Infections Flashcards by Daniel Guck

What % of acute bronchitis is caused by bacterial pathogens?

10%

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How long does acute bronchitis symptoms typically last?

<3 weeks

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What should you suspect if there is a cough >4 weeks in acute bronchitis?

B. pertussis

regardless of vaccination

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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

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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

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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

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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

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What medications can give false + galactomannan enzyme test?

Zosyn or Augmentin

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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

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True/False:

A negative culture from sputum or BAL rules out invasive aspergillosis

FALSE

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What aspergillus is notoriously resistant to amphotericin?

A. terreus

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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

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Which antifungal agents have activity against Aspergillus?

Voriconazole, itraconazole, amphotericin B, and the echinocandins–fluconazole is inactive against Aspergillus species

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What medications are used first line for candidemia in critically ill and neutropenic patients?

Echinocandins

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If there is a concern for concomitant mold coverage in someone with candidemia, what medication is used?

Voriconazole

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If someone develops CNS candidiasis, candida endopthalmitis, or candida endocarditis, which mecation is indicated?

Liposomal amphotericin B

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Mortality from candidemia?

15-47%

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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

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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

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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

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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)

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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

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True/False: urine and serum Histoplasma antigen have a sensitivity of ~60% each, but combined they have a sensitivity of ~90%

TRUE

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Patients getting worked up for what disease must be screened for histoplasmosis given similarities on imaging?

Sarcoidosis

esp before you start immunosupression!

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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

Treatment of mild disease in Sporothrix schenckii?

Itraconazole for 12 months

Treatment for severe disease in Sporothrix schenckii?

Ampho B with transition to prolonged intraconazole and consideration of surgery for localized pulmonary disease

At what CD4 level are HIV patients at risk for bacterial pneumonia with bacteremia, disseminated TB, Pneumocystis TB, and Cryptococcal neoformans?

<200 cells/uL

At what CD4 level are HIV patients at risk for bacterial pathogens such as staph, pseudomonas, pulmonary manifestations of Kaposi sarcoma, and toxoplasmosis?

<100

At what CD4 level are HIV patients at risk for endemic fungi, CMV, MAC, and nonendemic fungi?

50-100

Name three risk factors for Pneumocystis pneumonia (PCP) among HIV-infected patients.

CD4+ < 200, oropharyngeal candidiasis, and a history of PCP

Name two alternatives to TMP-SMX for PCP prophylaxis.

CD4+ < 200, Dapsone 100 mg daily, or aerosolized pentamidine 300 mg once per month

How should one test for latent TB in someone with recently diagnosed HIV?

skin test or INGg assay

Treatment for PJP pneumonia in HIV?

Bactrim for 21 days add steroids if moderate- to severe PJP to reduce mortality and respiratory failure

Most cases of CMV pneumonia in HIV are when the CD4 is less than what amt?

<50

What is the drug for prophylaxis in Toxoplasma gondii?

Bactrim (same as PJP)

Nonsmokers with signs of emphysema at an early age should be evaluated for what systemic diseases?

α1-antitrypsin deficiency, HIV, connective tissue diseases

What are two treatment options for excessive inflammation in immune reconstitution syndrome?

Steroids and NSAIDs

HIV patient presents with worsening dyspnea on exertion. Bronchoscopy reveals endobronchial flat red lesions. Diagnosis?

Kaposi sarcoma

# Fill in the following mnemonic for cavitary lung lesions: ``` C A V I T Y ```

Cancer Autoimmune (GPA, RA) Vascular (bland or septic emboli) Infection Trauma (pneumatocele) Youth (pulmonary sequestration, bronchogenic cyst, congenital pulmonary airway malformation)

What type of organism are you concerned about that causes pulmonary cavitation based on the following characteristics? Cervicofacial osteomyelitis or absess in alcoholic with recent dental procedure, possible sulfur granules, imaging shows mass lesion with consilidation, adenopathy, bronchiectasis, and air bronchograms if it invades through chest wall

Actinomyces

Treatment for actinomyces lung abscess?

PCN IV followed by 6-12 months or oral therapy can also use tetracycline, erythromycin, clindamycin, or imipenem

What type of organism are you concerned about that causes pulmonary cavitation based on the following characteristics? Immunocompromised patient with underlying lung disease and subacute pulmonary symptoms, hematogenous metastasis, culture takes weeks to grow, imaging shows bilateral multifocal pneumonia/masses/nodules/empema

Nocardia

Treatment for nocardia lung abscess?

Bactrim for 6-12 months

What type of organism are you concerned about that causes pulmonary cavitation based on the following characteristics? Australian patient presents with chronic cough with hemoptysis, imaging shows spherical cysts with smooth borders, might have been eating wolf poop

Echinococcus

Treatment for echinococcus cavities?

Macrolides, rifampin, vancomycin, fluoroquinolone, aminoglycoside, or imipenem

What type of organism are you concerned about that causes pulmonary cavitation based on the following characteristics? Asian patient presents with hemoptysis and eosinophilia, imaging shows cavities and cyst-like lesions with linear infiltrates and pleural effusion, BAL shows eggs, might have been eating crabs or boar meat

Paragonimiasis

Treatment for paragonimiasis?

Antihelminths

True/False: aztreonam, bactrim, aminoglycosides, and ciprofloxacin have anaerobic coverage

FALSE

What is the most effective mechanism for generating droplet nuclei?

Coughing—a forced expiratory maneuver that involves the sudden acceleration of air and disruption of a liquid surface and therefore aerosolizing of particles; sneezing, yelling, singing, and loud talking are also ways to transmit droplet nuclei

What is your % chance of becoming infected if you have close exposure to a patient with active pulmonary TB?

30-40%

In persons with both HIV and latent TB, which medication can be given in addition to antiretroviral therapy to reduce the risk for developing active TB?

INH

Which pro-inflammatory cytokine is released by activated monocytes/macrophages in response to TB infection, which is critical for maintaining granulomas?

TNFa | which is why anti-TNF agents cause reactivation

PPD induration size for positivity in anyone?

>15

What groups are considered positive when the PPD is >10?

``` Recent immigrants High risk populations (healthcare workers) IVDU Comorbid medical conditions Exposure to idnex case ```

What groups are considered positive when the PPD is >5?

Immunosupressed (including HIV) Close contact with active TB High clinical suspicion

True/False: positive INFg release assay can differentiate from active vs latent TB infection

FALSE

True/False: INFg release assay is more specific in those with BCG vaccination

TRUE

True/False: one of the benefits of INFg release assay is that it does not have false positive results

FALSE Mycobacterium szulgai, M. kansaii, and M. marinum can make it false positive

Who should get a screening tuberculin skin test or INFy assay?

Contacts of infectious cases, children younger than 17 years, pregnant women, recent immigrants, and health care workers should get a skin test or INFγ assay

This test for TB is very specific for mycobacteria but does not show information about species

AFB staining

This test for TB is necessary for drug susceptibility testing, which requires isolation of mycobacteria in culture, and takes weeks for final results

Mycobacterial culture

This test for TB is useful for studying epidemiology and transmission dynamics

Genetic polymorphisms

True/False: A patient is started on RIPE for active TB. After 4 months of therapy, sputum cultures remain positive. You should then start a new medication based on susceptibility testing.

TRUE After 3 months of therapy, 90% of patients have negative sputum cultures

What is the value of checking a pleural fluid adenosine deaminase?

Adenosine deaminase has been shown to have high sensitivity (except in HIV patients) but variable specificity in diagnosing TB pleural effusion

Name the bug that causes CAP based on the following characteristics: Most common cause of CAP, common cause of post-influenza pneumonia, severe infections with asplenia, vaccination reduces risk

S. pneumoniae

Name the bug that causes CAP based on the following characteristics: Patients with underlying lung disease are at higher risk, vaccination decreased incidence but not for the nontypeable strains

H. influenzae

Name the bug that causes CAP based on the following characteristics: Happens more often after influenza, resistant forms can cause severe necrotizing pneumonia that has a mortality rate of 29-60%

S. aureus

Name the bug that causes CAP based on the following characteristics: Uncommon but may require ICU admission for cAP, many different species, risk factiors are those who aspirate and have underlying lung disease

Gram negative bacili

Name the bug that causes CAP based on the following characteristics: Most common atypical, healthy persons in 20s-30s, URI pordrom followed by systemic symptoms, gram stain negative, CXR shows unilateral infiltrate or patchy bilateral interstitial infiltrates

Mycoplasma pneumoniae

Name the bug that causes CAP based on the following characteristics: Risk factors of those who are exposed to contaminated water, gram stain negative, associated with high fever, ICU care, transaminitis, renal failure, and GI/neuro abnormalities

Legionella species

Name the bug that causes CAP based on the following characteristics: Atypical, minimnally symptomatic but recovery may be slow (weeks to months), assocaited with COPD or asthma exacerbations

Chlamydophila pneumoniae

What causative organism is responsible for pneumonia associated with bat droppings? Birds? Rabbits? Farm animals?

Bat droppings: Histoplasma capsulatum Birds: Chlamydophila psittaci (if poultry, think avian influenza) Rabbits: Francisella tularensis; Farm animals: Coxiella burnetii (Q fever).

Outpatient treatment regimen for CAP?

Macrolide OR doxy Alternative: fluoroquinolone or anti-pneumococcal betal-lactam + macrolide

Inpatient treatment regiment for CAP?

Fluoroquinolone alone or anti-pneumococcal beta lactam + macrolide If concern for MRSA, add coverage If structural lung disease, cover P. aeruginosa

Duration of antibiotics for inpatient treatment of CAP?

5-7 days for typical organisms 10-14 for aytypical organisms

Inpatient ICU treatment regimen for CAP?

IV beta lactam + fluoroquinolone or macrolide Cover MRSA if indicated If suspecting P aeruginosa, add coverage

When is anaerobic coverage indicated for aspiration pneumonia?

With a history of loss of consciousness from alcohol/drug overdose or after seizures in people with gingival disease or esophageal motility disorders

If someone fails the first treatment regimen for CAP, what procedure is thus indicated?

Bronchoscopy

# Fill in the blanks for indications for PPSV23: Anyone over the age of ___ Age less than above but have the following risk factors: ____ Anyone who is ____ Revaccinate if over the age 65 and initial vaccine is > _ years prior

Anyone over the age of 65 Age less than above but have the following risk factors: COPD, CHF, DM, alcoholism, cirrhosis, CSF leaks, asplenia, those living in long term care facilities Anyone who is immunosuppressed (HIV, cancer, chronic steroids) Revaccinate if over the age 65 and initial vaccine is > 5 years prior

# Fill in the blanks for indications for PCV13: ``` Congenital or acquired ___ Have HIV Chronic __ failure __ syndrome Leukemia, lymphoma, MM, generalized malignancy __ __ transplant recipients Those who use ___ ```

Congenital or acquired immunodeficiency Have HIV Chronic renal failure Nephrotic syndrome Leukemia, lymphoma, MM, generalized malignancy Solid organ transplant recipients Those who use immunosupressants

How long after hospital admission to determine HAP or VAP if a pt develops new infiltrates that wasnt present on admission?

48-72 hrs

What antibiotic can be used to treat nosocomial pneumonia in a patient with a penicillin and/or a cephalosporin allergy?

Aztreonam; if the patient had a severe allergic reaction to ceftazidime in the past, then cross- reactivity is variable, and aztreonam should not be given until the patient is evaluated by an allergy specialist

Describe Lady Windermere syndrome.

Thin, postmenopausal women with NTM disease; often associated with right middle lobe and lingular bronchiectasis

Treatment of MAC is for 12 months after documentent sputum culture negativity with what 3 antibiotics

Macrolide Ethambutol Rifamycin

What is the preferred preventative therapy for MAC in HIV patients with CD4 < 50?

Azithromycin 1200mg weekly

Preferred treatment regimen for 12 months for M. kanasii?

Rifampin (600mg/day) Isoniazid (300mg/day) Ethambutol (15 mg/kg/day)