Lung abscess

1. Lung AbscessLung Abscess
Dr.Vemuri ChaitanyaDr.Vemuri Chaitanya

2. definitiondefinition
A localized area of destruction of lung A localized area of destruction of lung
parenchyma in which infection by pyogenic parenchyma in which infection by pyogenic
organisms results in tissue necrosis & organisms results in tissue necrosis &
suppuration .suppuration .
It manifests radiographically as a cavity with an It manifests radiographically as a cavity with an
air – fluid levels.air – fluid levels.

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

4. Lung Abscess - ClassificationLung Abscess - Classification
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 aspirationpatient or in a patient at risk for aspiration
SecondarySecondary = = associated bronchogenic associated bronchogenic
neoplasm or immunocompromised patient.neoplasm or immunocompromised patient.

5. 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 endotracheal tube, Impaired laryngeal closure ( cuffed endotracheal tube,
tracheostomy tube, recurrent laryngeal nerve palsy )tracheostomy tube, recurrent laryngeal nerve palsy )
•Disturbances of swallowingDisturbances of swallowing
•Dealayed gastric emptying. / gerd / vomitingDealayed gastric emptying. / gerd / vomiting

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

7. EtiologyEtiology
Hematogenous spread from a distal siteHematogenous spread from a distal site
•UTIUTI
•Abdominal sepsisAbdominal sepsis
•Pelvic sepsisPelvic sepsis
•Infective endocarditisInfective endocarditis
•IV drug abuseIV drug abuse
•Infected IV cannulaeInfected IV cannulae
•Septic thrombophlebitisSeptic thrombophlebitis

8. EtiologyEtiology
Pre existing lung diseasePre existing lung disease
•BronchiectasisBronchiectasis
•Cystic fibrosisCystic fibrosis
•Bronchial obstruction : tumour, foreign body, Bronchial obstruction : tumour, foreign body,
cong.abncong.abn
Infected pulmonary infarctInfected pulmonary infarct
TraumaTrauma
ImmunodeficiencyImmunodeficiency

9. Mechanisms of InfectionMechanisms of Infection
Commonest cause – Aspiration of Commonest cause – Aspiration of
oropharyngeal contentsoropharyngeal contents
75% of the abscesses occur in posterior segment 75% of the abscesses occur in posterior segment
of the Rt. upper lobe or Apical segments of of the Rt. upper lobe or Apical segments of
either lower lobe, these being the segments to either lower lobe, these being the segments to
which aspirated material has been shown to which aspirated material has been shown to
gravitate in the supine subject.gravitate in the supine subject.

10. Other MechanismsOther Mechanisms
The development of lung abscess favoured by The development of lung abscess favoured by
conditions that prevent normal clearance of conditions that prevent normal clearance of
pulmonary secretions – lung tumours, pulmonary secretions – lung tumours,
bronchiectasis , inhaled foreign bodies.bronchiectasis , inhaled foreign bodies.
Secondary infection – in cong.abn like Secondary infection – in cong.abn like
bronchopulmonary sequestration & lung cysts bronchopulmonary sequestration & lung cysts

11. Microbiological characteristicsMicrobiological characteristics
Caused by a wide variety of different organisms Caused by a wide variety of different organisms
& its common to obtain a mixed bacterial & its common to obtain a mixed bacterial
growth from single abscess when pus is culturedgrowth from single abscess when pus is cultured
Anaerobes – 69% of community acquired casesAnaerobes – 69% of community acquired 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

12. Anaerobic organismsAnaerobic organisms
Most frequently implicatedMost frequently implicated
Main groups Main groups
•Gram negative bacilli – Bacteroides- Bacteroides Gram negative bacilli – Bacteroides- Bacteroides
fragilis fragilis
•Gram positive cocci mainly Peptostreptococcus Gram positive cocci mainly Peptostreptococcus
•Long & thin gram negative rods – Long & thin gram negative rods –
Fusobacterium – Fusobacterium nucleatum, Fusobacterium – Fusobacterium nucleatum,
Fusobacterium necrophorum Fusobacterium necrophorum

13. Aerobic OrganismsAerobic Organisms
Tend to cause lung abscess as a part of Tend to cause lung abscess as a part of
necrotizing pneumonia necrotizing pneumonia
Gram positive aerobes : Gram positive aerobes :
•Staph.aureus – pneumonia , lung abscesses , Staph.aureus – pneumonia , lung abscesses ,
pneumatocelespneumatoceles
•Staph.aureus – leading cause of lung abscess in Staph.aureus – leading cause of lung abscess in
children children
•Strep.pyogenesStrep.pyogenes
•Strep.pneumoniae serotype 3Strep.pneumoniae serotype 3

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

15. Other causesOther causes
Tuberculosis & non tuberculous mycobacterial Tuberculosis & non tuberculous mycobacterial
infection – fluid filled cavities – upper lobes / apical infection – fluid filled cavities – upper lobes / apical
segments of lower lobessegments of lower lobes
Fungal infection – Histoplasma capsulatumFungal infection – Histoplasma capsulatum
Blastomyces dermatitidisBlastomyces dermatitidis
Coccidiodes immitisCoccidiodes immitis
Aspergillus Aspergillus
Cryptococcus neoformansCryptococcus neoformans
CandidaCandida

16. Other causesOther causes
Major risk factors for all opportunistic fungal Major risk factors for all opportunistic fungal
infections are neutropenia, coticosteroid use, infections are neutropenia, coticosteroid use,
HIV infectionHIV infection
Single large lung abscess – Actinomyces israeli. Single large lung abscess – Actinomyces israeli.
This infection – lung infiltrate with honey comb This infection – lung infiltrate with honey comb
of small abscess cavities that may communicate of small abscess cavities that may communicate
with chest wall with bony destruction and sinus with chest wall with bony destruction and sinus
formationformation

17. PathologyPathology
Most often -as a complication of Most often -as a complication of aspiration pneumoniaaspiration pneumonia
Oral anaerobes Oral anaerobes
““Typical patient”Typical patient” is predisposed to aspiration due to is predisposed to aspiration due to
compromised consciousnesscompromised consciousness
(ie, alcoholism, drug abuse, general anesthesia) or (ie, alcoholism, drug abuse, general anesthesia) or
dysphagiadysphagia
Periodontal diseasePeriodontal disease, especially gingivitis, with , especially gingivitis, with
concentrations of bacteria in the gingival crevice as high as concentrations of bacteria in the gingival crevice as high as
1010
1111
/mL/mL

18. pathologypathology
.
1
.
1
Inoculum from gingival crevice reach lower airways - Inoculum from gingival crevice reach lower airways -
while the patient is in the recumbent position.while the patient is in the recumbent position.
.
2
.
2
Pneumonitis arises first but progresses to tissue necrosis Pneumonitis arises first but progresses to tissue necrosis
after 7-14 days.after 7-14 days.
.
3
.
3
Necrosis results in lung abscess and/or an empyema; the Necrosis results in lung abscess and/or an empyema; the
latter can be due to a bronchopleural fistula or direct latter can be due to a bronchopleural fistula or direct
extension of infection into the pleural space extension of infection into the pleural space

19. pathologypathology
Lung abscesses begin as areas of pneumonia on which Lung abscesses begin as areas of pneumonia on which
small zones of necrosis ( microabscesses ) develop small zones of necrosis ( microabscesses ) develop
within consolidated lung. Some of these areas coalesce within consolidated lung. Some of these areas coalesce
to form single / sometimes multiple areas of to form single / sometimes multiple areas of
suppuration and when they reach a size of 1 -2 cm dia – suppuration and when they reach a size of 1 -2 cm dia –
abscess.abscess.
If the natural history of this pathological process is If the natural history of this pathological process is
interupted at an early stage by an appropriate interupted at an early stage by an appropriate
antimicrobial , then healing may be complete with no antimicrobial , then healing may be complete with no
residual radiographic evidence of damage.residual radiographic evidence of damage.

20. pathologypathology
If treatment is delayed / inadequate , the inflammatory If treatment is delayed / inadequate , the inflammatory
process may progress , entering a chronic phase.process may progress , entering a chronic phase.
Abscesses arising as a result of aspiration usually occur Abscesses arising as a result of aspiration usually occur
close to visceral pleural surface in dependent parts of close to visceral pleural surface in dependent parts of
lungs.lungs.
¾ ths of lung abscesses occur in posterior segement of ¾ ths of lung abscesses occur in posterior segement of
right upper lobe or apical segement of either lower right upper lobe or apical segement of either lower
lobes, the anatomical disposition of these segmental lobes, the anatomical disposition of these segmental
bronchi accepting the passage of aspirated liquid in bronchi accepting the passage of aspirated liquid in
supine position most readily.supine position most readily.
Those d/t haematogenous spread can occur in any part Those d/t haematogenous spread can occur in any part
of lungsof lungs

21. Clinical Features - SymptomsClinical Features - Symptoms
The presenting features of lung abscess vary The presenting features of lung abscess vary
considerably .considerably .
.
2
.
2
Symptoms progress over weeks to monthsSymptoms progress over weeks to months
.
3
.
3
Fever, cough, and sputum productionFever, cough, and sputum production
.
4
.
4
Night sweats, weight loss & anemiaNight sweats, weight loss & anemia
.
5
.
5
Hemoptysis, pleurisyHemoptysis, pleurisy

22. Clinical Features - SignsClinical Features - Signs
Therea are no signs specific for lung abscessTherea are no signs specific for lung abscess
Digital clubbing – develop within a few weeks if Digital clubbing – develop within a few weeks if
treatment is inadequate.treatment is inadequate.
Dullness to percussion Dullness to percussion
Diminished breath sounds if abscess is too large Diminished breath sounds if abscess is too large
and situated near the surface of lung.and situated near the surface of lung.
Amphoric / cavernous breath sounds Amphoric / cavernous breath sounds

23. diagnosisdiagnosis
.
1
.
1
CXR, CT CHESTCXR, CT CHEST
.
2
.
2
Difficult to isolate anaerobic bacteriaDifficult to isolate anaerobic bacteria
.
3
.
3
Generally, if symptoms and clinical setting right Generally, if symptoms and clinical setting right
for anaerobic infection, generally treat for anaerobic infection, generally treat
empiricallyempirically
.
4
.
4
Gram stain:both +ve &-ve,mixedGram stain:both +ve &-ve,mixed
.
5
.
5
AFB & Anaerobic cultureAFB & Anaerobic culture

24. diagnosisdiagnosis
Transtracheal aspirates (TTA), transthoracic Transtracheal aspirates (TTA), transthoracic
needle aspirates (TTNA), BAL, pleural fluid, or needle aspirates (TTNA), BAL, pleural fluid, or
blood cultures allow uncontaminated specimensblood cultures allow uncontaminated specimens
Bronchoscopy with quantitative culturesBronchoscopy with quantitative cultures
experience with anaerobic lung infections is experience with anaerobic lung infections is
limited limited
Further, none of these specimens likely to yield Further, none of these specimens likely to yield
anaerobes after antibiotic therapy initiatedanaerobes after antibiotic therapy initiated

25. diagnosisdiagnosis
•For patients presenting less typically, For patients presenting less typically,
differential diagnosis is broader and differential diagnosis is broader and
evaluation should include r/o TB with evaluation should include r/o TB with
AFB sputum smear x 3,AFB sputum smear x 3, possible possible
bronchoscopy for cx and biopsybronchoscopy for cx and biopsy
•Blood cultureBlood culture

26. 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

31. Treatment – antibiotic therapyTreatment – antibiotic therapy
1.1.Ampi / Amoxicillin x orallyAmpi / Amoxicillin x orally
2.2.Metronidazole 400mg TDS –AnaerobesMetronidazole 400mg TDS –Anaerobes
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

32. Duration of treatmentDuration of treatment
DebatedDebated
Some advocate Some advocate 4-6 weeks4-6 weeks
Most treat Most treat until radiographic abnormalities resolve until radiographic abnormalities resolve ,,
generally requiring months of treatmentgenerally requiring months of treatment

33. Surgical interventionSurgical intervention
•Surgery rarely required Surgery rarely required
•Indications:Indications: failure of medical management, suspected failure of medical management, suspected
neoplasm, or hemorrhage. neoplasm, or hemorrhage.
•Predictors of poor response to antibiotic therapy alone:Predictors of poor response to antibiotic therapy alone:
abscesses associated-abscesses associated-
•with an obstructed bronchus, large abscess (>6 cm in with an obstructed bronchus, large abscess (>6 cm in
diameter), relatively resistant organisms, such as P. aeruginosa. diameter), relatively resistant organisms, such as P. aeruginosa.
•The usual procedure in such cases is a The usual procedure in such cases is a lobectomy orlobectomy or
pneumonectomypneumonectomy

34. Treatment contd…Treatment contd…
•Alternative for patients who are considered Alternative for patients who are considered
poor operative risks is poor operative risks is percutaneous percutaneous
drainage.drainage.
•Bronchoscopy-Bronchoscopy- may be done as a may be done as a
diagnostic procedure, especially to detect diagnostic procedure, especially to detect
an underlying lesion, but is of relatively an underlying lesion, but is of relatively
little use to facilitate drainagelittle use to facilitate drainage

35. Response to treatmentResponse to treatment
•Usually show clinical improvement with ↓ fever within Usually show clinical improvement with ↓ fever within
3-4 days3-4 days after beginning antibiotics after beginning antibiotics
Should deffervesce in Should deffervesce in 7-10 days7-10 days
Persistent fevers beyond this time indicate delayed Persistent fevers beyond this time indicate delayed
response, and such patients should undergo further response, and such patients should undergo further
diagnostic tests to define the underlying diagnostic tests to define the underlying anatomy and anatomy and
microbiology of the infectionmicrobiology of the infection

36. delayed response to treatmentdelayed response to treatment
Consider:Consider:
•Erroneous microbial diagnosis Erroneous microbial diagnosis
•Obstruction with a Obstruction with a foreign body or neoplasmforeign body or neoplasm
•Large cavityLarge cavity size (>6 cm) which may require size (>6 cm) which may require
unusually prolonged therapy or unusually prolonged therapy or empyema empyema
which necessitates drainage which necessitates drainage
•Non-infectious causes - pulmonary infarctsNon-infectious causes - pulmonary infarcts

37. complicationscomplications
1.1.Empyema Empyema
2.2.Bronchopleural –fistulaBronchopleural –fistula
3.3.Pneumothorax , pyoneumothoraxPneumothorax , pyoneumothorax
4.4.Metastatic cerebral abscessMetastatic cerebral abscess
5.5.Sepsis Sepsis
6.6.Fibrosis,bronchiectasis,amyloidosisFibrosis,bronchiectasis,amyloidosis

38. Thank YouThank You