Lower Respiratory Tract Infections Flashcards
Which 3 fungi are common in LRTIs?
Aspergillus
Candida
Pneumocystistis Jroveci
Definition of chronic bronchitis
Cough productive of sputum on most days during more than 3 months of 2 successive years
Chronic bronchitis is associated with what risk factor?
Smoking
Bronchiolitis occurs in which age group?
Paediatrics
Causative organism for bronchiolitis
RSV
Infection affecting the most distal airways and alveoli- formation of inflammatory exudate
Pneumonia
What are the 2 anatomical patterns of pneumonia
Bronchopneumonia
Lobar pneumonia
Patchy distribution of pneumonia centred on inflamed bronchioles and bronchi then subsequent spread to surrounding alveoli
Bronchopneumonia
Pneumonia affecting a large part, or entire lobe
Lobar Pneumonia
Causative organism of lobar pneumonia
S. Pneumoniae
4 types of pneumonia based on where it is acquired
Community acquired
Hosptial acquired
-Ventilator acquired
-Aspiration
Hospital acquired pneumonia devleops how soon after hospital admission
> 48 hrs
Organisms that cause pneumonia but are difficult to grow, not sensitive to penicillin and clinical presentation and treatment is different
Atypical organisms
Typical organisms causing pneumonia
Streptococcus pneumoniae Hamophilus influenzae Moraxella Catarrhalis S.Aureus Klebsiella penumoniae
Atypical organisms causing pneumonia
Mycoplasms pneumonia Legionella pneuomphilia Chlamydophilia pneuomoniae Chlamydophilia psittaci Coxiella burnetii
Atypical organism causing pneumonia:
Autumn epidemics every 4-8 yrs. Children and young adults. Rare complications include pericarditis, arthritis, ghuillian barre ascending polyneuropathy, peripheral neuropathy
Mycoplasma pneumoniae
Atypical organism causing pneumonia:
Mild pneumonia or bronchitis in adolescents and young adults.
Chlamydophila pneumonia
Atypical organism causing pneumonia:
Associated with exposure to birds- splenomegaly, rash, hepatitis, haemolytic anaemia and reactive arthritis on presentation.
Chlamydophilia psittaci
Atypical organism causing pneumonia:
Colonises water pipes. High fevers, rigors, cough, dyspnoea, vomiting, diarrhoea, confusion
Legionella pneumophilia
What are the 2 types of pneumonia that develop from influenza?
Primary viral pneumonia: rare- occurs in patients with pre-existing cardiac and lung disorders.
Secondary bacterial pneumonia: may develop after initial influenza (flu) presentation
What is the assessment for disease severity used in pneumonia?
CURB65
Confusion, urea, resp. rate >30, blood pressure 65
Antibiotic used to treat typical pneumonia
Amoxicillin or co-amoxiclav
Antibiotic used to treat atypical pneumonia
Clarithromycin (lincosamide)
Pneumococcal vaccination is what organisms?
Streptococcus pneumoniae
Describe the shape of mycobacteria
Slender, bacilli
Why are mycobacteria different to all other bacterial genera?
Unusual waxy cell wall (high lipid content)
Slower growing
What stains are used to identify mycobacteria?
Ziehl Neelson, phenol auramine
Another name for mycobacteria
Acid fast bacilli
Mycobacteria:
Intra/extracellular pathogens?
Chronic infections or latent infections?
Longer or shorter course of treatment?
Intra
Latent
Longer
What types of mycobateria cause TB?
M.tuberculosis
M.bovis
What atypical mycobacteria are associated with HIV?
M avium complex
Atypical mycobacteria
M.avium
M.kansasii
M.marium
How does M.marium infections present
Fish tank granuloma
Common site of primary TB infections?
Periphery of lung midzone
Name of the collection of macrophages in the hilar lymph nodes in primary TB where intracellular muliplication takes place
Ghon focus
Describe the structure of the tubercles in primary lymph nodes
Granuloma Cell-mediated immune response Central area of epitheloid cells and giant cells surrounded by lymphocytes Central area is caseous encrosis Fibrosis/calcification of lesions
In the acquisition of TB, when will you have a positive tuberculin skin test?
3 months after primary acquisition
When is TB reactivated
immunosuppressed
Pathogenesis of reactivating TB
Coalescing tubercles, central caseous encrosis and cavity develops in centre- increases organism load- increases risk of tranmission
Where does TB classically reactive?
Lung apices (mycobacteria require O2)
extra-pulmonary manifestations of TB
-necrotic tubercle erodes into blood vessel. e.g. meningitis. Disseminates to pleura, lymph nodes, kidneys, epididymis, bone, intestines, brain,pericardium etc
Diagnosis of TB meningitis
Chest X-ray, Skin testing, interferon y release assay:IGRA
Sputum samples for TB diagnosis
3 early morning specimens
When is a direct microscopy for acid fast bacilli smear positive?
> 5000 organisms per ml sputum
Standard treatment for TB
2 months: rifampicin, isoniazid and 2 others
next 4 months: rifampicin, isoniazid
Treatment for meningitis TB
12 months therapy
Name of the standard treatment for TB
Directly observed therapy short course (DOTS)
Multi-drug resistant TB is resistant to what?
Rifampicin and izoniazid
Extensive drug resistant TB is resistant to what?
Rifampicin, izoniazind and fluorquinolones
Name of the TB skin test
Mantoux tes- tuberculin skin test- positive test if skin indurates (bubble and fibrosed patch develops)- person has acquired TB if >5mm
Diagnostic test to look for T cells that recognise TB specific antigens and release gamma interferon
Interferon-gamma release assays
What does BCG stand for?
Bacille Calmette Guerin
What mycobacteria is given in BCG vaccine?
Strain of M.Bovis
What disease is caused by M.leprae?
Leprosy-Hansen’s disease
Where is M.leprae cultivated?
On the nine banded armadillo
2 clinical forms of M. leprae
Tuberculoid- macules/plaques develop on nerves
Lepromatous- subcutaneous tissue accumulation
The name of the blood test for TB
Interferon y gamma release assay (IGRA)
