Respiratory Tract Infections 8 Flashcards by Gopu Premrajan

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

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what primary fungal pathogen is associated with skin lesions?

blastomyces dermatidis

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list the primary fungal pathogens that can cause pneumonia and other LRTI’s

histoplasma capsulatum
blastomyces dermatitis
coccidiodies immitis
paracoccidioides brasiliensis

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microscopic presentation of coccidiodes immitis

spherules with spores inside

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List the opportunistic fungal pathogens that can cause pneumonia and other LRTI’s

cryptococcus neoformans
aspergillus
pneumocystis jiroveci

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which fungal pathogen is capable of growing inside macrophages? how?

Histoplasma capsulatum (primary) 
↑'s phagolysosomal pH which interferes with enzyme activity and antigen processing

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which primary fungal pathogens can be found in the Mississippi River Valley and Ohio River Valley?

H. capsulatum

- B. dermatidis

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_________ 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

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_______ is a fungal pathogen that is endemic to the southwestern US and NW Mexico

coccidiodies immitis

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neutropenia is a predisposing factor for infection by which opportunistic fungal pathogen?

aspergillus

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the ______ of aspergillus is inhaled from _______

conidia;

decaying organic matter

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_______ agar is used for fungal pathogens

Sabouraud’s agar

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what CD4 cell count is an AIDS defining criteria?

CD4 Cell count < 200

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assisted ventilation is a predisposing factor for infection by which opportunistic fungal pathogen?

aspergillus

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Organ transplant is a predisposing factor for infection by which opportunistic fungal pathogen?

pneumocystis, C. neoformans

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allergic form of aspergillosis is associated with _____

recurrent infections from pathogen with asthma or cystic fibrosis

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Describe the appearance of the histoplasma capsulatum yeast in alveolar macrophages

non encapsulated, thick walled and budding yeasts

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single broad base bud in a yeast is the microscopic presentation of what fungal pathogen?

Blastomyces dermatidis

BBB = B
Broad Based Budding yeast = Blastomyces

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cryptococcus neoformans is an non/encapsulated yeast

encapsulated

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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