Pneumonia Flashcards
Pneumonia
is infection of the terminal air sacs (“alveoli”) and tissue of the lung.
how is pneumonia distinguished from lower respiratory tract infections (LRTI)
symptoms and signs (crackles)
Classification
- Community acquired
- Hospital acquire
- Opportunistic pneumonia
why is pneumonia severe and life threatening
Since the alveoli are the main air-exchange surface for replenishing the blood oxygen levels, infection and damage to the alveoli in viral and/or bacterial pneumonias can be severe and life-threatening.
the lower part of the respiratory tract is virtually ……….. despite the large numbers of microorganisms present in the upper airway and in inspired air.
sterile
host defence mechanisms exist to maintain this sterile environment
- Cough reflex that guards the lower respiratory tract from respiratory secretions.
- The mucociliary escalator is another mechanism.
The mucociliary escalator is another mechanism.
Cilia (tiny hairs in the mucosa of the respiratory tract) bind microorganisms that are inhaled and waft them upwards and out; this greatly reduces the number of organisms entering the lower respiratory tract.
what can reduce the efficacy of the mucociliary escalator
Cigarette smoking, narcotics and alcohol consumption can reduce the efficiency of this important defence mechanism.
Recent respiratory viral infections can also affect the function of the mucociliary barrier.
nonspecific cellular and humoral factors produced in the lung to protect against infection
- IgA
- Complement
- Neutrophils and macrophages that are able to destroy many potential respiratory pathogens by binding, engulfing, or directly killing them.
- The recruitment of macrophages from the reticuloendothelial system
The recruitment of macrophages from the reticuloendothelial system
especially the spleen, is particularly important for destroying capsulated organisms such as S. pneumoniae and H. influenzae, and therefore patients without a functioning spleen are particularly susceptible to these organisms.
Patient risk factors
- Weakened immune system
- Being hospitalised or ventilated
- Asplenic (encapsulated bacteria)
- Having chronic condition including COPD, structural lung disease and heart disease
- Smoking
main causative pathogens
streptococcus influenzae and hameophilus influenzae
streptococcus pneumoniae
haemophilus influenzae
Patient symptoms
- Chest pain when you breathe or cough
- Confusion or changes in mental awareness (age 65 and older)
- Cough
- Tachypnoea
- Tachycardia
- Fatigue
- Fever, sweating and shaking chills
Mechanism of infection
1) When viruses and bacteria that are commonly found in a child’s airways are inhaled
2) Spread via air-born droplets from a cough or sneeze
Pneumococci, characteristically in pairs (diplococci), multiply rapidly in alveolar spaces and induce extensive oedema. They also incite an acute inflammatory response in which neutrophils and congestion are prominent. As the inflammatory process progresses, macrophages replace the neutrophils and ingest debris. The process usually resolves.
management of infection: diagnosis
X-ray and sputum culture
X-rays show 3 patters
lobar pneumonia
bronchopneumonia
interstitial pneumonia
Lobar pneumonia
is pulmonary consolidation (white patches) demarcated (set the boundaries) by border of lung segment or lobe
Bronchopneumonia
seen as a patchy consolidation around larger airways
Interstitial pneumonia
fine area of shadowing in the lung fields. No sputum production at presentation
Mycoplasma
Legionella (atypical)
Viral
first line antibitic treatment
Beta lactam- Amoxicillin (PO TDS for 5 days)
Inhibit cell wall synthesis
amoxacillin
inhibits cell wall synthesis
if penicillin allergy
doxycycline orally 200mg D for 5 days
antivirals: adenovirus or herpes
acyclovir
antivirals: influenza
tamiflu
Outcome of infection
- Resolution
- Sepsis
