Lung abscess is a necrotic pulmonary infection that forms cavities containing fluid or debris. It is usually caused by microbial infection following aspiration or pneumonia. Without treatment, lung abscess was often fatal, but antibiotics have greatly improved outcomes. Most lung abscesses are now cured with prolonged antibiotic therapy targeting the usual culprits of anaerobic bacteria and occasionally aerobic pathogens. Imaging helps confirm the diagnosis and monitor response to medical management, with surgery rarely needed for uncomplicated cases.

1. Lung Abscess
Presented by Dr. Deena Abdel Hadi
Directed by Dr. Abdul-Rahman Abu Rubb
1

2. Background
:Definition
Necrosis of the pulmonary tissue &formation of
cavities containingnecrotic debris orfluid
.caused by microbial infection
The formation of multiple small )> 2 cm(
abscesses is occasionally referred to as
necrotizing pneumonia or.lung gangrene
2

3. Failure to recognize & treat lung abscess is associated
.with poor clinical out-come
Lung abscess was a devastating disease in thepre-
antibiotic era, when 1/3 of the patients died, another
1/3 recovered, & the remainder developed
debilitating illnesses]i.e. recurrent abscesses,
.]chronic empyema, bronchiectasis
3

4. In the early post-antibiotic period,sulfonamides didn‘t
improve the out-come of patients with lung abscess
until thepenicillin's &tetracycline's. were available
Althoughresectional surgery was often considered a
treatment option in the past,the role of surgery has
greatly diminished over time coz most patients with
un-complicated lung abscess eventually respond to
.prolonged antibiotic therapy
4

5. Lung abscesses can be classified based on the duration
. & the likelyetiology
Acute abscesses are less than 4-6 wks old, whereas
chronic abscesses .are of longer duration
Primary abscess isinfectious in origin, caused by
aspiration or pneumonia . in the healthy host
5

6. Secondary Abscess: is caused by
.)Pre-existing condition )obstruction -
.Spread from an extra-pulmonary site -
.Bronchiectasis -
.An immuno-compromised state -
Lung abscesses can be further characterized by the
responsible pathogen, such asStaphylococcus lung
abscess & anaerobic orAspergillus . lung abscess
6

7. Pathophysiology
Lung abscess arises as acomplication of aspiration
.pneumonia caused by mouth anaerobes
A bacterial inoculums from the gingival crevice
reaches the lower airways, & infection is initiated
coz the bacteria aren‘t cleared by the patient‘s host
.defense mechanism
7

8. Abscesses generally develop in theright lung and
involve theposterior segment of the right upper
lobe , thesuperior segment of the lower lobe, or
both. This isdue to gravitation of the infectious
material from the oropharynx into these dependent
.areas
8

9. Initially, the aspirated material settles in the distal
bronchial system and develops into a localized
pneumonitis. Within 24-48 hours, a large area of
inflammation results, consisting of exudate, blood,
and necrotic lung tissue. The abscess frequently
.connects with a bronchus and partially empties
9

10. Other mechanisms for lung abscess formation
: include
:Septic emboli to the lung ,caused by
)1.Bacteremia
)2 .Tricuspid valve endocarditis
10

11. Microbiology
Anaerobes are recovered in up to 89% of the patients,
46% of patients with lung abscess had only a
mixture ofanaerobes isolated from sputum
cultures while43% of patients had a mixture of
anaerobes &.aerobes
The most common anaerobes arePeptosretococcus,
Bacteroids ,Fusobacterium species &
.Microaerophilic streptococcus
11

12. Other organisms that may infrequently cause
lung abscess includeStaphylococcus aureus,
Streptococcus pyogens, Streptococcus
pneumoniae)rarely(, Klebsiella pneumoniae,
Hemophilus influenza, Actinomyces species,
.Nocardia species, & Gm negative bacilli
12

13. . Non-bacterial pathogens may also cause lung abscesses
:Theses micro-organisms include
.]Parasites ]Paragonimus , Entamoeba )1
Fungi] Aspergillus , Cryptococcus , )2
.] Histoplasma , Blastomyces , Coccidioides
.Mycobacterium )3
13

14. History
:Anaerobic infection
Patients often present with indolent symptoms that )1
.evolve over a period of weeks to months
The usual symptoms are )2 fever ,cough with sputum
.production ,night sweats ,anorexia &weight loss
The expectorated )3 sputum characteristically isfoul
.smelling & bad tasting
Patients may develop )4.hemoptysis or pleurisy
14

15. :Other bacterial pathogens
These patients generally present with conditions )1
that are more emergent in nature & are usually
.treated while they have bacterial pneumonia
)2Cavitation occurs subsequently as parenchymal
.necrosis ensues
Abscesses from fungi, )3 Nocardia& Mycobacteria
tend to have an indolent course & gradually
.progressive symptoms
15

16. Physical
Patients may havelow-grade fever in anaerobic
infections &.temperature < 38.5 C in other infections
. Generally,evidence of gingival disease is present
Clinical findings of consolidation may be present :
]decreased breath sounds, dullness to percussion,
.]bronchial breath sounds, course inspiratory crackles
16

17. Evidence of pleural friction rub signs of associated
pleural effusion, empyema & pyo-pneumothorax may
: be present. Signs include
dullness to percussion, contralateral mediastinal shifting]
.]& absent breath sounds over the effusion
.Digital clubbing may develop rapidly
17

18. Causes
The bacterial infection may reach the lungs in
several ways .that most common is
.aspiration of oro-pharyngeal contents
18

19. Factors contributing to lung abscess
Oral cavity disease
Periodontal disease
Gingivitis
Altered consciousness] inability to protect their
]airways coz of an absent gag reflex
Alcoholism
Coma
Drug abuse
Anesthesia
19
Seizures

20. Immunocompromised host
Steroid chemotherapy
Malnutrition
Multiple trauma
Esophageal disease
Achalasia
Reflux disease
Depressed cough and gag reflex
Esophageal obstruction 20

21. Bronchial obstruction
Tumor
Foreign body
Stricture
Generalized sepsis
21

22. patients with 1ry lung disorders
.Septic emboli from tricuspid endocarditis
.Vasculitic disorders
.Cavitating lung malignancies
.Pulmonary cystic diseases
22

23. The following infectious etiologies of pneumonia
infrequently progress to parenchymal necrosis & lung
:abscess formation
.Pseudomonas aerugenosa -
.Klebsiella pneumoniae -
.))may result in multiple abscesses Staph. aureus -
.Strept. Pneumonia -
.Nocardia species -
.Fungal species - 23

24. An abscess may occur2ry to bronchial
carcinoma , thebronchial obstruction causes
post-obstructive pneumonia which may lead
.to abscess formation
24

25. Differential Diagnosis
Alcoholism )1 Pneumocystis Carnii )7
Pleuro-pulmonary )2 .pneumonia
. Empyema .Aspiration pneumonia )8
.Hydatid Cysts )3 .Bacterial pneumonia )9
.Lung Cancer )4 .Fungal pneumonia )10
.Mycobacterium )5 .Pulmonary embolism )11
Pneumococcal )6 .Sarcoidosis )12
. infections .T.B )13
25

26. Lab Studies
CBC -
. Sputum forgram stain ,culture & sensitivity -
acid fast bacilli stain & If T.B. is suspected, -
mycobacterial culture. is requested
Blood culture may be helpful in establishing the -
. etiology
sputum forova & parasite whenever a Obtain -
. parasitic cause for lung abscess is suspected
26

27. Histopathology
A thick-walled lung abscess
27

28. Histology of lung abscess shows dense inflammatory
reaction((low power
28

29. Histology of lung abscess shows dense inflammatory
reaction((high power
29

30. Imaging Studies
:CXR
.Irregularly sharp cavity with an air-fluid level inside -
Lung abscess as a result of aspiration most frequently -
occur in the posterior segments of the upper lobes or
.the superior segments of the lower lobe
30

31. 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
31

32. The abscess may extend to the pleural surface, -
in which case it forms acute angles with the
.pleural surface
Up to one third of lung abscesses may be - -
.accompanied by an empyema
32

33. Pneumococcal pneumonia
complicated by lung necrosis &
abscess formation
33

34. A lateral CXR shows air fluid level
((characteristic of lung abscess
34

35. A 54 yr old pt. developed cough with foul-
smelling sputum production. A CXR
.shows lung abscess in the left lower lobes
35

36. A 42 y.o. man developed fever & production of foul-
smelling sputum. He had a H/O heavy alcohol use &
poor dentition, CXR shows lung abscess in the post
.segment of the Rt. up. lobe
36

37. CXR of a patient who had foul-smelling & bad
tasting sputum, an almost diagnostic feature of
anaerobic lung abscess
37

38. :CT scan -
Better in lung anatomy visualization to identify -
.empyema from lung infarction
An abscess is rounded radio-lucent lesion with a think -
.wall & ill-defined irregular margins
38

39. A 42 yr old man developed fever & production of foul-
smelling sputum. He had a H/O heavy alcohol abuse & poor
dentition, CXR shows lung abscess in the post. Segment of
the Rt. Up. Lobe. CT scan shows a thin-walled cavity with
.surrounding consolidation
39

40. Procedures
Trans-tracheal aspirate or trans-thoracic needle -
aspiration may provide microbiologic diagnosis,
obtaining pleural fluid and blood cultures in patients
.with lung abscess is easier
Flexible fiberoptic bronchoscopy is performed to -
exclude bronchogenic carcinoma whenever bronchial
.obstruction is suspected
40

41. Medical Care
:Antibiotic therapy
Clindamycin ]shown to be Anaerobic lung infection = -
superior over parenteral penicillin coz several
anaerobes may produce B-lactamase & therefore
.]develop penicillin resistance
metronidazole is an effective drug against Although -
anaerobic bacteria, a failure rate of 50% has been
.reported
41

42. In hospitalized patients who have aspirated and -
developed a lung abscess, antibiotic therapy should
include coverage againstS aureus andEnterobacter
andPseudomonas .species
Cefoxitin is a second-generation cephalosporin that -
has gram-positive, gram-negative, and anaerobic
coverage. This agent may be used when a
polymicrobial infection is suspected as cause of
.lung abscess 42

43. :Duration of therapy
Most clinicians prescribe antibiotic therapy generally -
for.4-6 weeks
Current recommendations are that antibiotic -
treatment should be continued until thechest
radiograph has shown either the resolution of lung
.abscess or the presence of a small stable lesion
43

44. :Response to therapy
Patients show clinical improvement, with -
improvement of fever, within 3-4 days after
.initiating the antibiotic therapy
Patients with poor response to antibiotic therapy -
include bronchial obstruction with a foreign body or
neoplasm or infection with a resistant bacteria,
.Mycobacteria, or fungi
44

45. Surgical Care
Surgery isvery rarely required for patients with
uncomplicated lung abscesses. The usual indications
for surgery arefailure to respond to medical
management, suspected neoplasm, or congenital
lung malformation. The surgical procedure
.performed is either lobectomy or pneumonectomy
45

46. Complications
.Rupture into pleural space causing empyema )1
.Pleural fibrosis )2
.Trapped lung )3
.Respiratory failure )4
.Bronchopleural fistula )5
.Pleural cutaneous fistula)6
In a patient with coexisting empyema and lung abscess,
draining the empyema while continuing prolonged
.antibiotic therapy is often necessary 46

47. Prognosis
The prognosis for lung abscess following
antibiotic treatment is generally favorable.
Over 90% of lung abscesses are cured with
medical management alone, unless caused by
.bronchial obstruction secondary to carcinoma
47

48. The End
Thank You
48