid form. Add clofazimine for lepromatous form
73
Q

MOA of INH

A

decreases synthesis of mycolic acids

- bacterial catalase peroxidase (encoded by Kat G) needed to convert INH to active metabolite

74
Q

How is INH metabolized?

A

different INH half lives in fast vs slow acetylators

75
Q

ADE of INH

A
  • think INH Injures Neurons and Hepatocytes
  • neuro and liver toxocity. Lupus
  • can lead to pyridoxine deficiency so replacement of it can prevent neurotoxicity.
76
Q

MOA of rifamycins

A

inhibits DNA dependent RNA polyermase

77
Q

When are the rifamycins used?

A

TB, delays resistance of dapsone when used for leprosy, meningococcal prophylaxis and chemoprophylaxis in contacts of kids w/ H influenza type B

78
Q

ADE of rifamycins

A
  1. Ramps up microsomal cytochrome P450 affecting other drugs
  2. Red/orange body fluids
  3. Rapid resistance is used alone
  4. Rifabutin favored over rifampin in pts w/ HIV infxns due to less cytochrome P450 stimulation
79
Q

MOA of pyrazinamide

A

Unkown - thought to acidify intracellular environment via conversion to pyrazinoic acid.
- effective in acidic pH of phagolysosomes, where TB engulfed by macrophages is found

80
Q

ADE of pyrazinamide

A

Hyperuricemia and liver toxicity

81
Q

MOA of ethambutol

A

decreases carbohydrate polymerization of cell wall by blocking arabinosyltransferase

82
Q

ADE of ethambutol

A

optic neuritis - red green colon blindness

83
Q

What are the proper antimicrobial prophylaxis for the following conditions?

  1. Endocarditis w/ surgical or dental procedures
  2. Gonorrhea
  3. History of recurrent UTI
  4. Meningococcal infxn
  5. Pregnancy woman carrying group B strep
A
  1. Penicillins
  2. Ceftriaxone
  3. TMP-SMX
  4. Ciprofloxacin, rifampin for kids
  5. Ampicillin
84
Q

What are the proper antimicrobial prophylaxis for the following conditions?

  1. Prevention of gonococcal or chlamydial conjunctivitis in newborns
  2. Prevention of postsurgical infxn due to S aureus
  3. Prophylaxis of strep pharyngitis in child w/ prior rheumatic fever
  4. Syphilis
A
  1. Erthyomycin ointment
  2. Cefazolin
  3. Oral penicillin
  4. Pencillin G
85
Q

What can be given to HIV pts if they are unable to tolerate TMP-SMX?

A

Aerosolized pentamidine but this may not prevent toxoplasmosis infxn concurrently.

86
Q

What is the treatment for MRSA?

A

vancomycin, daptomycin, linezolid ( can cause 5HT syndrome), tigecycline, cefratoline

87
Q

What is the treatment for VRE?

A

linezolid and streptogramins ( - pristins)

88
Q

What is used to treat the following protozoans?

  1. Toxoplasmosis
  2. Trypanosoma brucei
  3. T Cruzi
  4. Lesihmaniasis
A
  1. primethamine
  2. suramin and melarsopol
  3. Nifurtimox
  4. sodium stibogluconate
89
Q

MOA of Cholorquine

A

blocks detoxification of heme to hemozoin, heme accumulates and is toxic to plasmodia

90
Q

How does malaria get resistant to choloroquine

A
  • membrane pump that decreases intracellular concentrations of the drug
91
Q

What is the treatment for chloroquine resistant malaria

A

artemether/lumefantrine or atovaquone/proguanil

- for life threatening malaria, use quinidine in US or artesunate

92
Q

ADE of chlorquine

A

retinopathy, pruritus, QT prolongation

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