Not true about streptococcus pyogenes -

Ans. is 'c' i.e., Catalase positiveo Streptococcus pyogenes (group A streptococci) are gram-positive cocci arranged in chains. Chain formation is due to cocci dividing in one plane only and daughter cells failing to separate completely. Chain formation is more pronounced in broth media.o Fresh isolates form capsule which is made up of hyaluronic acid. It protects the organism from phagocytosisCultural characteristicso Virulent strains produce 'matt' (finely granular) colonyo Avirulent strains produce 'glossy' colonies.o Capsulated strains produce mucoid colonies, corresponding in virulence to the matt type.Biochemical reactionso Senstivity to bacitracin is employed as a convenient method for differentiating str. pyogenes from other hemolytic streptococci (Maxted's observation),o Catalase negativeo Not soluble in 10% bile.o Hydrolyse PYRo Ferment trehalose but not ribose.