1-Introduction.
2-Pathology and Pathogenesis.
3-Clinical Manifestations.
4-Diagnosis.
5-Treatment.
6-Prognosis.
Pulmonary abscesses are localized areas composed of
thick-walled purulent material formed as a result of
lung infection that lead to destruction of lung
parenchyma, cavitation, and central necrosis.
Lung abscesses are much less common in children than
in adults.
A primary lung abscess occurs in a previously healthy
patient with no underlying medical disorders.
A secondary lung abscess occurs in a patient with
underlying or predisposing conditions.
A number of conditions predispose children to the
development of pulmonary abscesses, including
aspiration, pneumonia, cystic fibrosis, gastroesophageal
reflux, tracheoesophageal fistula,
immunodeficiencies,FB, seizures, and a variety of
neurologic diseases.
In children, aspiration of infected materials or a foreign
body is the predominant source of the organisms
causing abscesses.
Initially, pneumonitis impairs drainage of fluid or the
aspirated material.
Inflammatory vascular obstruction occurs, leading to
tissue necrosis, liquefaction, and abscess formation.
If the aspiration event occurred while the child was
recumbent, the right and left upper lobes and apical
segment of the right lower lobes are the dependent areas
most likely to be affected.
In a child who was upright, the posterior segments of the
upper lobes were dependent and therefore are most
likely to be affected.
Primary abscesses are found most often on the right
side,
Whereas secondary lung abscesses, particularly in
immunocompromised patients, have a predilection for
the left side.
Both anaerobic and aerobic organisms can cause lung
abscesses.
Most lung abscesses arise as a complication of aspiration
pneumonia and are caused by species of anaerobes that are
normally present in the gingival crevices.
Common anaerobic bacteria that can cause a pulmonary
abscess include Bacteroides spp, Fusobacterium spp, and
Peptostreptococcus spp.
Abscesses can be caused by aerobic organisms such as
Streptococcus spp, Staphylococcus aureus, Escherichia
coli, Klebsiella pneumoniae, and Pseudomonas
aeruginosa.
Aerobic and anaerobic cultures should be part of the
work-up for all patients with lung abscess.
Fungi can also cause lung abscesses, particularly in
immunocompromised patients.
Non-bacterial pathogens can produce lung abscess
including parasites (eg, Paragonimus westermani and
Entamoeba histolytica)
Many fungi (eg, Aspergillus spp, Cryptococcus
neoformans, Histoplasma capsulatum, Blastomyces
dermatitidis, Coccidioides immitis)
The most common symptoms of pulmonary abscess in
pediatric population are
1-Cough
2-Fever
3-Tachypnea
4-Dyspnea
5-Chest pain
6-Vomiting
7-Sputum production
8-Weight loss
9-Hemoptysis.
Physical examination typically reveals :
1-Tachypnea
2-Dyspnea
3-Retractions with accessory muscle use,
4-Decreased breath sounds, and
5-Dullness to percussion in the affected area.
6-Crackles and, occasionally, a prolonged expiratory
phase may be heard on lung examination.
Diagnosis is most commonly made on the basis of chest
radiography.
A chest CT scan can provide better anatomic definition
of an abscess, including location and size.
An abscess is usually a thick-walled lesion with a lowdensity center progressing to an air-fluid level.
Abscesses should be distinguished from pneumatoceles,
which often complicate severe bacterial pneumonias and
are characterized by thin- and smooth-walled, localized
air collections with or without air-fluid level
Pneumatoceles often resolve spontaneously with the
treatment of the specific cause of the pneumonia.
The determination of the etiologic bacteria in a lung
abscess can be very helpful in guiding antibiotic choice.
Although Gram stain of sputum can provide an early
clue as to the class of bacteria involved, sputum cultures
typically yield mixed bacteria and are therefore not
always reliable.
Attempts to avoid contamination from oral flora include
direct lung puncture, percutaneous (aided by CT
guidance).
Bronchoscopic aspiration should be avoided as it can be
complicated by massive intrabronchial aspiration.
To avoid invasive procedures in previously normal hosts,
empiric therapy can be initiated in the absence of
culturable material.
Conservative management is recommended for pulmonary
abscess.
The duration of therapy is controversial.
Some treat for three weeks as a standard and others treat
based upon the response.
The practice is to continue antibiotic treatment until the
chest x-ray shows a small, stable residual lesion or is clear.
Most experts advocate a 2- to 3-wk course of parenteral
antibiotics for uncomplicated cases, followed by a
course of oral antibiotics to complete a total of 4-6 wk.
Antibiotic choice should include agents with aerobic
and anaerobic coverage.
Treatment regimens should include :
1-Penicillinase-resistant agent active against
S. aureus and anaerobic coverage, typically with
clindamycin.
If gram-negative bacteria are suspected or isolated,
an aminoglycoside should be added.
For severely ill patients or those whose status fails to
improve after 7-10 days of appropriate antimicrobial
therapy, surgical intervention should be considered.
Minimally invasive percutaneous aspiration techniques,
often with CT guidance, are the initial and, often, only
intervention required.
In rare complicated cases, thoracotomy with surgical
drainage or lobectomy and/or decortication may be
necessary.
Overall, prognosis for children with primary pulmonary
abscesses is excellent.
The presence of aerobic organisms may be a negative
prognostic indicator, particularly in those with
secondary lung abscesses.
Most children become asymptomatic within 7-10 days.
Radiologic abnormalities usually resolve in 1-3 m.
Lung abscess is defined as necrosis of the pulmonary
parenchyma.
Most lung abscesses arise as a complication of aspiration
pneumonia.
Lung abscesses are classified into a primary lung abscess
and secondary lung abscess.
A lung abscess is typically diagnosed when a chest
radiograph.
Better anatomic definition can be achieved with computed
tomographic (CT) scans.
Treatment regimens should include agents active against
S. aureus , anaerobic coverage and gram negative if
suspected.
Continue antibiotic treatment until the chest x-ray shows
a small, stable residual lesion or is clear.
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