Bacterial and Fungal Pneumonias; Tuberculosis Flashcards
What is the number one leading cause of death from infectious disease?
complicates the course of 1/20 hospital patients
How do smoking and alcoholism predispose to pneumonia?
Smoking - paralyzes cilia, also predisposes to COPD
Alcoholism - malnutrition, depressed level of consciousness, and poor ciiary function
What pneumonias are transmitted by inhalation of airborne organisms?
- Mycoplasma
- Tuberculosis
- Legionella
- Fungi
In what situations might you get hematogenous spread which leads to pneumonia?
IV drug users, infected IV lines, bloodborne infections from elsewhere in the body
How will a lobar pneumonia present via auscultation, percussion, and vocal fremitus? What classically causes this?
Auscultation - bronchial breath sounds
Percussion - dullness
Vocal fremitus - increased vibrations
Classically caused by S. pneumoniae, but need to keep in context the situation (nosocomial vs community acquired vs immunosuppressed)
What will patchy or interstitial pneumonia cause on auscultation?
rales (crackles)
How will pleural effusion present on tactile fremitus?
Decreased transmission
Associate each of the following sputum consistencies with a microbe:
- Rusty
- Currant jelly
- Creamy yellow
- Foul odor
Rusty - S. pneumoniae
Currant jelly - Klebsiella pneumoniae
Creamy yellow - S. aureus
Foul odor - anaerobes
What is the definition of a good sputum sample?
<10 epithelial cells and >25 PMNs per low power field
Who is mycoplasma pneumonia common in and how does its constitutional symptoms differ from S. pneumonia (usual)?
Occurs in young, healthy people, especially in outbreaks at school or in military recruits in fall and winter
Mycoplasma is an atypical so it has a more insidious onset (rather than abrupt), a nonproductive cough (rather than rusty sputum), and no leukocytosis
How does Mycoplasma appear on CXR and what is one rare but very specific finding seen in this infection?
CXR: Patchy bronchopneumonia, will cause rales on physical exam sometimes
Bullous myringitis - inflammation of tympanic membrane
Who typically gets Legionella?
Immunosuppressed, smokers, COPD, advanced age, male, with cardiac disease
-> need some degree of immunosuppression for severe infection
What is the primary cardiac symptom of Legionella? What treatment against it is effective?
Relative bradycardia
-> patient’s heart rate will only be high normal, which is lower than expected given how high their fever is
Treatment: Macrolides (think of crows on the crane)
What bacterial pneumonia occurs in COPD and is known for a very large amount of sputum production?
Haemophilus influenzae
What pneumonia is known for a lobar pneumonia causing bulging fissures because there is so much exudate? Who does it occur in?
Klebsiella pneumoniae
Occurs in alcoholics and diabetics
What types of pneumonias are known for causing an air-fluid level on CXR?
Necrotizing pneumonias like S. aureus, P. aeruginosa, and ESPECIALLY anaerobic pulmonary infections -> cause a cavity lung abscess
What is the treatment for anaerobic pneumonias? Is the course of the disease typically acute or chronic?
Long course of penicillin and clindamycin
Typically a subacute / chronic course - with h/o poor dental hygiene, malaise, and foul-smelling sputum
What pneumonia is marked by a slowly progressive infection causing worsening CXR infiltrates and hypoxemia in HIV patients? What is the treatment?
Pneumocystis jirovecii pneumonia
Treatment: TMP/SMX first line, with pentamidine IV if allergic (think of the pentagon ping pong paddles)
What does skin testing for coccidioides mean if it goes from negative to positive or positive to negative?
Negative to positive: new infection
Positive to negative: severe or disseminated disease
What is the usual testing used to detect Coccidioides which may be missing the diagnosis depending on when this is done? Why might this be preferred over cell culture?
IgM / IgG serologies
IgM positive after 2-4 weeks, IgG becomes positive later
High IgG titers is prognostic for a very high chance of disseminated disease
Preferred over culture because the mold grown in the lab is very infectious
What are common and more specific symptoms of primary coccidioidomycosis?
Fever, cough, joint aches (guy kneeling in sketchy)
Erythema nodosum - think shin lesions on wall in sketchy
Who is at highest risk for disseminated coccidioidomycosis and where does it tend to spread?
Young or old, immunosuppressed, blacks, mexicans, and native americans
Can disseminate to skin (erythema nodosum) or cause fatal meningitis (think of guy leaning on immunocompromised fountain with neck brace)
Who is at greatest risk for chronic and disseminated histoplasmosis?
Chronic - patients with COPD
Disseminated - Immunocompromised, can spread like miliary TB
What are the diagnostic tests best used for diagnosis of histoplasmosis and blastomycosis?
Histoplasmosis - urine and serological testing (think of red and yellow stalactites in sketchy)
Blastomycosis - Culture is definitive, organism grows fast
How are aspergillus hypersensitivity pneumonitis and allergic bronchopulmonary aspergillosis (ABPA, associated with asthma) treated? What will CXR and serology show?
Treat with corticosteroids, or avoidance of Aspergillus
CXR shows migratory infiltrates, serology shows elevated IgE
In what patient populations do we see aspergilloma and invasive aspergillosis?
Aspergilloma - site of pre-existing cavity (i.e. old TB) -> may need surgical excision to prevent vascular invasion, but rarely treated
Invasive aspergillosis - post transplant or bone marrow irradiation in immunocompromised, very high mortality
How are nontuberculous mycobacterial infections diagnosed definitively and why?
They may be just colonizers or actually pathogens
Diagnosed by at least TWO positive sputum cultures, or ONE positive culture from bronchial lavage / biopsy.
How are different nontuberculous mycobacteria told apart, and how do they appear on CXR?
Told apart by growth rate and specific pigment production
CXR - nodular or cavity lesions
What are risk factors for reactivation of latent TB?
Silicosis, HIV, substance abuse, corticosteroids / immunosuppressives, organ transplant, inflammatory bowl diseases, diabetes, etc
If a TB treatment regimen is failing, what should you do?
Add on at least TWO more medications, never just one, since resistance is likely
What is required for positive diagnosis of TB via sputum sampling?
At least three sputum samples taken 8 hours apart, with at least one being a morning sample
Three positives required, negative does not exclude TB
-> use these for culture in broth, 4-14 days
Where should the PPD skin test be injected?
INTRAdermally (not subdermally), can see 2-8 weeks after infection
What is the rule used to interpret a positive PPD test?
5/10/15 mm rules
5 or more: positive if HIV, CXR consistent with TB, any immunosuppression, or recent TB contacts
10mm or more: recent travel from high prevalence area, IV drug use, lab personnel, age <5 (common in young children), BCG vaccine falls here
15mm or more: positive even with no other known factors
How do the lymphocyte tests for TB work?
3 tubes or plates are run
Plate / Tube 1: lymphocytes alone (proliferation = background noise, nil
Plate / Tube 2: Lymphocytes + TB antigen
Plate / Tube 3: Lymphocytes + Known mitogen, positive control
Response is equal to plate 2 minus plate 1 (background noise). Certain threshold = sensitization vs TB = infection
