64
A. SARAGEA ET AL.
sometimes granules. Frequently show club-shaped swellings. Snapping
division produces angular and palisade (picket fence) arrangement of cells.
Generally, non-motile. Gram-positive, although some species (e.g. C. diphtheriue) lose the stain easily, especially in old cultures, while others are more
tenacious; granules, however, are strongly Gram-positive. Not acid-fast.
Cell wall composition is characterised by the presence of meso-diaminopimelic acid as the diamino-acid of the peptidoglycan, and by a polysaccharide
containing arabinose, galactose and often mannose.
Chemo-organotrophs : carbohydrate metabolism mixed fermentative and
respiratory.
Do not produce soluble hemolysins but on solid media containing blood
lysis may occur if the red cells are in contact with the colonies. Some pathogenic species produce exotoxins.
Aerobic and facultatively anaerobic; grow best aerobically often with a
surface pellicle.
Catalase positive.
Type species : Corynebucteriurn diphtheriae (Klebs, 1883 ; Lehmann and
Vernacular name : Klebs-Loeffler bacillus.
Corynebucteriurn diphtheriae: straight or slightly curved rods, frequently
swollen at one or both ends, 0.3-0-8 by 1 *0-8.0 pm; usually stain unevenly
and often contain metachromatic granules (polymetaphosphate) which
stain bluish purple with Methylene blue. Gram-positive, but rather
easily decolourised, especially in old cultures.
Three main distinct cultural types recognised (McLeod, 1943) called
gravis, intermedius and mitis, in accordance with the clinical severity of the
cases are most frequently isolated.
Typical strains produce acid from glucose and maltose, but not from
sucrose; however, a few strains produce acid from sucrose.
Aerobic and facultative mixed fermentative and respiratory metabolism,
does not produce indole, urease or gelatinase, optimum temperature 37"C,
range 1540°C.
Characteristic cell wall sugars are arabinose, galactose and mannose;
diamino-acid of peptidoglycan is meso-DAP .( Cummins and Harris,
1956).
A toxic glycolipid is present which is a 6-6'-diester of trehalose, containing corynemycolic acid and corynemycolenic acid in equimolar
proportions (Kato, 1970).
Pimelic acid, nicotinic acid and beta-alanine required by almost all
strains.
The guanidine + cytosine content of the DNA varies from 5 1 -8 to 60%.
Most strains of distinct cultural types (graais, intermedius, mitis) produce
an identical exotoxin, highly lethal; however non-toxigenic strains occur
which are typical in all other respects. Ability to produce toxin is deterNeumann, 1896).
A. SARAGEA ET AL.
sometimes granules. Frequently show club-shaped swellings. Snapping
division produces angular and palisade (picket fence) arrangement of cells.
Generally, non-motile. Gram-positive, although some species (e.g. C. diphtheriue) lose the stain easily, especially in old cultures, while others are more
tenacious; granules, however, are strongly Gram-positive. Not acid-fast.
Cell wall composition is characterised by the presence of meso-diaminopimelic acid as the diamino-acid of the peptidoglycan, and by a polysaccharide
containing arabinose, galactose and often mannose.
Chemo-organotrophs : carbohydrate metabolism mixed fermentative and
respiratory.
Do not produce soluble hemolysins but on solid media containing blood
lysis may occur if the red cells are in contact with the colonies. Some pathogenic species produce exotoxins.
Aerobic and facultatively anaerobic; grow best aerobically often with a
surface pellicle.
Catalase positive.
Type species : Corynebucteriurn diphtheriae (Klebs, 1883 ; Lehmann and
Vernacular name : Klebs-Loeffler bacillus.
Corynebucteriurn diphtheriae: straight or slightly curved rods, frequently
swollen at one or both ends, 0.3-0-8 by 1 *0-8.0 pm; usually stain unevenly
and often contain metachromatic granules (polymetaphosphate) which
stain bluish purple with Methylene blue. Gram-positive, but rather
easily decolourised, especially in old cultures.
Three main distinct cultural types recognised (McLeod, 1943) called
gravis, intermedius and mitis, in accordance with the clinical severity of the
cases are most frequently isolated.
Typical strains produce acid from glucose and maltose, but not from
sucrose; however, a few strains produce acid from sucrose.
Aerobic and facultative mixed fermentative and respiratory metabolism,
does not produce indole, urease or gelatinase, optimum temperature 37"C,
range 1540°C.
Characteristic cell wall sugars are arabinose, galactose and mannose;
diamino-acid of peptidoglycan is meso-DAP .( Cummins and Harris,
1956).
A toxic glycolipid is present which is a 6-6'-diester of trehalose, containing corynemycolic acid and corynemycolenic acid in equimolar
proportions (Kato, 1970).
Pimelic acid, nicotinic acid and beta-alanine required by almost all
strains.
The guanidine + cytosine content of the DNA varies from 5 1 -8 to 60%.
Most strains of distinct cultural types (graais, intermedius, mitis) produce
an identical exotoxin, highly lethal; however non-toxigenic strains occur
which are typical in all other respects. Ability to produce toxin is deterNeumann, 1896).