Pneumonia B&B

Question 1

What are the three patterns of pneumonia?

Answer 1

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

Question 2

what is the most classic form of pneumonia and how does it develop?

Answer 2

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

Question 3

What are the four stages of lobar pneumonia?

Answer 3

1. congestion (24h): alveolar capillaries dilate, bacterial exudate
2. red hepatization (2-3d): “fresh” exudate of intact RBC/WBC, neutrophils, fibrin; pneumococci alive, lobes look red
3. grey hepatization (4-6d): lobe is firm/grey, exudate with neutrophils/fibrin, RBC disintegrate, dying pneumococci
4. resolution: enzymes digest exudate, Type II pneumocytes key for regeneration, little scarring

Question 4

how does bronchopneumonia appear and what does it usually caused by?

Answer 4

patchy inflammation of multiple lobules

Most often caused by staphylococcus aureus

Question 5

describe atypical or “walking” pneumonia

Answer 5

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]

Question 6

legionella pneumophila, mycoplasma pneumoniae, and chlamydophila pneumoniae are possible viral causes of what kind of pneumonia?

Answer 6

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

Question 7

What are the most common pathogenic causes of pneumonia in neonates versus children?

Answer 7

neonates (<4 weeks): Group B strep, E. coli

children (<18 years): viruses (RSV), mycoplasma, chlamydia pneumoniae, streptococcus pneumoniae

Question 8

What is the most typical cause of pneumonia in adults?

Answer 8

Streptococcus pneumonia - causes lobar pneumonia

Question 9

in which patients is pneumonia caused by gram-negative rods such as klebsiella, E. coli, or pseudomonas most common?

Answer 9

Hospitalized patients

Question 10

In which patients is pneumonia caused by staphylococcus aureus most common?

Answer 10

post-influenza pneumonia

Question 11

Which microbe is associated with post influenza pneumonia?

Answer 11

Staphylococcus aureus

Question 12

Which type of microbe is associated with aspiration pneumonia?

Answer 12

Anaerobes

Question 13

What are the three usual and the three atypical causes of community acquired pneumonia, respectively?

Answer 13

usual: 1. Strep. pneumoniae, 2. H. influenza, 3. staph. aureus

atypical: 1. mycoplasma (dorms/barracks/closed communities), 2. chlamydia, 3. legionella (infected water)

Question 14

which type of microbes usually cause nosocomial or hospital acquired pneumonia?

Answer 14

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)

Question 15

What three drugs are typically used to manage uncomplicated community acquired pneumonia?

Answer 15

azithromycin, clarithromycin or doxycycline

*uncomplicated community acquired pneumonia implies there are no co-morbidities or recent antibiotic use and low community rates of resistance

Question 16

What drugs are typically used to manage complicated community acquired pneumonia?

Answer 16

complicated community acquired pneumonia implies co-morbidities (COPD, diabetes, CHF, alcoholism, etc) or recent antibiotic use

use fluoroquinolone (levofloxacin), amoxicillin plus azithromycin

Question 17

Describe the pathophysiology of ARDS (acute respiratory distress syndrome), which may be triggered by pneumonia

Answer 17

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

Question 18

which of these is a possible trigger for ARDS?
a. sepsis
b. infection (pneumonia)
c. aspiration
d. trauma
e. acute pancreatitis
f. TRALI

Answer 18

all of these can trigger acute repository distress syndrome

sepsis is most common trigger

[TRALI = transfusion related acute lung injury]

Question 19

what type of pneumonia can be a serious complication of ARDS?

Answer 19

ARDS = acute respiratory distress syndrome

treatment includes mechanical ventilation, which puts patient at risk for ventilation acquired pneumonia

Question 20

which pathogen is known to cause nosocomial pneumonia in nursing homes and how does it present?

Answer 20

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

Question 21

how can legionella be diagnosed as the cause of pneumonia? (how is it grown?)

Answer 21

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)

Question 22

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?

Answer 22

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]

Question 23

what microbe classically causes outbreaks of atypical pneumonia among college dorm residents and military recruits?

Answer 23

mycoplasma pneumonia

No cell wall (cannot Gram stain), CXR looks worse than symptoms, but can cause autoimmune “cold” hemolytic anemia (IgM to RBC antigen)

Question 24

how does atypical pneumonia develop from influenza A or B viral infection?

Answer 24

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

Question 25

what pathogen is known for causing pneumonia in transplant patients on immunosuppressive drugs?

Answer 25

Cytomegalovirus (CMV) - “owl eye” intranuclear inclusions

Question 26

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?

Answer 26

RSV (respiratory syncytial virus): often starts as upper airway infection (runny nose), progresses to lower tract symptoms (wheezing)

—> bronchiolitis, pneumonia, acute respiratory failure

Question 27

how are Ribavirin and Palivizumab used in the management of RSV, respectively? how do they work?

Answer 27

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]

Question 28

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?

Answer 28

classic case of RSV (respiratory syncytial virus): most common cause of lower respiratory tract illness in children

Question 29

What occurs in aspiration pneumonia and who are the classic patients?

Answer 29

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

Question 30

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?

Answer 30

most likely klebsiella (Gram neg. rod), via aspiration pneumonia

Question 31

what type of microbes usually are found in lung abscesses and what is the typical antibiotic treatment?

Answer 31

predominantly anaerobes, the typical treatment is clindamycin

(peptostreptococcus, prevotella, bacteroides, fusobacterium)

lung abscess usually consequence of aspiration

Question 32

which patients acquire pneumonia from pneumocystis jirovecci, and what kind of pneumonia does it cause?

*bonus if you can name first-line treatment

Answer 32

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