Lower Respiratory Tract Infections Flashcards
Lower respiratory Tract infections:
Acute (5)/Chronic (3) LRTI.
Acute LRTI:
- Pneumonia
- Bronchitis
- Bronchiolitis
- Legionnaires disease
- Whooping cough
Chronic LRTI:
- Tuberculosis
- Aspergillosis
- Cystic fibrosis
Pneumonia: The basics Definition? Acquired? How many people die PA? presentation AT, T? importance of identification?
- An acute LRTI associated with recent developed radiological signs, infection of the lungs due to bacteria, virus or fungi.
- May be acquired in the community (CAP) or hospital (HAP); associated risk factors.
- Approximately 30,000 die PA in UK.
- May present Atypically or Typically
- May be caused by several organisms therefore accurate identification is essential to ensure appropriate treatment.
Classification of pneumonia:
- Community acquired pneumonia (CAP)
- Hospital acquired pneumonia (HAP)
- Aspiration pneumonia
- Recurrent pneumonia
Community Acquired pneumonia:
- Approx. percentage of cases per year?
- when is it seen?
- The stats: How many diagnosed at GP?
- how many admitted to hospital?
- how many die?
- how does age affect?
- Every year 0.5% to 1% of uk adults will have CAP (~320,000 - 640,000 people)
- Mainly seasonal.
- CAP is diagnosed in 5 -12% of patients presenting to their GP.
- 22- 42% admitted to hospital.
- 5 - 14% die in hospital
- 50& of death occur in patients over 84 years or more.
Typical pneumonia: signs and symptoms:
Predominately respiratory: most commonly in elderly, may occur spontaneously in young adults.
Signs:
- cough
- cyanosis
- Tachypnoea
- Tachycardia
Symptoms:
- Fever
- Muscle aches
- shakes/rigor
- dsypnoea
- sputum production (rust coloured)
Micro-organisms most commonly associated with Typical pneumonia CAP:
- Common (1 + characteristic)
- Uncommon (3)
Most common bacteria:
- Streptococcus pneumoniae (diplococcus gram +ve)
Less common:
- Haemophilus influenzae
- Staphylococcus aureus (CF)
- Pseudomonas aeruginosa (CF)
Atypical pneumonia: signs and symptoms:
Predominately not respiratory. -common in very young and very old.
- S.pneumoniae not recovered from culture.
Signs:
- Rash
- Cyanosis
- Tachypnoea
- Tachycardia
- Dry cough
Symptoms:
- Headache
- Confusion
- Diarrhoea
- Incontinence
- No sputum
Micro-organisms associated with atypical CAP:
- Most common (1)
- Less common (3)
- Don’t forget the viruses
Most common:
- Mycoplasma pneumoniae
Less common:
- Legionella pneumophilia (legionnaires disease)
- Chlamydophila psittaci (Psittacosis) (birds)
- Chlamydophila pneumonia
Viruses:
- Influenza A/B
- Rhinovirus
- Covid-19
Radiological differences between atypical and typical pneumonia:
- Typical
- Atypical
- Typical: Widespread consolidation
- Atypical: Patchy consolidation
Organisms that cause CAP and associated risk factors:
Risk Factor:
- Elderly/young, S.pneumoniae, M. pneumoniae, presents typical and atypical.
Smokers/travelers abroad, L.pnemoniae, present atypically.
Alcoholic/vagrants: S.pneumonia
Contact with animals/bird: Cl. psittaci, present atypical.
Hospital Acquired pneumonia: Stats:
- 3rd most common hospital acquired infection (Nosocomial) (23% HAI)
- Patient may present with typical/atypical symptoms as described previously.
Risk factors for HAP include: (3)
- Ventilation support: Klebsiella pneumoniae, Pseudomonas aeruginosa. (hospital flora): VAP ~48hrs or more following incubation.
- Immunosupression: organ transplants - aspergillus fumigatus
- immobility and vomiting: Aspiration pneumonia - oral bacteria e.g. viridians streptococci and anaerobic bacteria.
Treatment of pneumonia:
- Uncomplicated CAP?
- Severe CAP of unknown aetiology?
- Atypical Pneumonia (CAP/HAP)
- HAP?
- Uncomplicated CAP: Amoxicillin or erythromycin, moxifloxacin is used now the other two show resistance.
- Sever CAP of unknown aetiology: Cefuroxime and erythromycin
- Atypical pneumonia: Erythromycin
- HAP: Cefotaxime +/- Gentamycin.
Streptococcus pneumonia mechanism of pathogenicity:
- Most common where? CAP/HAP?
- Capsule?
- avoiding host defense?
- how many types of capsular.
- ~how many serotypes cause serious disease?
- Vaccine?
- S.pneumoniae: most common cause of CAP
- Capsule (A major virulence factor) (Polysaccharide)
- Antiphagocytic (evasion)
- 92 different capsular types; serotypes differ virulence.
90% pneumonia are caused by about 23 serotypes (used to develop vaccine PPSV23; Pneumococcal pneumoniae vaccine 23).
Mechanism of pathogenicity:
- Adhesion protein?
- Protection proteins? avoiding host defense. (2)
- Toxin released proteins (2)?
- CbpA: a major pneumoccocal adhesion protein (adhesin). The adhesion interacts with carbohydrates on pulmonary epithelial surface.
- PspA (protective antigen): inhibits complement-mediated opsonizations.
- IgA1 protease: Cleaves IgA1 the principle immunoglobulin isotype for the respiratory tract.
- Autolysin: (LytA, LytB, LytC): breaks peptide cross linking in cell wall peptidoglycan releasing cell wall components; massive inflammation and pneumolysin release.
- Pneumolysin: Toxin released during autolysis: inhibits neutrophil chemotaxis, phagocytosis, lymphocyte proliferation and immunoglobulin synthesis. `
