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Microbiology Flashcards

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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
MOA of carbapenems
Broad spectrum Beta lactamase resistant Always given w/ cilstatin
26
What is cilastatin?
inhibits renal dephydropeptidase I to decrease inactivation of drug in renal tubules
27
Uses for carbapenems?
1. gram positive cocci 2. gram negative rods 3. anerobes
28
What is special about Meropenem?
- decreased risk of seizures | - stable to dephydropeptidase I in kidney
29
ADE of carbapenems?
GI distress Skin rash CNS toxicity (seizures) at very high plasma levels
30
MOA of vancomycin
inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall precursors - cidial
31
Vancomycin uses
Gram positives only, multidrug resistant organism, MRSA, enterococci, and Clostridium difficile
32
ADE of vancomycin
1. renal toxicity 2. otoxocitiy 3. Thrombrophlebitis 4. diffuse flushing - red man syndrome ( can be prevented w/ pretreatment w/ antihistamine and slow infusion rate)
33
Mechanism of resistance against vancomycin
Modification of D-ala D-ala to D-ala D-lac
34
MOA of Aminoglycosides
1. cidial 2. inhibits formation of initation complex and causes misreading of mRNA. Also blocks translocation - Needs O2 for uptake therefore ineffective against anaerobes
35
What are your aminoglycosides
Gentamicin, neomycin, amikacin, tobramycin, streptomycin
36
When are aminoglycosides used?
Severe gram negative rod infxns - syngergistic w/ beta lactam Abx. - use Neomycin for bowel surgery
37
ADE for Aminoglycosides
1. renal toxicity esp w/ cephalosporins 2. Neuromuscular blockade 3. ototoxicity esp w/ loop diuretics 4. teratogen
38
Mechanism of resistance for aminoglycosides
bacterial transferase enzyme inactivates the drug by acetylation, phosphorylation, or adenylation
39
MOA of tetracycline
1. static 2. Binds 30S and prevents attachement of aminoacyl-tRNA 3. limited CNS penetration
40
What tetracycline can be used in pts w/ renal failure?
Doxycycline b/c it is fecally eliminated
41
What are some cautions of tetracyclines?
don't take w/ milk (Ca2+) and antacids or Fe containing preparations b/c divalent cations inhibit its absorption in the gut
42
uses for tetracycline
1. Borrelia - Lyme dz 2. Mycoplasma pneumonia 3. Rickettsia and Chlamydia - b/c drug accumulates intracellularly 4. Also used to treat acne
43
ADE of tetracycline
1. GI distress 2. discoloration of teeth and inhibition of bone growth in kids 3. photosensitivity 4. Contraindicated in pregnancy
44
What is the mechanism of resistance for tetracyclines?
decrease uptake of increase efflux out of bacterial cells by plasmid encoded transport pumps
45
MOA of Macrolides
inhibit protein synthesis by blocking translations - binds to 23S rRNA of the 50S subunit - static
46
When are macrolides used?
1. Atypical pneumonia - mycoplasma, legionella, chlamydia 2. STDs- chlamydia 3. gram positive cocci - streptococcal infxns in pts allergic to penicillin
47
ADE of macrolides?
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
Mechanism of resistance for macrolides?
methylation of 23s rRNA binding site prevents binding of drug
49
MOA of chloramphenicol
blocks peptidyltransferase at 50S subunit | - static
50
When is chloramphenicol used?
meningitis (H flu, Nesseria, Strep pneumonia) and RMSF
51
ADE of chloramphenicol
1. dose dependent anemia 2. Aplastic anemia 3. Gray baby syndrome - b/c premies back UDP-glucuronyl transferase
52
Mechanism of resistance for chloramphenicol
plasmid encoded acetyltransferase inactivates the drug
53
MOA of Clindamycin
blocks peptide transfer (translocation) at 50S subunit | - static
54
When is clindamycin used?
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
ADE of clindamycin
Pseudomembranous colitis, fever, diarrhea
56
MOA of Sulfonamides
Inhibits folate synthesis - PABA antimetabolite that inhibits diphydropterorate synthase - static
57
When are sulfonamides used?
1. Gram positive 2. gram negative 3. Nocardia 4. Chlamydia Simple UTI
58
ADE of sulfonamides
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
Mechanism of resistance of sulfonamides
altered enzymes, decreased uptake, increased PABA synthesis
60
MOA of Trimethoprim
inhibits bacterial DHF reductase | - static
61
When is trimethoprim used?
1. combo w/ sulfonamides - causing sequential folate synthesis blockade. UTI, Shigella, Salmonella, PCP, toxoplasmosis prophylaxis
62
ADE of trimethoprim
Megaloblastic anemia, leukopenia, granulocytopenia | - may alleviate w/ supplemental folinic acid
63
MOA Fluoroquinolones
inhibits DNA gyrase (topoisomerase II) and topo IV - cidial - MUST NOT BE TAKEN W/ antacids
64
When are fluroquinolones used?
gram negative rods of urinary and GI tracts | Neisseria, some gram positive
65
ADE of fluoroquinolone
1. GI upset 2. Superinfxns 3. skin rashes 4. Headache, dizziness 5. Tendonitis, tendon rupture, leg cramps, myalgias 6. QT prolongation
66
What are fluoroquinolones contraindicated in pregnancy, nursing mothers, and kids less than 18?
possible damage to cartilage
67
Mechanism of resistance to fluoroquinolones
Chromosome encoded mutation in DNA gyrase, plasmid mediated resistance, efflux pump
68
MOA of metronidazole
forms free radical toxic metabolites in bacterial cell that damages DNA - bactericidal and antiprotozoal
69
When is metronidazole used?
GET GAP | Giardia, Entamoeba, Trichomonas, Gardnerella, Anaerobes, H Pylori w/ PPI and clarithomycin
70
ADE of metronidazole
1. disulfiram like rxn - severe flushing, tachycardia, hypotension w/ alcohol 2. HA 3. metallic taste
71
What are your drugs for prophylaxis of the following? 1. M Tuberculosis 2. M. avium - intracellulare 3. M leprae -
1. INH 2. Azithromycin, rifabutin 3. n/a
72
What are the treatments for the following? 1. M tuberculosis 2. M. avium - intracellulare 3. M leprae
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
MOA of INH
decreases synthesis of mycolic acids | - bacterial catalase peroxidase (encoded by Kat G) needed to convert INH to active metabolite
74
How is INH metabolized?
different INH half lives in fast vs slow acetylators
75
ADE of INH
- think INH Injures Neurons and Hepatocytes - neuro and liver toxocity. Lupus - can lead to pyridoxine deficiency so replacement of it can prevent neurotoxicity.
76
MOA of rifamycins
inhibits DNA dependent RNA polyermase
77
When are the rifamycins used?
TB, delays resistance of dapsone when used for leprosy, meningococcal prophylaxis and chemoprophylaxis in contacts of kids w/ H influenza type B
78
ADE of rifamycins
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
MOA of pyrazinamide
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
ADE of pyrazinamide
Hyperuricemia and liver toxicity
81
MOA of ethambutol
decreases carbohydrate polymerization of cell wall by blocking arabinosyltransferase
82
ADE of ethambutol
optic neuritis - red green colon blindness
83
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
1. Penicillins 2. Ceftriaxone 3. TMP-SMX 4. Ciprofloxacin, rifampin for kids 5. Ampicillin
84
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
1. Erthyomycin ointment 2. Cefazolin 3. Oral penicillin 4. Pencillin G
85
What can be given to HIV pts if they are unable to tolerate TMP-SMX?
Aerosolized pentamidine but this may not prevent toxoplasmosis infxn concurrently.
86
What is the treatment for MRSA?
vancomycin, daptomycin, linezolid ( can cause 5HT syndrome), tigecycline, cefratoline
87
What is the treatment for VRE?
linezolid and streptogramins ( - pristins)
88
What is used to treat the following protozoans? 1. Toxoplasmosis 2. Trypanosoma brucei 3. T Cruzi 4. Lesihmaniasis
1. primethamine 2. suramin and melarsopol 3. Nifurtimox 4. sodium stibogluconate
89
MOA of Cholorquine
blocks detoxification of heme to hemozoin, heme accumulates and is toxic to plasmodia
90
How does malaria get resistant to choloroquine
- membrane pump that decreases intracellular concentrations of the drug
91
What is the treatment for chloroquine resistant malaria
artemether/lumefantrine or atovaquone/proguanil | - for life threatening malaria, use quinidine in US or artesunate
92
ADE of chlorquine
retinopathy, pruritus, QT prolongation

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