Lower Respiratory Tract Infection and Pneumonia

Question 1

What is the microbial flora of the upper respiratory tract?

Answer 1

Common: Viridans Streptococci, Neisseria species, Anaerobes and candida species
Less Common: Streptococcus pneumoniae, Streptococcus Pyogenes and Haemophillus influenza
Others: Pseudomonas species and E.Coli

Question 2

Where does the lower respiratory tract begin and what is it’s normal flora?

Answer 2

Lower respiratory tract begins at the trachea. Upper respiratory tract has organisms living in it as normal flora, in the lower respiratory tract there are no other microorganisms.

Question 3

What defences are there in the respiratory tract against pathogens?

Answer 3

• Muco-ciliary clearance mechanisms
• Nasal Hairs
• Cough and sneeze reflex
• Respiratory mucosal immune system – lymphoid follicles of the pharynx and tonsils, alveolar macrophages and secretory IgA and IgG.

Question 4

How can the normal defenses of the respiratory tract become compromised?

Answer 4

Poor swallow (CVA, muscle weakness and alcohol), abnormal ciliary function due to smoking and viral infection, abnormal mucus (cystic fibrosis), dilated airways (bronchiectasis) and defects in host immunity such as due to HIV, immunosuppression.

Question 5

What are the common causes of upper respiratory tract infections?

Answer 5

These are most commonly caused by viruses such as rhinovirus, coronavirus, influenza/parainfluenza and respiratory syncytial virus (RSV). Bacterial super infection common with sinusitis and otitis media and can lead to mastoiditis, meningitis and brain abscess.
•	Rhinitis (common cold)
•	Pharyngitis
•	Epiglottitis
•	Laryngitis
•	Tracheitis
•	Sinusitis 
•	Otitis media

Question 6

What is Bronchiectasis?

Answer 6

Bronchiectasis abnormal widening of the bronchi due to damage that cause a build-up on mucus and increased risk of infection,

Question 7

What is bronchitis, how does it present, who normally gets it, how is it treated and what are the common causative organisms?

Answer 7

Inflammation of medium sized airways, mainly in smokers, cough fever, increased sputum production and increased shortness of breath. CRX is normal. Organisms usually causing it are Viruses, S.pneumoniae, H.influenzae and M.catarrhalis. Treated with Bronchodilators and physiotherapy +/- antibiotics depending if it’s viral or bacterial.

Question 8

What is Pneumonia?

Answer 8

Inflammation of the lung alveoli. Pneumonia is a general term denoting inflammation of the gas-exchanging region of the lung, usually due to infection (bacterial or viral). Pneumonia is therefore an infection of the lung parenchyma.

Question 9

What is pneumonitis?

Answer 9

Inflammation due to other causes, such as physical or chemical damage is often called pneumonitis. (pneumonitis = non-infective inflammatory disease).

Question 10

What are the survival rates of pneumonia and how does it present?

Answer 10

20-40% admitted to hospital and 5-10% mortality. Presents with fever, cough, pleuritic chest pain and shortness of breath. Often localising signs and abnormal chest x-ray.

Question 11

How does the body respond to pneumonia?

Answer 11

There is acute inflammatory response with the build-up on an exudate that is fibrin rich. Neutrophils and macrophages both invade.

Question 12

How do we classify different types of pneumonia?

Answer 12

1. Community acquired, hospital acquired
2. Presentation – acute or chronic
3. By organism
4. Lung pathology (lobar (a specific lobe is affected), bronchopneumonia, interstitial pneumonia.

Question 13

What predisposing factors are there for pneumonia?

Answer 13

• Pre-existing lung disease
• Immuno-compromise
• Geography, season, epidemics
• Travel and exposure to animals
• Ventilator associated

Question 14

What are the primary causative organisms for community acquired pneumonia (CAP)?

Answer 14

Main organisms are: strep pneumoniae, haemophilus influenza, these first two are most common and described as typical. Any other organism that causes pneumonia are atypical.

Question 15

What are the common symptoms for CAP?

Answer 15

Symptoms: shortness of breath, cough with or without sputum (yellow, rusty), fever, rigors, pleuritic chest pain (sharp chest pain), malaise, nausea and vomiting.

Question 16

How do CAP patients present on examination?

Answer 16

On examination: pyrexia, tachycardia, tachypnoea, cyanosis, dullness to percussion, tactile vocal fremitus (vibration felt on the chest when speaking), bronchial breathing and crackles.

Question 17

What tests and investigations should be done?

Answer 17

Investigations needed: FBC, U+E, CRP, ABG and CXR.

Microbiological samples – sputum/induced sputum, blood culture, Broncho alveolar lavage fluid, nose and throat swabs or NPAs (viruses), urine (antigens test for legionella/pneumococcus) and serum for an antibody test.

Question 18

How is Pneumonia managed?

Answer 18

CURB-65 score, if they have: confusion, Urea > 7mmol/l, respiratory rate > 30, blood pressure < 90 systolic or < 60 diastolic and are older than 65 years. If 2-4 of these are true then manage them as severe.

Antibiotic if bacterial, type of antibiotic depends on probable infection i.e. is it CAP, Hospital acquired also what is their severity. Usually it is pneumococcal meaning you should use penicillin (or like) antibiotics. If hospital acquired you are more likely to be dealing with Gram negative bacteria and so should treat with Co-amoxiclav.

Question 19

What complications can occur with CAP?

Answer 19

Lung abscess, bronchiectasis and empyema (pus in the pleural cavity). If the patient fails to improve it could be due to proximal obstruction (tumour), resistant organism, failure to absorb antibiotics or immunosuppression.

Question 20

What are the common causes of viral pneumonia and how do the viruses cause damage?

Answer 20

Causative organisms: Influenza, parainfluenza, respiratory syncytial virus (RSV) and adeno virus. These cause damage to the cells lining the airways/alveoli by the virus itself or by the immune response. Fluid builds up in air spaces interfering with gas exchange.

In severe case there is necrosis and haemorrhage into the lung parenchyma.

Question 21

When does Hospital acquired pneumonia usually occur and what normally causes it?

Answer 21

Usually occurs when spending more than 48 hours in hospital, often previously on antibiotics, and may or may not have been using a ventilator.

Causative organisms:
•	Staph Aureus
•	Enterobacteriaciae
•	Pseudomonas species
•	Haemophilus Influenzae
•	Acinetobacter baumanii
•	Fungi such as candida

Question 22

Wht is a bronchial lavage?

Answer 22

Bronchial lavage (bronchoscope squirts liquid into small part of lungs then sucks it back up for examination) is used to differentiate between upper respiratory flora from lower respiratory flora.

Question 23

What are the treatments for hospital acquired pneumonia?

Answer 23

With hospital acquired pneumonia the first treatment is always Co-amoxiclav, second line of treatment once in ITU is pipperacilin/tazobactum or meropenem.

Question 24

What is aspiration pneumonia?

Answer 24

This is pneumonia caused by aspiration of exogenous material or endogenous secretion into the respiratory tract. It is common in patients with dysphagia, epilepsy, alcoholics and drowning. At risk groups are nursing home residents and people who overdose. The organisms causing it are mixed by usually Viridans streptococci and anaerobes. Treated with co-amoxiclav.

Question 25

What is lobar pneumonia and its causative organisms?

Answer 25

Pneumonia localised to a particular lobe/s of the lung.

Most often due to Streptococcus pneumoniae

Question 26

What is broncho pneumonia and its causative organisms?

Answer 26

Pneumonia that is diffuse and patchy. Infection starts in the airways and spreads to adjacent alveoli and lung tissue.
Streptococcus pneumoniae, Haemophilus influenza, Staphylococcus aureus, anaerobes, coliforms

Question 27

What is interstitial pneumonia?

Answer 27

Inflammation of the Interstitium of the lung (Alveolar epithelium, pulmonary capillary endothelium, basement membrane, perivascular and peri lymphatic tissues).

Question 28

When someone has pneumonia what are the commonly associated clues linking their pneumonia to certain causative organisms?

Answer 28

S.Pneumoniae - elderly, co-morbidities, acute onset and high fever

H.Influenza - COPD

Legionella - recent travel, young, smokers and multi system involvement

Mycoplasma - young, prior antibiotics, extra-pulmonaryi inolvement

S.Aureus - post-viral and IVDU

Chlamydia - contact with birds

Coxiella - animal contact specifically sheep

Question 29

Which type of pneumonias are patients with different immunosuppression susceptible to?

Answer 29

1. Patients with HIV are susceptible to LRTI from PCP (pneumocystis pneumonia caused by fungi called pneumocystis jiroveci), TB and atypical mycobacterium.
2. Patients with Neutropenia (low neutrophils) are susceptible to fungal infections causing pneumonia such as from Aspergillus species.
3. Patients with bone marrow transplants are susceptible to cytomegalovirus infections.
4. Patients with splenectomies are susceptible to encapsulated organisms such as S. pneumoniae and H. Influenzae and malaria.

Question 30

How can we prevent pneumonia?

Answer 30

• Flu vaccine – given annually to high risk patients and a pneumococcal vaccine every 5 years.
• Chemoprophylaxis – oral penicillin/erythromycin given to patients with high risk of LRTI such as Asplenic patients, and immunodeficiency’s.
• Smoking advice