Opportunistic Fungal Infections

Question 1

Characteristics of opportunistic fungal infections

Answer 1

All able to grow at body temperature, normal cell defenses of host can destroy them, and ubiquitous in nature. Disease depends on altered host resistance.

Question 2

germ tubes

Answer 2

unique feature of Candida albicans

Question 3

Oropharyngeal candidiasis (thrush)

Answer 3

Most frequent finding in HIV patients with CD4 lt 200. May also be caused by oral antibiotics, hyperglycemia in diabetics or pregnancy.

Question 4

Candida parapsilosis

Answer 4

Associated with infected devices

Question 5

Candida krusei

Answer 5

Rare, inherently resistant to fluconazole

Question 6

Candida glabrata

Answer 6

Increasing in frequency, reduced susceptibility to fluconazole

Question 7

Candida lusitaniae

Answer 7

rare, variable susceptibility to amphotericin

Question 8

Esophageal candidiasis

Answer 8

In immunocompromised individuals, should be considered systemic so requires systemic admin of oral fluconazole or IV antifungal therapy.

Question 9

Candida vulvovaginitis

Answer 9

Same predisposing factors as thrush. Creamy white exudate that is odorless but may be pruritic.

Question 10

Systemic candidiasis

Answer 10

Severely impaired immunity allows candida to invade deep tissues. Hepatosplenic candidiasis, candidemia (via catheter), endophthalmitis (do an eye exam of patient has candidemia)

Question 11

Aspergillus lab identification

Answer 11

Cannot use blood culture isolation.

In tissue: acute 45 degree angle branching, septation of hyphae. Stain best with PAS or methenamine silver.

Question 12

Aspergillus species most common in human disease

Answer 12

Aspergillus fumigatus and flavus

Question 13

Allergic bronchopulmonary aspergillosis

Answer 13

Respiratory disease in patients with asthma. Aspergillus is an antigen, increases IgE levels. Treat with avoiding provoking environments and steroid therapy.

Question 14

Aspergilloma

Answer 14

Mycelia, results from colonization of preformed cavities or ma result de novo in invasive disease.

Question 15

Invasive aspergillosis

Answer 15

Angioinvasive, results in thrombosis and necrosis of surrounding tissue. Two patterns:

1) Chronic necrotizing pulmonary aspergillosis: slowly progressive course
2) Acute/fulminant necrotizing: With greater degrees of immunosuppression.

Question 16

Disseminated aspergillosis

Answer 16

Organism no longer contained in lung, find lesions in brain, kidney and other vascularized structures.

Question 17

Aspergillus treatment

Answer 17

IV amphotericin for invasive aspergillus used to be used, but now voriconazole is the drug of choice.

Question 18

Cryptococcus neoformans testing

Answer 18

Serologic tests for antigen in serum and CSF are highly sensitive and accurate

Question 19

Where is cryptococcus found?

Answer 19

In soil contaminated by pigeon droppings

Question 20

Cryptococcus pathogensis

Answer 20

Usually non-specific characterized by a headache. Pulmonary infection, can progress to CNS and cause meningitis. Important reservoir for latent infection is prostate gland. Lesions characteristically gelatinous at first but then become mixed cell granulomas.

Question 21

Cryptococcus lab procedure

Answer 21

Direct examination with India ink stain.
Histology: Capsule stains with mucicarmine
Serology: Latex agglutination test for capsular antigen should always be performed, much more sensitive than above two.

Question 22

Cryptococcus treatment

Answer 22

1. Amphotericin B, often combined with 5-fluorocytosine for synergy
2. Fluconazole can penetrate CSP and can be used after a 2 week course of ampho induction
3. Since cell wall does NOT contain glucan, cannot use echinocandins

BE CAREFUL TO MONITOR INTRACRANIAL PRESSURE

Question 23

Zygomycosis predisposing factors

Answer 23

diabetes, metabolic acidosis, corticosteroids, hematologic malignancies, transplants

Question 24

Zygomycosis presentation

Answer 24

Severe acute sinus infection, nasal ulceration or necrosis/palatal necrosis.

Question 25

Zygomycosis lab characteristics

Answer 25

Direct exam: Wide, non-septate, 90 degree angle branching hyphae

Serology: no value

Question 26

Treatment of zygomycosis

Answer 26

Surgical resection and high dose IV amphotericin B or oral POSACONAZOLE