Micro - Mycology (Opportunistic fungal infections & Others) Flashcards Preview

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Flashcards in Micro - Mycology (Opportunistic fungal infections & Others) Deck (34):
1

What category(-ies) of infection does Candida albicans cause?

Systemic or superficial fungal infection

2

In what 6 ways can Candida albicans present, and where applicable, in what patient populations?

(1) Oral and esophageal thrush in immunocompromised (neonates, steroids, diabetes, AIDS) (2) Vulvovaginitis (diabetes, use of antibiotics) (3) Diaper rash (4) Endocarditis in IV drug users (5) Disseminated candidiasis (to any organ) (6) Chronic mucocutaneous candidiasis

3

How might Candida albicans infection present in immunocompromised patients? Give examples of immunocompromised patients.

Oral and esophageal thrush; Neonates, steroids, diabetes, AIDS

4

How might Candida albicans infection present in diabetic patients?

(1) Oral and esophageal thrush (since immunocompromised) (2) Vulvovagnitis

5

In what patient populations is Candida albicans likely to cause vulvovaginitis?

Diabetic, Users of antibiotics

6

What condition is Candida albicans likely to cause in drug users?

Endocarditis

7

How is Candida albicans infection treated in the following instances: (1) Vaginal (2) Oral/esophageal (3) Systemic?

(1) Topical azole (2) Fluconazole or Caspofungin (3) Fluconazole, Amphotericin B, or Caspofungin

8

What are the morphological characteristics of Candida albicans that may appear under microscope?

White (hence "alba"), Dimorphic yeast (may see pseudohyphae and budding yeasts [at 20 C] or germ tubes [at 37 C])

9

What are 3 ways that Aspergillus fumigatus may present, and in what patient populations and/or contexts?

(1) Invasive aspergillosis, especially in immunocompromised & those with chronic granulomatous disease (2) Allergic bronchopulmonary aspergillosis (ABPA): with asthma or CF (3) Aspergillomas in lung cavities, especially after TB infection

10

What kind of toxins do some species of Aspergillus fumigatus produce? With what kind of cancer are such toxins associated?

Aflatoxins; Hepatocellular carcinoma (HCC)

11

What are morphological characteristics of Aspergillus fumigatus that may be seen under microscope?

Not dimporphic, Septae hypae that branch at 45 degrees angle; Conidophore (specialized hyphal branch) with radiating chains of spores; Think: " 'A' for Acute Angles in Aspergillus

12

What disease(s)/condition(s) does Crytococcus neoformans cause?

(1) Crytococcal meningitis (2) Crytococcosis

13

Where is Cryptococcus neoformans found in nature?

Found in soil, pigeon droppings

14

How is Cryptococcus neoformans acquired?

Acquired through inhalation with hematogenous dissemination to meninges

15

How is Crytococcus neoformans cultured? How is it stained?

Culture on Sabouraud's agar; Stains with India ink and mucicarmine

16

What is the test used for Crytococcus neoformans? What does it detect? How does it compare to culture or stain?

Latex agglutination test detects polysaccharide capsular antigen; More specific

17

With what specific CNS finding is Crytococcus neoformans associated?

"Soap bubble" lesions in brain

18

What are morphological characteristics of Crytocococcal meningitis that may be seen under microscope?

Heavily encapsulated yeast. Not dimorphic. With capsular halos and unequal budding in India ink stain

19

What condition/disease do Mucor and Rhizopus fungi cause, and mostly in what patient populations?

Mucormycosis; Disease mostly in ketoacidotic diabetic and leukemic patients

20

What is the mechanism by which Mucor and Rhizopus proliferate and dissemiante after infection?

Fungi proliferate in blood vessels when there is excess ketone and glucose, penetrate cribiform plate, and enter brain

21

What CNS/ENT findings are associated with Mucor and Rhizopus infections?

Rhinocerebral, frontal lobe abscesses.

22

How do Mucor and Rhizopus infections present in history or on physical exam?

Headache, facial pain, black necrotic eschar on face, may have cranial nerve involvement

23

What are morphological characteristics of Mucor and Rhizopus that may be seen under microscope?

Irregular, broad, nonseptate hyphae branching at wide angles

24

What condition/disease can Pneumocystis jirovecii cause? What predisposes patients to this condition/disease?

Causes Pneumocystis pneumonia (PCP), a diffuse interstitial pneumonia; Immunosuppression (e.g., AIDS)

25

What was the original classification of Pneumocystis jirovecii? How are they classified now?

Protozoan; Yeast

26

How is Pneumocystis jirovecii acquired?

Inhaled

27

How do most Pneumocystis jirovecii infections present?

Most infections are asymptomatic

28

What is PCP? How does it appear on Chest X-Ray (CXR)? How is it diagnosed (give procedure & specific finding)?

Pneumocystis pneumonia (caused by Pneumocystis jirovecii); Diffuse, bilateral CXR appearance; Diagnosed by lung biopsy or lavage. Disc-shaped yeast forms on methenamine silver stain of lung tissue

29

How is PCP treated/managed, and in what contexts? How is it handled in HIV patients?

Treatment/Prophylaxis: TMP-SX, pentamidine, dapsone (prophylaxis only), atovaquone (prophylaxis only); Start prophylaxis when CD4 drops < 200 cells/mm^3 in HIV patients

30

What condition/disease does Sporothrix schenckii cause?

Sporotrichosis

31

How does Sporotrichosis present? What is typically the mechanism or method for acquiring infection?

When spores are traumatically introduced into the skin, typically by a thorn ("rose gardener's" disease), causes local pustule or ulcer with nodules along draining lymphatics (ascending lymphangitis). Little systemic illness

32

Why is Sporotrichosis also known as "rose gardener's disease"?

When spores are traumatically introduced into the skin, typically by a thorn ("rose gardener's" disease), causes local pustule or ulcer with nodules along draining lymphatics (ascending lymphangitis). Little systemic illness

33

What pathogen causes Sporotrichosis? What are options for its treatment? What is a way to remember one of the treatments?

Sporothrix schenckii; Itraconazole or Potassium iodide; "plant a ROSE in the POT" (Note: Sporotrichosis = Rose gardener's disease)

34

What characterizes Sporothrix schenckii?

Dimorphic, cigar-shaped budding yeast that lives on vegetation

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