Respiratory Tract Infections 8 Flashcards
What are some clinical features seen with fungal causes of RTI’s?
- mild fever
- non productive cough
- progress dyspnea
- weight loss
- rheumatologic syndromes: arthritis, erythema nodosum and erythema multiform
- CXR: pulmonary nodules, hilar lymphadenopathy and patchy infiltrates
what primary fungal pathogen is associated with skin lesions?
blastomyces dermatidis
list the primary fungal pathogens that can cause pneumonia and other LRTI’s
- histoplasma capsulatum
- blastomyces dermatitis
- coccidiodies immitis
- paracoccidioides brasiliensis
microscopic presentation of coccidiodes immitis
- spherules with spores inside
List the opportunistic fungal pathogens that can cause pneumonia and other LRTI’s
- cryptococcus neoformans
- aspergillus
- pneumocystis jiroveci
which fungal pathogen is capable of growing inside macrophages? how?
Histoplasma capsulatum (primary) ↑'s phagolysosomal pH which interferes with enzyme activity and antigen processing
which primary fungal pathogens can be found in the Mississippi River Valley and Ohio River Valley?
- H. capsulatum
- B. dermatidis
_________ fungi is found in soil that has a lot of bird and bat droppings
Histoplasma capsulatum (primary) because the soil is high in nitrogen content
_______ is a fungal pathogen that is endemic to the southwestern US and NW Mexico
coccidiodies immitis
neutropenia is a predisposing factor for infection by which opportunistic fungal pathogen?
aspergillus
the ______ of aspergillus is inhaled from _______
conidia;
decaying organic matter
_______ agar is used for fungal pathogens
Sabouraud’s agar
what CD4 cell count is an AIDS defining criteria?
CD4 Cell count < 200
assisted ventilation is a predisposing factor for infection by which opportunistic fungal pathogen?
aspergillus
Organ transplant is a predisposing factor for infection by which opportunistic fungal pathogen?
pneumocystis, C. neoformans
allergic form of aspergillosis is associated with _____
recurrent infections from pathogen with asthma or cystic fibrosis
Describe the appearance of the histoplasma capsulatum yeast in alveolar macrophages
- non encapsulated, thick walled and budding yeasts
single broad base bud in a yeast is the microscopic presentation of what fungal pathogen?
- Blastomyces dermatidis
BBB = B
Broad Based Budding yeast = Blastomyces
cryptococcus neoformans is an non/encapsulated yeast
encapsulated
opportunistic fungal pathogens are usually monomorphic/dimorphic
monomorphic
what are the predisposing factors for infection by aspergillus?
chemotherapy, assisted ventilation and neutropenia
patient with AIDS comes in complaining of headache, vomiting, and confusion. He has exposure to areas with a lot of bird droppings. What would you do identify the most likely causal pathogen?
- pathogen: cryptococcus neoformans
- do an india ink stain of the CSF
narrow based budding yeast is indicative of what fungal pathogen?
cryptococcus neoformans
broad based budding yeast: blastomyces dermatidis
what is a requirement for infection by pneumocystis jirovecii?
CD4 < 200
a patient comes to the clinic with weight loss, mild fever, progressive dyspnea and arthritis like symptoms. He likes to go hike in caves. Where in the body are you most likely to find the causal pathogen?
causal pathogen: H. capsulatum because he is not immunocompromised (if he was and was in soil with bird droppings, would be cryptococcus neoformans) ;
inhale the microconidia aerosols
non encapsulated thick walled and budding yeasts found in the alveolar macrophages
coccidiodes immitis is associated with the inhalation of ______
only a few conidia
MOST VIRULENT of all human mycotic pathogens
what is the main virulence factor of cryptococcus neoformans
- capsule that can down regulate the immune response
patient has a lung nodule and biopsy shows spherules that contains spores. No budding is seen. What pathogen has a similar microscopic presentation?
- Coccidiodies immitis
what are the major forms of aspergillosis
- allergic: asthma, CF
- invasive: hyphae invade tissue and seen in transplant patients and will have neutropenia (immunocompromised patients)
what is the mode of transmission of H. capsulatum
- microconidia and hyphae are aerosolized and inhaled
what is a virulence factor for Paracoccidiodies brasiliensis?
primary fungal pathogen;
has a α 1,3 glucan in the cell wall
acute angle branching form septate hyphae with branching tree like pattern seen with ____
aspergillus
hemoptysis is seen by pneumonia caused by what fungal pathogen?
invasive aspergillosis (opportunistic fungal pathogen)
outbreaks of histoplasma capsulatum are associated with what areas?
- areas where birds roost
- caves
- old/decaying buildings
- areas where buildings are undergoing demolition
histoplasmosis capsulatum is a primary/opportunistic fungal pathogen
primary
what fungal pathogen lacks ergosterol in their cell wall?
pneumocystis jirovecii
cyptococcus neoformans is a primary/opportunistic fungal pathogen
opportunistic
HIV/AIDS is a predisposing factor for infection by which opportunistic fungal pathogen?
C. neoforman, pneumocystis
when trying to diagnose blastomycosis, what is an additional clinical feature to look for?
- skin lesions associated with pulmonary symptoms
has similar epidemiology to that of H. capsulatum
what is the geographical distribution of H. capsulatum
Mississippi River Valley and Ohio River Valley
____ form of aspergillosis is seen with immunocompromised patients
invasive; lung transplantation
high morality, hemoptysis
chemotherapy is a predisposing factor for infection by which opportunistic fungal pathogen?
Aspergillus and pneumocystis
cryptococcal _______ is a common manifestation of C. neoformans infection in AIDS patients
meningitis;
what are two fungal pathogens that can grow in pidgeon dropping enriched soil?
how can you tell when one is the more likely cause
- Histoplasma capsulatum
- cryptococcus neoformans
H. capsulatum is a primary pathogen while cryptococcus neoformans is a opportunistic. If the patient is NOT immunocompromised, the most likely pathogen is H. capsulatum
_______ stain is used to stain for cyrtocopcus neoformans in the lungs
mucicarmine stain; will see a thick staining because of the thick capsule
primary/secondary pathogens are ALL dimorphic: _____ and _______
PRIMARY: exist as moulds in the environment and yeasts in the tissues
_______ has cholesterol in their cell wall
pneumocystis jirovecii
india ink stain is used to diagnose ________
cryptococcus neoformans in patients with cryptococcal meningitis by staining them found in the CSF
