In this article, we will discuss the Pathology and Clinical Features of Acute Empyema Thoracis. So, let’s get started.


In acute empyema, there is accumulation of large amount of pleural fluid with many polymorphs, bacteria, and cellular debris. Fibrin gets deposited on both layers of pleura (visceral and parietal) and there is a tendency towards loculation. Later, as the disease progresses (empyema becomes chronic), fibroblasts grow from both the layers into the exudate resulting in adhesions of both the surfaces of pleura and form an inelastic membrane called thickened pleura or pleural peel.

Clinical Features

Patients with aerobic infection (parapneumonic pleural effusion) present with acute onset of fever with chills, productive cough with mucopurulent expectoration (bronchopleural fistula), dyspnea and chest discomfort.

Patients with anaerobic infection present with subacute illness with non-specific signs and symptoms such as weight loss, leucocytosis, mild anemia and history of predisposing factor for aspiration from the oral cavity. Tubercular empyema presents with long-standing (for weeks and months) low-grade fever along with weakness and cough.

In acute phase, there are signs of toxemia such as fever, tachypnea, tachycardia, and pleural effusion. Presence of tenderness on percussion with some edema of the chest wall. Clubbing of fingers and toes are usually seen. Rarely there is a sign of empyema necessitans (empyema may track into the subcutaneous tissue of chest wall and presents as a localized swelling with positive cough impulse, and is mostly seen with actinomycotic infections).

Chronic cases present with pleural thickening and loculation of pus will show significant deformity with retraction of chest on the same side of empyema and even scoliosis. The signs will be dull percussion note with diminished breath sounds. extensive pleural calcification may occur. Tubercular empyema is often chronic and present with thickened pleura.


In this article, we will discuss various Pathogenic organisms that are responsible for causing Acute Empyema Thoracis. So, let’s get started.

Pathogenic organisms

Gram-positive bacteria e.g. Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogens.

Gram-negative bacteria e.g. E. coli, B. proteus, H. influenza, Klebsiella, Pseudomonas and Enterobacter species.

Anaerobic bacterias e.g. Bacteroides, Fusobacterium, peptostreptococci.

Mycobacterium tuberculosis

Parasites e.g. E.histolytica, T.echinococcus.

Fungi e.g. Aspergillus, Cryptococcus, Blastocomycosis, etc.

In this article, we will discuss about various Causes of Acute Empyema Thoracis. So, let’s get started.


Diseases of the lung (infection travels from the lung to pleura) such as lung abscess, bronchiectasis, pneumonia, tuberculosis, fungal infection, bronchopleural fistula.

Diseases of abdominal viscera (infection travels from abdominal viscera to pleura) such as liver abscess, subphrenic abscess, and perforated peptic ulcer.

Diseases of the mediastinum (there may be an infective focus in the mediastinum from which it travels to the pleura) such as cold abscess, esophageal perforation, osteomyelitis e.g vertebrae, sternum.

Trauma with a superadded infection like chest wall injuries or postoperative injuries

Iatrogenic (infection introduced during procedure) such as chest aspiration, liver biopsy, etc.

Blood-borne infection such as septicemia



In this article, we will discuss the Definition of Acute Empyema Thoracis. So, let’s get started


It is defined as the collection of pus in the pleural cavity or grossly purulent effusion. The most common cause is bacterial pneumonia. 30-40% hospitalized cases of bacterial pneumonia have an associated pleural effusion. A small percentage of these parapneumonic effusions require drainage for their resolution and are called complicated parapneumonic effusion.

Recently, the term empyema has been broadened to include all these cases of complicated parapneumonic effusion. The characteristic feature of these effusions is exudative pleural effusion which contains significant number of WBCs (but less than empyema)and contains organisms as demonstrated by pathological (Gram stain and/or culture) tests.

(The term empyema was previously used for frank pus in the pleural space)