1. Lung Abscess UNIT B Tripoli Medical Centre. Respiratory Department.
Prepared & presented by: Dr :WADIE MADI
د:وديع مادي
TUESDAY
11th/March/2014

3. Differential diagnosis
Background
Classification
Risk Factors
Pathophysiology
Differential diagnosis
Diagnosis
Treatment
Etiology
Lung Abscess

4. Background: Definition of Lung Abscess is:
-Necrosis of the pulmonary tissue & 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.
- It manifests radiographically as a cavity with an air – fluid levels.

5. Epidemiology: IN U.S.A
Frequency: the frequency of lung abscess in the general population not known.(MEDSCAPE.COM.USA
Mortality & morbidity : most patients with primary lung abscess improve with antibiotics , with cure rates documented at 90-95%.(MEDSCAPE.COM.USA).
Incidence :
sex: male< female Age: lung abscess likely occur more commonly in elderly patients bcz increase incidence of periodontal diseases.(MEDSCAPE.COM.USA)
In U.K(affect all age groups slight more in young adults (P.DR-ANTHONY J FREW ,MD SOUTHAMPTON.UK)

6. Classification Duration of symptoms prior to diagnosis;
Acute < 1 month
Chronic > 1 month
Primary lung abscess or Secondary lung abscess;
Primary lung abscess:
used when abscess develops in individuals prone to aspiration or in general good health
60-80% of lung abscess is primary (50% of these associated with putrid sputum)
Secondary lung abscess:
obstructive airway neoplasm as a complication of intrathoracic surgery or systemic condition/treatment that compromises host immune defense mechanisms .
Putrid lung abscess (foul odor of expectorated sputum)

7. Etiology: 1-infectious Causes Bacteria Mycobacteria Fungi Parasites
mouth flora anaerobes :Pepto strepto,Fuso bacterium nucleatum, also Staph aureus, . Strepto pyogenes, Pseudomonas aeruginosa, Klebsiella pneumoniae , Strepto pneumoniae
gram-negative bacilli, such as E. coli , Homophiles influenza type B
Mycobacteria
M. tuberculosis, (TUBERCULOUS LUNG ABSCESS) ,M. kansasii,)
Fungi
Aspergillus spp., Histoplasma capsulatum, Pneumocystis carinii,
Parasites
Entamoeba histolytica, Paragonimus westermani,

8. 2-Noninfectious Causes
Etiology:
2-Noninfectious Causes
Airway disease
Bullae, blebs,cystic fibrosis ,bronchiectasis (usually thin-walled)
Neoplasms
Primary lung cancer, metastatic carcinoma, lymphoma
Septic embolism
Infective endocarditis due to S. aureus, Jugular venous septic phlebitis due to Fusobacterium necrophorum (Lemierre syndrome)
Pulmonary infarction
Due to bland embolus (may be secondarily infected in <5%)
Vasculitis
Wegener's granulomatosis, rheumatoid lung nodule

9. Pathophysiology
Most occur as a complication of aspiration pneumonia ,
due to anaerobic bacteria that are normal oral flora.
Aspirated bacteria are carried by gravity to dependent portions of the lung.
Due to bronchus/carina anatomy, occur most frequently in posterior segment of RtUL then posterior segment of LtUL and then the superior segments of RtUL/LtLL.
studies of patients with known time of aspiration suggest that tissue necrosis with lung abscess formation takes at least 1 week and up to 2 weeks to develop.

10. Histopatholgy of lung abscess

11. :Risk Factors for lung abscess
Predisposition to aspiration
stroke, IV drug abuser , general anesthesia, dysphasia, respiratory muscle dysfunction, tooth extractiont ,seizers,alcoholics .
45% of health adults aspirate during sleep(1ml of saliva with > 109 live bacteria.)
Poor dentition with gingivitis
Airway Obstruction:
-Neoplasm, Foreign bodies, extrinsic compression (enlarged lymph node).
Immunocompromised patients:
- Steroid ,chemotherapy
-Malnutrition , HIV ,AIDS,DM
- Multiple trauma

12. Esophageal disease: Other processes: -Achalasia -Reflux disease(GERD)
-Depressed cough and gag reflex
-Esophageal obstruction.
Other processes:
bronchiectasis,
secondary infection from bland pulmonary infarction/PE,
septic emboli from Tri V endocarditis
suppurative phlebitis
Lemierre syndrome:
septic phlebitis of the neck (Fusobacterium) with embolic infection in the lung may complicate oropharyngeal infection (peritonsillar abscess)

13. Diagnosis Laboratory studies Procedures Clinical features
Radiological diagnosis
Laboratory studies
Diagnosis
Procedures

14. 1-Clinical features Symptoms The onset may be abrupt or gradual.
Symptoms include : fever, night sweating, cough and Pleuritic chest pain, cough is often non productive at first then produce mucoid or mucopurulent expectorate from bronchial inflammation close to the abscess area and sometimes there is blood streaking
Weigh loss,, anaemia, and clubbing or pulmonary osteo arthropathy, hymptosis in 1/3 of cases,

15. Signs
Patients may have low-grade fever in anaerobic infections & temperature > 38.5 C in other infections.
Clinical findings of consolidation may be present: [decreased breath sounds, dullness in percussion, bronchial breath sounds, course inspiratory crackles].
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.

16. Amebic lung abscess
Patients who develop an amebic lung abscess often have symptoms associated with a liver abscess.
These may include right upper quadrant pain and fever.
After perforation of the liver abscess into the lung, the patient may develop a cough and expectorate a chocolate–like sputum that has no odor.

17. 2-Laboratory Studies
Routine investigations:
e.g CBC may show leukocytosis, blood glucose , LFT , RFT, U/E/C.
Sputum for gram stain, culture & sensitivity
If tuberculosis is suspected, ZeilNelsen and mycobacterial culture is requested.
Obtain sputum for ova if parasitic is suspected

18. 3-Radiological diagnosis
Chest X-ray
- Irregularly sharp cavity with an air-fluid level inside.
- Lung abscess as a result of aspiration most frequently occur in posterior segments of the upper lobes or superior segments
of lower lobes.
- Chest films may also reveal associated primary lesions,
e.g., a bronchogenic carcinoma.
- Malignant abcess shows eccentric cavitations with thick rough irregular walls.

20. PA and lateral chest radiographs 3 weeks later show decreased size of lung abscess and development of cavitation with fluid level . The patient was a 43-year-old woman with lung abscess secondary to Haemophilus infection

21. Pneumococcal pneumonia complicated by lung necrosis
and abscess formation.
A lateral chest radiograph shows air-fluid level characteristic of lung abscess.

22. 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.

23. - Better in lung anatomy visualization to identify empyema from lung
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.

24. Contrast-enhanced (CT) scan demonstrates large focal area of decreased attenuation with rim enhancement (arrow) characteristic of lung abscess.
Because empyema with an air-fluid level could be mistaken for parenchymal abscess, a CT scan may be used to differentiate this process from lung abscess

25. 4-Procedures
Blood culture & Microbiology.
Bronchoalveolar lavage with quantitative cultures
Transtracheal aspirate
Flexible fiberoptic bronchoscopy is performed to exclude bronchogenic carcinoma whenever bronchial obstruction is suspected.

26. Differential diagnosis
Cavitating lung cancer
Localized empyema
Infected congenital pulmonary lesion:
e.g bronchogenic cyst or sequestration
Pulmonary hematoma
Cavitating pneumoconiosis
Hiatus hernia
Lung parasites (eg, hydatid cyst, Paragonimus infection)
Actinomycosis
Wegener granulomatosis and other vasculities
Cavitating lung infarcts
Cavitating sarcoidosis

27. Surgical treatment
Prognosis
Medical treatment
Treatment

28. Treatment Medical therapy Anaerobic lung infection
Treatment of lung abscess is guided by the available microbiology and knowledge of the underlying or associated conditions.
No treatment recommendations have been issued by major societies specifically for lung abscess;
Medical therapy
Anaerobic lung infection
Clindamycin Is T.O.C [shown to be superior over parenteral penicillin coz several anaerobes may produce B-lactamase therefore develop penicillin resistance].
Metronidazole is an effective drug against anaerobic bacteria, a failure rate of 50% has been reported.
May combine both Metronidazole & Penicillin
Other options: carbopenems, quionlones with good anaerobic activity (Moxiflox, Gatiflox)

29. In hospitalized patients who have aspirated and developed a lung abscess
antibiotic therapy should include coverage against S aureus and Enterobacter and Pseudomonas species.
Duration of therapy
Although the duration of therapy is not well established,
most clinicians generally prescribe antibiotic therapy for 4-6 weeks.
Expert opinion suggests that antibiotic treatment should be continued until
the chest radiograph has shown either the resolution of lung abscess or
presence of a small stable lesion.
The risk of relapse exists with a shorter antibiotic regimen.

30. Causes of delayed response to antibiotics
Response to therapy
Clinical improvement, decrease fever, within 3-4 days after initiating ABX therapy.
Defervescence is expected in 7-10 days.
Persistent fever beyond this time indicates therapeutic failure, and these
patients should undergo further diagnostic studies to determine the cause
of failure.
Causes of delayed response to antibiotics
lung infarction
cavitating neoplasm,
bronchial obstruction with a foreign body
The infection of a preexisting sequestration, cyst, or bulla
Large cavity size ( > 6 cm in diameter) usually requires prolonged therapy..

31. Complications of lung abscess
Rupture into pleural space causing Empyema
Pleural fibrosis
Trapped lung
Respiratory failure
Bronchopleural fistula
Pleural cutaneous fistula(T.B)
In a patient with coexisting empyema and lung abscess,
Draining the empyema while continuing prolonged antibiotic therapy is often necessary.

32. Surgical intervention
Surgery is rarely required for patients with uncomplicated lung abscess
The usual indications for surgery are
-- failure to respond to medical management,
-- suspected neoplasm, or
-- congenital lung malformation.
The surgical procedure performed is neither lobectomy or pneumonectomy.
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.

33. THANK
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