Pneumonia B&B Flashcards
What are the three patterns of pneumonia?
lobar: classic form, involves entire lobes or entire lung
bronchopneumonia: patchy inflammation of multiple lobules
interstitial/atypical: inflammatory infiltrate of alveolar walls only, more indolent course
what is the most classic form of pneumonia and how does it develop?
lobar pneumonia – bacteria in nasopharynx aerosolized to alveolus, enter alveolar type II cells —> pneumococci multiply in alveolus and invade alveolar epithelium
passed between alveoli via pores of Cohn —> inflammation/ consolidation of lobes, can involve entire lung
What are the four stages of lobar pneumonia?
- congestion (24h): alveolar capillaries dilate, bacterial exudate
- red hepatization (2-3d): “fresh” exudate of intact RBC/WBC, neutrophils, fibrin; pneumococci alive, lobes look red
- grey hepatization (4-6d): lobe is firm/grey, exudate with neutrophils/fibrin, RBC disintegrate, dying pneumococci
- resolution: enzymes digest exudate, Type II pneumocytes key for regeneration, little scarring
how does bronchopneumonia appear and what does it usually caused by?
patchy inflammation of multiple lobules
Most often caused by staphylococcus aureus
describe atypical or “walking” pneumonia
A.k.a. interstitial pneumonia: inflammatory infiltrate of alveolar walls only, more indolent course/ milder than strep pneumonia
caused by viruses such as legionella pneumophila, mycoplasma pneumoniae, and chlamydophila pneumoniae
[atypical because it is caused by atypical pathogens]
legionella pneumophila, mycoplasma pneumoniae, and chlamydophila pneumoniae are possible viral causes of what kind of pneumonia?
interstitial, pneumonia, a.k.a. atypical or walking pneumonia – atypical because it is caused by atypical pathogens
more indolent/milder than strep pneumonia
Inflammatory infiltrate of alveolar walls only
What are the most common pathogenic causes of pneumonia in neonates versus children?
neonates (<4 weeks): Group B strep, E. coli
children (<18 years): viruses (RSV), mycoplasma, chlamydia pneumoniae, streptococcus pneumoniae
What is the most typical cause of pneumonia in adults?
Streptococcus pneumonia - causes lobar pneumonia
in which patients is pneumonia caused by gram-negative rods such as klebsiella, E. coli, or pseudomonas most common?
Hospitalized patients
In which patients is pneumonia caused by staphylococcus aureus most common?
post-influenza pneumonia
Which microbe is associated with post influenza pneumonia?
Staphylococcus aureus
Which type of microbe is associated with aspiration pneumonia?
Anaerobes
What are the three usual and the three atypical causes of community acquired pneumonia, respectively?
usual: 1. Strep. pneumoniae, 2. H. influenza, 3. staph. aureus
atypical: 1. mycoplasma (dorms/barracks/closed communities), 2. chlamydia, 3. legionella (infected water)
which type of microbes usually cause nosocomial or hospital acquired pneumonia?
gram-negative bacteria, such as pseudomonas, Klebsiella, E. coli, enterobacter, acinetobacter
Ventilator-acquired pneumonia (VAP), healthcare-associated pneumonia (HCAP - nursing homes)
worse infection than community acquired pneumonia (stronger bugs)
What three drugs are typically used to manage uncomplicated community acquired pneumonia?
azithromycin, clarithromycin or doxycycline
*uncomplicated community acquired pneumonia implies there are no co-morbidities or recent antibiotic use and low community rates of resistance
What drugs are typically used to manage complicated community acquired pneumonia?
complicated community acquired pneumonia implies co-morbidities (COPD, diabetes, CHF, alcoholism, etc) or recent antibiotic use
use fluoroquinolone (levofloxacin), amoxicillin plus azithromycin
Describe the pathophysiology of ARDS (acute respiratory distress syndrome), which may be triggered by pneumonia
injury causes release of pro-inflammatory cytokines (TNF, interleukins) —> neutrophils and recruited to lungs and release toxic mediators (ROS, proteases)
—> damage to capillary/ alveolar epithelium —> protein escapes vascular space, fluid pours into interstitium
which of these is a possible trigger for ARDS?
a. sepsis
b. infection (pneumonia)
c. aspiration
d. trauma
e. acute pancreatitis
f. TRALI
all of these can trigger acute repository distress syndrome
sepsis is most common trigger
[TRALI = transfusion related acute lung injury]
what type of pneumonia can be a serious complication of ARDS?
ARDS = acute respiratory distress syndrome
treatment includes mechanical ventilation, which puts patient at risk for ventilation acquired pneumonia
which pathogen is known to cause nosocomial pneumonia in nursing homes and how does it present?
Legionella - initially mild pneumonia symptoms, can progress to severe pneumonia
G.I. symptoms, Dash watery diarrhea, nausea, vomiting, and abdominal pain
Hyponatremia (Na <130meq/L) is common
how can legionella be diagnosed as the cause of pneumonia? (how is it grown?)
does not gram stain well
use buffered charcoal yeast extract agar (BCYE): iron and cysteine added for growth, antibiotics to prevent competing overgrowth, silver dye
also urinary antigen test available (minutes)
Patient is an 89-year-old male living in a nursing home, presenting with mild cough, watery diarrhea, and confusion. Gram stain shows no bacteria. The patient responds well to fluoroquinolone and azithromycin. What is the most likely cause of their illness?
classic presentation of pneumonia, caused by legionella – does not Gram stain, spreads via contaminated water
Can cause nosocomial pneumonia in nursing homes
[confusion due to hyponatremia]
what microbe classically causes outbreaks of atypical pneumonia among college dorm residents and military recruits?
mycoplasma pneumonia
No cell wall (cannot Gram stain), CXR looks worse than symptoms, but can cause autoimmune “cold” hemolytic anemia (IgM to RBC antigen)
how does atypical pneumonia develop from influenza A or B viral infection?
major complication of influenza infection is secondary pneumonia by bacteria such as strep. pneumonia, staph. aureus, or H influenzae
presents as worsening symptoms after initial improvement, cause of death in patients infected by influenza virus
what pathogen is known for causing pneumonia in transplant patients on immunosuppressive drugs?
Cytomegalovirus (CMV) - “owl eye” intranuclear inclusions
this pathogen is seen in seasonal outbreaks (Nov-April) and is the most common cause of lower respiratory tract in illness in children and also causes viral respiratory infections in infants. What is?
RSV (respiratory syncytial virus): often starts as upper airway infection (runny nose), progresses to lower tract symptoms (wheezing)
—> bronchiolitis, pneumonia, acute respiratory failure
how are Ribavirin and Palivizumab used in the management of RSV, respectively? how do they work?
Ribavirin (treatment): inhibits synthesis of guanine nucleotides
Palivizumab (prevention): mAb of F (fusion) protein which causes respiratory epithelial fusion, used in pre-term infants (with high risk of RSV) [Prevention targeting F Protein for Pre-term infants]
Patient is a one year old female, presenting with fever and a runny nose, which has progressed to cough and wheezing. What is the most likely pathogen causing the illness?
classic case of RSV (respiratory syncytial virus): most common cause of lower respiratory tract illness in children
What occurs in aspiration pneumonia and who are the classic patients?
aspiration of microorganisms from oral cavity and nasopharynx to lungs (Klebsiella, Staph. aureus, anaerobes)
Classically debilitated nursing home patient or alcoholic
risk factors: reduced consciousness/anesthesia, seizures, Alkaholiks, dysphasia from neuromuscular weakness
*Clindamycin is first-line therapy
Patient is a 45-year-old male with a PMH of alcohol abuse presenting with lobar pneumonia. Marked inflammation/necrosis is noted as well as thick mucoid and blood tinged sputum described as “currant jelly.” What is the most likely pathogen?
most likely klebsiella (Gram neg. rod), via aspiration pneumonia
what type of microbes usually are found in lung abscesses and what is the typical antibiotic treatment?
predominantly anaerobes, the typical treatment is clindamycin
(peptostreptococcus, prevotella, bacteroides, fusobacterium)
lung abscess usually consequence of aspiration
which patients acquire pneumonia from pneumocystis jirovecci, and what kind of pneumonia does it cause?
*bonus if you can name first-line treatment
PCP causes diffuse interstitial pneumonia in immuno-compromised patients (classically HIV – AIDS defining illness)
yeast that is inhaled, cannot be cultured (must use silver stain on sputum)
TMP-SMX is first-line treatment
