Infectious Diseases Flashcards
Who is more exposed to having pneumonia?
Extremes of age, co-morbidities, pre-existing lung disease, lifestyle, iatrogenic
Where can pneumonia anatomically occur?
Lobar pneumonia and bronchopneumonia
What are the different types of acquired pneumonia you can have?
community acquired, hospital acquired, aspiration, immunocompromised, atypical pneumonia
What organisms are responsible for community acquired pneumonia?
strep. pneumoniae, haemophilus influenzae, mycoplasma
What organisms are people with pre-existing lung disease more likely to have with community acquired pneumonia?
pseudomonas, s.aureus, moraxella catarrhalis
What organisms are responsible for hospital acquired pneumonia?
pseudomonas, klebsiella, s.aureus, anaerobic bacteria
True/False:
is enterobacter a type of aerobic bacteria?
False:
anaerobic bacteria
Does aspirated content preferentially go down the left bronchus?
No it goes down the right bronchus
What does aspiration increase the risks of?
Stroke
What organisms are responsible for immunocompromised pneumonia?
pneumocystis jirovecii, myobacteria
aspergillus
viruses e.g. HSV
True/False:
Coxiella burnetti is from birds
False:
Coxiella burnetti is from animal fluids (often sheep)
Chlamydia Psitacci is from birds
How else is Coxiella burnetti called?
Q-fever
What are the 2 types of atypical pneumonia causing organisms other than Coxiella burnetti and chlamydia psitacci?
Legionella (infected water), chlamydophilia pneumonia
What is pneumonia…
infection of the lungs
What is the most common organism that causes pneumonia?
staphylococcus pneumoniae
How does pneumonia spread from person to person?
By droplets
How does lobar pneumonia occur?
involves whole lung lobe, undergoes acute inflammatory response
How does bronchopneumonia occur?
Usually occurs with pre-existing lung disease- starts in airways then moves to lung lobes
What is the aetiology for pneumonia?
cold, pre-existing lung disease (e.g. p.fib as air isn’t circulated well)
What are the presenting symptoms for pneumonia?
cough, pleurisy, dyspnoea, purulent sputum, malaise, anorexia, myalgia, sweats, fever, confusion, diarrhoea
What are the physical signs of pneumonia?
fever, cyanosis, rigors, herpes labialis, crackles, tachypnoea
Ix for pneumonia?
bloods, serology, sputum sampling, urea, CXR (consolidation)
What index is used to measure the severity of pneumonia?
Confusion Urea (>pH7) Resp rate (>30/min) Blood pressure (diastolic <60, systolic <90) 65
1 point for each: 3= ICU, 2= hosp admin
What is the tx for bacterial pneumonia?
Antibiotics: Amoxicillin, doxycycline
O2 (if stats <92%)
fluids
What is to be noted for pneumonia severity scoring beyond the CURB65 score?
temperature, cyanosis (paO2<8pka?), WBC
What are complications of pneumonia and when are these more likely to occur..
resp failure, parapneumonic effusion, empyema, chronic infection, organising pneumonia
More likely to occur if pneumonia caused by unknown organism/ host doesn’t respond to penicillin
Where are the majority of cases of TB found?
Africa and Asia
What are the 3 categories of TB?
Latent, 1y progressive TB, 2y (reinfection of TB)
What are the types of TB from most dangerous to least dangerous?
Miliary, meningeal, pulmonary, localised extra pulmonary, lymph nodes
What is TB…
airborne infection spread via droplets
Where is TB more likely to settle in the lung?
Apex
What organism causes TB and what does it attack?
Myobacterium TB complex: M.TB, M.Bovis, M.africanum, M.Microti
Attack phagocytes
How does 1y TB become latent?
if bacilli cleared before it reaches lymph nodes then no infection.
if this doesn’t happen then formation of Ghon focus occurs (cavities). In the meantime macrophages take bacilli to Hilar lymph nodes causing lymphadenopathy.
BOTH of these mechanisms from Ghon Complex which contains bacilli (hence infection) in granuloma indefinitely
How long does the Ghon Complex formation take to form?
4-6 weeks
What is Latent TB?
non-infectious, not active TB that may persist for years
What is 1y progressive TB…
resembles acute pneumonia, spreads through lymph and blood hence affects extra pulmonary organs e.g. CNS, GI tract etc.
Where does 1y progressive TB consolidation normally occur?
mid & lower lobe
How does Latent TB > 2y (reactivated) TB?
reduced host immunity/ re-exposure a hypersensitivity reaction occurs causing tissue destruction = cavitation & caveating granulomas
Where does 2y TB consolidation normally occur?
upper lobes
True/False:
Risk factors associated to TB are contact with high risk groups, immune deficiency, lifestyle (e.g. drugs), genetic susceptibility
True
What are the factors that promote reactivation of disease?
HIV, diabetes mellitus, renal disease, malnutrition
What are the presenting symptoms of TB?
cough & sputum, haemoptysis, wt loss, fever & sweats, hoarse voice if laryngeal involvement
True/False:
Latent TB disease causes fever & pleuritic pain
False:
Usually asymptomatic
Ix for latent TB…
tuberculin skin test: memory to mycobacteria proteins
interferon gamma release assays: blood sample mixed with TB antigen proteins
Ix for active TB…
CXR: 1y= patchy consolidation, hilar lymphadenopathy, 2y= cavities, miliary= millet seeds
3 sputum samples: Zehil-Neelsen stain (turns bacilli red on blue background)
bronchoalveolar lavage/ biopsy
culture and staining
What is PCR good for in TB ix?
identifying CNS TB and rifampicin resistance
Tx for TB?
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
What are treatment and timings for active & latent TB?
active: 6 drugs, 6 months
latent: 4 drugs, 3-6months
What are some side-effect to TB tx?
colour blindness, peripheral neuropathy, gout, all are hepatoxic
What are the complications of TB?
everyone has to be screened for TB that have been in touch with patient, drug resistance
Name 2 chronic infections?
Abscess & Bronchiectasis
Why do chronic infections occur…
- Abnormal host response (e.g. immunodeficiency-HIV)
- Abnormal innate host defence (damaged bronchial mucosa, abnormal cilia, abnormal secretions)
- Repeated Insult (e.g. drain)
What damages bronchial mucosa?
smoking, pneumonia, malignancy
What 2 conditions cause abnormal cilia?
Kartagener’s Syndrome & Young’s Syndrome
What condition causes abnormal secretions?
CF
When are abscesses most common?
After aspiration bronchopneumonia, streptococcus pneumonia, or with TB cavities
What organisms can Abscesses be caused by?
Bacteria e.g. e.coli, streptococcus, staphylococcus
Fungi e.g. aspergillus
True/False:
Abscess is a localised collection of pus in the pleura?
False
that is an empyema.
Abscess is a localised collection of pus in the lung tissue
What are the triggers of an abscess?
aspiration, TB, non-resolved pneumonia, septic emboli with s.cocci (PWIDs= normally multiple abscesses), foreign bodies
What are the presenting symptoms of abscess?
slow resolve of pneumonia, cough, sputum production, swinging fever, haemoptysis, malaise, wt loss
True/False:
Abscess sputum stinks
True :o
What are the signs of an abscess?
clubbing and crepitations
What are the Ix for abscess…
CT*, CXR, bronchoscopy, blood, sputum culture
abscess Tx…
drainage, antibiotics (prolonged: 4-6 weeks)
What is bronchiectasis caused by?
50% idiopathic, 50% caused by other diseases
What organisms cause bronchiectasis?
H. influenzae, s.aureus, pseudomonas
what is bronchiectasis?
permanently dilated airways susceptible to collapse
Pathophysiology of bronchiectasis…
chronic inflammation of bronchial wall > permanent dilation of bronchioles due to destruction of elastic and muscular component of bronchial walls = build up of mucus > retained inflammatory secretions and microbes so recurrent damage (CYCLE)
most common causes of bronchiectasis…
COPD, TB, congenital, intrinsic, extrinsic (tumour), granuloma, RLD, immunodeficiency
Presenting symptoms of bronchiectasis…
cough with purulent sputum, haemoptysis, recurrent infection, SOB, wt loss fever
Signs of bronchiectasis?
coarse crackles, clubbing
Ix for bronchiectasis..
HRCT (signet ring sign visible), CXR, sputum culture
What is the signet ring sign?
airway diameter larger than pulmonary artery
bronchiectasis tx…
airway clearance (physio, bronchodilators, smoking cessation), anti-inflammatories, antibiotic treatment (2 weeks)
Bronchiectasis complications?
chronic breathlessness
What is bronchiectasis prognosis?
variable, worse if low FEV1 & infected by pseudomonas
Name another 2 chronic infections?
septic emboli, chronic bronchial sepsis
What is unique about chronic bronchial sepsis?
has all the hallmarks of bronchiectasis except no evidence on CT- usually found in women with a lot of child exposure (e.g. nurseries)
