Infections

Question 1

Consider B. pertussis in patients presenting with cough of > 4 weeks, even those who have been vaccinated.

Question 2

A false-positive galactomannan enzyme immunoassay can occur from treatment with piperacillin–tazobactam or amoxicillin–clavulanate.

Question 3

COPD and critically ill patients in the ICU have been identified recently as at-risk groups for invasive pulmonary aspergillosis despite not having traditional risk factors of overt immunocompromise such as prolonged neutropenia or high-dose steroids.

Question 4

A negative culture from a sputum or BAL sample does not rule out invasive aspergillosis.

Question 5

Aspergillus terreus is terribly resistant to amphotericin.

Question 6

What is the characteristic branching angle when Aspergillus is viewed on histopathologic (potassium hydroxide, India ink) stains?

Answer 6

45-degree branching with septations; do not confuse with mucormycosis, which is characterized by 90- degree branching without septations

Question 7

Which antifungal agents have activity against Aspergillus?

Answer 7

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

Question 8

All patients with candidemia require early dilated retinal examination to rule out Candida endophthalmitis. Echinocandins do not have good eye penetration.

Question 9

All immunocompromised patients with pulmonary cryptococcal infection require work-up for disseminated disease with serum and CSF cryptococcal antigen and with blood and CSF cultures.

Question 10

Cryptococcus gattii more often infects immunocompetent hosts and is found in the Northwest United States.

Question 11

Which antifungal is preferred for treatment of invasive candidiasis in pregnant women?

Answer 11

Systemic amphotericin B; echinocandins and most azoles are category C; flucytosine and voriconazole are contraindicated because of fetal abnormalities in animal studies

Question 12

Urine and serum Histoplasma antigen studies each has a sensitivity of ~60%, but combined they have a sensitivity of >90%.

Question 13

Given its clinical and radiographic similarities to sarcoidosis, histoplasmosis must be excluded prior to diagnosing sarcoidosis and starting immunosuppressive treatment.

Question 14

What extrathoracic findings suggest histoplasmosis as the cause of a patient’s fibrosing mediastinitis?

Answer 14

Splenic and hepatic calcifications

Question 15

Patients of Korean, Filipino, Japanese, Hispanic, and African- American descent are at increased risk of developing disseminated coccidioidomycosis, even in the absence of immunosuppression.

Question 16

Blastomyces dermatitidis are broad-based budding yeast.

Question 17

Which fungal infection has the classic presentation of a rose gardener injuring his finger with a thorn?

Answer 17

Sporothrix schenckii

Question 18

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

Answer 18

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

Question 19

Name two alternatives to TMP-SMX for PCP prophylaxis.

Answer 19

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

Question 20

Most cases of CMV pneumonia occur in patients with CD4+ < 50.

Question 21

The prophylaxis of choice for T. gondii is TMP-SMX, the same drug as for PCP.

Question 22

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

Answer 22

α1-antitrypsin deficiency, HIV, connective tissue diseases

Question 23

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

Answer 23

Nonsteroidal antiinflammatory drugs (NSAIDs) and steroids

Question 24

Noninfectious causes of cavitary lung lesions:

Answer 24

CAVITY
Cancer

Autoimmune (Wegener’s,
rheumatoid)

Vascular (bland or septic
emboli) Infection

Trauma (pneumatocele)

Youth (pulmonary
sequestration, bronchogenic cyst, congenital pulmonary airway malformation)

Question 25

NOCARDIA
Nodules seen on imaging Organ spread
Cavitary lesions SulfonAmide antibiotic to
treat
Respiratory symptoms Dirt exposure Immunocompromised Acid fast (weak)

Question 26

CXR shows infiltrates within a cavity, typically in the parts of the lung that are dependent in the recumbent position (superior segment of the lower lobe or posterior segment of the upper lobes).

Question 27

The mortality for lung abscess ranges between 5–20%. Larger size is a worse prognostic marker.

Question 28

Routine bronchoscopy to aspirate lung abscesses is not recommended due to lack of evidence of benefit and potential risk of massive fatal aspiration of abscess contents. If it is performed, requires experienced operator.

Question 29

Aztreonam, TMP-SMX, aminoglycosides, and ciprofloxacin do not cover anaerobes.

Question 30

What is the most effective mechanism for generating droplet nuclei?

Answer 30

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

Question 31

TB is acquired by inhalation of one or more tubercle bacilli contained in an airborne particle small enough (1–5 μm) to reach an alveolus.

Question 32

In persons with both HIV and latent TB infection, antiretroviral therapy and prophylactic therapy with isoniazid substantially decrease the risk of developing active TB.

Question 33

BCG should not be given to immunocompromised persons, including those with symptomatic HIV infection and pregnant women.

Question 34

In patients with HIV infection, a normal chest radiograph occurs in as many as 11% of patients with positive sputum
cultures.

Question 35

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

Answer 35

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

Question 36

Rifampin can stain urine, saliva, tears, and soft contact lenses orange.

Question 37

Because of the frequency of extrapulmonary TB in HIV-infected patients, diagnostic specimens from any suspected site of disease should be cultured for mycobacteria.

Question 38

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

Answer 38

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

Question 39

Necrotizing/cavitary infiltrates or empyema should raise suspicion for Staphylococcus aureus.

Question 40

Diagnostic yield of PCR > culture/antigen detection assays but may overestimate viruses being a cause of community acquired pneumonia since they can be present in the nasopharynx in healthy people.

Question 41

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

Answer 41

Bat droppings:
Histoplasma capsulatum

Birds: Chlamydophila psittaci (if poultry, think avian influenza)

Rabbits: Francisella tularensis;

Farm animals: Coxiella burnetii (Q fever).

Question 42

Agents such as Legionella species, mycobacterial TB, mycobacterial pneumonia, C. pneumoniae or C. psittaci are rarely ever colonizers and represent true disease. On the other hand, some organisms are virtually never pathogenic: Candida species, coagulase-negative Staphylococcus aureus, enterococci, gram-positive rods (except Nocardia), H. parainfluenzae.

Question 43

Elderly patients may present with confusion, failure to thrive, weakness, or delirium and frequently do not have fever.

Question 44

Follow-up imaging after treatment may not show resolution for up to 12 weeks in certain patients.

Question 45

Sputum gram stains represent lower respiratory tract secretions when PMNs > 25 and epithelial cells < 10/lpf.

Question 46

Both macrolides and fluoroquinolones can cause prolonged QTc. Use doxycycline instead (unless patient is pregnant).

Question 47

20% of nonresolving pneumonia cases are due to noninfectious causes (neoplasm, vasculitis, Bronchiolitis obliterans organizing pneumonia/ cryptogenic organizing pneumonia, eosinophilic pneumonias, drug-induced lung disease, and pulmonary edema/ embolism). In such cases, bronchoscopy with biopsy is useful, especially in young, nonsmokers with diffuse parenchymal involvement.

Question 48

What is an appropriate antibiotic regimen for a patient with a prolonged QT and risk factors for drug resistance?

Answer 48

Monotherapy with a macrolide is NOT recommended due to concern for macrolide- resistant S. pneumoniae. Doxycycline plus β-lactam is a good choice.

Question 49

Staphylococcus epidermidis, enterococci, most gram-positive bacilli (except Actinomyces and Nocardia) are not pathogenic.

Question 50

Daptomycin does not achieve high concentrations in the lung.

Question 51

Ceftaroline is approved by FDA for community acquired pneumonia but not if caused by MRSA; not to be used for hospital- acquired pneumonia/ventilator- associated pneumonia/HCAP.

Question 52

Tigecycline has activity against MRSA but is associated with an increased risk of death, therefore do not use unless other agents are not suitable.

Question 53

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

Answer 53

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

Question 54

Describe Lady Windermere syndrome.

Answer 54

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

Question 55

Mycobacterium abscessus
infection in patients with cystic fibrosis who have undergone lung transplantation has been associated with severe and sometimes fatal disease.