Bacterial pneumonia is an infection of the lungs caused by bacteria, leading to inflammation and fluid accumulation in the air sacs. Common bacteria responsible for this condition include Streptococcus pneumoniae and Haemophilus influenzae. Symptoms often include cough, fever, chest pain, and difficulty breathing. This illness can affect anyone but is particularly serious for young children, the elderly, and individuals with weakened immune systems. Diagnosis typically involves a physical examination, chest X-rays, and laboratory tests. Treatment usually consists of antibiotics to eliminate the bacteria and supportive care to help with breathing and recovery.