Respiratory Tract Infections Flashcards

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1
Q

What examples are there of compromise to respiratory defences?

A

Poor swallow- cva, muscle weakness, alcohol. Aspirating of salivary secretions
Abnormal ciliary function- smoking, viral infection, kartageners
Abnormal mucus- cf
Dilated airways- bronchiectasis
Defects in host immunity- HIV, asplenic, complement deficient

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2
Q

What is pneumococcus known as?

A

Old mans friend but actually one of the commonest caused of CAP.
Bacteraemic
Green alpha haemolysis
Bile soluble optochin sensitivity

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3
Q

What is s pneumonia?

A

Gram positive diplococci
30-50% of cap
Acute onset, severe pneumonia, fever, rigours, lobar consolidation
Almost always penicillin sensitive, know travel history
Resistance in Europe

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4
Q

What is pneumonia?

A

Inflammation of lung alveoli
Patients are sick, mortality of 5-10%
Fever, cough, pleuritic chest pain, shortness of breath
Often localising signs and abnormal cxr or normal in atypical

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5
Q

How is pneumonia classified?

A

Community acquired
Hospital acquired- ventilator associated
Pre existing lung disease, immunocompromised, geography, season, epidemics, travel, exposure to animals and contacts

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6
Q

What are the main organisms in cap?

A
S pneumonia
H influenzae 
Moraxella catarrhalis- follows viral infection
S aureus 
Klebsiella pneumoniae
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7
Q

What ages are various pathogens likely to infect people?

A

0-1 months- E. coli, gbs, listeria
1-6 months- chlamydia trachomatis, s aureus, Rsv
6 months-5 years- mycoplasma, influenza
16-30 years- m pneumoniae, s pneumoniae

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8
Q

What are the causes of cap?

A

Typical- s pneumonia, h influenzae
Atypical- legionella
mycoplasma (barking cough)
coxiella burnetti. (Q fever) , farm animals, hepatitis
Chlamydia psittaci- birds, splenomegaly, rash, haemolytic anaemia

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9
Q

What would you expect to find in examination of cap?

A
Pyrexia
Tachycardia, tachypnoea
Cyanosis, dullness to percussion, tactile vocal fremitus 
Bronchial breathing 
Crackles
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10
Q

What investigation would you ask for cap?

A

Fbc, u&e, crp
Bc, sputum and mc&S
Abg- useful in PCP, desaturate on exertion
Cxr

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11
Q

How do you manage cap?

A

CURB 65 score- confusion, urea more than 7, rr more than 30, bp less than 90 systolic, less than 60 diastolic, more than 65 years
Score 2- maybe admit
Score 2-5 manage as severe

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12
Q

What is bronchitis?

A

Inflammation of medium sized airways
Mainly in smokers
Cough, fever, increased sputum production, increased sob
Cxr is normal
Organisms- virus, s pneumonia, h influenza, m catarrhalis
Bronchodilation, physiotherapy, humidified oxygen

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13
Q

Which organisms can give cavitating pneumonia?

A

S aureus
Klebsiella
H influenza gram neg bacilli

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14
Q

What is h influenzae?

A

Gram neg coccobacillus
15-35% of cap
More common with pre existing lung disease
May produce b lactamase- augmentin plus or minus clarithromycin

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15
Q

What clincal signs point to legionella?

A
Confused 
Smoker
Hyponatriaemic
Infected water droplets
Multi organ failure 
Special culture- buffered charcoal yeast extract 
Asymptomatic- Pontiac fever
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16
Q

What are atypical pneumonia caused by?

A

Organisms without a cell wall- mycoplasma, legionella, chlamydia, coxiella
Cell wall active abx eg pencillin don’t work
Need agents that work on protein synthesis- clari, erithromycin, tetracycline like doxycycline
Extrapulmonary feature- hepatitis, low sodium, flu like

17
Q

What is the respiratory tract split into?

A

Upper- sinusitis, tonsillitis

Lower- bronchitis, pneumonia, empyema, bronchiectasis, lung abscess

18
Q

How is legionella spread?

A

Aerosol spread
Environmental breakouts
Associated with confusion, abdo pain and diarrhoea
Lymphopenia, hyponatraeima
Diagnosis by antigen in urine/serum serotype 1
Sensitive to macrolides

19
Q

How are coxiella burnetti and chlarmyida psittaci spread?

A
Common in domestic farm animals 
Transmitted by aerosol or milk 
Dx by serology 
Sensitive to macrolides 
Psittaci- spreads by birds by inhalation 
Dx by serology
Sensitive to macrolides
20
Q

What should be done if empyema is found?

A

Send sample for microbiology, cytology, check ldh, low ph

Needs removal

21
Q

What are the differentials for failing to improve on treatment?

A
Empyema
Proximal obstruction 
Resistant organism 
Not receiving/ absorbing abx 
Immunosuppression 
Other diagnosis- lung cancer, cryptogenjc organising pneumonia
22
Q

How can s aureus lead to necrotising pneumonia?

A

Production of pvl, recurrent boils, cabuncles, young person
Want to know if colonised
Contacts

23
Q

What is a hospital acquired pneumonia?

A

More than 48 hours in hospital
Often previous abx, plus or minus ventilator
Infectious vs non infectious causes of abnormal Cxr/lung function
Bronchial lavage- desirable to differentiate upper respiratory from lower flora

24
Q

What pathogens would cause hospital acquired pneumonia?

A
Enterobacteriaciae
S aureus 
Pseudomonas 
Other 
H influenza 
Acinetibacter baumanii
25
Q

What is PCP?

A
Pneumocystis carinii, Protozoa
Ubiquitous in environment 
Insidious onset 
Dry cough, weight loss, SOB, malaise 
Cxr bat wings 
Immunofluroscence on BAL
Treat with co amox and prophylaxis too 
Apple green
26
Q

What diseases can aspergillus fumigatus cause?

A

Allergic bronchopulmonary aspergillosis- chronic wheeze, eosinophilia, bronchiectasis
Aspergilloma- fungal ball often in pre existing cavity, may cause haemoptysis
Invasive aspergillosis- immunocompromised, treat with amphotericin B

27
Q

What lower tract infections can be associated with immunosupression?

A

HIV- PCP, TB, atypical mycobacteria
Neutropenia- fungi, aspergillus
Bone marrow transplant- CMV
Splenectomy- encapsulated organisms, s pneumonia, h influenza, malaria

28
Q

What can be done in the microbiology lab for diagnosis of lrti?

A
Sputum
Blood cultures 
BAL
Pleural fluid 
Antigen tests 
Antibody tests 
Immunofluroscence 
PCR
29
Q

What are antibody tests useful for?

A

Useful in paired serum samples
Usually collected on presentation and 10-14 days later
Look for rise in antibody level over time
Useful for organisms that are difficult to culture- chlaymida, legionella

30
Q

What is empric therapy for cap?

A

Amoxicillin or erythromycin/clarithromycin
Admision- augmentin and clari
Allergic- cefuroxime and clari

31
Q

What is the therapy for hospital acquired?

A

1st line- ciprofloxacin plus minus vanco/ tazocin
2ndline/ITU- piptazobactam and vanco
Specific therapy- mrsa- vanco
Pseudo- piptazobactam or ciprofloxacin plus minus gentamicin