09-11-22 – Respiratory Tract Infections 2 Flashcards
Learning outcomes
- Describe the normal host defence mechanisms of the respiratory tract and how these influence infection
- Detail the infective agents which cause respiratory tract infections
- Recognise and describe the clinical features of respiratory tract infections
- Define how to make a diagnosis of respiratory tract infections
- Identify the main treatment modalities for respiratory tract infections
What are considered respiratory tract infections?
What are the 3 main types of pathogens that cause respiratory infections?
- Respiratory tract infections are from the nose to the alveolus
- 3 main types of pathogens that cause respiratory infections:
1) Virus
2) Bacteria (typical’ vs ‘atypical’)
3) Other – other bacteria, Mycobacteria (TB, MOTT/NTM), Actinomyces, fungus (mould, yeasts), parasite
What are the 2 types of respiratory tract infections?
What are 5 examples of URTI?
What are 3 examples of LRTI?
What are 5 other respiratory tract infections?
- 2 types of respiratory tract infections:
- Upper respiratory tract infections (URTI)
1) Rhinitis
2) Sinusitis
3) Pharyngitis
4) Tonsillitis (Quinsy)
5) laryngitis - Lower respiratory tract infections (LRTI
1) laryngo-tracheo-bronchitis (LTB)
2) Bronchiolitis
3) Pneumonitis - 5 other respiratory tract infections:
1) Pneumonia
* Pneumonia is inflammation of the lungs, usually caused by a bacterial or viral infection.
* Classically lobar
2) Bronchopneumonia
* usually, bilateral
3) Empyema
* Collections of pockets of Pus in the pleural cavity
* Can form if bacterial infection is left untreated
4) Bronchiectasis
* Abnormal widening of the bronchi or their branches, which increases risk of infection
5) Lung abscesses
* Lung abscess is a type of liquefactive necrosis of the lung tissue and formation of cavities (more than 2 cm) containing necrotic debris or fluid caused by microbial infection.
* The formation of these cavities is called cavitation
* It can be caused by aspiration, which may occur during altered consciousness and it usually causes a pus-filled cavity
* Cavitating pneumonia - complication that can occur with severe necrotising pneumonia
* Mycosis (e.g Aspergillosis) - infection caused by Aspergillus, a common mould
What exacerbations of pre-existing diseases do we have to consider?
What are the tools needed for?
- Exacerbations of pre-existing diseases we have to consider:
1) COPD
2) Asthma
3) Bronchiectasis
4) Fibrotic lung disease
5) Infective vs non-infective exacerbations - Infections can provoke an inflammatory response, which can be damaging
- Tools required/needed to differentiate infection from inflammation
What 4 things do we have to consider in the treatment of RTIs?
What is infection outcome equal to?
- 4 things do we have to consider in the treatment of RTIs:
1) Source control – ensure we are dealing with source of infection
2) Consider the pathogen
3) Consider the host (immune system)
4) Consider the severity - Infection Outcome = pathogen x host (different hosts respond differently)
What 2 types of organisms may cause RTIs?
What do commensal organisms do?
What is an example of a condition caused by commensals?
What is an example of a commensal causing RTIs?
- RTIs may be caused by commensal organisms in the lung microbiome or respiratory pathogens
- Commensal bacteria act on the host’s immune system to induce protective responses that prevent colonization and invasion by pathogens
- Microorganisms frequently considered commensals can have a major role in the pathogenesis of pneumonia (Such as streptococcus pneumoniae)
- Another example is Staphylococcus epidermidis, which is a common inhabitant of the upper airways, but can cause disease under certain conditions
What 5 things do we have to consider with respiratory antibiotics?
- 5 Things we have to consider with respiratory antibiotics:
1) Spectrum of antibiotics (range of different microorganisms that an antibiotic or antimicrobial agent inhibits or kills them)
2) Route of administration
3) Bioavailability
4) Duration
5) Goal of treatment (cure, control, maintenance – immune modulation)
What are the 2 types of immune system?
How fast do they each respond?
How are each improved?
What does the 2nd have that the 1st does not?
- 2 types of immune system:
1) Innate immune system
* First line of defence
* Ready, prepared, and can respond rapidly
* Not improved by further exposure
1) Adaptive immune system
* Second line of defence
* Requires a period of time to generate activity and respond
* Improved by further exposure.
* The adaptive immune system has specificity and memory for pathogens it has previously seen, leading to faster and stronger responses against a reoccurring pathogen
What are 3 physical protections of the immune system?
What are 2 biochemical protections of the immune system?
- Physical protections of the immune system
1) Barriers e.g epithelia and skin
2) Movement e.g cilia
3) Trapping e.g mucus - Biochemical (toxic to invading organisms)
1) Low pH e.g sweat, stomach acid, vaginal secretions
2) Lysozyme (hydrolytic enzyme) secretion
What is sepsis?
What is septic shock?
What 2 factors are classified as septic shock?
What should we consider sepsis alongside?
- Sepsis is a syndrome that complicates severe infection and arises when the body’s responses to infection also cause serious injury to distal host tissues and organs.
- AKA dysregulated inflammation following infection
- Sepsis is the body’s extreme response to an infection
- Septic shock is a life-threatening condition that happens when your blood pressure drops to a dangerously low level after an infection
- Septic shock is when there is arterial hypotension (systolic BP <90 mmHg, MAP <65 mmHg, or reduction in systolic BP >40 mmHg from baseline) persisting for at least 1 hour, despite adequate fluid resuscitation, which will require vasopressors (vasoconstrictors) or
- Serum lactate >4mmol/L after adequate fluid resuscitation (caused by inadequate perfusion of tissue and organs)
- We need to consider sepsis alongside consideration of pneumonia & antibiotics
4 Standards of care:
- 4 Standards of care:
1) BTS guidelines of practice; BTS Audit
2) NICE Pneumonia Guidelines, 2014
3) British Infection Association (BIA) guidelines – see BTS/NICE
4) International guidelines
* European Respiratory Society – ERM (Monograph) on CAP, 2014
* ATS/IDSA Guidelines, 2019
How do we treat URTI?
Why is this?
What tests should we consider as part of treatment?
What is supportive treatment?
What are 3 special URTI diagnoses?
What are 3 special diagnoses we can make?
What are 3 underlying diagnoses for RTIs?
- We use supportive treatment for URTIs and probably not anti-biotics
- This is because it is likely caused by a virus, which can’t be treated using anti-biotics
- We should consider ENT (ear, nose, throat) review and direct nasendoscopy
- Supportive treatment is any medical treatment of a disease that only affects its symptoms, not the underlying cause
- 3 special diagnoses we can make:
1) Stridor
* Noisy breathing that occurs due to obstructed air flow through a narrowed airway.
* Stridor breathing is not in and of itself a diagnosis, but rather is a symptom or sign those points to a specific airway disorder
2) Croup
* A childhood condition that affects the windpipe (trachea), the airways to the lungs (the bronchi) and the voice box (larynx).
* Children with croup have a distinctive barking cough and will make a harsh sound, known as stridor, when they breathe in
3) Quinsy
* Abscess (a collection of pus) forms between one of your tonsils and the wall of your throat.
* This can happen when a bacterial infection spreads from an infected tonsil to the surrounding area.
* Quinsy can occur at any age, but most commonly affects teenagers and young adults.
- 3 underlying diagnoses for RTIs:
1) Allergy
2) Polyps
* Teardrop-shaped polyps often appear after chronic inflammation of the upper respiratory system.
* Small nasal polyps often go unnoticed, but larger polyps can interfere with breathing and your sense of smell.
* Polyps can trap mucous, preventing it from draining through the nose, leading to frequent sinus infections
3) Immunity
How do we treat LRTIs?
Why is this?
What do we need to do in this case?
What 4 other related morbidities should we consider?
- We use supportive treatment for LRTIs, and maybe anti-biotics
- This is because even though anti-biotics can be used, these conditions can be self-limiting and resolve themselves
- If we decide not to prescribe anti-biotics, we have to make a backup plan, where we can consider CXR, antibiotics, and referral
- 4 other related morbidities should we consider:
1) URT
2) LRT
3) Asthma
4) Chronic cough
How does pneumonia appear on imaging?
What treatment do we use for pneumonia?
How do we decide antibiotics used?
How long do we prescribe for?
What else should we consider?
What 6 other underlying diagnosis should we also consider?
- Pneumonia appears as consolidation in chest imaging
- For pneumonia, we use support treatment and antibiotics
- It is difficult not to use antibiotics even if the pneumonia is caused by a virus
- This because it is difficult to know if pneumonia is caused by just a virus or a virus and bacteria, where the streptococcus pneumoniae cant be cultured
- Our choice of antibiotics is based on the type of bacteria causing the pneumonia
- We typically prescribe for 5-10 days
- We should also consider admission
- 6 other underlying diagnosis should we also consider:
1) Allergy
2) Polyps
* Teardrop-shaped polyps often appear after chronic inflammation of the upper respiratory system.
* Small nasal polyps often go unnoticed, but larger polyps can interfere with breathing and your sense of smell.
* Polyps can trap mucous, preventing it from draining through the nose, leading to frequent sinus infections
3) Immunity
4) Co-morbidities
5) Bronchiectasis
6) COPD
What is empyema?
How can they form?
How do we treat empyema?
What is a better strategy than this if available?
What are 4 potential factors we have to support?
What are 2 underlying diagnoses do we have to consider?
- Empyema are collections of pockets of pus in the pleural cavity
- They can form if bacterial infection is left untreated
- To treat empyema, we definitely use antibiotics and we definitely drain using a chest drain
- A better strategy than this if available is surgery and/or a thoracoscopy
- Medical treatment is second choice, and will usually last about 6 weeks + antibiotics (ABX)
- 4 potential factors we have to support:
1) Comorbidities
2) Psycho-social
3) Pain (drain)
4) Oxygen - 2 underlying diagnoses do we have to consider:
1) Pathogen
2) Immunity
How does acute covid present?
How long is the pre-symptomatic stage?
What 3 things do we need to consider with acute covid?
How is suspected/mild covid treated different based on presence of (in picture – other comorbidities):
* Mild illness?
* Pneumonia?
* ARDS (acute respiratory distress syndrome)?
* Sepsis (severe sepsis/septic shock)?
- A majority of patients with acute covid have low or minimal symptoms of infection
- We also have to note the pre-symptomatic stage, which is about 3 days
- 3 things we need to consider with acute covid:
1) Mild illness (self-resolving) vs acute disease (subtype, severity)
2) Urgent/immediate treatment priorities
3) Ceiling of care
* Refers to the maximum level of care which the patient is set to receive,
* This is often a complex and sensitive decision reached between the patient, their family and the healthcare team responsible for the patient.
What is CURB65?
Describe the CURB65 flowchart?
How does CURB65 affect 30-day mortality rate?
What is another scale we can use?
- The CURB-65 is a severity score to predict mortality secondary to community acquired pneumonia
- We can also use the Pneumonia Severity Index (PSI)
