A child was suffering from fever (38 ºC), cough, pharyngitis and his chest x-ray showed pneumonia at lower part of left lung. He was treated with penicillin and did not respond to treatment. Gram-stain and Acid-fast staining of sputum did not show Streptococcus pneumoniae or Mycobacterium tuberculosis. Using a molecular method (PCR), no virus was detected. What is this type of pneumonia is called and what is the most possible bacterial causative agent and how you confirm it