Lower respiratory tract infections Flashcards
What groups does pneumonia occur more frequently in
Very old and very young
In what % of patients with pneumonia can no cause be identified?
40-60
Which nosocomial infection has the highest mortality
Pneumonia
Predisposing factors for hospital acquired pneumonia?
Abnormal conscious state Intubation Ventilation Surgery Immunosuppresion
What type of organisms tend to cause pneumonia
Gram neg
Name 2 typical bacterial causes of community acquired pneumonia
- Streoptococcus pneumoniae
- Haemophilus influenzae
Name 2 atypical bacterial causes of community acquired pneumonia
Mycoplasma pneumoniae
Chylamydia pneumoniae
Signs and symptoms of typical community acquired pneumonia
- Sudden onset chills
- Fever
- Pleuritic chest pain
- Productive cost: sputum is thick, purulent and rusty
How does white blood cell count differ
Usually very high
What is the commonest cause of lobar pneumonia
Streptococcus pneumoniae
What would gram stain of sputum show in a person with S. pneumonia
- Catalase neg
- Alpha haemolytic colonies
- Bile soluble
- Susceptible to optochin
2 definitions of atypical pneumonia
1) Pneumonia not due to S. pneumoniae
2) Pneumonia not responding to conventional beta lactam therapy
Describe clinical presentation of atypical pneumonia
- Usually insidious onset
- Not productive cough
- Fever, headache
- CHEST X-RAY MORE ABNORMAL THAT EXAM WOULD SUGGEST
How are mycoplasma pneumoniae acquired
Droplet transmission
How does mycoplasma pneumoniae pneumonia present
Fever Headache Myalgia Earache Dry cough Haemolytic anaemia
How is M. pneumoniae diagnosed
CXR- patchy bilateral bronchopneumonia
Antibodies produced against patients own RBCs
IgM test
PCR
What bacteria causes Legionnaires disease?
Gram postive or negative?
Legionella pneumophilia
Gram negative
How does legionella pneumophilia grow
On buffered charcoal yeast extract
Clinical presentation of Legionellaires disease
- Confusion
- Muscle aches
- Pneumonia
- Renal failure
- (Diarrhoea)
Is chlamydia pneumoniae an intracellular or extracellular organism
Intracellular
What pathogen that causes atypical pneumonia is also implicated as copathogen in coronary artery disease/ cerebrovascular disease?
Chlamydia pneumoniae
What diagnostic tools are used to identify chlamydia pneumoniae?
Immuno-fluoresence
Cell culture
Serology
What causes Q fever and how is it transmited
Coxiella burnetti
Via infected animals/ excreta
What can Q fever lead to
atypical pneumonia
Name a cause of pneumonia in the severely immunocompromised
Pneomocystis
How does classic pneymocytis present
Slight fever
Dyspnoea
Non productive cost
What is respiratory syncytiall virus
Common cause of acute bronchitis in infancy which occurs in epidemic form in winter months
Treatment of respiratory syncytial virus
Mainly supportive (humidification and oxygen) Ribavirin in severe cases
What percentage of people get pleural effusion following pneumonia
3-5% pleural effusion
What are the risk factors for severe pneumococcal disease
Children <2
Adults >65
Underlying medical conditions (splenectomy, unable to clear encapsulated bacteri, chronic cv disease)
What organism is beta lactam inactive against
M.pneumoniae as this does not have a cell wall
How is tuberculosis primarily contracted
Inhaling infected droplets from a cough or sneeze by infected person
Describe myobacterium
- Aerobic
- Non-motile
- Straight or slightly curved rods
- Distinctive cell wall
What is the significance of mycobacterium having a waxy cell wall
Resistant to drying Hydrophobic Resistant to antibiotics Resustance to acid and alkali Survives in macrophages
What 2 stains can be used to diagnose TB
Ziehl-Neelsen
Auramine-phenol
Define multi drug resistant TB
Resistant to rifampicin and isoniazid
