False regarding streptococcus pyogenes: (A) Causes necrotizing fascitis, (B) Beta hemolytic, (C) M Protein is virulence factor, (D) Resistant to bacitracin
Answer is D. A convenient method for the identification of Streptococcus pyogenes is based on Maxted's observation that they are more sensitive to bacitracin than other streptococci. Bacitracin sensitivity test: A filter paper disc of 0.04U is applied on the surface of an inoculated blood agar. After incubation, a wide zone of inhibition is seen with Streptococcus pyogenes and not with other streptococci. Reference: Textbook of Microbiology; Anathanarayan and paniker's; 10th edition; Page no: 216.