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PCM Exam 1 > Antibacterials 5 > Flashcards

Antibacterials 5 Flashcards

1
Q

Chloramphenicol is a ____________ spectrum and inhibits _________

A

Broad spectrum; protein synthesis

Bactiostatic

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2
Q

Chloramphenicol binds to ______ and inhibits __________

A

50S; peptidyltransferase

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3
Q

What is an adverse effect of chloramphenicol?

A

Bone marrow toxicity

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4
Q

Presence of ___________ codes for resistance against chloramphenicol

A

Acetyltransferase

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5
Q

What is the method of resistance for chloramphenicol?

A
  • presence of a factor that codes for acetyltransferase

- changes in membrane permeability

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6
Q

When is chloramphenicol used clinically?

A

Only for serious infections due to the severe toxicity (last resort)

  • used against VRE
  • eye drops
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7
Q

Chloramphenicol inhibits ________ and thus can have a lot of drug interactions

A

Hepatic oxidases (3A4 and 2C9)

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8
Q

What is a unique adverse effect of choloramphenicol?

A

Gray baby syndrome (cyanosis) due to drug accumulation because they don’t have well developed livers yet

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9
Q

MOA of clindamycin

A

Same as macrolides: binds to 50S and blocks translocation

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10
Q

clindamycin is used against _________

A

Primarily Gram positive anaerobic (and aerobic) bacteria and bacteriodes

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11
Q

Most _______________ and ________are intrinsically resistance to clindamycin

A

Gram negative aerobes; enterococcus

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12
Q

Clindamycin has cross resistance with ______

A

Macrolides

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13
Q

Can clindamycin used to treat MRSA?

A

Yes

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14
Q

Clinical applications of clindamycin

A

Used as an alternative for pencillin allergic patients (like macrolides)

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15
Q

Adverse effects of clindamycin

A
  • fatal pseudomembranous colitis (C difficile)
  • GI irritations
  • skin rashes
  • neutropenia and impaired liver function
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16
Q

What antibiotics can cause pseudomembranous colitis?

A
  • clindamycin

- ampicillin

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17
Q

Drugs that are in the class of streptogranins (protein synthesis inhibitors)

A

Quinupristin and Dalfopristin

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18
Q

Which antibacterial have a postantibiotic effect?

A

Stretogranins and Aminoglycosides

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19
Q

MOA of streptogranins

A

Bind to 50S ribosome

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20
Q

Clinical applications of streptogramins

A
  • gram positive cocci
  • multi drug resistance bacteria (MRSA, VRE)
  • can attack intracellularly because they penetrate macrophages and polymorphonucleocytes (PMP’s)
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21
Q

Streptogramins can have drug interactions because they can inhibit _________

A

CYP3A4

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22
Q

Linezolid is mainly bacteriostatic but is bacteriocidal against ______ and _________

A

Streptococci and Clostridum perfringens

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23
Q

MOA of linezolid

A

Inhibits the 70S invitation complex by binding to the 23S rRNA of the 50S subunit

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24
Q

Linezolid has a similar MOA as _______ but what is the difference?

A

Aminoglycosides; they both inhibit the initiation complex except Aminoglycosides bind to the 30S subunit

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25
Q

Clinical applications of linezolid

A
  • mainly gram positive organisms including MRSA and VRE

- moderate activity against mycobacterium tuberculosis

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26
Q

Linezolid is also a weak ______

A

MAOI

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27
Q

Linezolid is well tolerated for short term but what are some long term administration adverse effects?

A
  • bone marrow suppression especially thrombocytopenia
  • optic and peripheral neuropathy
  • lactic acidosis
  • serotonin Syndrome (it is a weak MAOI)
28
Q

Fidaxomicin has activity against _________

A

ONLY gram positive; NO action on gram negative

29
Q

MOA of fidaxomicin

A

Inhibits protein synthesis by binding to bacterial RNA polymerase

30
Q

Clinical applications of fidaxomicin

A

Treatment of C. Difficile in adults

31
Q

_______________ is a bacterial protein synthesis inhibitors that is used in people > 18 because safety and effectiveness in people younger have not been established

A

Fidaxomicin

32
Q

Mupirocin’s route of administration is __________ and has activity against ________

A

Topical/intranasal;

Most gram positive cocci including MRSA

33
Q

Mupirocin binds to _________ and inhibits protein synthesis

A

Bacterial isoleucyl tRNA synthetase

34
Q

Clinical applications of mupirocin

A

Intranasally: eradicate nasal colonization of MRSA in adult patients and healthcare workers

Topically: impetigo or secondary infected traumatic skin lesions

35
Q

_____________ (skin condition) is treated using mupirocin

A

Impetigo

36
Q

Adverse effects of mupironcin

A

Mainly local and dermatology effects such as burning, edema, tenderness, dry skin, etc

37
Q

Classes of drugs that affect nucleic acid synthesis

A
  • fluoroquinolones
  • sulfonamides
  • trimethoprim
38
Q

Describe the type of bacteria that is mainly affected as you move from 1st to 4th generation of fluoroquinoles

A

↑ activity against gram positive and ↓ activity against gram negative

Opposite of cephalosporins

39
Q

MOA of fluoroquinolones

A

Broad spectrum, bacteriocidal and enter bacteria via porins

Inhibits DNA replication via topoisomerase II and topoisomerase IV

40
Q

Fluoroquinoles inhibit ____________ and _________

A

Topoisomerase II and IV

41
Q

Mechanism of resistance against fluoroquinoles

A
  • chromosomal mutation that encode subunits of DNA gyrase and topoisomerase IV or ones that regulate expression of efflux pumps
  • cross resistance with other drugs
42
Q

What drug is a 1st generation fluoroquinolone

A

Nalidixic acid

43
Q

What is a 2nd generation fluorquinolone drug and what is its antimicrobial spectrum

A

Ciprofloxacin;

Synergistic activity with β lactams

44
Q

What is a 3rd generation fluoroquinolone drug and what does it have good activity against

A

Levofloxacin; excellent activity against S. Pneumonia

45
Q

What are the two 4th generation fluoroquinolone drugs

A

Moxifloxacin and gemifloxacin

46
Q

What are the three drugs that are used against meningitis

A
  • ceftriaxone
  • rifampin
  • ciprofloxacin
47
Q

What are the respiratory fluoroquinolones

A

3rd and 4th generation:

  • levofloxacin
  • moxifloxacin
  • gemifloxacin

Can be used to treat atypical pneumonia because those bacteria dont have cell walls

48
Q

When are respiratory fluoroquinolones used for treatment

A

Used to treat pneumonia but when first line agents have failed (macrolides w/ or w/o tetracyline)

Or in the presence of comorbidities

49
Q

___________ and _______ absorption are affected by divalent cations

A

Fluoroquinoles and tetracyclines

50
Q

Most fluoroquinolones are excreted via __________ except ________

A

Renal; moxifloxacin

51
Q

Which fluoroquinolone would you prescribe to a patient with renal dysfunction

A

Moxifloxacin because it is excreted in the bile

52
Q

What are the adverse effects of fluorquinolones

A
  • Connective tissue problems (avoid in pregnancy, nursing mothers and under 18)
  • peripheral neuropathy
  • QT prolongation
  • GI distress
  • CNS, rash, photosensitivity
  • superinfection
53
Q

Connective tissue problems is an adverse effect to taking ______

A

Fluoroquinolones

54
Q

What type of patients CANNOT take fluoroquinolones?

A

Pregnant, nursing mothers and patients under 18 years old

55
Q

What drugs have an adverse effect of QT prolongation

A
  • fluoroquinolones: moxifloxacin, gemifloxacin, levofloxacin
  • macrolides
56
Q

______, _______, and ______ enhance the toxicity of fluoroquinolones

A

Theophylline, NSAIDS and corticosteroids

57
Q

What are the drug interactions of 3rd and 4th generation fluoroquinolones

A
  • ↑ serum levels of: warfarin, caffeine and cyclosporine
58
Q

What are the drugs in the sulfonamide family and what kind of bacteria do they act against

A
  • sulfamethoxazole
  • sulfadiazine
  • sulfasalazine

Bacteristatic against gram positive and negative

59
Q

MOA of sulfanomides and how is it specific to bacteria?

A

Inhibits bacterial folic acid synthesis;
They are synthetic analogs of PABA and thus are competitive inhibitors of dihydropteroate synthase (this enzyme is only used by bacteria to create folate)

60
Q

Sulfonamides are compete with PABA for the enzyme ________

A

Dihydropteroate synthetase

61
Q

Mechanisms of resistance against sulfonamides

A
  • altered dihydropteroate synthase
  • ↓ cellular permeability
  • enhanced PABA production
  • ↓ intracellular drug accumulation
62
Q

What are some clinical applications of sulfonamides and what are they used for?

A

Topical: ocular and burns
Oral: simple UTI’s

63
Q

What is sulfasalazine used to treat?

A
  • ulcerative colitis
  • enteritis
  • IBD

(This one is oral NON absorbable)

64
Q

Unique adverse effects of sulfonamides

A
  • Crystalluria (nephrotoxicity)
  • hypersensitivity reactions
  • hematopoietic disturbances (especially in those with G6PD deficiency)
  • kernicterus in newborns and infants
65
Q

What drugs can cause kernicterus

A

Ceftriaxone and sulfonamides

66
Q

Sulfonamides can displace drugs such as _____, ______, and _______ from albumin

A

Warfarin, phenytoin, and methotrexate

67
Q

Trimethroprim is a potent inhibitor of _________

A

Bacterial dihydrofolate reductase

Inhibits purine, pryrimidine, and AA synthesis

PCM Exam 1 (22 decks)

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