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Preventing, Diagnosing and Treating Pleural Infection and Malignant Pleural Effusion
Antibiotic choice is normally initially empirical, based on likely Table 2: Illustrative Empirical Antibiotics in
causative organisms. Furthermore, identification of one bacterium
Pleural Infection
using microbiological techniques does not exclude co-infection –
studies have shown that 12% of pleural infections are polymicrobial.
11 Community-acquired Pleural Infection
Therefore, treatment is normally with appropriate broad-spectrum
Intravenous (Initial)
antibiotics. Table 2 contains illustrative empirical antibiotic regimes;
Co-amoxiclav 1.2g tid + metronidazole 500mg tid
the choice of regime is primarily based on whether pleural infection
Oral (Follow-on)
was community- or hospital-acquired. Specific antibiotic choices
Co-amoxiclav 625mg tid + metronidazole 400mg tid
or clindamycin 300mg qid + ciprofloxacin 500mg bid
should be based on local microbiological prevalence and resistance
patterns. It should be noted that aminoglycosides are not used
Hospital-acquired Pleural Infection
routinely as they have poor tissue penetration and are inactivated in
Intravenous (Initial)
Meropenem 500mg tid + vancomycin 1g bid
the acidic pleural milieu. Other antibiotics penetrate the infected
pleural space effectively.
Oral (Follow-on)
Clindamycin 300mg qid + ciprofloxacin 500mg bid
(+ rifampicin 300mg bid if MRSA suspected)
The optimum duration of the antibiotic course has never been
bid = twice a day; MRSA = methicillin-resistant Staphylococcus aureus; qid = four times
subjected to a randomised controlled trial. Usual therapy duration
a day; tid = three times a day.
is at least two weeks, but is often longer, with intravenous-to-oral
switch determined by clinical response. Antibiotic duration is Malignant Pleural Effusion
determined by a number of factors, including fever defervescence Pleural effusions are a common finding in malignancy: there are about
and response of acute-phase reactants. 300,000 new cases of malignant pleural effusions each year in the
UK and US.
24,25
They account for about 22% of all pleural effusions.
26
Owing to the rich fibrinous septations characterising many pleural Such effusion may result from a primary pleural malignancy
infections, treatment with intrapleural fibrinolytics seems (mesothelioma), from a local spread of another primary malignancy
attractive. Small trials have shown that this therapy increases the (such as breast cancer) or from haematogenous dissemination. In the
volume of chest tube pleural fluid drainage.
21
Such therapy may context of malignancy, effusions can also occur from local disruption
have a role when volume of pleural fluid per se is a problem, for of the normal parietal lymphatic drainage or even from thoracic duct
example to relieve breathlessness or to improve respiratory disruption (e.g. in lymphoma).
function in a ventilated patient. However, a large trial has shown
that intrapleural streptokinase does not reduce mortality, surgery Mesothelioma is a malignancy of the mesothelial cell layer lining the
rates or hospital stay or improve lung function.
5
Further large trials pleura. It is strongly associated with asbestos exposure. ‘Asbestos’
to evaluate other intrapleural agents are currently recruiting. describes a group of fibrous silicates, with chrysotile (a curly
serpentine mineral) being the most commonly produced. Other forms
Some bacterial pleural infections fail to improve clinically and of asbestos include crocidolite, amosite and anthophyllite – all needle-
radiographically. One should always seek underlying mechanical like amphiboles. These fibres are extremely resistant to degradation,
reasons for ongoing infection, such as bronchial obstruction from a and such resistance greatly reduces the effects of phagocytosis. Thus,
neoplasm or aspiration. Treatment considerations should include inhaled fibres persist in the lung, often being resistant to the
re-evaluation of microbiological data and/or antibiotic changes. mucociliary escalator. They induce chronic inflammation, including in
Other considerations include further image-guided pleural drainage. the pleura; the long, thin fibres of crocidolite are particularly resistant
About 15% of cases require surgical intervention; modalities include to clearance and have the greatest association with mesothelioma.
video-assisted thoracoscopic surgery (VATS), mini-thoracotomy, Another fibrous silicate, found in volcanic rock, is erionite; endemic
thoracotomy with decortication or rib resection and open drainage.
5–7
exposure (in Turkey) is also associated with mesothelioma, as are
ionising radiation and chest injuries.
Treatment of tuberculous effusion has a different emphasis.
The effusion is thought to be secondary to cellular-mediated Adverse effects of mesothelioma include local mechanical effects,
immunity in the pleural space; inflammatory stimuli derived from with restriction of lung expansion from fluid or malignant tissue and
mycobacteria (lipoproteins and glycoproteins) cause an pain being commonplace. As with other malignancies, constitutional
immunological reaction of the mesothelial cells, neutrophils, symptoms and general debility are typical findings. Metastases are
lymphocytes and monocytes, leading to pleural fluid generation. fairly common at autopsy,
27
but are not uniformly detected clinically.
Tuberculous pleural infection would normally be treated by
standard antituberculous therapy. The use of steroids has not been Other primary cancers often demonstrate metastatic haematogenous
demonstrated to be beneficial.
22,23
Early pleural drainage is not spread to the pleura (via the lung parenchyma). This brings about
usually a cornerstone of therapy (unless required for symptoms); malignant pleural deposits, frequently causing pleural effusion
most would advocate removal of fluid during any biopsy (although effusion does not always occur).
28
Direct tumour spread also
procedure, but not necessarily chest drain insertion. occurs, through the lung (lung cancer), through the chest wall (breast
cancer), across the diaphragm (ovarian cancer) or from the
Further work is needed to define the optimal management of mediastinum (thymoma).
bacterial pleural infection, in particular the role of intrapleural
agents. It remains unclear why some patients have a good response Prevention
to current standard therapy while others progress to surgery; more Recognition of the exquisitely close association of asbestos and
work is required to elucidate the underlying mechanisms. mesothelioma has led to public recognition of the requirement
EUROPEAN RESPIRATORY DISEASE 51
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