Lung AbscessLung Abscess

Dr.Vemuri ChaitanyaDr.Vemuri Chaitanya

definitiondefinition A localized area of destruction of A localized area of destruction of

lung parenchyma in which infection lung parenchyma in which infection by pyogenic organisms results in by pyogenic organisms results in tissue necrosis & suppuration .tissue necrosis & suppuration .

It manifests radiographically as a It manifests radiographically as a cavity with an air – fluid levels.cavity with an air – fluid levels.

Necrotizing PneumoniaNecrotizing Pneumonia

necrosis with multiple micro necrosis with multiple micro abscesses form a larger cavitary abscesses form a larger cavitary lesion; actually represents a lesion; actually represents a continuum of the same continuum of the same process(less than 2cm in diam)process(less than 2cm in diam)

Lung Abscess - Lung Abscess - ClassificationClassification

May be May be primary primary or or secondarysecondary PrimaryPrimary = = abscess in previously healthy abscess in previously healthy

patient or in a patient at risk for patient or in a patient at risk for aspirationaspiration

SecondarySecondary = = associated bronchogenic associated bronchogenic neoplasm or immunocompromised neoplasm or immunocompromised patient.patient.

EtiologyEtiology Aspiration of Oropharyngeal floraAspiration of Oropharyngeal flora• Dental / Periodontal sepsisDental / Periodontal sepsis• Paranasal sinus infectionParanasal sinus infection• Depressed conscoius levelDepressed conscoius level• Impaired laryngeal closure ( cuffed Impaired laryngeal closure ( cuffed

endotracheal tube, tracheostomy tube, endotracheal tube, tracheostomy tube, recurrent laryngeal nerve palsy )recurrent laryngeal nerve palsy )

• Disturbances of swallowingDisturbances of swallowing• Dealayed gastric emptying. / gerd / vomitingDealayed gastric emptying. / gerd / vomiting

EtiologyEtiology Necrotizing pneumoniaNecrotizing pneumonia• Staph aureusStaph aureus• Strep milleri / intermediusStrep milleri / intermedius• Klebsiella pneumoniaeKlebsiella pneumoniae• Pseudomonas aeruginosaPseudomonas aeruginosa

EtiologyEtiology Hematogenous spread from a distal Hematogenous spread from a distal

sitesite• UTIUTI• Abdominal sepsisAbdominal sepsis• Pelvic sepsisPelvic sepsis• Infective endocarditisInfective endocarditis• IV drug abuseIV drug abuse• Infected IV cannulaeInfected IV cannulae• Septic thrombophlebitisSeptic thrombophlebitis

EtiologyEtiology Pre existing lung diseasePre existing lung disease• BronchiectasisBronchiectasis• Cystic fibrosisCystic fibrosis• Bronchial obstruction : tumour, Bronchial obstruction : tumour,

foreign body, cong.abnforeign body, cong.abn Infected pulmonary infarctInfected pulmonary infarct TraumaTrauma ImmunodeficiencyImmunodeficiency

Mechanisms of InfectionMechanisms of Infection Commonest cause – Aspiration of Commonest cause – Aspiration of

oropharyngeal contentsoropharyngeal contents 75% of the abscesses occur in 75% of the abscesses occur in

posterior segment of the Rt. upper posterior segment of the Rt. upper lobe or Apical segments of either lobe or Apical segments of either lower lobe, these being the segments lower lobe, these being the segments to which aspirated material has been to which aspirated material has been shown to gravitate in the supine shown to gravitate in the supine subject.subject.

Other MechanismsOther Mechanisms The development of lung abscess The development of lung abscess

favoured by conditions that prevent favoured by conditions that prevent normal clearance of pulmonary normal clearance of pulmonary secretions – lung tumours, secretions – lung tumours, bronchiectasis , inhaled foreign bronchiectasis , inhaled foreign bodies.bodies.

Secondary infection – in cong.abn like Secondary infection – in cong.abn like bronchopulmonary sequestration & bronchopulmonary sequestration & lung cysts lung cysts

Microbiological Microbiological characteristicscharacteristics

Caused by a wide variety of different Caused by a wide variety of different organisms & its common to obtain a organisms & its common to obtain a mixed bacterial growth from single mixed bacterial growth from single abscess when pus is culturedabscess when pus is cultured

Anaerobes – 69% of community Anaerobes – 69% of community acquired casesacquired cases

Anaerobes – 7% hosp acquired casesAnaerobes – 7% hosp acquired cases Staph aureus, Klebsiella pneumoniae, Staph aureus, Klebsiella pneumoniae,

Pseudomonas aeruginosa – imp rolePseudomonas aeruginosa – imp role

Anaerobic organismsAnaerobic organisms Most frequently implicatedMost frequently implicated Main groups Main groups • Gram negative bacilli – Bacteroides- Gram negative bacilli – Bacteroides-

Bacteroides fragilis Bacteroides fragilis • Gram positive cocci mainly Gram positive cocci mainly

Peptostreptococcus Peptostreptococcus • Long & thin gram negative rods – Long & thin gram negative rods –

Fusobacterium – Fusobacterium nucleatum, Fusobacterium – Fusobacterium nucleatum, Fusobacterium necrophorum Fusobacterium necrophorum

Aerobic OrganismsAerobic Organisms Tend to cause lung abscess as a part Tend to cause lung abscess as a part

of necrotizing pneumonia of necrotizing pneumonia Gram positive aerobes : Gram positive aerobes : • Staph.aureus – pneumonia , lung Staph.aureus – pneumonia , lung

abscesses , pneumatocelesabscesses , pneumatoceles• Staph.aureus – leading cause of lung Staph.aureus – leading cause of lung

abscess in children abscess in children • Strep.pyogenesStrep.pyogenes• Strep.pneumoniae serotype 3Strep.pneumoniae serotype 3

Aerobic OrganismsAerobic Organisms Gram negative aerobesGram negative aerobes• Klebsiella pneumoniae Klebsiella pneumoniae • Pseudomonas aeruginosaPseudomonas aeruginosa• Hemophilus influenzaeHemophilus influenzae• E.coliE.coli• AcinetobacterAcinetobacter• ProteusProteus• LegionellaLegionella

Other causesOther causes Tuberculosis & non tuberculous Tuberculosis & non tuberculous

mycobacterial infection – fluid filled cavities – mycobacterial infection – fluid filled cavities – upper lobes / apical segments of lower lobesupper lobes / apical segments of lower lobes

Fungal infection – Histoplasma capsulatumFungal infection – Histoplasma capsulatum Blastomyces dermatitidisBlastomyces dermatitidis Coccidiodes immitisCoccidiodes immitis Aspergillus Aspergillus Cryptococcus neoformansCryptococcus neoformans CandidaCandida

Other causesOther causes Major risk factors for all opportunistic Major risk factors for all opportunistic

fungal infections are neutropenia, fungal infections are neutropenia, coticosteroid use, HIV infectioncoticosteroid use, HIV infection

Single large lung abscess – Single large lung abscess – Actinomyces israeli. This infection – Actinomyces israeli. This infection – lung infiltrate with honey comb of lung infiltrate with honey comb of small abscess cavities that may small abscess cavities that may communicate with chest wall with communicate with chest wall with bony destruction and sinus formationbony destruction and sinus formation

PathologyPathology Most often -as a complication of Most often -as a complication of aspiration aspiration

pneumoniapneumonia Oral anaerobes Oral anaerobes ““Typical patient”Typical patient” is predisposed to aspiration is predisposed to aspiration

due to compromised consciousnessdue to compromised consciousness (ie, alcoholism, drug abuse, general anesthesia) (ie, alcoholism, drug abuse, general anesthesia)

or dysphagiaor dysphagia Periodontal diseasePeriodontal disease, especially gingivitis, with , especially gingivitis, with

concentrations of bacteria in the gingival concentrations of bacteria in the gingival crevice as high as 10crevice as high as 101111/mL/mL

pathologypathology1.1. Inoculum from gingival crevice reach Inoculum from gingival crevice reach

lower airways - while the patient is in the lower airways - while the patient is in the recumbent position.recumbent position.

2.2. Pneumonitis arises first but progresses to Pneumonitis arises first but progresses to tissue necrosis after 7-14 days.tissue necrosis after 7-14 days.

3.3. Necrosis results in lung abscess and/or an Necrosis results in lung abscess and/or an empyema; the latter can be due to a empyema; the latter can be due to a bronchopleural fistula or direct extension bronchopleural fistula or direct extension of infection into the pleural space of infection into the pleural space

pathologypathology Lung abscesses begin as areas of pneumonia on Lung abscesses begin as areas of pneumonia on

which small zones of necrosis ( microabscesses ) which small zones of necrosis ( microabscesses ) develop within consolidated lung. Some of these develop within consolidated lung. Some of these areas coalesce to form single / sometimes areas coalesce to form single / sometimes multiple areas of suppuration and when they multiple areas of suppuration and when they reach a size of 1 -2 cm dia – abscess.reach a size of 1 -2 cm dia – abscess.

If the natural history of this pathological If the natural history of this pathological process is interupted at an early stage by an process is interupted at an early stage by an appropriate antimicrobial , then healing may be appropriate antimicrobial , then healing may be complete with no residual radiographic complete with no residual radiographic evidence of damage.evidence of damage.

pathologypathology If treatment is delayed / inadequate , the If treatment is delayed / inadequate , the

inflammatory process may progress , entering a inflammatory process may progress , entering a chronic phase.chronic phase.

Abscesses arising as a result of aspiration Abscesses arising as a result of aspiration usually occur close to visceral pleural surface in usually occur close to visceral pleural surface in dependent parts of lungs.dependent parts of lungs.

¾ ths of lung abscesses occur in posterior ¾ ths of lung abscesses occur in posterior segement of right upper lobe or apical segement segement of right upper lobe or apical segement of either lower lobes, the anatomical disposition of either lower lobes, the anatomical disposition of these segmental bronchi accepting the of these segmental bronchi accepting the passage of aspirated liquid in supine position passage of aspirated liquid in supine position most readily.most readily.

Those d/t haematogenous spread can occur in Those d/t haematogenous spread can occur in any part of lungsany part of lungs

Clinical Features - Clinical Features - SymptomsSymptoms

The presenting features of lung abscess The presenting features of lung abscess vary considerably .vary considerably .

1.1. Symptoms progress over weeks to Symptoms progress over weeks to monthsmonths

2.2. Fever, cough, and sputum productionFever, cough, and sputum production

3.3. Night sweats, weight loss & anemiaNight sweats, weight loss & anemia

4.4. Hemoptysis, pleurisyHemoptysis, pleurisy

Clinical Features - SignsClinical Features - Signs Therea are no signs specific for lung Therea are no signs specific for lung

abscessabscess Digital clubbing – develop within a few Digital clubbing – develop within a few

weeks if treatment is inadequate.weeks if treatment is inadequate. Dullness to percussion Dullness to percussion Diminished breath sounds if abscess is Diminished breath sounds if abscess is

too large and situated near the surface too large and situated near the surface of lung.of lung.

Amphoric / cavernous breath sounds Amphoric / cavernous breath sounds

diagnosisdiagnosis1.1. CXR, CT CHESTCXR, CT CHEST2.2. Difficult to isolate anaerobic bacteriaDifficult to isolate anaerobic bacteria3.3. Generally, if symptoms and clinical Generally, if symptoms and clinical

setting right for anaerobic infection, setting right for anaerobic infection, generally treat empiricallygenerally treat empirically

4.4. Gram stain:both +ve &-ve,mixedGram stain:both +ve &-ve,mixed5.5. AFB & Anaerobic cultureAFB & Anaerobic culture

diagnosisdiagnosis Transtracheal aspirates (TTA), Transtracheal aspirates (TTA),

transthoracic needle aspirates (TTNA), transthoracic needle aspirates (TTNA), BAL, pleural fluid, or blood cultures allow BAL, pleural fluid, or blood cultures allow uncontaminated specimensuncontaminated specimens

Bronchoscopy with quantitative culturesBronchoscopy with quantitative cultures experience with anaerobic lung infections experience with anaerobic lung infections is limited is limited

Further, none of these specimens likely to Further, none of these specimens likely to yield anaerobes after antibiotic therapy yield anaerobes after antibiotic therapy initiatedinitiated

diagnosisdiagnosis1.1. For patients presenting less For patients presenting less

typically, differential diagnosis typically, differential diagnosis is broader and evaluation is broader and evaluation should include r/o TB with should include r/o TB with AFB AFB sputum smear x 3,sputum smear x 3, possible possible bronchoscopy for cx and biopsybronchoscopy for cx and biopsy

2.2. Blood cultureBlood culture

Differential diagnosisDifferential diagnosis Cavitating lung cancerCavitating lung cancer Localized empyemaLocalized empyema Infected bulla containing a fluid level Infected bulla containing a fluid level Infected congenital pulmonary lesionsInfected congenital pulmonary lesions Pulmonary haematomaPulmonary haematoma Cavitated pneumoconiotic lesionsCavitated pneumoconiotic lesions Hiatus herniaHiatus hernia Hydatid cystsHydatid cysts Infection with paragonimus westermaniInfection with paragonimus westermani Cavitating pulmonary infarctsCavitating pulmonary infarcts Wegeners granulomatosisWegeners granulomatosis

Treatment – antibiotic Treatment – antibiotic therapytherapy

1.1. Ampi / Amoxicillin x orallyAmpi / Amoxicillin x orally

2.2. Metronidazole 400mg TDS –Metronidazole 400mg TDS –AnaerobesAnaerobes

3.3. Cry.penicillin & clindamycin +/- Cry.penicillin & clindamycin +/- metronidazole IV – in hospitalised pts.metronidazole IV – in hospitalised pts.

4.4. Can change – according to sensitivityCan change – according to sensitivity

Duration of treatmentDuration of treatment DebatedDebated Some advocate Some advocate 4-6 weeks4-6 weeks Most treat Most treat until radiographic until radiographic

abnormalities resolve abnormalities resolve ,, generally generally requiring months of treatmentrequiring months of treatment

Surgical interventionSurgical intervention1.1. Surgery rarely required Surgery rarely required 2.2. Indications:Indications: failure of medical management, failure of medical management,

suspected neoplasm, or hemorrhage. suspected neoplasm, or hemorrhage. 3.3. Predictors of poor response to antibiotic Predictors of poor response to antibiotic

therapy alone:therapy alone: abscesses associated-abscesses associated-4.4. with an obstructed bronchus, large abscess (>6 with an obstructed bronchus, large abscess (>6

cm in diameter), relatively resistant organisms, cm in diameter), relatively resistant organisms, such as P. aeruginosa. such as P. aeruginosa.

5.5. The usual procedure in such cases is a The usual procedure in such cases is a lobectomy orlobectomy or pneumonectomypneumonectomy

Treatment contd…Treatment contd…1.1. Alternative for patients who are Alternative for patients who are

considered poor operative risks considered poor operative risks is is percutaneous drainage.percutaneous drainage.

2.2. Bronchoscopy-Bronchoscopy- may be done as a may be done as a diagnostic procedure, especially diagnostic procedure, especially to detect an underlying lesion, to detect an underlying lesion, but is of relatively little use to but is of relatively little use to facilitate drainagefacilitate drainage

Response to treatmentResponse to treatment1.1. Usually show clinical improvement with ↓ Usually show clinical improvement with ↓

fever within fever within 3-4 days3-4 days after beginning after beginning antibioticsantibiotics

Should deffervesce in Should deffervesce in 7-10 days7-10 days Persistent fevers beyond this time indicate Persistent fevers beyond this time indicate

delayed response, and such patients delayed response, and such patients should undergo further diagnostic tests to should undergo further diagnostic tests to define the underlying define the underlying anatomy and anatomy and microbiology of the infectionmicrobiology of the infection

delayed response to delayed response to treatmenttreatment

Consider:Consider:1.1. Erroneous microbial diagnosis Erroneous microbial diagnosis 2.2. Obstruction with a Obstruction with a foreign body or foreign body or

neoplasmneoplasm3.3. Large cavityLarge cavity size (>6 cm) which may size (>6 cm) which may

require unusually prolonged therapy or require unusually prolonged therapy or empyema empyema which necessitates drainage which necessitates drainage

4.4. Non-infectious causes - pulmonary Non-infectious causes - pulmonary infarctsinfarcts

complicationscomplications

1.1. Empyema Empyema 2.2. Bronchopleural –fistulaBronchopleural –fistula3.3. Pneumothorax , pyoneumothoraxPneumothorax , pyoneumothorax4.4. Metastatic cerebral abscessMetastatic cerebral abscess5.5. Sepsis Sepsis 6.6. Fibrosis,bronchiectasis,amyloidosisFibrosis,bronchiectasis,amyloidosis

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