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Block 5 - Pulm and Skeletal > Fungi - Ew > Flashcards

Fungi - Ew Flashcards

0
Q

What two filamentous bacteria are important in human disease?

A

Nocardia - immunocompromised

Actinomyces - part of normal flora, immunocompetent

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1
Q

What is the most common cause of invasive mold infections in transplant and cancer patients?

A

Aspergillus

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2
Q

What are the main differences between yeasts and molds?

A

Yeasts - reproduce by budding, colonies with smooth surfaces

Moulds - branching hyphae, hairy or fuzzy appearance

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3
Q

What is the general treatment for opportunistic pathogens?

A

Prolonged therapy with or without surgical debridement

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4
Q

What are the basics of actinomyces?

A 
Gram positive rods
* does not stain with acid stain
Lack mycolic acids 
Anaerobic or slightly aero tolerant 
Normal in GI tract and female genital tract
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5
Q

Why is actinomyces often missed as a diagnosis?

A
  • Common sinuses and fistulae resemble malignancies

* it does not respect normal anatomical boundaries - spreads into adjoining organs

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6
Q

What are the three main clinical syndromes of actinomyces?

A

Orocervicofacial - poor dental hygiene or procedures, lumpy jaw, draining sulfur sinuses
Pulmonary - pneumonia with fevers chills, night sweats, weight loss - *can be confused with tb but has foul halitosis
Abdominal and pelvic infection - trauma or IUDs can cause

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7
Q

What is the treatment of actinomyces?

A

Pen g treatment of choice - IV for a few weeks then 6-12 mos oral therapy (amoxil or amoxil/clavulanic acid)
Can also use ampicillin, clindamycin, moxifloxacin, doxycycline, but not metronidazole
Surgery if needed

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8
Q

What are the basics of nocardia?

A 
Obligate aerobes, gram pos rod
*beaded appearance
*weakly acid fast 
Have mycolic acids
Lives in soil
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9
Q

What allows for nocardia to have intracellular growth?

A

Trehalose dimycolate cord factor

Can live within macrophages

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10
Q

Who does nocardia typically infect?

A

Those with cell mediated immune defects - steroids, lymphoma, transplant

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11
Q

What are the three clinical syndromes caused by nocardia?

A

Sub acute pneumonia - infiltrates or cavitary nodules like tb, have usually failed antibiotics
Disseminated infection in patients with pneumonia - brain abscesses, *image brain!
Cutaneous - direct inoculation, ulcers, nodules or mycetomas, pustule with fever and tender lymphadenitis

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12
Q

How is nocardia diagnosed?

A

Culture on blood agar - *tell lab to hold places longer, may take weeks

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13
Q

What is the treatment for nocardia?

A

*sulfonamides - trimethoprim-sulfamethoxazole (bactrim)

Treatment for 6-12 months

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14
Q

What are some common opportunistic fungi causing human disease?

A

Candida albicans
Aspergillus
Cryptococcus neoformans
Mucor (rhizopus)

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15
Q

What are the basics of Candida albicans?

A

Opportunistic commensal eukaryotic organism
Other types of candida more likely to be fluconazole resistant
Forms germ tubes in culture for 90 min, other Candida’s don’t

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16
Q

What are common clinical syndromes from candida?

A

Oral and vaginal thrush - can possibly be asymptomatic, affects other most surfaces
Esophagitis - dysphagia and chest pain, only if immunocompromised
Deep infections - iatrogenic introduction by procedures
Bloodstream infections - life threatening
Hepatosplenic - neutropenia patients
Rarely cause of pneumonia - usually from saliva or bronchoscope contamination

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17
Q

What are candida infections often preceded by antibiotic therapy?

A

It disrupts normal flora of mucosal surfaces

18
Q

How is candida diagnosed?

A

*positive blood culture hardly ever represents contamination
Clinical appearance for mucosal surfaces
Culture for deep infections

19
Q

What is the treatment of candida?

A

Oral, vaginal, skin - topical antifungals, single dose oral fluconazole for vaginal, esophagitis needs systemic Rx
Systemic - *remove medical device - amphotericin b or echinocandins or fluconazole, might be drug resistance
Azoles are fungistatic but neutropenic require fungicidal

20
Q

What are the basics of cryptococcus neoformans?

A

Encapsulated yeast - capsule promotes survival in macrophages
Found worldwide - typically soil with bird droppings (var neoformans) or eucalyptus trees (var gattii)
Stain gram positive - esp with India ink

21
Q

How can cryptococcus neoformans be distinguished from candida?

A

It is bigger

It doesn’t form germ tube or psuedohyphae

22
Q

What is the transmission and pathogenesis of cryptococcus?

A

Acquiring by inhalation - lung main portal of entry
Usually asymptomatic
Spreads to brain and causes meningitis in AIDS patients
Cell mediated immunity is necessary
Melanin negative generally a virulent

23
Q

What clinical syndromes are associated with cryptococcus?

A

Pulmonary - coin lesions that rarely cavitate

Disseminated - most commonly meninges in immunocompromised, then skin nodules

24
Q

How is cryptococcus diagnosed?

A

*antigen testing in blood and CSF

25
Q

What is the treatment of cryptococcus?

A

Amphotericin and 5-FU for severe

Fluconazole for mild and long term maintenance

26
Q

What are the basics of aspergillus?

A

Ubiquitious and unavoidable in environment
Conidia extensively disseminated and inhaled
Immunocompetent can clear conidia with mucociliary clearance and phagocytic defense

27
Q

What are the clinical syndromes caused by aspergillus?

A

Colonization of abnormal mucosal surfaces - usually asymptomatic, in those with lung diseases, aspergilloma = fungus ball - grows inside cavity from something else (can sometimes be serious)
Invasive infection - severely immunocompromised, bad prognosis
Hypersensitivy reaction - aberrant host response with TH2, difficult to control asthma

28
Q

What is one special characteristic aspergillus growth in tissue?

A

The hyphae invade blood vessels

29
Q

What is the most widely recognized risk factor for invasive aspergillosis?

A

Prolonged and severe neutropenia

30
Q

How is aspergillus diagnosed?

A

*definitive diagnosis requires histology and microbiology
Hyphae at 45 degree angle
Antigen tests for galactomannan - for invasive and disseminated not local

31
Q

What is the treatment of aspergillus?

A

*dont wait for definitive diagnosis - recovery of neutrophils function is most important
Voriconazole, then amphotericin b (terreus is resistant)
Fluconazole has no activity

32
Q

How does zygomycetes grow?

A

*broad, ribbon like nonseptate hyphae in tissue

Twice as wide as aspergillus which is septate

33
Q

What are the risk factors for zygomycetes?

A

Severe immunosuppression

Diabetic ketoacidosis

34
Q

What are the clinical syndromes of zygomycetes?

A

Invasive rhino sinusitis - sinus pain, fever, nasal discharge progressing to neurologic deficits, black necrotic areas in nasal mucosa or hard palate, medical emergency
Invasive pneumonia - less common

35
Q

How is zygomycetes diagnosed?

A

Biopsy - non septae branching at 90 degrees

36
Q

What is the treatment of zygomycetes?

A

Immediate surgical resection
Amphotericin b
Posaconazole as salvage
Control underlying disease

37
Q

What is the major host defense against histo?

A

Prefers to grow in alveolar macrophages
Cell mediated immune response
Interferon gamma particularly important

38
Q

How is histo diagnosed?

A

Serologically - immunodiffusion (more specific - H and M bands) and complement fixation tests (more sensitive)
High LDH suggests dissemination

39
Q

What is the treatment of histo?

A

Mild pneumonia may not need - resolves
Ampho b in severe
Itraconazole in mild and maintenance

40
Q

How is Blasto diagnosed?

A

Lollipop appearance of septate hyphae
Antigen and serology cross reacts with histo
Skin test not useful

41
Q

What is the treatment for Blasto?

A

All patients get it - high risk of dissemination
Amphotericin b in severe and CNS diseases
Intraconazole for mild

42
Q

What is the treatment of coccidioidomycosis?

A

Uncomplicated pneumonia - questionable benefit
Diffuse pneumonia and disseminated - ampho b (intrathecally if meningitis)
Milder - itraconazole or fluconazole
Meningitis - fluconazole
Lifelong maintenance required for all patients with disseminated

43
Q

What is the treatment for paracoccidioidomycosis?

A

Itraconazole treatment of choice
Ampho b for severe cases
Sulfa drugs but treat for longer

Block 5 - Pulm and Skeletal (19 decks)

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