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Chapter 3: Respiratory infections 107

The neuraminidase inhibitors zanamivir and os- emboli, e.g. from right-sided infective endocarditis or

eltamivir are effective in treating acute influenza oc- an infected central line. Infarcted lung may cavitate, and
curring during annual influenza epidemics. They rarely it becomes secondarily infected.
work against Influenza A and B if given within 48
hours of symptoms and especially in the first 24 hours. Clinical features
They are particularly indicated in the elderly, those Patients present with worsening features of pneumonia,
with underlying respiratory disease such as chronic usually with a swinging pyrexia, and can be severely ill.
obstructive pulmonary disease, and those with other If there is communication between the abscess and the
underlying disorders such as cardiovascular disease, airways the patient coughs up large amounts of foul spu-
diabetes or renal failure. These drugs are also highly tum. Clubbing may develop.
effective for prophylaxis in family or institutional set-
tings.
Investigation
Prophylaxis by vaccination is effective in up to 70%

Anaemia, a high neutrophil count and raised inflamma-
and in elderly people reduces hospital admission and
tory markers (ESR, CRP) are common. X-ray demon-
mortality by about 50%. Some are manufactured in
strates one or more round opacities often with a fluid
chickembryosandtheseshouldnotbegiventoanyone
level. Sputum and blood cultures may be positive, but
allergic to eggs. Routine vaccination is reserved for
bronchoscopy may be necessary to exclude obstruction,
susceptible people with chronic heart, lung or renal
to look for underlying carcinoma, and to obtain biopsies
disease,diabetes,immunosuppressionandtheelderly.
and broncho-alveolar lavage for microbiology. Some-
It needs tobegiven yearly.
times CT or ultrasound guided aspiration is needed
The vaccine needs to be prepared each year based on

and can also be therapeutic with insertion of a drain.
predictions of which antigenic variants are present.
Echocardiogram should be considered to look for infec-
These predications depend on global surveillance or-
tive endocarditis.
ganised by the World Health Organisation (WHO).
This surveillance depends on viruses being cultured
Complication
and therefore on nose/throat swabs being taken and
Breach of the pleura results in an empyema.
sent to local labs.
Management
Lung abscess Posturaldrainage,physiotherapyandaprolongedcourse
of appropriate antibiotics to cover both aerobic and
Definition
anaerobic organisms will resolve most smaller ab-
Localisedinfectionanddestructionoflungtissueleading
scesses.Largerabscessesmayrequirerepeatedaspiration,
to acollection of pus within the lung.
drainage and even surgical excision.
Aetiology Aspergillus fumigatus
Tuberculosisisthemostcommoncauseof lungabscesses
butisconsideredseparately.Organismswhichcausecav- Definition
itation and hence lung abscess include Staphylococcus Thereareessentiallythreepatternsof lungdiseasecaused
and Klebsiella.Itismore common in aspiration pneu- by Aspergillus infection: Allergic bronchopulmonary
moniaorbronchialobstruction(bybronchialcarcinoma aspergillosis (ABPA), aspergilloma and invasive asper-
or a foreign body). gillosis.
Pathophysiology Aetiology
The abscess may form during the course of an acute It is a filamentous fungus, the spores (5 µmin diame-
pneumonia, or chronically in partially treated pneu- ter) are ubiquitously present in the atmosphere. It rarely
monia. Multiple lung abscesses may form from septic causes disease. The pattern of disease that arises depends