Infections Flashcards
What % of acute bronchitis is caused by bacterial pathogens?
10%
How long does acute bronchitis symptoms typically last?
<3 weeks
What should you suspect if there is a cough >4 weeks in acute bronchitis?
B. pertussis
regardless of vaccination
Name the antifungal category given the following characteristics:
Converted to 5-FU in target cells and inhibits DNA replication through premature chain termination, used for pathogenic yeasts and adjunctive treatment
Flucytosine
Name the antifungal category given the following characteristics:
Binds to erosterol causing leakage of cell contents from disturbed cell membrane, broad spectrum, can cause nephrotoxicity
Amphotericin B
Name the antifungal category given the following characteristics:
Inhibit cytochrome P450 dependent enzyme lanosterol 14a-demethylase in ergosterol biosynthetic pathway causing cell membrane dysfunction, has meny medication interactions
Azoles
Old = itroconazole, fluconazole
Newer = voriconazole, posaconazole
Name the antifungal category given the following characteristics:
Target fungal cell glucan synthesis by inhibiting the enzyme 1,3-6-D-glucan synthase, leading to impaired integrity of the fungal cell wall, active against candida species, no activity against endemic mycoses, only IV
Echinocandins
caspofungin, micafungin, anidulafungin
What medications can give false + galactomannan enzyme test?
Zosyn or Augmentin
True/False:
COPD and critically ill patients in the ICU are at-risk groups for invasive pulmonary aspergillosis despite not having traditional risk factors of overt immunocompromise such as prolonged neutropenia or high-dose steroids
TRUE
True/False:
A negative culture from sputum or BAL rules out invasive aspergillosis
FALSE
What aspergillus is notoriously resistant to amphotericin?
A. terreus
What is the characteristic branching angle when Aspergillus is viewed on histopathologic (potassium hydroxide, India ink) stains?
45-degree branching with septations; do not confuse with mucormycosis, which is characterized by 90- degree branching without septations
Which antifungal agents have activity against Aspergillus?
Voriconazole, itraconazole, amphotericin B, and the echinocandins–fluconazole is inactive against Aspergillus species
What medications are used first line for candidemia in critically ill and neutropenic patients?
Echinocandins
If there is a concern for concomitant mold coverage in someone with candidemia, what medication is used?
Voriconazole
If someone develops CNS candidiasis, candida endopthalmitis, or candida endocarditis, which mecation is indicated?
Liposomal amphotericin B
Mortality from candidemia?
15-47%
Say a neutropenic patient has pulmonary infiltrate, and BAL shows candida infection. What should you check next?
Screen for disseminated disease with serum and CSF cryptococcal antigen and with blood and CSF cultures
Which antifungal is preferred for treatment of invasive candidiasis in pregnant women?
Systemic amphotericin B; echinocandins and most azoles are category C; flucytosine and voriconazole are contraindicated because of fetal abnormalities in animal studies
25 y/o with HIV presents with pulmonary infiltrates. BAL shows halos on India ink stain. Patient is stable on room air. Treatment?
Cryptococcus neoformans
Tx for mild-mod pulm disease or asymptomatic immunocompromised patients is with fluconazole for 6-12 months
43 y/o with HIV presents with CNS depression and fevers. CSF shows cryptococcal neoformans positivity. Treatment regimen?
Induction:
Consolidation:
Maintenance:
Induction: Ampho B and flucytosine (2-4 weeks)
Consolidation: fluconazole 400-800mg daily (8 weeks)
Maintenance: fluconazole 200mg daily (6-12 months)
32 y/o with ALL presents with dyspnea. CT shows multiple pulmonary nodules. Bronch done with BAL, which is negative for bacteria and fungal elements. Biopsy from nodule shows broad nonseptate hyphae branching at right angles. Treatment
Amphotericin B
Posaconazole
True/False: urine and serum Histoplasma antigen have a sensitivity of ~60% each, but combined they have a sensitivity of ~90%
TRUE
Patients getting worked up for what disease must be screened for histoplasmosis given similarities on imaging?
Sarcoidosis
esp before you start immunosupression!
Treatment for mild-moderate histoplasmosis?
Itraconazole
Treatment for moderate or severe acute histoplasmosis? (2 drugs)
Ampho B for 1-2 weeks followed by itraconazole
Methylprednisolone 0.5-1mg/kg daily for 1-2 weeks
What extrathoracic findings suggest histoplasmosis as the cause of a patient’s fibrosing mediastinitis?
Splenic and hepatic calcifications
Patients of which ethnicities are at risk of developing disseminated cocciodiodomycosis regardless of immunosupression?
Korean Filipino Japanese Hispanic African-American
This form of coccidio infection is when there is a pulmonary cavitation and interstitial fibrosis, seen in diabetics, imaging shows reticulonodular or miliary infiltrates, and can have extrapulm infections
Chronic fibrocavitary pneumonia
What tests are used for screening for cocci infections?
Cocci IgG and IgM EIA
What are specific tests that are used for confirmation of cocci infections?
Cocci tube precipitin
Cocci immunodiffusion
What are tests that used to quantifies IgG in cocci infections to determine active infection and extent of disease?
Cocci complement fixation
Treatment for limited pulmonary disease in cocci?
Fluconazole or itraconazole
Treatment for diffuse pulmonary disease in cocci?
Ampho B until clinical improvement followed by fluconazole or itraconazole for >1 year
Treatment for meningitis in cocci?
Lifelong itraconazole or fluconazole plus intrathecal amphotericin B in severe cases
Treatment for most cases of blastomycosis?
Itraconazole
Treatment for life-treatening severe blastomycosis, ARDS, or meningeal infection?
Ampho B until clinically improved followed by long-term itraconazole
Treatment of paracoccidioidomycosis?
Itraconazole
Sulfonamides, azoles, and ampho B are backups
Which fungal infection has the classic presentation of a rose gardener injuring his finger with a thorn?
Sporothrix schenckii
Pulmonary disease with Sporothrix schenckii?
Chronic cavitary fibronodular disease, especially in middle-aged men with risk factors (alcoholism, COPD)
Sporothrix schenckii diagnosis?
Culture (gold standard) with histopathology showing ixed granulomatous and pyogenic inflammatory process