Systematic Veterinary Bacteriology and Mycology

MORPHOLOGY

• Streptococci are Gram positive, spherical or ovoid cells, arranged in chains or pairs.
• Chain formation is due to the cocci dividing in one plane only and the daughter cells failing to separate completely. Each coccus is about 1 mm in diameter.
• They are facultative anaerobes, catalase negative, oxidase-negative, and non-spore forming and non-motile with exception of some of the enterococci.
• Capsulation is not a regular feature of streptococci but some strains of S.pyogenes and some group C strains have capsules composed of hyaluronic acid while polysaccharide capsules are encountered in members of group B and D.
• Protoplasts (L-forms) may be induced by penicillin or phage associated lysine and may be propagated on hyper tonic media.