Pulmonary Fungal Infections 2

Question 1

cryptococcosis organisms

Answer 1

5 serotypes: A, D, and AD are neoformans. B and C are gattii. Neoformans is environmental, found worldwide in soil contaminated with bird droppings. Gattii is found under eucalyptus trees. Oval yeasts with narrow based buds and wide polysaccharide capsule. pathogenic strains grow at 37C. not thermally dimorphic, but does have a moldlike sexually reproducing form (filobasidiella). no human to human transmission except organ transplant or needle sticks.

Question 2

cryptooccosis pathogenesis

Answer 2

transmitted by inhalation. lung infection may be asymptomatic or lead to pneumonia. can be intracellular infection through alveolar macrophages. immunocompetent restrict infection to lungs. successful hosts raise helper Ts, skin test conversion, antibodies to the capsule. dissemination leads to meningitis w/ skin nodules. Neoformans raises little inflamm response, damages by distorting tissue through growing yeast.

Question 3

cryptococcosis virulence factors

Answer 3

capsule, melanin in cell wall (antiphagocytic), phospholipase B for invading tissue

Question 4

cryptococcosis exam

Answer 4

history of steroid use, malignant disease, transplantation, HIV infection. Skin: take biopsies of nodules. Meningitis symptoms if CNS is affected. Cryptococcomas can cause focal neurologic defects. blunted inflammatory response complicates diagnosis and means that presentation is late in disease

Question 5

cryptococcosis lab

Answer 5

CSF: stain with india ink to see yeast. Biopsies: stain with silver or schiff. Culture at 37C from CSF, blood, urine, sputum. cultures produce melanin. serology: crag latex agglutination for cryptococcal antigen in blood and CSF. routine bloodwork may be normal

Question 6

cryptococcosis treatment

Answer 6

meningitis or cryptococcoma: amphotericin B plus flucytosine followed by fluconazole.
Prostate: fluconazole
Skin, bones, other: amphotericin B

Question 7

aspergillosis organisms

Answer 7

Aspergillus fumigatus, niger, flavus, clavatus. ubiquitous environmental molds. only mold, not dimorphic. septate hyphae with V- shaped branhes. walls are nearly parallel, conidia form radiating changes

Question 8

4 syndromes caused by aspergillosis

Answer 8

1. allergic bronchopulmonary aspergillosis
2. aspergilloma or colonizing aspergilliosis (fungal ball in lung)
3. chronic necrotizing pulmonary aspergillosis
4. invasive aspergillosis

Question 9

aspergillosis pathogenesis

Answer 9

widespread on decaying vegetation. infectious conidia are airborne. ABPA is hypersensitivity reaction to infection of bronchi by aspergillus. aspergilloma has balls that form when aspergillus invades cavitary lesions of TB or CF. CNPA are granulomas that form in immunocompromised. Invasive aspergillosis is a rapidly progressive invasion of blood vessels in severely immunosuppressed patients, involves infarction, hemorrhage, necrosis, often fatal.

Question 10

aspergillus virulence factors

Answer 10

gliotoxin: immunosuppressive. toxic metabolites interfere with phagocytosis and opsonization. proteases may be involved in tissue invasion.

Question 11

ABPA exam

Answer 11

positive skin test for aspergillus allergy with asthma or CF. coughing up brownish bronchial plugs containing hyphae. fever, wheezing, pulmonary infiltrates unresponsive to antibiotics. Xray/CT may show grape cluster or hand in mitten clusters of bronchi

Question 12

aspergilloma/colonizing aspergilliosis exam

Answer 12

fungal ball visible on xray or CT. doesnt invade tissue but may cause dangerous hemoptysis. cough, fever.

Question 13

CNPA exam

Answer 13

subacute pneumonia unresponsive to antibiotics. underlying disease of alcoholism, collagen-vascular disease, chronic granulomatous disease or COPD. longterm corticosteroid therapy. fever, cough, night sweats, weight loss. history of ineffective treatment for TB. needle biopsy, aspirate fluid if present

Question 14

invasive aspergillosis

Answer 14

history of profound immunosuppression or COPD with long term corticosteroid therapy. fever, cough, dyspnea, pleuritic chest pain, neutropenia, sometimes hemoptysis, worsening hypoxemia. CT scan may show halo sign: ground glass infiltrate surrounding a nodular density. do biopsy of lung

Question 15

aspergillosis lab

Answer 15

cultures from sputum, needle biopsy, or bronchoalveolar lavage fluid. visualize with silver stains, colonies with radiating chains of conidia. grows fast. invasive shows septate hyphae at acute angles, tissue necrosis, blood vessel invasion. ABPA shows high levels of IgE and eosinophilia, along with mucus with hyphae

Question 16

aspergillosis treatment

Answer 16

ABPA: oral corticosteroids and itraconazole.
Aspergilloma: remove surgically if hemoptysis, oral itraconazole
Invasive or CNPA: voriconazole and ampho B. decrease immunosuppression if possible. surgical resection of diseased area.

Question 17

mucormycosis organisms

Answer 17

rhizopus, mucor, absidia, and others. rare sinus infections. widespread environmental. not dimorphic. risk factors include diabetes, neutropenia. must treat underlying disease and add amphotericin B

Question 18

mucormycosis pathogenesis

Answer 18

transmitted by airborne asexual spores. ubiquitous worldwide. cause disease in vulnerable patients. usually inhaled. invade tissues of patient with immunosuppression. neutrophils are main host defense. not highly associated with AIDS. mainly hit paranasal sinuses, lungs, gut, skin, or disseminated. cause infarction and necrosis of tissue downstream from blocked vessel.

Question 19

mucormycosis exam

Answer 19

symptoms at affected site. rhinocerebral shows unilateral retro-orbital headache, face pain, numbness, fever. progresses to diplopia and visual loss, loss of consciousness etc. wound infections unresponsive to antibiotics. Lung and GI are nonspecific, biopsy useful. Cutaneous: cellulitis progressing to dermal necrosis and black eschar formation

Question 20

mucormycosis lab

Answer 20

bloodwork: neutropenia, diabetic acidosis, iron overload. no useful antigen tests or CSF. biopsy shows nonseptate hyphae branching at right angles. culture is difficult.

Question 21

mucormycosis treatment

Answer 21

send to tertiary care facility. change any pre-existing bandages/splints. if early diagnosis, treat with amphotericin B and aggressive surgical removal of necrotic tissue. surgery needed.

Question 22

fusarium mycology

Answer 22

fusarium species are environmentally ubiquitous. identified microscopically by a banana shaped macroconidia. primarily pathogens of plants, including important crops. Solani is most common.

Question 23

fusarium virulence factors

Answer 23

immunosuppressive mycotoxins. collagenases and proteases. ability to adhere to prosthetic material.

Question 24

mycotoxicosis pathogenesis

Answer 24

trichothecene mycotoxins -> alimentary toxic aleukia. widespread bleeding and immunosuppression with secondary sepsis, often fatal. yellow rain

Question 25

immunocompetent local infection of fusarium

Answer 25

skin, cornea, allergic sinusitis, colonization of prosthetics and catheters. treat with amphotericin B, voriconazole, posaconazole.

Question 26

immunosuppressed opportunistic infection of fusarium

Answer 26

prolonged neutropenia. long term use of steroids. profound T cell deficiency.

Question 27

disseminated infection of fusarium

Answer 27

usually invades from sinus or at a wound site. presents as fungemia with skin lesions. may also seed eye, lung, cause local symptoms there.

Question 28

fusarium diagnosis

Answer 28

grows easily on fungal media, but is ubiquitous. need multiple samples and sites. histology can only differentiate from aspergillus if yeast form is present along with the acute branching hyphae. PCR-based tests and fungal metabolism tests are available.

Question 29

fusarium treatment

Answer 29

more resistant to antifungals than the other pathogenic fungi. surgical excision. try amphotericin B with natamycin or voriconazole. prognosis in disseminated is poor.

Question 30

fusarium prevention

Answer 30

keep high risk patients in a HEPA filtered room at positive pressure. pre-op workup must include screening for fusarial infection, as it could be bad after you get immunosuppressed.