From Big Medical Encyclopedia

CAPSULAR BACTERIA (Latin capsula Box; bacteria) — the bacteria capable to synthesize the capsule. In the broadest sense any bacteria of taxonomical groups can be carried to capsular. In narrow sense bacteria of a sort belong to capsular Klebsiella (see).

The capsule is created both by spore-forming bacteria, and the bacteria which are not forming a dispute. Among bacteria of the Streptococcaceae family the capsule is formed by some strains of a pyogenic streptococcus (Streptococcus pyogenes) and a pneumococcus (Streptococcus pneumoniae). The expressed mucous capsule is created by Leuconostoe mesenteroides, a bacterium of the Streptococcaceae family.

Among bacilli the capsule is created by Bac. anthracis, Bac. subtilis, Cl. perfringens. The capsule is not the vital structure since the active bacterial mutants which are not forming the capsule are allocated for bacteria. However for pathogenic bacteriums the capsule is the protective mechanism interfering phagocytosis that promotes an invasion of a bacterium in an organism.

The chemical structure of bacterial capsules is not identical: at pneumococci the capsule consists of polysaccharides, at bacilli — of polypeptides.

See also Bacteria .

D. M. Goldfarb.