A patient has pleural effusion with empyema. The following are clinical manifestations except:

A. Fungus: While fungal infections can cause infective endocarditis, they are much less common compared to bacterial infections. Fungal endocarditis typically occurs in immunocompromised individuals or those with specific risk factors.

B. Virus: Viral infections can affect the heart, but they are not a common cause of infective endocarditis. Most cases of endocarditis are associated with bacterial infections rather than viral ones.

C. Bacterium: The most common cause of infective endocarditis is bacterial infection. Bacteria, particularly Staphylococcus aureus, Streptococcus viridans, and Enterococcus, are frequently implicated in this condition. These bacteria can enter the bloodstream and adhere to heart valves or damaged cardiac tissue, leading to infection and inflammation.

D. Rickettsiae: Rickettsial infections are caused by a specific type of bacteria that are typically transmitted through arthropod vectors, such as ticks. While they can cause various illnesses, they are not a common cause of infective endocarditis.

A. Pus in the pleural space: This describes empyema, a condition in which infection leads to pus accumulation in the pleural space. Empyema is commonly associated with bacterial pneumonia, lung abscess, or thoracic surgery and requires drainage and antibiotic therapy. It does not cause the lung collapse seen in pneumothorax.

B. Collapse of small airways: While airway collapse can occur in conditions like bronchiolitis or atelectasis, it is not the defining feature of pneumothorax. Pneumothorax specifically involves air leaking into the pleural space, which disrupts the negative pressure necessary for lung expansion and results in partial or complete lung collapse.

C. Blood in the chest cavity: This describes hemothorax, a condition in which blood accumulates in the pleural space due to trauma, ruptured blood vessels, or certain medical conditions. Unlike pneumothorax, which involves air in the pleural space, hemothorax requires different management, including drainage with a chest tube and possible fluid resuscitation.

D. Air in the pleural space: Pneumothorax occurs when air enters the pleural space, causing a loss of negative pressure and leading to lung collapse. This can result from chest trauma, spontaneous rupture of alveoli, underlying lung disease, or mechanical ventilation. Symptoms may include sudden chest pain, dyspnea, and decreased breath sounds on the affected side.