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A. SARAGEA ET AL.
Pleomorphism is very rare. Gram stain is more tenaciously retained than by
C. diphtheriae. It is non-motile, non-spore forming, and non-capsulated.
3 . Growth characteristics
Aerobic and facultatively anaerobic; optimal temperature, 37°C. Growth
is less vigorous than that of the diphtheria bacillus and isolated colonies are
smaller on tellurite-blood agar. Their colour is dark black and they have
a glossy surface. An inexperienced technician may confuse them with
C. diphtheriae type intermedius colonies. However, differences between the
glossy surface of C. xerosis and the granular aspect of C. diphtheriae type
are notable. On Tinsdale plates, it gives dark colonies without a brown
halo.
Broth remains clear with a slight granular deposit at the bottom.
4. Enxymes
Acid from glucose, sucrose, maltose arid fructose. Nitrates are reduced.
Urea is hydrolysed by most strains. C. xerosis lacks cystinase and is not
haemolytic. C. xerosis is, in many respects, similar to C. cutis communis
which however does not ferment maltose.
5 . Antigenic structure
Not well known. but certainly different from C. diphtheriae.
6. Pathogenicity
There is no evidence of pathogenicity.
7 . Bacteriophages
Have not yet been described for C. xerosis.
8. Bacteriocins
C. xerosis possesses bacteriocins active against other mzmbers of the
genus Corynebacterium and against other genera. A highly bacteriocinogenic C. xerosis strain is included in the set of bacteriocinogenic
strains used in bacteriocin typing of C. diphtheriae (see above).
D. Atypical corynebacteria
Variants of atypical corynebacteria have been reported in Romania by
Saragea et al. (1962). They were isolated usually towards the end of some of
the diphtheria outbreaks during the epidemic period up to 1965. Their
occurrence after application of extensive prophylactic procedures and
antibiotic treatment of carriers as well as certain similarities with atypical
A. SARAGEA ET AL.
Pleomorphism is very rare. Gram stain is more tenaciously retained than by
C. diphtheriae. It is non-motile, non-spore forming, and non-capsulated.
3 . Growth characteristics
Aerobic and facultatively anaerobic; optimal temperature, 37°C. Growth
is less vigorous than that of the diphtheria bacillus and isolated colonies are
smaller on tellurite-blood agar. Their colour is dark black and they have
a glossy surface. An inexperienced technician may confuse them with
C. diphtheriae type intermedius colonies. However, differences between the
glossy surface of C. xerosis and the granular aspect of C. diphtheriae type
are notable. On Tinsdale plates, it gives dark colonies without a brown
halo.
Broth remains clear with a slight granular deposit at the bottom.
4. Enxymes
Acid from glucose, sucrose, maltose arid fructose. Nitrates are reduced.
Urea is hydrolysed by most strains. C. xerosis lacks cystinase and is not
haemolytic. C. xerosis is, in many respects, similar to C. cutis communis
which however does not ferment maltose.
5 . Antigenic structure
Not well known. but certainly different from C. diphtheriae.
6. Pathogenicity
There is no evidence of pathogenicity.
7 . Bacteriophages
Have not yet been described for C. xerosis.
8. Bacteriocins
C. xerosis possesses bacteriocins active against other mzmbers of the
genus Corynebacterium and against other genera. A highly bacteriocinogenic C. xerosis strain is included in the set of bacteriocinogenic
strains used in bacteriocin typing of C. diphtheriae (see above).
D. Atypical corynebacteria
Variants of atypical corynebacteria have been reported in Romania by
Saragea et al. (1962). They were isolated usually towards the end of some of
the diphtheria outbreaks during the epidemic period up to 1965. Their
occurrence after application of extensive prophylactic procedures and
antibiotic treatment of carriers as well as certain similarities with atypical