3: Resp ID 2 Handout Flashcards
What are pneumocytes? What are type 1 pneumocytes?
Cells lining alveoli. 1: large thin cell doing gas exchange, cannot replicate, susceptible to toxins.
Type 2 pneumocytes
Produces and secretes surfactant. Granular, smaller, found @ alv septal junctions, can replicate and replace damaged type 1s
Alveolar defenses (3 main things)
Alveolar macrophages (most important), complement, alveolar lining fluid containing surfactant, phospholipid, IgG, IgE, IgA, sec IgA, Factor B, B&T cells
What helps to facilitate ingestion of microorganisms by alveolar macrophages?
IgG opsonization (slower phagocytosis if nothing can opsonize)
What do alveolar macrophages do once they have phagocytosed? (2)
- Present antigens on its surface activating B and T cells -> further activation of macrophages & prod of antibody 2. Release factors to stim immune response
2 ways microorganisms get around alveolar macrophages (general)
- kill them 2. survive inside them
Mechanisms to avoid phagocytosis (5)
capsule, toxin prod, large size (parasites & fungi), enter cells, mimicry
What toxins might a microorganism produce to avoid phagocytosis?
cytotoxins, leukocidins, exotoxin
Mechanisms to survive in a phagocyte (4)
Inhibition of lysosome fusion w phagosome, escape phagosome, resistance to digestion, growth in phagocyte
How does Legionella pneumophila handle alveolar macrophages?
Grows in the phagocytic ell
How does the influenza virus deal with alveolar macrophages?
Escapes the phagosome
Two major bacteria that utilize capsules to avoid phagocytosis?
S. pneumo and H. flu
Unilateral vs bilateral pneumonia suggest what?
Bilateral: hematogenous spread. Unilateral: transmitted via bronchioles
How might exogenous penetration or contamination of the lung occur?
Accident/trauma or surgery
By what microorganism-dependent mechanism might pneumonia result in fever and septic shock?
Endotoxin from gram negative
Common causes of bronchitis (8)
Influenza viruses A and B, parainfluenza viruses, adenovirus, respiratory syncytial virus (RSV), rhinovirus, coxsackievirus groups A and B
Fever with bronchitis is suggestive of what type of microorganism (general)
Bacteria
What level of the respiratory system is affected in bronchiolitis? (What is the cutoff)
Airway down to bronchioles but not involving alveoli
How can RSV be diagnosed? Who would this be done for?
Antigen tests of nasal washings, done for hospitalized children and those at risk for severe disease
What treatment options for RSV bronchiolitis are available for high risk children?
RespiGam (IG vs RSV) or palivizumab (humanized mab vs RSV)
Influenza: mild strain and strains causing most epidemics
Mild: C
Epidemics: A & B
Presentation of influenza
sudden onset high fever, chills, rigors, HA, congested conjunctiva, extreme prostration, myalgia, non-prod cough
Influenza sx usually only seen in children (2)
Diarrhea, vomiting
Clinical course of influenza
fever 3-4d, recovery w/in 1 week though cough and tiredness may be 2+ weeks
Influenza -> bact pneumonia 2* infection most common organisms (4)
Staph aureus, H flu, Strep pneumo, Strep pyogenes
Timing of being contagious
1 day before symptoms til ~5 days after onset.
How can you differentiate influenza from the common cold?
Flu: high fever. Common cold: generally afebrile.
Clinical course of pertussis
Incubation 7-10d, increasing severity of cough for 1-2w -> 2nd phase: episodic sudden cough 2-4w
Lab dx of pertussis (3 options)
narsophary aspirates plated on Bordet-Gengou medium, IF staining, ELISA
Lab abnormality often seen in pertussis in children
WBC shows lymphocytosis (weird for bacterial)
Treatment of pertussis
Erythromycin if before phase 2, otherwise supportive
Pertussis prophylaxis
All close contacts treated wtih antibiotics regardless of immunization status
Most common causes of typical pneumonia (5)
Most common: strep pneumo
Others: Klebsiella, H. flu, Moraxella catarrhalis, Staph aureus
How does clinical presentation of atypical pneumonia differ from typical?
Gradual onset of dyspnea and cough (non-prod). More prominent extrapulm signs e.g. HA, sore throat, diarrhea
3 major causes of atypical pneumonia
Mycoplasma (walking pneumonia), chlamydia, legionella
What types of atypical pneumonia are more common in young adults? Assoc sx (2)
Mycoplasma pneumonia and chlamydia pneumonia. Often w pharyngitis and milder whereas Legionella can be quite severe
Viral cause of pneumonia in children
RSV, influenza
Viral cause of pneumonia in immunocomporomised
CMV
Cause of pneumonia in patients with chronic corticosteroids? Manifestation?
Nocardia. Fever, cough, cavities or nodules that can look like TB.
Most common causes of pneumonia in neonates
Strep agalactiae (GBS) and e.coli
Most common causes of pneumonia in children 6 weeks - 18 years
Viruses (RSV & influenza), mycoplasma pneumo, Chlamydia pneumo, strep pneumo
Most common causes of pneumonia in adults 18-40
Mycoplasma pneumo, chlamydia pneumo, strep pneumo
Most common causes of pneumonia in adults 40-65
Strep pneumo, H flu, anaerobic bacteria, viruses
Most common causes of pneumonia in elderly >65
Strep pneumo, viruses, anaerobic, H. flu, Gram neg rods
Most common causes of nosocomial pneumonia
Gram neg rods, staph aureus (MDR)
Most common causes of pneumonia in immunocompromised patients
Gram neg rods, strep pneumo, fungi, filamentous bacteria, pneumocystis jiroveci, viruses
Pneumonia special risks - gross aspiration
Anaerobes
Pneumonia special risks - alcoholics
Strep pneumo, klebsiella pneumo, anaerobes
Pneumonia special risks - IV drug use
Staph aureus
Pneumonia special risks - post viral secondary infection
staph aureus
Chronic steroids
nocardia spp
What is the most common cause of meningitis in newborns?
Strep agalactiae (GBS)
Virulence factor of strep agalactiae (1)
capsule
Clinical presentation of strep agalactiae
Neonatal meningitis, neonatal pneumonia, neonatal sepsis
How do neonates get strep agalactiae?
Present in maternal genital tract. Causes pneumonia within days or meningitis within weeks.
Classification of strep agalactiae (gram, hemolysis, bacitracin)
Gram + cocci, beta hemolytic, bacitracin resistant.
Treatment for strep agalactiae
Penicillin G
Mycoplasma pneumonia characteristics (gram, shape, microscopic appearance)
Gram staining doesn’t work. Pleomorphic, no cell wall. Resistant to beta lactams. Fried egg appearance.
Diagnosis of mycoplasma pneumoniae
Presence of cold hemagglutinin, fried egg, serology.
Treatment of mycoplasma pneumoniae
Erythromycin or tetracycline
Mycoplasma pneumoniae pathology
Adheres to ersp epithel, inhib ciliary motion, destroys mucosa. B cell response can -> autoreactive ab vs erythrocytes (IgM - cold agglutinins), brain, and heart.
Clinical presentation of chlamydia pneumoniae
Atypical pneumonia
Pathology of chlamydia pneumoniae
Obligate intracellular parasite (phagocytosed by macrophages). Lymphocytes respond -> local pulm edema, necrosis, hemorrhage
Diagnosis of chlamydia pneumoniae
Giemsa stain to see intracytoplasmic inclusions. Serology.
Treatment for chlamydia pneumoniae
Doxycycline
Staph aureus virulence factors
Protein A (grabs Fc portion), coagulase, hemolysins, leukocidins. Deeper infec w hyaluronidase, staphylokinase, lipase.
Treatment of staph aureus
Penicillinase-resistant penicillins or vanco
Legionella = common cause of ____ in _(group)__
comm-acquired pneumonia in elderly smokers
Legionella’s usual route of infection
Inhabits water reservoirs -> inhaled aerosols from resp devices and air conditioners
Microscopic happenings with Legionella
Pili -> adhesion to resp epithel. Alveolar macs phagocytose -> prolif in macs -> secrete PMN chemoattractants -> pontiac fever or Legionnaire’s disease (atypical pneumo, severe)
Legionella diagnosis
Poor gram stainer - use silver stain. Cultures on charcoal yeast extract with iron and cysteine. Serology.
Treatment of Legionella
Erythromycin
What has decreased the incidence of pneumocystis jirovecii pneumonia (PCP) in AIDS patients?
TMP-SMX prophylaxis at CD4+ count of <200
Diagnosis of pneumocystis jirovecii
Sputum silver stain. Bronchoalveolar lavage or lung bx. Cysts forming dark oval bodies.
Treatment of PCP
TMP-SMX or pentamidine
How do immunocompromised individuals get PCP?
jirovecii is inhaled by most during childhood -> latent in lungs -> immunocomp -> infec
Clinical presentation of nocardia asteroides
Pneumonia, abscesses in kidney and brain
Diagnosis of nocardia. What must it be distinguished from?
Gram + aerobe, weakly acid-fast. Presentation can resemble TB. Distinguish by beaded, filamentous growth.
Pathology of nocardia asteroides
Found in soil, inhaled. Phagocytosis -> intracellular prolif -> caseous granulomas -> pneumonia with cavitations. Hematog spread -> abscesses in kidney and brain
Treatment of Nocardia asteroides
TMP-SMX, surgical drainage of abscesses
Nocardia infection is common in
Immunocompromised patients, pts on corticosteroids.
