Case 12 - Pneumonia and TB Flashcards
What are normal host defences against respiratory tract infections?
Epithelium - cilia, mucus, antimicrobials
Mechanical - nasal hairs, turbinate bones, coughing, sneezing
Inflammatory cell recruitment
Immunity
Specific pathogen recognition
What is humoral immunity?
Mediated by B cells
Antigens presented to B cells
Plasma cells made > make antibodies that recognise and bind to, antigens on the pathogen’s surface
They can then mark the cells out for phagocytosis by macrophages or opsonisation
What is cell mediated immunity?
Mediated by T cells
Antigens are presented by dendritic cells and macrophages, that then induce clonal expansion of T cells
T cells can be cytotoxic (CD8 directly destroy pathogen), or helper cells (CD4 activate the plasma cells with cytokines to produce antigen-specific antibodies)
What are signs and symptoms of pneumonia?
Depends on the organism causing it:
- Sputum production - in pneumonia, purulent; in pneumococcal, red rusty
- Cough
- Fever
- Arthalgia/myalgia - in legionella and mycoplasma
- Abdo pain
- SOB
- Hameoptysis
- Anorexia
- Crackles in lung fields
- Dullness to percussion
What is the pathophysiology of pneumonia?
An organism infects the alveolar sac
Immune cells flock to the site of infection
Inflammatory exudate is produced which reduces gas exchange and fills the lung interstitium along with neutrophils
May be obstruction caused by the exudate
Over time the inflammation should reduce, but in some may leave lasting damage e.g. fibrosis or abscess
What do you want to ask in a cough history?
Duration Productive Any blood SOB Fever Night sweats Chest pain Wheeze Myalgia
What are atypical and typical organisms?
Typical can be cultured, atypical are unable to be cultured ie. they are intracellular and thus need to be treated with abx that get into the cell like macrolides
What are common causes of children’s CAP?
Depends on the age:
Neonates - E.Coli, group B. Strep, Listeria
1-6 months - RSV, Stap Aureus
6 months - 5y - RSV, parainfluenzae virus
What are typical and atypical bacterial causes of CAP?
Typical: Streptococcus pneumoniae (seen in pairs) Haemophilius Influenza Klebsiella pneumoniae Staph Aureus (bunch of grapes appearance)
Atypical:
Mycoplasma pneumoniae
Legionella
Chlamydia strains
What are viral causes of CAP?
Influenza
Adenovirus
Parainfluenza
RSV
Diagnosis made with PCR after throat swab
What are fungal causes of CAP?
Pneumocystis jivorecii
What is HAP?
New onset of symptoms alongside CXR changes within 48 hours of hospital stay
What is early and late onset HAP?
Early is within 5 days of discharge - these are usually community and antibiotic sensitive
Later is greater than 5 days discharge - usually more resistant to treatment
RFs for HAP?
Ventilator required ICU admission Extended period of hospital stay Underlying respiratory disease Severe illness/comorbidities Abdo surgery/vomiting/aspiration
What are bacterial causes of HAP?
E.Coli Klebsiella Enterobacter Staph Aureus Pseudomonas
How does pneumonia present in the immunosuppressed?
Will often be more rare organisms - more likely to be commensal or fungal etc.
Organism that wouldn’t usually cause an infection in immunocompetant patients
Can lead to complications and severe symptoms more quickly
What is aspiration pneumonia?
When an object is aspirated, it will block air entry to one part of the lung
Anaerobic bacteria become pathogens
Chemical pneumonitis
Those with swallowing problems and low GCS are at risk
Usually RLL
What is CURB-65?
Used to assess the severity of CAP
Confusion (new onset) Urea >7 RR 30+ BP (<90 systolic, diastolic <60) Over 65
One point for each
0-1 = low 2 = moderate 3-5 = high
When should you admit a patient with pneumonia?
Low can often be managed in the community
In someone with CURB-65 of 2+, should admit
Also those who can’t manage at home
Those with severe signs
Those who need further investigation
What investigations should you do for pneumonia?
FBC- WCC U and Es - contrast Gas exchange tests CRP - inflammation Blood cultures - and microscopy for mycoplasma Urine culture and antigen testing for legionella and Pneumococcal Throat swab for PCR Sputum cultures Bronchial lavage if unable to get sputum sample HIV test CXR CT potentially USS for pleural effusion
How do you treat pneumonia?
For mild - 5 days amoxicillin
Broad spectrum antibiotics - amoxicillin and clarithromycin
Add tazocin if not working
Then narrow down based on culture and sensitivity
Can be given IV if severe
Step down to oral when apyrexial for 24 hours
What are the complications of pneumonia?
Para-pneumonic effusion Abscess PE Metastatic infections SE of antibiotics Sepsis
What causes TB?
Mycobacterium strains
All types cause varying illnesses and are acid and alcohol fast
Mycobacterium tuberculosis causes TB
How can TB be transmitted?
Through air droplets:
Coughing
Sneezing
Breathing
Also post-mortem, abscess and through infected milk
Stop becoming infective 2 weeks of completed treatment
