Respiratory tract infections Flashcards
Which part of the lung is inflamed in pneumonia?
Alveoli, usually in one lobe. Can also be bronchopneumonia.
How does pneumonia present?
Fever, cough, pleuritic chest pain, SOB
What are the signs of pneumonia on CXR?
Airspace opacity, lobar consolidation, or interstitial opacities. No loss of volume.
How is pneumonia severity assessed? (scoring system)
CURB 65
C: confusion of new onset (defined as an AMTS of 8 or less)
U: Blood Urea nitrogen greater than 7 mmol/l (19 mg/dL)
R: Respiratory rate of 30 breaths per minute or greater
B: Blood pressure less than 90 mmHg systolic or diastolic blood pressure 60 mmHg or less
Age 65 or older
Each scores 1 point to give a total score /5. Used to predict severity, mortality, whether treatment should be oral or IV and whether to admit: -
0-1: Treat as an outpatient
2: Consider a short stay in hospital or watch very closely as an outpatient
3-5: Requires hospitalization with consideration as to whether they need to be in the intensive care unit
What is the treatment for pneumonia?
Supportive (O2, fluids etc) and antibiotics
Abx
Community: Amoxicillin (or, if penicillin allergy, clarithromycin or doxycycline)
What is bronchitis?
Inflammation of the medium sized airways, usually in smokers.
Criteria for diagnosis: cough with sputum most days for 3 months, for 2 or more consecutive years.
How does an acute exacerbation of chronic bronchitis (AECB) present?
Cough, fever, increased sputum production, increased SOB
What are the signs of bronchitis on CXR?
None - it will look normal
Which organisms are most commonly implicated in an acute exacerbation of chronic bronchitis (AECB)?
Viruses
S. pneumoniae
H. influenzae
M. catarrhalis
What is the treatment for bronchitis/AECB?
Bronchodilation
Physiotherapy
+/- Abx if clinically indicated (eg worsening presentation)
Which 5 pathogens are most likely to cause a classical pneumonia? (Signs present on both chest exam and CXR)
S. pneumoniae H. influenzae M. catarrhalis S. aureus K. pneumoniae
Which pneumonia-causing pathogen can be vaccinated against?
S. pneumonia
Vaccination given to at-risk groups incl babies and >65
NB Hib also vaccinated against, not in path guide
Which pneumonia-causing pathogen causes rust-coloured sputum?
S. pneumonia
Which pneumonia-causing pathogens are associated with smoking?
H. influenza and M.catarrhalis
Which pneumonia-causing pathogen is associated with a recent viral infection (eg post influenza) and cavitation on CXR?
S. aureus
Name 4 atypical pneumonia-causing pathogens. (NB, these cause a pneumonia with no signs on chest exam or not in keeping with CXR)
Legionella pneumophilia
Mycoplasma pneumonia
Chlamydia pneumonia
Chamydia psittaci
In atypical pneumonias, what feature do the “atypical” pathogens have in common?
All lack a cell wall
As the atypicals lack a cell wall, what problem does this pose for their treatment?
Don’t respond to penicillin abx, therefore require macrolides and tetracyclines
Which atypical should you consider if a hx includes: travel, air conditioning or water towers?
Legionella pneumophilia
Which 3 autoimmune conditions can be triggered by the atypical Mycoplasma pneumophilia?
Cold agglutinin disease
Stevens Johnson Syndrome (SJS)
Autoimmune haemolytic anaemia (AIHA)
What are the extrapulmonary features in Legionella pneumophilia?
Hepatitis and low Na
Due to its autoimmune sequelae, which systemic features may occur in Mycoplasma pneumophilia infection?
Joint pain and erythema multiforme. Cold agglutinin test should be performed.
What is the TWAR agent?
Former name of Chlamydia pneumoniae (Taiwan acute respiratory agent). Very difficult to diagnose.
Which atyptical pneumonia-causing pathogen is associated with birds?
Chlamydia psittaci
When should you worry about Bordatella pertussis?
Whooping cough in someone unvaccinated, eg travellers
What might suggest that a pneumonia is actually TB?
Poor response to antibiotics
Which pathogens are associated with resp tract infection in immunosuppression due to HIV?
Pneumocystis jiroveci (pneumocystis pneumonia/PCP) (fungus) TB Cryptococcus neoformans (encapsulated yeast)
Which pathogens are associated with resp tract infection in immunosuppression due to neutropaenia?
Fungi - several Aspergillus species
Which pathogens are associated with resp tract infection in immunosuppression due to bone marrow transplant?
Aspergillus
CMV
Which pathogens are associated with resp tract infection in immunosuppression due to splenectomy?
Encapsulated organisms: H. influenzae, S. pneumoniae, N. meningitidis
Which pathogens are associated with resp tract infection in immunosuppression due to cystic fibrosis?
Pesudomonas aeruginosa Burkholderia cepacia (v high mortality)
Aside from blood culture, name 3 methods of diagnosing the specific pathogen in pneumonia.
Urine antigen tests
Antibody tests
Immunofluorescence
When is urine antigen testing used and what can it test for?
Used in severe community acquired pneumonia (CAP) which is not responding to treatment.
Can be used to test for Legionella and Strep. pneumoniae.
How are antibody tests performed and what do they test for?
Used for difficult-to-culture organisms. Serum antibodies measured at presentation and 10-14 days later. Rise over time indicates infection.
Used for Chlamydia and Legionella
Name two methods of testing for pneumocystis pneumonia (PCP - fungus - associated w/HIV)
- Immunofluorescence - antibody labelled w/ fluorescent dye, normally used in virology
- Silver stain in cytology lab - “boat shaped organisms”
Which pathogen has a “boat shaped” appearance with silver staining?
Pneumocystis (PCP) - yeast, common in HIV
What are the criteria to define a pneumonia as hospital acquired (HAP)?
> 48hr hospital stay with no previous infection
When would you use bronchoalveolar lavage (BAL) in pneumonia?
To differentiate between URT and LRT microbes.
Name two sub-types (sites) of URTI
Sinusitis
Tonsilitis
Name five sub-types (sites) of LRTI
Bronchitis Pneumonia Empyema Bronchiectasis Lung abscess
What are the standard antibiotics for a mild-moderate community acquired pneumonia?
Amoxicillin or macrolide for 5-7 days
What are the standard antibiotics for a moderate-severe community acquired pneumonia?
Claritromycin + Co-amoxiclav/cefuroxime for 2-3 weeks
What are the standard antibiotics for an atypical community acquired pneumonia?
Depends on local policy, but must be an antibiotic that targets protein synthesis, ie macrolide (eg clarythromycin) or tetracycline
What are the 1st line antibiotics for hospital acquired pneumonia (HAP)?
Ciprofloxacin +/- vancomycin
What are the 2nd line antibiotics for hospital acquired pneumonia (HAP)?
Piptazobactam +/- vancomycin
What are the standard antibiotics for aspiration pneumonia?
Cefuroxime +/- metronidazole
Which antibiotics are indicated for community acquired legionella pneumonia?
Macrolide + rifampicin
Which antibiotics are indicated for community acquired staph aureus pneumonia?
Flucloxacillin
Which antibiotics are indicated for hospital acquired pseudomonas pneumonia?
Piperacillin + tazobactam (tazocin) or ciprofloxacin +/- gentamicin
Which antibiotics are indicated for hospital acquired MRSA pneumonia?
Vancomycin
