lung abcsess

موضوع: lung abcsess الثلاثاء ديسمبر 29, 2009 7:24 pm

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Synonyms
Pyogenic lung infection/pneumonia, necrotising pneumonia

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Right Lung
Trachea Windpipe
Left Lung
Abscess Pus Pocket

Severe, localised suppurative infection in the substance of the lung, associated with necrotic cavity formation. The process is usually surrounded by a fibrous reaction, forming the abscess wall. Multiple small abscess formation may occur and is sometimes referred to as necrotising pneumonia. The most
frequent cause is aspiration of anaerobic organisms from the mouth in those predisposed to pulmonary aspiration, with impaired immune defences and cough reflex. A pneumonitis develops which progresses to abscess formation over a period of days or weeks..

Precipitating mechanisms include

Inhalation of foreign body
Bacteraemia seeding in the lungs
Tricuspid endocarditis leading to septic pulmonary embolus
Extension of hepatic abscess
Associated with bronchial carcinoma
Proximal to bronchial obstruction
Complication of severe or incompletely treated pneumonia (particularly Staphylococci or Klebsiellae
Penetrating pulmonary trauma e.g. stab wound

Lung abscesses may present acutely or present more chronically

Types1

Primary abscess - occurs in previously normal lungs and may follow aspiration
Secondary abscess - occurs in patients with an underlying lung abnormality

Causative Organisms

Anaerobic bacteria are involved in about 90% of cases. About half of these are lone
anaerobic infection, the other half are mixed with aerobes. Hospital-acquired infections show a higher proportion of Gram-negative bacteria and staphylococci. Community-acquired lung abscesses similarly, are caused mostly by multiple anaerobic bacteria with less aerobic organisms.2

Anaerobes

Peptostreptococcus spp
Bacteroides spp
Fusobacterium spp
Microaerophilic streptococci

Aerobes

Staphylococcus aureus
Streptococcus pyogenes
Haemophilus influenzae
Pseudomonas aeruginosa
Klebsiella pneumoniae- becoming more prevalent3
Burkholderia cepacia
associated with cystic fibrosis
Streptococcus pneumoniae
Actinomyces spp
Nocardia spp
Proteus mirabilis
Pasteurella multocida

Other organisms

Mycobacterial infections
Fungi such as Aspergillus, Cryptococcus, Histoplasma, Blastomyces, Coccidioides
Parasitic protozoa such as Entamoeba histolytica, Paragonimus

Risk Factors

Alcoholism/drug misuse
Post-general anaesthesia
Pneumonia
Diabetes mellitus
Choking/near-drowning/aspiration
Penetrating pulmonary trauma1
Severe periodontal disease
Stroke/cerebral palsy/cognitive impairment/impaired consciousness leading to increased risk of aspiration
Immunosuppression, particularly chronic granulomatous disease in children
Congenital heart disease
Chronic lung disease, particularly cystic fibrosis
Hepatic abscess/chronic liver disease
Bacteraemia

Symptoms

Onset of symptoms is often insidious (more acute if follows pneumonia
Spiking temperature with rigors and night sweats
Cough ± phlegm production often foul-tasting and foul-smelling and often blood-stained
Pleuritic chest pain
Breathlessness
Tachypnoea
Tachycardia
Finger clubbing in chronic cases
Dehydration
High temperature

Management

Supportive measures
Analgesia
Oxygen if required
Rehydration if indicated
Postural drainage with chest physiotherapy

Antibiotics

Begin with intravenous treatment usually for about 2-3 weeks and follow with oral antibiotics for further 4-8 weeks.
Recommended first line therapy includes beta lactam/beta-lactam inhibitor or cephalosporin (second or third generation) plus clindamycin
If condition fails to resolve, consider bronchoscopy/trans-thoracic drainage/cardiothoracic surgical intervention
Surgery is associated with a number of complications such as, empyema and bronchoalveolar air leak and especially so in children.
Where slow resolution occurs, the possibility of malignancy or unusual organisms must be considered

موضوع: رد: lung abcsess الأربعاء ديسمبر 30, 2009 3:00 pm

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