Lower Respiratory Tract Infection and Pneumonia Flashcards
What is the microbial flora of the upper respiratory tract?
Common: Viridans Streptococci, Neisseria species, Anaerobes and candida species
Less Common: Streptococcus pneumoniae, Streptococcus Pyogenes and Haemophillus influenza
Others: Pseudomonas species and E.Coli
Where does the lower respiratory tract begin and what is it’s normal flora?
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.
What defences are there in the respiratory tract against pathogens?
- 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.
How can the normal defenses of the respiratory tract become compromised?
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.
What are the common causes of upper respiratory tract infections?
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
What is Bronchiectasis?
Bronchiectasis abnormal widening of the bronchi due to damage that cause a build-up on mucus and increased risk of infection,
What is bronchitis, how does it present, who normally gets it, how is it treated and what are the common causative organisms?
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.
What is Pneumonia?
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.
What is pneumonitis?
Inflammation due to other causes, such as physical or chemical damage is often called pneumonitis. (pneumonitis = non-infective inflammatory disease).
What are the survival rates of pneumonia and how does it present?
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.
How does the body respond to pneumonia?
There is acute inflammatory response with the build-up on an exudate that is fibrin rich. Neutrophils and macrophages both invade.
How do we classify different types of pneumonia?
- Community acquired, hospital acquired
- Presentation – acute or chronic
- By organism
- Lung pathology (lobar (a specific lobe is affected), bronchopneumonia, interstitial pneumonia.
What predisposing factors are there for pneumonia?
- Pre-existing lung disease
- Immuno-compromise
- Geography, season, epidemics
- Travel and exposure to animals
- Ventilator associated
What are the primary causative organisms for community acquired pneumonia (CAP)?
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.
What are the common symptoms for CAP?
Symptoms: shortness of breath, cough with or without sputum (yellow, rusty), fever, rigors, pleuritic chest pain (sharp chest pain), malaise, nausea and vomiting.
How do CAP patients present on examination?
On examination: pyrexia, tachycardia, tachypnoea, cyanosis, dullness to percussion, tactile vocal fremitus (vibration felt on the chest when speaking), bronchial breathing and crackles.
What tests and investigations should be done?
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.
How is Pneumonia managed?
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.
What complications can occur with CAP?
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.
What are the common causes of viral pneumonia and how do the viruses cause damage?
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.
When does Hospital acquired pneumonia usually occur and what normally causes it?
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
Wht is a bronchial lavage?
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.
What are the treatments for hospital acquired pneumonia?
With hospital acquired pneumonia the first treatment is always Co-amoxiclav, second line of treatment once in ITU is pipperacilin/tazobactum or meropenem.
What is aspiration pneumonia?
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.
What is lobar pneumonia and its causative organisms?
Pneumonia localised to a particular lobe/s of the lung.
Most often due to Streptococcus pneumoniae
What is broncho pneumonia and its causative organisms?
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
What is interstitial pneumonia?
Inflammation of the Interstitium of the lung (Alveolar epithelium, pulmonary capillary endothelium, basement membrane, perivascular and peri lymphatic tissues).
When someone has pneumonia what are the commonly associated clues linking their pneumonia to certain causative organisms?
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
Which type of pneumonias are patients with different immunosuppression susceptible to?
- Patients with HIV are susceptible to LRTI from PCP (pneumocystis pneumonia caused by fungi called pneumocystis jiroveci), TB and atypical mycobacterium.
- Patients with Neutropenia (low neutrophils) are susceptible to fungal infections causing pneumonia such as from Aspergillus species.
- Patients with bone marrow transplants are susceptible to cytomegalovirus infections.
- Patients with splenectomies are susceptible to encapsulated organisms such as S. pneumoniae and H. Influenzae and malaria.
How can we prevent pneumonia?
- 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
