lung abscess (د وديع مادي)

Lung Abscess

Prepared & presented by: Dr :WADIE MADI

مادي: وديع د

Respiratory Department.Tripoli Medical Centre. UNIT B

TUESDAY11th/March/2014

Background

Classification

Risk Factors

Pathophysiology

Differential diagnosis

Diagnosis

Treatment

Etiology

Lung

Abs

cess

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.

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)

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)

Etiology:

Bacteriao 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,

1-infectious Causes

2-Noninfectious Causes

Vasculitis Wegener's granulomatosis, rheumatoid lung nodule

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%)

Etiology:

Pathophysiology

Most occur as a complication of aspiration pneumonia , due to anaerobic bacteria that are normal oral flora.

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.

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.

Histopatholgy of lung abscess

: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

Esophageal disease:- 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)

Clinical features

Radiological diagnosis

Laboratory studies

Diagnosis

Procedures

1-Clinical features

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

Symptoms

Weigh loss,, anaemia, and clubbing or pulmonary osteo arthropathy, hymptosis in 1/3 of cases,

The onset may be abrupt or gradual.

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].

Signs

Digital clubbing may develop rapidly.

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.

2-Laboratory Studies

Sputum for gram stain, culture & sensitivity

If tuberculosis is suspected, ZeilNelsen and mycobacterial culture is requested.

Routine investigations: e.g CBC may show leukocytosis, blood glucose , LFT , RFT, U/E/C.

Obtain sputum for ova if parasitic is suspected

3-Radiological diagnosis

- Chest films may also reveal associated primary lesions,

e.g., a bronchogenic carcinoma.

- Malignant abcess shows eccentric cavitations with thick rough irregular walls.

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.

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

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.

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.

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

4-Procedures

Flexible fiberoptic bronchoscopy is performed to exclude bronchogenic carcinoma whenever bronchial obstruction is suspected.

Blood culture & Microbiology.

Transtracheal aspirate

Bronchoalveolar lavage with quantitative cultures

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

Differential diagnosis

Surgical treatmen

t

Prognosis

Medic

al treatm

ent

Treatment

TreatmentTreatment 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

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)

Anaerobic lung infection

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.

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

Large cavity size ( > 6 cm in diameter) usually requires prolonged therapy..

lung infarction

cavitating neoplasm,

The infection of a preexisting sequestration, cyst, or bulla

bronchial obstruction with a foreign body

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.

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.

THANK

YOU