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Host and Defense > EXAM 2 Antimicrobials V > Flashcards

EXAM 2 Antimicrobials V Flashcards

1
Q

___ have nearly impermeable cell walls made up of mycolic acids

A

mycobacterium

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2
Q

>60% of the cell wall of mycobacteria is lipid, which does what?

A

shields and thus prevents many drugs from accessing the cell membrane

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3
Q

describe how mycobacterial defenses make it exceptionally difficult for antimicrobials to do their jobs

A
  • they have very thick, hydrophobic cell walls rich in mycolic acid
  • efflux pumps
  • some species can hid inside host cells
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4
Q

what are two key mycobacterium-related diseases?

A

mycobacterium tuberculosis (TB) and mycobacterium leprae (hansen’s disease or leprosy)

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5
Q

describe mycobacterium tubercosis (TB)

A

9 million new cases of TB and 2 million deaths annually

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6
Q

what bacteria has the following characteristics?

  • hansen’s disease, leprosy
  • 2 million new cases worldwide
  • the bacteria grow better in areas with cooler body temperatures closer to skin surfaces (ex. extremities)
A

mycobacterium leprae

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7
Q

in 1882, TB killed ___ out of every ___ people living in the US and Europe

A

1/7

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8
Q

among infectious diseases, TB remains the ___ leading killer of adults in the world, with ___ million TB-related deaths annually

A
  • 2nd
  • 2 million
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9
Q

what is used to test for tuberculosis?

A

mantoux tuberculin skin test (TST)

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10
Q

with latent/asymptomatic primary TB infections, there will be no active disease, but a ___ TST

A

positive

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11
Q

what is the preventative treatment for latent/asymptomatic primary TB?

A
  • initiate immediately
  • prophylactic treatment of choice is isoniazid for 9 months
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12
Q

what type of infection is described by the following:

usually in lungs, but can effect other organs; dyspnea, fever, productive cough and night sweats for >2 months; upper lobe consolidation on chest x-ray; acid fast bacilli on sputum test, positive TST

A

overt/active primary TB

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13
Q

the following is the treatment of choice for what type of tuberculosis?

  • 2 months treatment with combination of ribampin + isoniazid + pyrazinamide + ethambutol (R+I+P+E)
  • followed by 4 months with rifampin + isoniazid
  • “2 with 4, then 4 with 2”
A

overt/active primary tuberculosis

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14
Q

describe the treatment of overt/active primary tuberculosis when it is an intracellular organism

A
  • treat with RIPE for 12 months + azithromycin (macrolide)
  • restrict use of pyrazinamide to only the 1st 2 months
    • hepatotoxic
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15
Q

secondary, reactivated (resistant) TB is of greater risk in what patients?

A

HIV-positive, immunosuppressed, or other “high risk” patients

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16
Q

describe the secondary TB “rule of 5’s”

A
  • otherwise healthy patients infected with mycobacterium tuberculosis have a 5% risk of reactivation in the first 2 years and then a 5% lifetime risk of reactivation
  • high risk patients have a 5%+5% risk of reactivation per year
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17
Q

T or F

secondary tuberculosis can only reactivate in the lungs

A

false

it can reactivate in a variety of different locations

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18
Q

the following is the treatment of choice for what type of tuberculosis?

  • RIPES
    • 2 months treatment with combination of rifampin, isoniazid, pyrazinamide, and ethambutol, PLUS STREPTOMYCIN
  • followed by 4 months treatment with isoniazid and firampin (2 with 5, then 4 with 2)
A

secondary TB

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19
Q

what can be done in cases of secondary TB where drug resistance is a problem?

A

second line drugs can be added to overcome drug resistance

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20
Q

what are 7 tuberculosis drugs?

A
  • streptomycin - aminoglycoside
  • azithromycin - macrolide
  • rifampin - nucleic acid synthesis inhibitor
  • isoniazid
  • pyrazinamide
  • ethambutol
  • bedaquiline
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21
Q

what is the clinical use of isoniazid (INH)?

A
  • drug of choice for prophylaxis of mycobacterium tuberculosis
  • also effective in combo against active TB
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22
Q

what is the mechanism of isoniazids?

A

decreases mycolic acid synthesis

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23
Q

___ is a prodrug that must be activated by the bacterial enzyme, KatG (TB catalase oxidase enzyme)

A

isoniazid

24
Q

___ activation of isoniazid also produces free radicals, like NO (oxidative stress)

A

KatG

25
Q

the following are adverse effects for which drug?

hepatotoxicity

can cause a pyridoxine deficiency, so always administer along with vitamin B6 to maintain heme synthesis and prevent neurotoxicity

tell patients to avoid alcohol 72 hours before and after administration (disulfuram-like reaction)

A

isoniazid (INH)

26
Q

is pyrazinamide (PO) a prodrug?

A

yes

27
Q

which drug has the following clinical use?

treatment of active mycobacterium tuberculosis infection, especially tuberculous meningitis

A

pyrazinamide

28
Q

is pyrazinamide bacteriostatic or bactericidal?

A

bacteriostatic

29
Q

the following mechanism describes what drug?

  • inhibits mycolic acid synthesis
  • the net effect is that more pyrazinoic acid accumulates inside granulomas (more absorbed at high pH than at neutral pH)
A

pyrazinamide

30
Q

pyrazinamide requires ___ pH to be activated, and is an essential part of the treatment of ___

A
  • acidic pH, aka low pH
  • tuberculous meningitis
31
Q

what drug has the following adverse effects?

  • hepatotoxicity if used >2 months
  • increases uric acid (can cause gout or make it worse)
  • rash
  • contraindicated in pregnancy
A

pyrazinamide

32
Q

what are the contraindications of pyrazinamide?

A

pregnancy

33
Q

what is ethambutal used for?

A

treatment of active mycobacterium tuberculosis infections

34
Q

the following mechanism describes what drug?

  • obstructs the mycobacterial cell wall formation
  • decreases carbohydrate polymerization by inhibiting arbinosal transferase
A

ethambutal

35
Q

can ethambutal cross the BBB?

A

yes

36
Q

what drug has the following adverse effects?

  • ocular toxicity
  • color blindness
  • ocular neuritis → blindness (in up to 6% of patients within the first 3 months of use
A

ethambutal

37
Q

what are the drugs used for TB (RIPES)?

A
  • rifampin
  • isoniazid (INH)
  • pyrazinamide
  • ethambutol
  • streptomycin (aminoglycoside)
38
Q

of the RIPES drugs, which 3 are orally absorbed with excellent tissue penetration, but can cause hepatotoxicity?

A
  • rifampin
  • isoniazid (INH)
  • pyrazinamide
39
Q

isoniazid (INH) should always be given with ___ to prevent peripheral neuropathy

A

vitamin B6

40
Q

___ should always be avoided during pregnancy and its administration should always be limited to 2 months max (hepatotoxic >2 months)

A

pyrazinamide

41
Q

which of the RIPES drugs can be given IV or IM, it ototoxic, nephrotoxic, and should be avoided during pregnancy?

A

streptomycin (aminoglycoside)

42
Q

in cases of mycobacterium avium (intracellular), ___ should be added in addition to the RIPES regimen

A

azithromycin

43
Q

___ is generally safe, but may prolong QT interval and cause acute cholestatic hepatitis in certain patient populations at high doses

A

azithromycin

44
Q

___ was approved in Dec 2012 for multi-drug resistant TB

A

bedaquiline

45
Q

what is the mechanism of bedaquiline?

A

inhibits mycobacterial ATP synthase

46
Q

the following adverse effects describe which drug?

nausea, vomiting, arthralgias, headache

black box warning for patients with arrhythmias

prolonged QT syndrome

A

bedaquiline

47
Q

what are the two possible drugs of choice for the treatment of leprosy?

A
  • rifampin
    • treatment for TB and leprosy
  • dapsone
    • prophylaxis
48
Q

what is the mechanism of dapsone?

A

competes with PABA to inhibit bacterial dihydrofolate synthesis (antimetabolite)

49
Q

which drug has the following clinical use?

prophylaxis of leprosy and prophylaxis of pneumocystis jiroveci

A

dapsone

50
Q

the following adverse effects apply to which drug?

hepatotoxicity, hemolysis, cross-sensitivity if allergic to sulfonamides

A

dapsone

51
Q

most (80%) traveller’s diarrhea infections are caused by ___, but other bacterial species include ___, ___, and ___

A
  • e. coli
  • campylobacter jejuni, shigella, and salmonella
52
Q

what drug should be used to treat traveller’s diarrhea caused by e. coli

A

rifaximin

53
Q

what drug should be used to treat traveller’s diarrhea caused by invasive campylobacter and shigella, or salmonella?

A

ciprofloxacin (fluoroquinolone)

54
Q

pseudomembranous colitis is caused by an overgrowth of ___ and the drug of choice for treatment is ___

A
  • c. difficile
  • metronidazole
55
Q

which type of hansen’s disease is described by the following:

well-demarcated lesions

good immune response

only exhibits a few skin lesions

the disease is mild, and is only mildly contageous

A

tuberculoid leprosy

56
Q

which type of hansen’s disease is described by the following:

poorly demarcated lesions

poor immune response

affects the skin, nerves, and other organs

A

lepromatous leprosy

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