Pneumonia Flashcards
Who does pneumonia most commonly affect
- Young children
- Elderly
- Immunocompromised
Which bacteria cause pneumonia
- Most commonly streptococcus pneumoniae
- Haemophilus influenzae
- Mycoplasma pneumoniae
- RSV,influenza,staphyloccous aureus, klebsiella pneumoniae, pneumocystis jirovecii
-The following cause atypical/walking pneumonia chlamydophilia pneumoniae,legionella pneumonia
How is pneumonia spread?
- Nasopharyngeal aspiration
- droplet spread
- Inhalation of airborne microorganisms
- Haematogenous spread
Describe the components of the respiratory immune system
- ) Mucociliary clearance: entrapment in mucus, ciliary escalator
- )Alveolar macrophages: phagocytosis, inflammation
- ) Neutrophils: phagocytosis
- )Complement&antibodies: opsonisation, agglutination
- )Lymphocytes: inflammation, activation of other immune cells
Describe the pathophysiology of pneumonia
- Alveoli with pus
- Impaired gas exchange
- SIRS
- Bacteraemia
What makes up the pus that fills the alveoli?
- Pathogen
- Congestion: vascular engorgement, intra-alveolar fluid
- Red hepatisation: exudation of RBCs, neutrophils, fibrin
- Grey hepatisation-Disintegration of RBC,persisting inflammatory cells
- Resolution
What is red hepatisation?
-Red cells,neutrophils &fibrin present in the alveoli
What is grey hepatisation?
- Follows red hepatisation
- The red cells have been broken down leaving a fibrinosuppurative exudate
How does the lung appear in pneumonia?
-Large & heavy
What are the symptoms of infection?
- Dyspnoea
- Cough
- Sputum+/- purulence
- Fever
What are the clinical signs of infection?
- Tachypnoea
- Tachycardia
- Hypotension
- Pyrexia
- Crackles
- Whispering pectoriloquy,increased tactile fremitus and vocal resonance
- Cental cyanosis
- Altered mental status
What investigations can we use when trying to diagnose pneumonia?
- Arterial blood gas( ABG)
- Chest X ray (CXR)
- Full blood count (FBG)
- U&E, CRP, liver function test (LFT)
- Blood & sputum cultures
- Viral PCR
- Atypical serology
- Urine Ag for Legionella & S.pneumoniae
What is systemic inflammatory response syndrome?
- Serious condition related to systemic inflmmation, organ dysfunction and organ failure
- Subset of cytokine storm in which there’s abnormal regulation of various cytokines
- Closely related to sepsis, in which patients satisfy criteria for SIRS and have a suspected or proven infection
What are the 4 SIRS criteria?
- Tachycardia(HR>90bpm)
- Tachypnea(RR>20 Breaths/min)
- Fever
- Hypothermia (temp>38 or <36)
3 additional criteria…
- Leukocytosis
- Leukopenia
- Bandemia
What are the 4 stages of pneumonia?
1.) Congestion days 1-2
2.)Red hepatisation dqays 3-4
3.) grey hepatisation days 5-7
4.)Resolution day 8-3 weeks
NB hepatisation refers to the lung taking on a lung like appearance
Outline the use of antibiotics in pneumonia
- Should be used within 4 hours
- Empirical (& broad spectrum if patient unwell) at intitiation, then narrow if specific organism cultured
- OP- Penicillin derivative
- IP moderate severity- penicillin derivative+ macrolide
- IP severe- iv Blactamase resistant Abx + macrolide
What is the role of S.pneumoniae in pneumonia?
- Most common pathogen
- Especially post influenza
- More common with splenic dysfunction
- Capsule that inhibits phagocytosis
- Pneumolysin-cytotoxic toxin
- Culture and urine Ag
- Usually very sensitive to penicillin
How is pneumonia managed according to the ABCDE method?
A-Ensure patent airway
B-Oxygen to maintain desired saturation range (mechanical ventilation)
C-IV fluids if required (inotropes, haemofiltration)
D-GCS
E-Analgesia, antipyretics, antibiotics
How do we diagnose pneumonia?
- Cytology- intranuclear or cytoplamic inclusion bodies
- Viral culture
- PCR
- Rapid Ag detection
- Serology
How are infections of the lung managed?
- Largely supportive
- Influenza-amantadine
- RSV-ribavirin
- HSV,VZV-aciclovir
What is the role of S.aureus in pneumonia?
- More common post influenza
- Common in IVDU-likely haematogenous spread
- increased risk of rapidly progressing necrosis and cavitation
- often associated GI Sx
- Has a variety of toxins-rarely develop toxic shock syndrome( superantigens that cause widespread T cell activation and cytokine release)
- Flucloxicillin
What is Legionnaire’s disease?
- A serious pneumonia caused by the legionnaire bacteria
- Contaminated water supply often seen in endemic outbreaks
- Resist intracellular killing by alveolar macrophages unless activated by Th cells
- Neuro Sx-confusion,agitation,ataxia, lethargy
- Gi Sx- watery diarrhoea, abdominal pain,
- other systems- myo/peri-carditis, cellulitis, pancreatitis
- Pontiac fever-flu-like, self limiting
Outline atypical pneumonia
- More systemic Sx( myalgia,fatigue,headache, often non-productive cough)
- CXR- often multilobar
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
Outline aspiration pneumonia
- Alcohol excess
- Dysphagia/GORD
What is CURB-65?
A scale for calculating the severity of pneumonia. Can be used to calculate mortality
Which factors are included in the CURB-65 scale
- Confusion, AMTS< OR =8
- Serum urea>7 mmol/L
- RR> OR = 30
- Systolic BP>90 or diastolic BP< OR= 60mmHg
- Age > OR =65
What are the different types of acquired pneumonia?
- Community acquired pneumonia
- Hospital acquired pneumonia
- Viral pneumonia
- Atypical pneumonia
- Aspiration pneumonia
What is the role of S.pneumoniae in pneumonia?
- Most common pathogen
- Especially post influenza
- More common with splenic dysfunction
- Capsule that inhibits phagocytosis
- Pneumolysin-cytolytic toxin
- Culture and urine Ag
- Usually very sensitive to penicillin
Outline hospital acquired pneumonia.
- Inhalation/aspiration/haematogenous
- More gram -ve organisms e.g Ecoli
- Increased risk of drug resistance
- Broader spectrum antbiotics e.g antipseudomonal penicillins, aminoglycosides, MRSA cover
Pneumonia may take advantage of an immunocompromised host; how may this host be brought about?
- Neutrophil defect: post chemo, AML, bacteria,filamentous fungi
- Antibody defect
- T cell defect
- High dose steroids
How can aspergillus cause pneumonia?
- Ubiquitous mould, inhaled
- Has toxic metabolites that inhibit macrophage and neutrophil function
- Immunosuppressed, allowing haematogenous spread
What is the role of nocardia in pneumonia?
- genus of bacteria
- Often affects patient with T cell dysfunction
- pneumonia with cavitation & abscesses, empyema or inflammatory endobronchial lesions
- Often concurrent non tender erythrmatous nodules that may drain purulent material
How can HIV make someone more prone to developing pneumonia?
- Increased risk of bacterial pneumonia
- Increased risk of infection with endemic mycoses. and more likely to be disseminated
- With low CD4 high risk of diseminated mycobacterium avium/ intracellulare
- cryptococcal pneumonia more likely to be symptomatic
How may a person become immunosuppressed ( thus making them more prone to pneumonia)?
- Malignancy
- Steroids
- Asplenia
- Diabetes mellitus
- CKD
List some of the differential diagnoses of pneumonia
- Malignancy
- vasculitides
- infarcted lung, PE
- Pulmonary oedema
What complications may arise from pneumonia?
- Septic shock
- Adult respiratory distress syndrome
- Parapneumonic effusion & empyema
- Cavitation &abscess
- MI
What is Legionnaire’s disease
-Contaminated water supply often seen in endemic
outbreaks – cooling towers, humidifiers, portable
water distribution
-Resist intracellular killing by alveolar macrophages
unless activated by Th cells
- Neuro Sx – confusion, agitation, ataxia, lethargy
-GI Sx – watery diarrhoea, abdominal pain, N,V
-Other systems – myo/peri –carditis, cellulitis,
pancreatitis
-Pontiac fever – flu-like, self limiting
How can we use a chest c-ray to diagnose different types of pneumonia
- ) bronchopneumonia- patchy areas spread throughout
- )lobar pneumonia- fluid localised to a single lobe
- ) atypical pneumonia- spread throughout the lung but concentrated in the peri-hilar region& reticular pattern (there will be more lined shape opacities in the chest c-ray_
which examinations will help in the diagnosis of pneumonia
- Dullness to percussion: indicates lung consolidation
- Tactile vocal fremitus:more vibrations from pts back on repeating certain phrases cos sound travels better through the fluid filled consolidated tissue than the air filled healthy tissue
- bronchophony &egophony may be heard
