Partha Roy1, Shobha Srinivasan2, A Chattoraj3. 1. Professor (Microbiology), Base Hospital Delhi Cantt, New Delhi 110010, India. 2. Associate Professor (Microbiology), Base Hospital Delhi Cantt, New Delhi 110010, India. 3. Assistant Professor (Pathology), Base Hospital Delhi Cantt, New Delhi 110010, India.