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%.