0%
Topic
Review Topic
0
0
N/A
N/A
Questions
0 6
0
0
100%
0%
Evidence
0 7
0
0
Topic
Snapshot
  • A 36-year-old man presents to the emergency department with an altered level of consciousness and fever. He is accompanied by a friend, who says that prior to being altered, he experienced a productive cough, chills, and night sweats. His temperature is 103°F (39.4°C), blood pressure is 70/60 mmHg, pulse is 130/min, and respirations are 14/min. He is immediately started on intravenous fluids, blood cultures are drawn, is started on vancomycin and piperacillin/tazobactam, and is admitted to the medical intensive care unit. In the unit, the patient is stabilized but is still febrile. KOH and calcofluor white are added to fresh wet preparations of the patient's sputum, which demonstrate refractile cell wall, and single, broad-based buds. He is then started on intravenous amphotericin B. (Blastomycosis)
Introduction
  • Mechanism of action
    • binds to ergosterol, which leads to the formation of pores in fungal membranes leaking its internal cellular contents   
  • Mechanism of resistance
    • alterations in ergosterol
  • Clinical use
    • serious (potentially life-threatening) systemic mycoses 
      • aspergillosis
      • cryptococcosis
      • blastomycosis 
      • systemic candidiasis
      • coccidioidomycosis
      • histoplasmosis
      • zygomycosis
      • fungal meningitis
        • medication must be administered intrathecally to target the central nervous system
  • Adverse effects
    • nephrotoxicity
      • hydration decreases the risk
    • intravenous phlebitis
    • anemia
    • cardiac arrhythmia
    • fevers and chills
    • hypokalemia and hypomagnesemia 
      • should supplement these electrolytes in patients in treatment
Topic Rating

Please rate topic.

Average 5.0 of 8 Ratings

 

Questions (6)
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

(M1.MC.15.75) A 45-year-old male seismologist with a 10-year history of AIDS returns from a two-month long stay in Los Angeles three weeks ago and is hospitalized for concurrent pneumonia, meningitis, and vertebral osteomyelitis. A sputum sample was taken and shown to have spherules containing spores (Figure A). Treatment was initiated with a systemic medication that causes fever and chills upon infusion. Which of the following is the mechanism of action of this medication? Tested Concept

QID: 106851
FIGURES:
1

Inhibits ergosterol synthesis

13%

(30/227)

2

Binds to ergosterol, forming destructive pores in cell membrane

76%

(173/227)

3

Inhibits squalene epoxidase

7%

(15/227)

4

Inhibits formation of beta glucan

2%

(4/227)

5

Inhibits pyrimidine synthesis

1%

(3/227)

M 1 D

Select Answer to see Preferred Response

(M1.MC.14.1) A 15-year-old year male with a prior history of a kidney transplant presents to his pediatrician complaining of cough, fatigue, and fever after returning from visiting his father for two months in Wisconsin for the spring. He is treated empirically with antibiotics for a possible lower respiratory tract infection. Three weeks goes by and his symptoms do not resolve; he is now experiencing lower back pain and returns to the pediatrician. A spinal tap is performed, and a methenamine silver stained is performed showing a specimen with broad-base budding (Figure A). Which of the following treatments would eliminate the causative agent by binding to ergosterol in the membrane altering the permeability of the membrane? Tested Concept

QID: 106423
FIGURES:
1

Clotrimazole

3%

(2/64)

2

Flutocytosine

2%

(1/64)

3

Caspofungin

3%

(2/64)

4

Amphotericin B

81%

(52/64)

5

Fluconazole

11%

(7/64)

M 3 E

Select Answer to see Preferred Response

Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

(M1.MC.13.5) A 35-year-old African American male is admitted to the hospital following a recent diagnosis of systemic histoplasmosis and subsequently treated with an intravenous anti-fungal agent. During the course of his hospital stay, he complains of headaches. Work-up reveals hypotension, anemia, and elevated BUN and creatinine. His medication is known to cause these side-effects through its binding of cell membrane ergosterol. With which anti-fungal is he most likely being treated? Tested Concept

QID: 100808
1

Fluconazole

16%

(51/328)

2

Flucytosine

1%

(3/328)

3

Amphotericin B

77%

(254/328)

4

Terbinafine

2%

(5/328)

5

Griseofulvin

3%

(11/328)

M 3 E

Select Answer to see Preferred Response

Evidence (7)
Topic COMMENTS (5)
Private Note