Deck 61: Opportunistic Atypical Fungus: Pneumocystis Jiroveci

Question 1

The cell membrane of Pneumocystis jirovecii contains _______ rather than _______, which differentiates it from other fungi.

A) sterols; cholesterol
B) ergosterol; sterols
C) cholesterol; ergosterol
D) sitosterol; sterols

Answer 1

C
Although P.jirovecii has been shown to be a fungus, it differs from other fungi in various aspects.The cell membrane of P.jirovecii contains cholesterol rather than ergosterol.A flexible-walled trophozoite form exists that is susceptible to osmotic disturbances.In addition, this organism contains only one to two copies of the small ribosomal subunit gene, whereas most other fungi contain numerous copies of this gene.

Question 2

Which form is considered diagnostic in the life cycle of Pneumocystis jirovecii?

A) Bradyzoite
B) Trophozoite
C) Sporocyte
D) Cyst

Answer 2

D
This organism exists as three forms in its life cycle: (1)trophozoite, (2)precyst (sporocyte), and (3)cyst.The cyst form is considered diagnostic.

Question 3

Which therapy has decreased the incident of pneumocystis infection in patients with human immunodeficiency virus or acquired immunodeficiency syndrome (HIV/AIDS)?

A) Metronidazole
B) Trimethoprim-sulfamethoxazole combination
C) Aminoglycosides with fluconazole
D) Highly active antiretroviral therapy (HAART)

Answer 3

D
Since the epidemic of HIV/AIDS, pneumocystis has been defined as the most common opportunistic infection in this patient population in the United States.With the introduction of HAART therapy for patients with HIV, the incidence of disease has decreased.Numerous patients with HIV do not respond to therapy, and many are not compliant with therapy or do not know they are infected.Consequently, pneumocystis pneumonia (PCP)remains a major problem.

Question 4

Which type of molecular assay has been developed to identify Pneumocystis jirovecii but is not yet available in commercial kits?

A) Nucleic acid sequence-based amplification (NASBA)
B) Strand displacement amplification (SDA)
C) Transcription-mediated amplification (TMA)
D) Real-time polymerase chain reaction (PCR)

Question 5

In patients who do not have HIV, which underlying condition is considered a risk factor for acquiring PCP?

A) Malaria
B) Cystic fibrosis
C) Cytomegalovirus
D) Myasthenia gravis