Micro Flashcards
1
Q
coccidiodes
A
- thermal dimorphes (mold/spherule) endemic to SW US
- high morbidity; low mortality
- 60% mild: flu with clearance/ contained by CMI
- moderate: valley fever/ desert rhematism (pulmonary + EN)
- severe: major pneumonia or desseminiation (bare or in PMNs)
- RFs: age, race, immunocomp (pregnancy), job
- Dx: history, PPD, biopsy for spherules, serology for dissemination
- Tx: azoles (if comorbid), fluconazole (meningitis), AmphoB (pregnant or disseminated)
2
Q
erythema nodosa
A
delayed cell-mediated HSR to fungal antigens→ red tender nodules on exterior surfaces
- immunogenic complication of granulomatous disease
- means risk of dissemination is low
3
Q
histoplasma
A
- therma dimorph (mold/intracellular yeast); soil-based (bird and bat poop; “spelunker’s disease”); endemic to OH, MI, MS river valleys
- low dose fungus flu: innate immunity kills/ contains in granulomas→ EN
-
high dose= TB-like; CMI deficient disseminates in PMNs to mucocutaneous sites
- pancytopenia and ulcerations on tongue
- Dx: history, biopsy for yeast in PMNs
- Tx: itraconazole (serious lung), fluconazole (meningitis), AmphoB (disseminated)
4
Q
blastomyces
A
- thermal dimorph (mold/yeast); broad based budding yeast endemic to E. US
- innate immunity destroys conidia; yeasts harder to kill (BAD1)
- immunocomp or pulm disease predisposes hematogenous spread
- pneumonia: high fever, chills, cough w/sputum, pleuritic pain
- moderate acute: pneumonia and sputum
- moderate chronic: TB-like
- severe acute: ARDS
- EN or ulcerating skin lesions (dermatiditis)
- Dx: cultures (sputum, lesion, suppurating granuloma)
- Tx: itra/fluconazole, AmphoB if severe
5
Q
paracoccidiodes
A
- thermal dimorph (mold/multibud yeast); endemic to rural S.A.
- semi-opportunistic
- severe in children/ immunocomp
- moderate in adults (men in agriculture/consulting); long latency
- Dx: pus or tissue KOH
- Tx: itraconazole, AmphoB and combine with treatment for correction of anemia, improved diet, rest smoking cessation, EtOH use
6
Q
thermal dimorphs
A
- coccidioes: spherules
- histoplasma: yeast in PMNs
- blastomyces: broad based budding yease
- paracoccidiodes
7
Q
opportunistic pulmonary fungal infections
A
- seldom dangerous without specific predispositions (prolonged neutropenia, uncontrolled HIV or diabetes, profound T cell suppression)
- cryptococcus: MC meningitis in HIV, yeast w/wide capsule, crag (latex agglutination)
- aspergillosis:“peace sign” septate hyphae
- mucormycosis: uncontrolled DM (ketoacidosis), Fe overload, immunocomp (leukemia); nonseptate hyphae w/90 degree angles; ribbon-like
- fusarium: banana macroconidia
8
Q
cryptococcosis
A
- MC form of meningitis in HIV
- widespread environmental; inhalation from pigeon droppings
- infection originates in lung but clears or progresses to meningitis
- patient presents late in disease with meningitis and skin nodules, or pulm symptoms
- organ damage by tissue distortion from growing yeast; crytococcomas→ focal neuro defects
- Dx: biopsy, CSF (yeast w/wide capsule), crag (latex agglutination)
- Tx: azoles + ampho B; + flucytosine; fluconazole for LT suppression in AIDS
9
Q
aspergillosis
A
- ABPA: HSR to infection complicating astham, CF; Tx: inhaled sterois + itraconazole
- Aspergilloma: colonizing fungus ball compliating cavitary lung disease; air crescent on scan; Tx: itraconazole + surgery
- CNPA: mimics TB; Tx: voriconazole + AmphoB
- Invasive: most severe, profound immunocomp→ respiratory distress, MI, hemorrhage; Dx: halo sign on scan (small hemorrhage), biopsy (hyphae branching at acute angles “peace sign”); Tx: voriconazole + AmphoB
10
Q
mucormycosis
A
- mucor or rhizopus→ v. rare deadly invasive vasculitis by environmental mold
- invades brain from sinuses→ infarction; black pus
- RF: uncontrolled DM (ketoacidosis), Fe overload, immunocomp (leukemia)
- Dx: biopsy nonseptate hyphae w/90 degree angles; ribbon-like
- Tx: AmphoB + aggressive surgical removal of disease
11
Q
fusarium
A
- ubiquitous environmental mold via sinus or wound; infection is rare but fatal
- mycotoxicosis: contaiminated grain
- local infection: burns, prosthetics, contaminated contact lens solution
- disseminated infection: fungemia→ skin lesions; due to prolonged neutropenia, HSCT recipients
- Dx: blood culture (banana macroconidia); histology to differentate from asperillus
- Tx: aggressive surgery, AmphoB, voriconazole
12
Q
mycobacteria characteristics
A
- gram stain poorly; acid-fast; v. slow growing (2-3 wks)
- virulence factors
- obligate aerobe (grow in lung apex); most important
- mycolic acid: resistant to desiccation and chemicals
- cord factor
- phosphatides: caseating necrosis
13
Q
mycobacteria pathogenesis
A
- almost always to lung by inhalation; hematogenous spread to lymph, kidney, bones, CNS; GI by swallowing infected sputum
- healthy host rases strong CMI: intracellular infection of naive PMN→ CD4 activate PMN that clear it→ CD8 cells kill infected PMN and establish caseating granulomas→ latency for decades, reactivates with immunosenescence/ suppression
- TNFa also important for containment
14
Q
classic pulmonary TB
A
- cough, weight loss, fever, night sweats, hemoptysis, chest pain
- cavitary lesions: indicate advanced infection, assc w/ high bacterial load
- noncalcified round infiltrates look like carcinoma vs. calcified nodules of old infection
- xray may look normal if HIV+
15
Q
extrapulmonary TB
A
- CNS: high inflammation meningitis→ brudzinski’s sign
- Miliary: hematogenous spread→ tiny noncalcified foci of infection in lung (more likely to develop after primary infection)
- Pediatric: must be recently acquired (trace source), watch for miliary and meningitis; culture from gastric lavage (can’t cough hard enough to bring up sputum)
- scrofula: painless enlarging lymph nodes
- skeletal: Pott’s disease in spine
- GI
- GU
