What is A child with pyoderma becomes toxic and presents with respiratory distress. His chest radiograph shows patchy areas of consolidation and multiple bilateral thin-walled air containing cysts. The most likely etiological agent in this case is – and explain in detail?
Pneumonia with pneumatoceles (multiple thin-walled breaths of air containing cysts) is s/o staphylococcal pneumonia.

Clinical features of staphylococcal pneumonia

The illness usually follows upper respiratory tract infection, pyoderma or another associated purulent disease.
Besides the usual features of pneumonia child has fever and anorexia and is listless and irritable.
The abdomen is usually distended due to septicemia and ileus.
Cyanosis may be present
Progression of the symptoms and signs is rapid.

Diagnosis-

The diagnosis of staphylococcal pneumonia is suspected in a newborn or an infant with respiratory infection who has evidence of staphylococcal infection elsewhere in the body (here it is pyoderma).
Complications such as pyopneumothorax and pericarditis are highly suggestive of diagnosis (Empyeina in a child below 2 yrs of age is nearly always staphylococcal in etiology)
Presence of Pneumatoceles is considered pathognomic for staphylococcal pneumonia (It can also be seen in pneumonia due to Klebsiella)

Note: Pyoderma or impetigo is a superficial infection of the skin caused primarily by group A streptococci and occasionally by other streptococci and staphylococci.

Tachypnea is the most consistent clinical manifestation of pneumonia.  - Nelson 18th /e 1797