LUNG ABSCESS PRESENTED BY DR B. HANUMA
SRINIVAS P
G
UNDER GUIDANCE OF DR SUDHAKAR MS
MCH (CT SURGEON)
DEFINITIONLung abscess is defined as necrosis of the
pulmonary tissue and formation of cavities containing necrotic debris or fluid caused by microbial infection.
The formation of multiple small (<2 cm) abscesses is occasionally referred to as necrotizing pneumonia or lung gangrene.
INTRODUCTON
Lung abscess was a devastating disease in the preantibiotic era 1/3 of pts died,
1/3 recovered, the remaining 1/3 developed debilitating
illnesses such as recurrent abscesses, chronic empyema, bronchiectasis, or other consequences of chronic pyogenic infections.
CLASSIFICATION BASED ON DURATION 1.Acute abscesses -less than 4-6 weeks old, 2.chronic abscesses -longer duration >6
weeks BASED ON ETIOLOGY
1. Primary abscess
2. secondary abscess
Primary abscessis infectious in origin,
caused by Aspiration or pneumonia in the healthy host
secondary abscessis caused by a preexisting condition
(eg, obstruction),
spread from an extrapulmonary site, bronchiectasis, and/or an immunocompromised state..
PathophysiologyMost frequently, the lung abscess arises as a
complication of aspiration pneumonia caused by mouth anaerobes.
The patients who develop lung abscess are predisposed to aspiration and commonly have periodontal disease. A bacterial inoculum from the gingival crevice reaches the lower airways, and infection is initiated because the bacteria are not cleared by the patient's host defense mechanism
This results in aspiration pneumonitis and progression to tissue necrosis 7-14 days later, resulting in formation of lung abscess.
Other mechanismsinclude bacteremia tricuspid valve endocarditis, causing septic
emboli (usually multiple) to the lung. an acute oropharyngeal infection followed by
septic thrombophlebitis of the internal jugular vein, is a rare cause of lung abscesses.
The oral anaerobe F necrophorum is the most common pathogen.
RISK FACTORSPatients at the highest risk for developing lung abscess have the following risk factors: Periodontal disease Seizure disorder Alcohol abuse Dysphagia
INFECTIOUS AGENTSAnaerobic bacteria are the most significant
pathogens in lung abscess. MC anaerobes are Peptostreptococcus species, Bacteroides species, Fusobacterium species, and microaerophilic streptococci.
Aerobic bacteria that may infrequently cause lung abscess include
Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae (rarely), Klebsiella pneumoniae, Haemophilus influenzae, Actinomyces species, Nocardia species, and gram-negative bacilli.
Nonbacterial and atypical bacterial pathogens may also cause lung abscesses, usually in the immunocompromised host.
These includeparasites (eg, Paragonimus and Entamoeba
species) fungi (eg, Aspergillus, Cryptococcus,
Histoplasma, Blastomyces, and Coccidioides species), and
Mycobacterium species
Histology of a lung abscess shows dense inflammatory reaction
INCIDENCESex - Male predominance
Age -MC in elderly patients because of the increased incidence of periodontal disease prevalence of dysphagia and aspiration
SIDE - MC in right lung
CLINICAL FEATURESSymptoms depend on whether the abscess is
caused by anaerobic or other bacterial infection.
Anaerobic infection in lung abscess Patients often present with indolent symptoms that
evolve over a period of weeks to months. The usual symptoms are fever, cough with sputum
production, night sweats, anorexia, and weight loss.
The expectorated sputum characteristically is foul smelling and bad tasting.
Patients may develop hemoptysis or pleurisy
Physical Generally, patients with in lung abscess have evidence of
gingival disease.
Clinical findings of concomitant consolidation may be present (eg, decreased breath sounds, dullness to percussion, bronchial breath sounds, course inspiratory crackles).
Evidence of pleural friction rub and signs of associated pleural effusion, empyema, and pyopneumothorax may be present.
Signs include dullness to percussion, contralateral shift of the mediastinum, and absent breath sounds over the effusion.
Digital clubbing may develop rapidly.
Differential Diagnoses
AlcoholismPneumococcal
InfectionsEmpyema, Pneumocystis Carinii PneumoniaHydatid CystsPneumonia, Aspiration
Pulmonary EmbolismTuberculosisMycobacterium KansasiiWegener Granulomatosis
Infective EndocarditisPneumonia, BacterialLung Cancer, Non-Small Cell
MANAGEMENT
Laboratory StudiesCBP&DC -may reveal leukocytosis and a left shift.
sputum for Gram stain, culture, and sensitivity. (If tuberculosis is suspected, acid-fast bacilli
stain and mycobacterial culture is requested. )
Blood culture may be helpful
Obtain sputum for ova and parasite whenever a parasitic cause for lung abscess is suspected.
Chest radiographyA typical chest radiographic appearance of a
lung abscess is an irregularly shaped cavity with an air-fluid level inside. Lung abscesses as a result of aspiration most frequently occur in the posterior segments of the upper lobes or the superior segments of the lower lobes.
The wall thickness of a lung abscess progresses from thick to thin and from ill-defined to well-circumscribed as the surrounding lung infection resolves. The cavity wall can be smooth or ragged but is less commonly nodular, which raises the possibility of cavitating carcinoma.
Anaerobic infection may be suggested by cavitation within a dense segmental consolidation in the dependent lung zones.
Ultrasonography
Lung abscess appears as a rounded hypoechoic lesion with an outer margin
CT scanning of the lungs may help visualize the anatomy better than chest radiography
Treatment MEDICAL
SURGICAL
Medical
Most abscesses develop secondary to
aspiration and are caused by anaerobes.
USE OF Antibiotics
Clindamycin (Cleocin) Adult600 mg IV q8h, followed by 150-300 mg PO qidPediatric25-40 mg/kg/d IV divided tid/qid-
Ampicillin plus sulbactam is well tolerated and as effective as clindamycin with or without a cephalosporin in the treatment of aspiration pneumonia and lung abscess.
Cefoxitin (Mefoxin)Adult2 g IV q6-8hPediatric80-160 mg/kg/d IV divided q4-6h
Penicillin G (Pfizerpen) Adult2 million U IV q4hPediatric150,000 U/kg/d IV divided q4h
Metronidazole is an effective drug against anaerobic bacteria
SURGICALSurgery is very rarely required for
patients with uncomplicated lung abscesses.
Indications for surgery a.failure to respond to medical
management, b.suspected neoplasm, or c.congenital lung malformation.
Although resectional surgery was often considered a treatment option in the past, the role of surgery has greatly diminished over time because most patients with uncomplicated lung abscess eventually respond to prolonged antibiotic therapy.
The surgical procedure performed is either lobectomy
or pneumonectomy
When conventional therapy fails, either percutaneous catheter drainage or surgical resection is usually considered
Pneumococcal pneumonia complicated by lung necrosis and abscess formation.
A lateral chest radiograph shows air-fluid level characteristic of lung abscess.
A 54-year-old patient developed cough with foul-smelling sputum production. A chest radiograph shows lung abscess in the left lower lobe, superior segment.
A 42-year-old man developed fever and production of foul-smelling sputum. He had a history of heavy alcohol use, and poor dentition was obvious on physical examination. Chest radiograph shows lung abscess in the posterior segment of the right upper lobe.
Chest radiograph of a patient who had foul-smelling and bad-tasting sputum, an almost diagnostic feature of anaerobic lung abscess.
Mortality/Morbidity
Most patients with primary lung abscess improve with antibiotics, with cure rates documented at 90-95%.
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