Respond in the JSON format with a summary for the following text: {‘diagnosis’: diagnosis}, where the possible diagnoses are Pneumonia, Acute bronchitis, Asthma exacerbation, Congestive heart failure, Chronic obstructive pulmonary disease (COPD), Pulmonary embolism, Pleural effusion, Interstitial lung disease, or Lung cancer.
Text: The patient presented with shortness of breath and a persistent cough. On physical examination, crackles were heard in the lower lung fields. Chest X-ray revealed bilateral infiltrates consistent with pneumonia. The patient was started on antibiotics and showed improvement in symptoms within 48 hours.
Diagnosis: