Microbiology Lower Resp Tract infections Flashcards Preview

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Flashcards in Microbiology Lower Resp Tract infections Deck (102)
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1

Definition of LRTI:

• Any Infection of the respiratory tract from the vocal cords downwards

• Includes bronchi, bronchioles, alveoli, parenchyma, pleura and pleural cavities.

2

Normal flora of the LRT

• The NORMAL LRT is bacteriologically strile
• Inhaled particles including micro-organisms are trapped by mucus and moved to the URT by epithelial cilia (mucociliary excalator)

3

Abnormal flora of LRT

• Paralysis of cilia
• Excessive volume and/or viscosity of mucus
• Macro-ventiliation: LOC, Paralysis, ventilation, failure to protect LRT
• Failure to cough/loss of swallowing reflex

4

Common colonisers of the LRT and origin

• “Colonisers” of LRT are often from URT such as Haemophilus influenza and Streptococcus pneumonia

5

Iatrogenic causes of change of antibiotics

• Antibiotic therapy will effect URT colonisation.

6

Types od LRTI

• Bronchiolitis (not covered) - viral
• Bronchitis (acute and chronic)
• Pneumonia
→ Community-acquired
→ Hospital-acquired
→ Aspiration
→ Immunocomprimised host

• Bronchiectasis
• Lung abscess/Emypema

7

Acute Bronchitis causes


Most are Viral:
• Influenza
• RSV
• Rhinovirus
• Adenovirus
• Parainfluenza virus

Pertusis (bacterial cause)

8

Manifestations with % frequency

• Cough (98%)
• Trouble sleeping (60%)
• Dyspnoea (50%)
• Nasal congestations (50%)
• Rhinorrhoea (50%)
• Sore throat (50%)
• Inability to work (33%)
• Fever (10-20%)

9

Chronic obstructive airway disease – chronic bronchitis clinical definition

• Productive cough for more than 3 months per year for at least 2 years
• Wheezing
• Dyspnoea (shortness of breath)
COPD = chronic bronchitis with airflow limitation. Most chronic bronchitis develops COPD or time.

10

Infective exacerbations of chronic bronchitis common

• 1-3 exacerbations per year in COPD patients

11

Criteria used

Anthonisen criteria – used to optimising antibiotic selection in COPD patients
Antibiotic therapy indicated if two if:
• Increased breathlessness
• Increased sputum volume
• Increased sputum purulence

12

Infective exacerbations of chronic bronchitis % viral/Bacteria

40% of acute exacerbations are viral
→ Patients with COPD may have colonisation of the LRT with organisms normally found in the URT such as H. influenza, M. cattarhalis

13

Infective exacerbations of chronic bronchitis treatment

Amoxicillin
Tetracycline

14

Community Acquired required length of stay and causative organisms

< 48 hours in hospital or in community (definition)
Usually bacterial Due to S. Pneumonia and sometimes-other organisms. Sometimes viral in children (always consider TB).

15

Community Acquired treatment

Narrow spectrum therapy

16

Hospital Acquired stay in hospital and causative organisms

>48 hours in hospital and not intubated on admission (definition)
Due to multi-resistant “hospital flora”

17

Hospital Acquired treatment

Broad spectrum agents

18

Pneumonia general clinical features

Fever/rigors/sweats
Headache
Confusion (esp. elderly)
Vomiting/diarrhoea

19

Pneumonia localised clinical features

Breathlessness
Cough (may be productive)
Haemoptysis
Pleuritic chest pain

20

Clinical Syndromes – Aspiration

(Macro aspiration) Inhalation of material, about 10% of community cases

21

Predisposition to aspiration

Neurological deficit and commonly affects the posterior segment of right upper lobe

22

Aspiration complication

Abscess formation
Can be associated with chemical pneumonitis

23

Aspiration prevention

Protection of the airway

24

Aspiration treatment

Antibiotics to cover URT flora e.g. penicillin or cephalosporin plus metronidazole.

25

Acute community acquired pneumonia x-ray and the differentials for x-ray findings:

Lots of acute CXR shadowing
Sometimes non-infective e.g. Cardiac failure, chemical (smoke infection), severe infection elsewhere (ARDS)

26

Acute-community acquired

Ilness progresses over days to a few weeks

27

Chronic-community acquired

Illness progresses over weeks to a months

28

Differentials for chronic community acquired pneumonaie

TB is the most important cause
Differential is wide including Vasculitides (non infectious)
Specialist assessment is needed.

29

CAP epi

More common in water
Male/Female ratio 2:1
More common in older people
750,000 cases/year in UK
150,000 consult GP
50,000 hospitalised
10% mortality among hospitalised patients
Up to 50% mortality if severe

30

Assessing severity of CAP

CURB-65
Confusion (AMT of 8 or less)
Urea raised >7mmol/l
Resp rate >30/min
Blood pressure:
• Systolid <60 mmhg
65 +

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