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Chapter 3: Respiratory infections 99
Table 3.9 Histological stages of pneumococcal lobar pneumonia
Stage Microscopy
Congestion & oedema Engorgement of the alveolar walls, air spaces filled with oedematous fluid.
Red hepatisation Organisation of the fluid into a fibrin mesh containing red cells, neutrophils and bacteria.
Grey hepatisation Clearance of the red blood cells and neutrophils and predomination of macrophages in an attempt
to clear the remaining bacteria.
Resolution The fibrin meshwork is broken down, neutrophil debris is ingested by macrophages which are
cleared through the lymphatics.
scopy and bronchial lavage may be considered, as this
Macroscopy/microscopy
is more likely to give microbiological results.
Bronchopneumonia: The affected areas of the lung are Patients should have a follow-up chest X-ray after
consolidated. The air spaces are filled with an acute
6weeks to ensure resolution, and to exclude any un-
inflammatory exudate causing the lung to be firm and
derlyinglesionsuchascarcinomacausingobstruction.
a dark red or grey colour. The bronchi are inflamed
and pleural involvement is common.
Lobar pneumonia: The affected lobe is consolidated Management
with the acute inflammatory exudate being contained 1 Non-pharmacological: Fluids, physiotherapy to clear
in a single segment, lobe or lung. Several identifiable secretions,analgesiaforpleuriticpainwherenecessary
stages are seen in a pneumococcal lobar pneumonia andoxygenifthereishypoxia(guidedbyarterialblood
(see Table 3.9): gases).
2 Empirical antibiotic treatment should be commenced
immediately based on knowledge of the likely organ-
Complications isms, modified where necessary by local microbiol-
Development of lung abscesses and pleural effusion ogy guidelines and on the basis of culture results (see
(which may be reactive or infected, i.e. an empyema), Table 3.10, p. 102).
pleural infection (pleurisy) and septicaemia. 3 Patients with sickle cell disease, asplenia or severe
dysfunction of the spleen, chronic renal disease or
nephrotic syndrome, coeliac disease, immunodefi-
Investigations ciency or immunosuppression, haematological malig-
Achest X-ray will demonstrate areas of consolidation, nancy, cardiovascular disease, chronic pulmonary dis-
any abscesses, effusions and masses (such as under- ease, chronic liver disease or diabetes mellitus should
lying bronchial carcinoma). X-ray changes generally receivepneumovax prophylaxis.
lag behind clinical features so the X-ray may occa-
sionally be normal at presentation, and may remain
abnormal for several weeks after the pneumonia has Prognosis
resolved. Outcome depends greatly on the age of the patient and
The white cell count will normally demonstrate a neu- concurrent disease (including diabetes mellitus, chronic
trophilia. If patients require admission, sputum and renal failure, congestive heart failure and underlying res-
blood cultures should be taken and specific serologi- piratory disease such as chronic obstructive pulmonary
cal tests are available for Legionella and other atypical disease). Mortality for community-acquired pneumonia
pneumonias. is about 14% (about 20% for those requiring hospital
Urea and electrolytes are measured for hydration and admission and up to 35% for those requiring intensive
to detect any co-existing renal disease. care).
Blood gases may be required to monitor oxygenation
British Thoracic Society guideline for identifying pa-
and to assess for respiratory failure. tients with severe community acquired pneumonia:
In severe cases, immunosuppressed individuals and Core features (score 1 for each): Confusion, urea ≥
those unresponsive to standard therapy, broncho- 7 mmol/L, respiratory rate ≥ 30 breaths per minute,