Fungus, Immunocompromised Pneumonia Flashcards
define endemic mycoses
caused by dimorphic fungi; can cause serious disease in both healthy and immunocompromised pts
define opportunistic mycosis
can cause life threatening disease in immunocompromised pts
what is the most common etiologic agents of pulmonary infection by fungi in healthy hosts, cause over 1 million infections/year in the US
dimorphic fungi
how and in what form do dimorphic fungi grow, including where
grow as yeast in human tissue and as mold under some laboratory conditions (typically room temperature)
after inhalation of dimorphic fungi, what happens to the shit? what do they differentiate into
within the lungs, the spores differentiate into yeasts or spherules
are most fungus lung infections self limited or disseminated?
most lung infections are self-limited and even asymptomatic, however all can cause pneumonia and disseminate
what are the 4 dimorphic fungi that we talked about?
1 - Blastomyces dermatitidis
2 - Histoplasma capsulatum
3 - Coccidioides immitis
4 - Paracoccidioides brasiliensis
what is some of the epidemiology for histoplasma capsulaturm? - where is it found and in what mediums does it grow
endemic in Mississippi and Ohio River valleys
grows in soil and bird droppings
For Histo, what is commonly the presenting symptoms
asymptomatic pulmonary infection
For Histo with intense exposure, what is the common presenting symptoms?
respiratory infection - fever, chills, cough, chest pain
If you have an AIDS pt w/ suspected histo, what are you worried about them developing and what are the manifestations of this?
severe disseminated disease
pancytopenia (due to bone marrow infiltration)
Mouth/ GI ulcers
Skin rash (pustules, nodules)
what is the mortality rate of disseminated histo in AIDS pts
10%
how do you make the dx of histo based on tissue biopsy?
tissue biopsy will show oval yeast cells w/in macrophages
other than tissue biopsy, what are other ways of making dx of histo?
serology
urinary antigen
CXR - variable - infiltrates, mediastinal LAD, cavitary lesions
What is the treatment for Histo? one for severe disease, one for otherwise
Amphotericin for severe disease
Itraconazole otherwise
what clinical finding in Histo indicates a good prognosis? is it specific for Histo?
Erythema nodosum manifests as red, tender nodules (“desert bumps”) on extensor surfaces such as the skin over tibia and ulna - it is delayed cell mediated hypersensitivity that indicates a good, active cell mediated immunity - not specific for Histo - seen in other granulomatous diseases
what fungus is endemic in Ohio/Mississippi River Valley and Missouri and Arkansas River Basins?
Blastomyces dermatitidis
where does Blasto grow?
moist soil
what is the common clinical manifestation of Blasto
asymptomatic respiratory illness -
50% will have cough, chest pain, sputum production, fever/night sweats
How does Blasto usually resolve
spontaneously
in what pt populations can disseminated blasto infection be seen? what are the clinical manifestations of dissemination?
disseminated disease can be seen in both immunocompetent and immunocompromised
results in ulcerated granulomatous lesions of the skin (70%), bone (33%), GU tract (35%), and CNS (10%)
CNS manifestations can help diff from Histo
How do you make diagnosis of Blastomyces on tissue biopsy? This is high yield
Broad Based Bud
Thick-walled yeast cells a single broad based bud
looks like snowman
What other means of dx Blasto?
CXR - variable, but can see lobar consolidation, multilobar infiltates, multiple nodules, etc
serology
What is the treatment of blasto? one for severe dz, one in general
Amphotericin for severe dz
Itaconazole otherwise
describe the cutaneous lesions seen in Blasto
verucous (wart like lesion), can be ulcerated, gray to violet colored
what fungus is endemic in Southwestern US and Latin America
Coccidioides Immitis (this is one of the most defining features)
what is the pathogenesis of coccidioides (what happens in the lung)
in the lungs, large spherules form and are filled w/ endospores. Upon rupture of spherule wall, endospores are released and differentiate to form new spherules
what is the most common clinical manifestation of Coccidioides?
most infections asymptomatic
For symptomatic Coccidioides infxns, what will you see
mild influenza-like illness w/ fever and cough (“valley fever”) in 10%
can see erythema nodosum
what popoulations are more susceptible to dissemination by Coccidioides, and what are the most common sites of dissemination
African Americans, Filipinos, and women in 3rd trimester of pregnancy
Bone, meninges, skin
For Coccidioides, what is the most distinguishing dx feature
eosinophilia
what are other means of diagnosing Coccidioides
serology
spherules seen microscopically
skin test reativity (not very common)
what is the treatment for Coccidioides with persistent lung lesions of disseminated disease
Amphotericin
what is the treatment for Coccidioides meningitis
Fluconazole - can cross BBB
also use in long term suppression to prevent recurrence
what fungal infxn is common in rural latin America, especially Brazil?
Paracoccidioides brasiliensis
what are the clinical manifestations of Paracoccidioides
mild respiratory infection which can progress w/ dissemination
development of oral, nasal, and facial nodular ulcerated lesions and submandibular LAD ***
This is much more extensive lesions than a blasto disseminated infxn
what is the Dx for paracoccidioides? tissue biopsy and serology
tissue biopsy shows yeast cells w/ multiple buds
serology (looks like the wheel of a ship)
what is the tx for Paracoccidioides
several months of Itraconazole
Amphotericin for severe disease
what is the buzzword for the microscopic appearance of Paracoccidioides
pilot wheel configuration
where do you find Aspergillus fumigatus?
Mr. Worldwide
what type of fungi (morphology?) is Aspergillus, and where does it grow
mold with septate hyphae
grow on decaying vegetation producing chains of conidia
what are some of the features of an Aspergillus infection?
1) something that produces hempotysis
2) something you can detect via a titer,
3) appearance of expactorations
4) disease process
1) fungus ball formed within cavities of the lungs, can produce hemoptysis
2) allergic infection of the bronchi that produces asthmatic symptoms and high IgE titer
3) allergic infection of bronchi - causes expectoration of brownish bronchial plugs containing hyphae
4) invasive PNA producing hemmorrhage, infarction, and necrosis
What pt population is highest risk factor for Aspergillus? esp producing hemorrhage and shit
those with hematologic malignancies and neutropenia - invasive PNA producing hemorrhage is common cause of death in these pts
how do you make dx of Aspergillus via tissue biopsy? this is high yield
septate, acute angle branching hyphae
radiating chains of conidia
what is a dx feature of Aspergillus seen on CT scan?
halo sign - areas of focal hemorrhage around the lesion
can see single or multiple nodules with or without cavitation
what is the first line treatment of Aspergillus
Voriconazole
if pts do not tolerate Voriconazole well, what is alternative tx for Aspergillus
Amphotericin or echinocandins
what do you need to do in Aspergillus pts to control the hemoptysis
remove the fungus balls
what do you use to treat ABPA? (allergic bronchopulmonary Aspergillosis)
steroids and antifungal agents
what are opportunistic infections caused by bread mold?
Mucormycosis
give 4 examples of Mucormycetes
Mucor, Rhizopus, Cunninghamella, Lictheimia
what are 5 risk factors for Mucormycosis
Diabetes neutropenia iron overload burns/surgical wounds corticosteroid use
how is mucormycosis transmitted? what does it invade in host?
transmitted by airborne spores
invades tissue and angioinvasive - pts w/ reduced host defenses
besides penumonia, what are 2 clinical manifestations of Mucormycosis
1) invasive rhinocerebral sinusitis, frontal lobe abscesses
2) cutaneous infections
describe the pathogenesis of invasive rhinocerebral sinusitis and frontal lobe absceses seen in mucormycosis
it originates in the paranasal sinuses and spreads tothe orbit, hard palate and brain
what is the presentation of a pt w/ mucormycosis w/ the rhinocerebral shitusitis and front lobe asses? mortality rate
headache and facial pain
carries a high mortality rate
what are the defining features of mucormycosis on biopsy? high yield, must know
nonseptate broad hyphae with frequent right angle branching
spores in a sporangium
(as oppo to conidia for aspergillus)
what is the treatment for Mucormycosis? what is an alternate?
treat the underlying disorder
Amphotericin + surgical resection of necrotic infected tissue
alternate - Posaconazole can also be used
what kind of organism is Pneumocystic jiroveci?
yeast
what are the most common symptoms of Pneumocystis infxn
most infxns are asymptomatic
Pneumocystis and immunosuppressed patients - what are we worried about?
PCP - pneumocystis carinii pneumonia
carinii = jiroveci
what pt population specifically are we worried about Pneumocystis in?
AIDS pts
common opportunistic infxn, one of leading causes of death in AIDS pts
What is the pathogenesis of Pneumocystis jiroveci?
cysts in alveoli produce inflammatory responses, resulting in forthy exudate that blocks oxygen exchange
how does the Pneumocystis organism get into tissue?
Pneumocystis does not invade lung tissue
How does the immune system clear the pneumocystis organism? What is the importance of this?
CD4+ T cells recruit monocytes and macrophages which are responsible for clearance of the organism
AIDS pts - a CD4 count less than 200 is main risk factor for getting pneumocystis infxn
what are 5 clinical manifestations of PCP
dry cough dyspnea that is progressive Fever tachypnea hypoxemia
What are CXR findings in PCP?
diffuse, bilateral, interstitial, or alveolar infiltrates
CXR normal in up to 1/4
what is another clinical manifestation that can occur from PCP
pneumothorax
you see an AIDS pt that is dyspnic and hypoxemic, but has a normal CXR - can this be PCP?
yes - negative CXR does not rule out
what is the O2 sat of a pt w/ PCP, and why
O2 sats low, in the 80s - the frothy exudate is blocking gas exchange
dx of PCP - what stains can you use to visualize cysts?
visualization of cysts by methenamine silver, Giemsa stain or other stains
What is the appearnace of PCP on microscopic examination
helmet shaped cells
what are 2 other dx techniques used in PCP
fluorescent antibody staining
PCR on respiratory tract specimens
what is the first line treatment for PCP
trimethoprim-sulfamethoxazole (Bactrim)
what are the 3 options for 2nd line tx of PCP
Clindamycin/Primaquine
Atovaquone
Pentamidine
PCP prophylaxis in AIDS pts
what level of CD4 count
what 3 medications
AIDS pts w/ CD4 count less than 200
Bactrim, Dapsone, Atovaquone
in genenral, what is cryptococcus neoformans? and where is it found?
yeast present in soil and bird (pigeon) droppings
what is the morphology of crypto (high yield)
oval budding yeast with wide polysaccharide capsule;
forms narrow-based bud**
what specific disease are you worried about in crypto infxn of immunocompromised pts
meningitis
most common life-threatening disease in AIDS pts
what other disease are you worried about with crypto infxn of either immunocompromised or immunocompetent
what are the symptoms in each case
pneumonia
immunocompetent - asymptomatic
immunocmpromised - fever, chest pain, dyspnea, cough, and hemoptysis
what is the appearance of crytpo on CXR
nodules and or ground glass opacities
what is morphology of cytomegalovirus
DNA enveloped virus similar in morphology and structure to other Herpes viruses
what is pathogenesis of CMV
enters latent state primarily in monocytes and can be reactivated when cell-mediated immunity is decreased
what common disease process commonly develops in immunosuppressed pts (transplants) w/ CMV
pneumonitis
what disease processes develop in AIDS pts w/ CMV
colitis and retinitis
typically NOT pneumonitis
what is the appearance of CMV on CXR?
diffuse infiltrates, ground glass opacities
What is a characteristic finding of CMV pneumonitis on biopsy of lung tissue
viral inclusion body
if you see pneumonia and a brain abscess, what bug should you be thinking abou
Nocadria asteroides - causing nocardiosis
Nocardia asteroides - aerobic or anaerobic? where found? morphology? gram stain? weakly also stain what?
aerobes found in the soil thin branching filaments gram + many isolates weakly acid fast
Nocardiosis, immunocompromised pt - what disease process and predilection for what tissue
produces lung infection and may disseminate, has predilection for brain tissue
Nocardiosis - what specific pathologic findings do you see in lungs
pneumonia, lung abscesses w/ cavity formation, lung nodules or empyema
how do you dx nocardiosis?
gram stain/ acid-fast stain
culture
tx for nocardiosis
Trimethoprim-sulfamethoxazole (Bactrim), sometimes combination therapy is needed, ressitance can occur, sensitivities should be performed
Ohio/Mississippi River Valleys, Intracellular, found in phagocytes
Histo
Ohio/Mississippi River Valleys, Missouri and Arkansas River basins
Broad based bud
Blasto
“Valley fever” Southwestern US and Latin America
Pregnant Women, African Americans and Filipinos at risk for dissemination to bones and meninges
Eosinophilia
Coccidioides immitis
yeast w/ multiple buds, “pilot wheel” configuration
Rural Latin America, espp Brazil
Oral, nasal, facial nodular ulcerated lesions
Paracoccidioides
How often do AIDS pts get Aspergillus infxn? and why?
AIDS pts do not get Aspergillus - AIDS pts are lymphopenic and susceptibility to Aspergillus is being neutropenic
what is the most common opportunistic infxn in AIDS pts
PCP (pneumocystis)
why can you not use traditional antifungals on pneumocystis
it does not contain ergosterol
compare and contrast the morphology of Aspergillus and Mucor on tissue biopsy
1 - septate or non
2 - angle of branching
3 - spores
Aspergillus - septate hyphae, acute angle branching, radiating chains of conidia
Mucor - nonseptate hyphae, 90 degree angle branching, spores in sporangium
pneumothroax - what fungus are you worried about
pneumocystis
