Bacterial Respiratory Tract Infections Flashcards
What is the epidemiology of community acquired pneumonia?
5-11 per 1000 population Highest is the very young and elderly 22-42% of patients with community acquired pneumonia get admitted to hospital - 30% of them end up in ITU - 8-14% mortality rate
What are the most common typical bacterial causes of community acquired pneumonia?
Streptococcus Pneumoniae
Haemophilus influenzae
Moraxella catharralis -COPD or emphysema
What are the most common atypical bacterial causes of community acquired pneumonia?
Mycoplasma pneumoniae
Legionella pneumoniae
Chlamydophilia pneumoniae
Chlamydophilia psittaci
What is the number one cause of community acquired pneumoniae?
Streptococcus pneumoniae - gram positive diplococci
What are the risk factors for acquiring S.pneumoniae?
Alcohol
Smoking - destroys the innate defences
Immunosuppression - HIV, asplenia, drugs
Airway disease - COPD, asthma
Influenza - relationship between S.Pneumoniae and influenza
What is a typical pneumonia presentation? (I.e. If the causative organism if S.Pneumoniae or Haemophilus Influenzae)
Abrupt onset
Cough
Fever
Pleuritic chest pain
Dull percussion - due to increased density of tissue
Coarse crepitus
Increased vocal resonance - this increases when there is increased density tissue mass
What is the clinical definition of pneumonia?
Consolidation seen on X-Ray
How is pneumonia caused by streptococcus pneumoniae treated?
Penicillin - resistance is rare in UK, but more common in south Europe, Asia and north America.
- amoxicillin
If they have a penicillin allergy or resistance
- macrolides (Clarithromycin)
- tetracyclines (doxycicline)
What is the microbiology of Haemophilus influenzae, and who does it normally effect?
Gram negative
Most common in older people and/or those with an underlying lung disease
Describe the symptoms of pneumonia caused by a non-typeable Haemophilus influenzae infection?
Red eyes, conjunctivitis, meningitis, headache, otitis media and pneumonia
- good at colonising the upper respiratory tract, eyes and nose
How is a Haemophilus influenzae infection treated?
Amoxicillin is the first choice even though 30% of Haemophilus types are resistant (beta-lactamase) If this doesn't work - co-amoxiclav - macrolides (Clarithromycin) - tetracyclines (doxycicline)
What is the most common atypical bacteria that causes community acquired pneumonia?
Mycoplasma pneumonia
- smallest free living bacterium
- very difficult to grow
Which population of people are most likely to catch mycoplasma pneumoniae?
Young adults (person-to-person spread) in the autumn and winter months
What is an atypical pneumonia presentation? (I.e. If the causative organism is an atypical one)
Headache Malaise Fever Consolidation on X-Ray Systemic effects - Guillain Barre - Heamolysis - cold type - erythema multiforme - cardiac conduction issues - arthritis
How is mycoplasma pneumoniae diagnosed?
Serology - rise in antibodies (if they have had the infection more long term)
PCR (sputum/throat swab) - identifies the nucleic acid of the organism
How is Mycoplasma pneumoniae treated?
Can’t use beta-lactams because the organisms has no cell wall for them to destroy
Macrolides (Clarithromycin) and tetracyclines (doxycicline) can be used as they bind to ribosomes and prevent protein production
Quinolones (ciprofloxacin) can be used as they bind to DNA and prevent nucleic acid replication
How is Legionella pneumophila spread?
Ubiquitous in the environment (soil and water)
- immunocompromised patients can catch this from compost
Aerosolisation of the organism - gets into air supply in buildings that use AC
How is Legionella diagnosed?
Sputum/throat swab culture
Serology
Urinary antigen test
How is Legionella pneumophila treated?
Can’t use beta-lactams because the organisms has no cell wall for them to destroy
Macrolides (Clarithromycin) and tetracyclines (doxycicline) can be used as they bind to ribosomes and prevent protein production
Quinolones (ciprofloxacin) can be used as they bind to DNA and prevent nucleic acid replication
What are the components of the CURB65 score (estimates the mortality of community acquired pneumonia)?
Confusion Urea >7 Respiratory rate >30 Blood pressure (<60 diastolic or <90 systolic) 65 - being either 65 or over
What are the SIRS (systemic inflammatory response syndrome) criteria?
Temperature of over 38C or less than 36C
Heart rate over 90bpm
Respiratory rate over 20/min
White blood cells >12 or <4
If a patient comes in with pneumonia, what tests should be run on them?
Blood tests - U&Es, FBC and ABGs Chest X-Ray ECG - possibility of endocarditis Blood cultures - cant put someone on antibiotics without taking blood cultures from them Sputum culture Throat swab Legionella urine antigen test
How is a patient with pneumonia managed?
Dr ABC
Antibiotics are given for the appropriate bacteria once the blood cultures come back. They are IV if;
- CURB65 score is 2 or more and/OR
- SIRS core is 2 or more
- they are hypoxic
When patients are discharged they must be give oral antibiotics and oxygen
