Lower Resp tract infections and pneumonia Flashcards
What are 3 defences of the resp tract?
- mucociliary escalator
- cough and sneezing reflexes
- Respiratory mucosal immune system: secretory IgA and IgG, alveolar macrophages, lymphoid follicles of pharynx and tonsils
What defines acute vs chronic bronchitis? What is the phase between the two?
Acute: viruses and bacteria, may lead to pneumonia and commonly in the winter and <5 yr olds
Sub-acute (between)
Chronic: At least 2 years, a consequence of repeated infections, irritation from smoking, can form the bases of COPD and pneumonia
What is pneumonia?
Infection of pulmonary parenchyma; the part of the lung tissue involved in gas exchange
What is characteristic of the pathology of pneumonia?
- Fluid-filled airspaces (more involving distal airspaces) creating a heavy, stiff lung and impairment of gas exchange
- results in inflammatory exudation
Name the scenarios where you could acquire pneumonia
- community-acquired
- hospital-acquired
- Aspiration pneumonia (inhale food, stomach acid, saliva in the lungs, slow onset)
- pneumonia in an immuno-compromised patient
Describe the 3 lung pathologies:
a) lobar pneumonia
b) bronchopneumonia
c) interstitial pneumonia
a) Respects the fissures
b) infection starts in airways (bronchi/bronchioles) and spreads to alveoli (most common)
c) lungs are globally infected, virus or toxin (more rare)
How would you classify pneumonia?
- by clinical setting
- by presentation (acute - chronic)
- by organism (virus, bacteria, fungus)
- by lung pathology
What are the predisposing factors for pneumonia? INSPIRATION
- immunosuppression
- neurological impairment of cough reflex
- secretion retention
- pulmonary edema
- Impaired mucociliary escalator
- resp tract infection
- antibiotics and cytotoxins used by CD8 cells to destroy infected cells
- Tracheal instrumentation
- impaired alveolar macrophages
- other
- neoplasia
What might you analyze to check for pneumonia and which 3 organisms would you more commonly see in community-acquired pneumonia and what features are associated with them?
Sputum culture
- streptoccocus pneumonia; elderly, co-morbidities, fever, pleuritic pain, pus
- klebsiella pneumonia; tend to be alcoholics and IV drug users
- hemophilis influenza; COPD
Name 3 atypical bacteria that may cause community-acquired pneumonia? What features are associated with them?
- Legionella: recent travel, smokers, exposure to aerosols, a notifiable disease
- Mycoplasma: young, extrapulmonary involvement, may present with rashes, joint pain, malaise, can cause pulmonary fibrosis
- Chlamydia species through contact with birds
Name 3 kinds of organisms that commonly cause pneumonia in hospital-acquired pneumonia
- Viruses: influenza, parainfluenza, resp syncytial virus
- Mixed infections
- Bacteria (hospital-acquired): staphyloccocus aureus, pseudomonas, Gram (-) enteric bacteria like coxiella
Name 3 things that commonly cause pneumonia in an immunocompromised host?
Candida, aspergillus, viruses
What makes you more at risk for acquiring Coxiella and klebsiella?
Coxiella: contact with animals
Klebsiella: thrombocytopenia, leucopenia
Which organism commonly causes lobar bronchitis? What is the pathology? What might you see on an X-ray?
Streptococcus pneumonia
Typical acute inflammatory response:
1. fibrin rich exudate
2. neutrophil and macrophage infiltration
X ray: lobar consolidation
What is hepatization?
When the lung tissue transforms into liver-like substance
Name 5 characteristics of acquiring bronchopneumonia
- seen with pre-existing disease
- if you have a viral infection
- aspiration pneumonia
- complication of COPD
- cardiac failure predisposes you as your interstitium is already filled with fluid
How would bronchopneumonia appear on a chest x-ray?
Patchy consolidation more in the bases of the lungs
Name 4 organisms likely to cause bronchopneumonia, what will help in deciding which one?
- streptococcus pneumonia
- staphyloccocus aureus
- anarobes
- coliforms
Use clinical context to decide
What are the complications of acute bacterial pneumonia?
Lung abscess, bronchiectasis, empyema (pus in the pleural cavity)
What makes a lung abscess so difficult to resolve?
May form a wall around it making aspiration difficult, may need 2-3 months of antibiotics to get through the wall
What is bronchiectasis and what is the consequence? What can you infer about the patient’s past?
Increased collection of mucus in permanently dilated alveoli, so the patient will always be prone to pneumonia as they have juicy cavities in their lungs
Means they either had CF or an infection when they were young
How might atypical pneumonia look on an x-ray
Patchy segmental filtrates usually on the lower lobes
How would viral pneumonia appear on an x-ray? What does severe viral pneumonia lead to?
Patchy or diffuse ‘ground-glass’ opacity, severe viral pneumonia leads to necrosis and hemorrhage into the lung parenchyma
Why does influenza commonly cause pandemics and epidemics? When is it most common?
As the virus is constantly mutating making variations of the virus (antigenic shift), common in the winter
What condition often predisposes you to aspiration pneumonia?
Neurological dysphasia; problems swallowing means more likely to aspirate exogenous material or secretions into the lungs
Name 5 common symptoms of pneumonia
- chills/fever/sweats
- cough
- hemoptysis
- dyspnoea
- anorexia and vomiting
Name 5 common signs of pneumonia
- wheeze
- crackles
- increased vocal resonance
- bronchial breath sounds
- dull percussion due to consolidation
Name 4 investigations you might do for pneumonia
- Chest x-ray
- FBC (platelets and white count)
- O2 saturation and blood gases
- Urea, liver function tests and CRP
When would you admit pneumonia?
More than 2 of the following:
- confusion
- urea >7mmol/L
- resp rate >30
- Low BP (systolic <90 or diastolic <60)
- Age >65
Name 4 methods you could attain a sample for microbiology (and 2 for bonus)
- blood tests
- sputum
- nose and throat swabs
- urine antigens for atypical organisms
+endotracheal aspirates and bronch-alveolar lavage
How would you base your decision on which antibiotic to prescribe?
Name 2 commonly used antibiotics for pneumonia and one commonly used antibiotic for legionella.
Based on the local guidelines:
2 commonly used: clarithromycin and penicillin
Legionella: levofloxacin
When would you inform ITU of a pneumonia patient?
- resp failure (going hypoxic)
- rising pCO2 - worsening acidosis
- hypotension despite fluids - the systemic inflammatory response causes vasodilation
What are some prevention steps against pneumonia?
Annual influenza immunization, and immunisation for vulnerable risk patients (chemoprophylaxis)
What is pneumocystis pneumonia and what organism commonly causes this?
opportunistic infection of immune-compromised patients, caused by pneumocystis jirovecii
How does whooping cough present and which organism commonly causes this?
Starts like a cold and develops into a cough sounding like a ‘whoop’, Bordetella pertussis
