8.4-PNEUMOCYSTIS PNEUMONIA+PENICILLIOSIS+OTHER OPPORTUNISTIC MYCOSES Flashcards
What organism causes Pneumocystis pneumonia (PCP)?
Pneumocystis jiroveci (formerly P. carinii)
What type of patients does P. jiroveci primarily affect?
Immunocompromised patients
How common is dissemination of P. jiroveci?
Rare
Before the AIDS epidemic, what was the main population affected by P. jiroveci?
Malnourished infants and immunosuppressed patients
Before effective prophylaxis, what was a major cause of death in AIDS patients?
Pneumocystis pneumonia (PCP)
What organs can P. jiroveci affect apart from the lungs?
Spleen, lymph nodes, bone marrow
What are the major stages in the life cycle of P. jiroveci?
Trophozoite → Precyst → Cyst → Sporozoites → Trophozoites
What is the function of trophozoites in P. jiroveci?
Feeding stage
Is P. jiroveci an intracellular or extracellular pathogen?
Extracellular
Where does P. jiroveci grow in the lung?
Surfactant layer above alveolar epithelium
What are the two morphologically distinct forms of P. jiroveci?
Thin-walled trophozoites and thick-walled cysts
What are the characteristics of the cysts?
Thick-walled, spherical to elliptical (4–6 µm), containing 4–8 nuclei
What surface marker is found in P. jiroveci and can be detected in sera?
Surface glycoprotein
What is the ideal specimen for diagnosing Pneumocystis pneumonia?
Bronchoalveolar lavage (BAL)
What other specimens can be used?
Lung biopsy tissue, induced sputum
What stains are appropriate for detecting P. jiroveci?
Giemsa, toluidine blue, methenamine silver, calcofluor white
Can P. jiroveci be cultured?
No
Does P. jiroveci cause disease in immunocompetent individuals?
No
Has a natural reservoir for P. jiroveci been identified?
No
What is known about the mode of infection for P. jiroveci?
Unclear
When are most individuals infected with P. jiroveci?
Early childhood
What is the global distribution of P. jiroveci?
Worldwide
What type of immunity plays a dominant role in resistance to disease?
Cell-mediated immunity
At what CD4 count does Pneumocystis pneumonia usually appear in AIDS patients?
Below 400 cells/µL
What are the two main treatment options for Pneumocystis pneumonia?
Trimethoprim-sulfamethoxazole or pentamidine isethionate
How can prophylaxis be achieved?
Daily trimethoprim-sulfamethoxazole or aerosolized pentamidine
What organism causes Penicilliosis?
Penicillium marneffei (Talaromyces marneffei)
What type of infection does P. marneffei cause?
Systemic infection in immunocompromised patients
How has P. marneffei emerged as a pathogen?
As an endemic, opportunistic pathogen
In which regions is P. marneffei endemic?
Southeast Asia, including China, Thailand, Vietnam, Indonesia, Hong Kong, Taiwan, Manipur (India)
Where is P. marneffei commonly isolated from?
Soil, especially soil associated with bamboo rats and their habitats
What is the colonial appearance of P. marneffei in mold form?
Green-yellow colony with diffusible reddish pigment
What is the microscopic appearance of P. marneffei in mold form?
Septate, branching hyphae, brushlike aerial conidiospores, phialides, and basipetal chains of conidia
What is the microscopic appearance of P. marneffei in tissue form?
Unicellular yeast-like cells (2 × 6 µm) dividing by fission
What are the major risk factors for Penicilliosis?
HIV/AIDS, tuberculosis, corticosteroid treatment, lymphoproliferative diseases
What are the clinical manifestations of Penicilliosis?
Fungemia, skin lesions, systemic involvement (especially reticuloendothelial system)
What are the signs and symptoms of Penicilliosis?
Cough, fever, fatigue, weight loss, lymphadenopathy, cutaneous/subcutaneous papules or rashes
What specimens are used for diagnosing Penicilliosis?
Skin, blood, or tissue biopsies
How is Penicilliosis diagnosed?
Microscopic observation of yeast-like cells and positive cultures
What is the treatment for Penicilliosis?
Amphotericin B (initial course), Itraconazole (follow-up therapy)
What are opportunistic mycoses?
Globally distributed fungal infections with high incidence, severity, and mortality
What innate host defenses protect against systemic candidiasis, invasive aspergillosis, and mucormycosis?
Neutrophils & monocytes
What types of patients are at high risk for opportunistic mycoses?
Those with hematologic dyscrasias, immunosuppressive or cytotoxic drug treatment
What fungal infections commonly affect HIV/AIDS patients?
Mucosal candidiasis (e.g., thrush, esophagitis)
Which fungal infections occur in AIDS patients with CD4 counts <100 cells/µL?
Cryptococcosis, Pneumocystis pneumonia, Aspergillosis, Penicilliosis, Endemic mycoses
Why is invasive aspergillosis or candidiasis difficult to diagnose?
Blood cultures are negative in aspergillosis, <50% positive in systemic candidiasis
What is the key to successful management of opportunistic mycoses?
Early diagnosis, rapid antifungal therapy, control of underlying disease
What diseases does Geotrichum candidum cause?
Pulmonary disease, wound infections, and oral thrush
What is the key microscopic feature of Geotrichum candidum?
Abundant arthroconidia due to fragmentation of hyphae
What disease is Fusarium commonly associated with?
Mycotic keratitis
What is the distinctive microscopic feature of Fusarium?
Banana- or canoe-shaped macroconidia clustered in mats (sporodochia)
What is unique about Fusarium macroconidia?
Only mycoses with banana-/canoe-shaped macroconidia
What are the colony colors of Fusarium?
Rose, mauve, purple, yellow
What are opportunistic mycoses?
Globally distributed fungal infections that cause high morbidity and mortality in immunocompromised patients
Which mycoses have the highest incidence, severity, and mortality?
Systemic opportunistic mycoses
What innate host defenses protect against systemic opportunistic mycoses?
Neutrophils & monocytes
What part of the immune system plays an additional role in defense?
Adaptive immune response, particularly cell-mediated immunity
What patients are at high risk for opportunistic mycoses?
Patients with hematologic dyscrasias (e.g., leukemia, anemia) and immunosuppressive or cytotoxic drug treatment
What fungal infection is common in most HIV/AIDS patients?
Mucosal candidiasis (thrush, esophagitis)
Patients with CD4 counts <100 cells/µL are at risk for what infections?
Cryptococcosis, Pneumocystis pneumonia, Aspergillosis, Penicilliosis, Endemic mycoses, Other opportunistic fungal infections
