Lower Respiratory Infections Flashcards
What is the leading cause of death in older adults in those with impaired resistance?
pneumonia caused by strep. pneumoniae (Gram + cocci)
infections by this pathogen are most common in IV drug users, older adults, in people with recurrent influenza virus infection, and individuals with cystic fibrosis. What is?
staphylococcus aureus (Gram + cocci) - can cause severe necrotizing pneumonia
what are the top three bacterial causes of community acquired pneumonia?
- Streptococcus pneumonia! most common by farrrr
- Haemophilus influenza.
- Staphylococcus aureus
to what family of viruses do influenza virus type A/B and respiratory syncytial virus (RSV) belong to and what kind of viruses are these? (what are the features of this family)
Paramyxoviridae: single stranded, negative sense, helical, enveloped
both viral causes of community acquired pneumonia
what kind of illness does parainfluenza virus cause and in whom?
human parainfluenza viruses type 1-4: confined to the respiratory tract, influenza like symptoms
—> pneumonia, croup, bronchiolitis
Mainly in infants and children
What are the three most common bacterial causes of atypical pneumonia?
- mycoplasma pneumoniae
- Chlamydia pneumoniae
- Legionella pneumophila
(more common than viruses)
mycoplasma pneumonia is the most common cause of what illness? what protein allows mycoplasma pneumoniae to cause infection?
mycoplasma pneumoniae: most common cause of atypical/walking pneumonia, most common in older children/young adults
P1 cytoadhesin allows M. pneumoniae to adhere to ciliated bronchial epithelial cells - inhibiting cilia reaction —> patches of affected mucosa desquamate
this bacterial cause of atypical pneumonia replicates in cells of the monocyte–macrophage system in the alveoli, causing a necrotizing multifocal pneumonia. In the environment this bacteria replicate in amoebas. what is?
Legionella pneumophila (Gram - rod)
This virus is known to cause outbreaks of lower respiratory tract infections (which can progress to pneumonia) in crowded environments such as military bases. Infected infants most commonly suffer from febrile pharyngitis. What is?
adenovirus: double stranded, non-enveloped
what kinds of infections result from the follow immunological defects:
a. MYD88 mutation adaptor protein
b. defective IgA production
c. defective TH1 cell-mediated immunity
a. MYD88 mutation adaptor protein —> severe necrotizing, pneumococcal infections
b. defective IgA production —> pneumonias from encapsulated organisms (H. influenza, pneumococcus)
c. defective TH1 cell-mediated immunity —> infections with Intracellular organisms (atypical mycobacteria)
define the following types of pneumonia:
a. Patchy distribution with inflammation from bronchioles to alveoli (patchy consolidation)
b. intra-alveolar exudate (consolidation of a lobe)
c. Diffuse, patchy inflammation localized to interstitial areas and alveolar walls.
a. Patchy distribution with inflammation from bronchioles to alveoli (patchy consolidation): bronchopneumonia
b. intra-alveolar exudate (consolidation of a lobe): lobar pneumonia
c. Diffuse, patchy inflammation localized to interstitial areas and alveolar walls: interstitial pneumonia
how do you reticular versus nodular interstitial opacities caused by pneumonia appear radiographic Lee?
reticular interstitial opacities = lines
Nodular interstitial opacities = dots
how do you alveolar opacities versus interstitial opacities caused by pneumonia appear radiographically?
alveolar opacities – lobar/segmental distribution, fluffy
Interstitial opacities – no respect for boundaries, reticular/nodular
what do the following colors of patient sputum indicate?
a. Yellow/green.
b. Pink/red/bloody.
c. White
d. Charcoal/gray.
e. Brown
a. Yellow/green: infection
b. Pink/red/bloody: infection or cancer
c. White: allergies, asthma, or viral infections.
d. Charcoal/gray: environmental, common in people who work in coal mines/factories or heavy smokers
e. Brown: chronic lung disease, cystic fibrosis or bronchiectasis.
*note this isn’t actually very reliable in clinical practice (but remember for boards!)
You are examining a blood sample from your patient who is presenting with community acquired pneumonia (more reliable than sputum). You identify a gram-positive lancet-shaped diplococci. What is it?
Streptococcus pneumoniae: most common cause of community acquired pneumonia
On rounds, you encounter a five year old child with community acquired pneumonia and concurrent epiglottitis. The child has not yet received their vaccinations. You identify an aerobic gram-negative bacteria in their sputum sample. What is the most likely cause of their pneumonia?
Haemophilus influenzae: aerobic, gram-negative bacteria, usually seen in infants and children or individuals with COPD/cystic fibrosis/bronchiectasis
Causes epiglottitis in suppurative meningitis in children
Uncommon in the US because of vaccination (Hib)
What kind of illness is Moraxella catarrhalis known to cause?
gram-negative bacteria, second most common cause of COPD exacerbation
Seen more in elderly, can cause community acquired pneumonia
Also commonly causes otitis media in children
use of IV drugs leading to right-sided endocarditis following pneumonia is associated with what bacteria?
Staphylococcus aureus: often causes secondary bacterial infections in children and adults
Associated with high incidence of complications - lung abscess, emphysema
why can daptomycin be used for staphylococcus aureus blood infections but not for pneumonias?
Daptomycin is inactivated by surfactant
What is the most frequent cause of gram-negative bacterial pneumonia?
Klebsiella pneumoniae – increased frequency with malnourishment or alcoholism
Produces thick/gelatinous sputum that is hard to expel, can form abscess
High mortality rate in elderly
in which setting is pseudomonas aeruginosa most commonly seen and in which patients?
most common in nosocomial settings, increased frequency in individuals with cystic fibrosis, neutropenia (malignancy/chemo), extensive burns or chronic granulomatous disorder
propensity to invade blood vessels, causes coagulative necrosis of pulmonary parenchyma
Pontiac fever versus legionnaire disease
Both caused by legionella pneumophila - gram-negative, intracellular bacteria, flourishes in artificial aquatic environments
Pontiac fever: self limited upper respiratory tract infection
Legionnaire disease: epidemic and sporadic form of pneumonia
what three pathogens are classically associated with exposure to birds?
- chlamydia psittaci
- histoplasma capsulatum
- cryptococcus neoformans
what pathogen is classically associated with exposure to dogs?
bordetella bronchiseptica
what pathogen is classically associated with exposure to cats?
Pasteurella multocida
what 2 pathogens are classically associated with exposure to farm animals?
- coxiella burnetii
- Brucella species
what pathogen is classically associated with exposure to horses?
Rhodococcus equi
what pathogen is classically associated with exposure to rodent droppings?
Hantavirus
what pathogen is classically associated with exposure to rabbits?
Francisella tularensis
what pathogen is classically associated with exposure to hot tubs?
Legionella pneumoniae, or atypical mycobacteria (causing hypersensitivity pneumonitis)
what pathogen is classically associated geographically to the middle east?
MERS
what pathogen is classically associated geographically to southeast asia?
SARS, avian influenza
what pathogen is classically associated geographically to the southwest US?
coccidioides
what 2 pathogens are classically associated geographically to the eastern US?
- Histoplasma capsulatum
- Blastomyces dermatitidis
what 3 pathogens are classically associated with late fall, winter, or early spring in the Western hemisphere?
- influenza virus
- parainfluenza virus
- rhinovirus
what are the histological findings of viral community acquired pneumonia?
red/blue congested lung, widened/edematous septa, mononuclear infiltrate (lymphocytes, macrophages)
*however alveolar spaces usually do not have exudate
what is the function of the following influenza virus proteins?
a. Hemagglutinin.
b. Neuroaminidase
c. M2 (Matrix) protein.
a. Hemagglutinin (HA): host cell recognition, entrance of viral genome into cell
b. Neuroaminidase (NA): cellular release of virus
c. M2 (Matrix) protein: coats the inside of the viral envelope, viral assembly and budding
- community is directed against HA & NA proteins
What is the most common site for aspiration pneumonia to develop? Why does this make sense?
right lower lobe most common site - large caliber, and more vertically oriented
What two things can occur if a lung abscess ruptures into the pleural cavity and develops into broncoplural fistula?
pneumothorax or empyema
which 4 fungi are known to cause pneumonia in immunocompromised patients?
- Pneumocystis jiroveci
- Candida.
- Aspergillus.
- Cryptococcus neoformans
Patience with AIDS and transplants are at higher risk for what type of pneumonitis?
cytomegalovirus (CMV) pneumonitis: “owl eye” appearance due to gigantism of both cytoplasm and nucleus of infected cell
nucleus with large inclusion surrounded by clear halo
*most common opportunistic viral pathogen in AIDS
from where is cryptococcus neoformans infection usually acquired?
Aerosolized contaminated soil or bird droppings
Manifests as pulmonary, CNS, or disseminated disease
A 29yo F w/ HIV infection and CD4+ T cell count of 633 is presenting with 3 days of fever/chills/productive cough/chest pain. CXR shows left lower lobe consolidation. Which of the following organisms is most likely present in her sputum?
a. mycoplasma pneumoniae
b. streptococcus pneumoniae
c. legionella pneumophila
d. pseudomonas aeruginosa
e. PJP
b. streptococcus pneumoniae - causes lobar pneumonia
CD4+ T cell count is helpful in infection of HIV patients:
>200: bacterial/tubercular infection
<200: PJP
<50: CMV, M. avium
Which of the following infections is known to increase susceptibility to pneumonia caused by Strep. pneuomniae?
a. Epstein-Barr virus
b. Haemophilus influenza
c. Influenza virus
d. Mycobacterium tuberculosis
e. Mycoplasma pneuomniae
c. Influenza virus - damages mucociliary escalator
A 50yo M w/ history of alcoholism found in stuporous condition after 3 days of binge drinking with fever. CXR shows lung abscess. Which of the following organisms are most likely to be detected?
a. staphylococcus aureus and Bacteroides fragilis
b. Mycobacterium tuberculosis and Aspergillus fumigatus
c. Nocardia asteroids and Actinomyces Israeli
d. Cytomegalovirus and Pneumocystis carinii
e. Cryptococcus neoformans and Candida albicans
a. staphylococcus aureus and Bacteroides fragilis
Staph and anaerobes are most likely to produce lung abscess
Bronchoalveolar lavage fluid from a 40yo F w/ PMH of 5 years of illness is collected. The fluid is positive for staining with Gomori methenamine silver (GMS). The underlying illness in this patient is most likely:
a. systemic lupus erythematous (SLE)
b. acquired immunodeficiency syndrome (AIDS)
c. sarcoidosis
d. severe combined immunodeficiency
b. AIDS
GMS stain is used to diagnose Pneumocystis jirovecci (carinii) infection, which is most often associated with AIDS
what kind of pneumonia do bacteria vs virus cause?
bacteria —> lobar pneumonia, abscesses
viruses —> interstitial pneumonia
