<prompt> A 36 years male presented with complain of productive cough and fever for last 2 months. He has undergone kidney transplantation 2 years back. His sputum examination revealed a gram positive filamentous bacteria that showed acid fastness with modified Ziehl-Neelsen staining 1 H2SO4. The most likely etiological agent is ?Actinomyces israeliiNocardia asteroidesBlastomyces dermaiiidisCrfptosperidium parvum  <response>: Ans. is b i.e., Nocardia asteroides 