96
A. SARAGEA ET AL.
The species must be divisible into as many types as possible.
The types and reactions, should be stable.
The technique must be simple, easy to perform and interpret and
reproducible.
The method must be standardisable.
The value of the classification must be verified through intensive field
applications, i.e. the incidence of types should be interpreted on a
sufficiently representative sample of biological material.
Due to its stability, diversity and specificity, the “original” phage-typing
scheme meets all of these criteria.
(a) Stability of the C. diphtheriae original phage-typing scheme has been
proven both in vitro and in vivo. Strains stored in vitro (irrespective of
storage method, i.e. freeze-dried, or by monthly subcultures) retained their
lytic pattern for about 20 years (the period of our observation) and did not
change after passage in experimental animals. The phage type stability
could also be fully demonstrated in epidemic situations. During an outbreak the same type could be isolated from patients and from their contacts.
Bearing this in mind, the whole area of an outbreak could be determined
from the spread of the prevalent epidemic phage type and could readily be
cleared up, until the last healthy carrier or contact was identified and
treated.
In a certain geographical area, the same phage type could persist for a
long time if all healthy carriers were not treated.
The same phage type was found over a long period of time in healthy
carriers showing pathological modifications of the rhinopharynx.
(b) The specijicity of phage ty’pe is demonstrated by the fact that each
biotype is specifically lysed by groups of phages and that other bacterial
genera, pseudodiphtheric species or other members of the genus Corynebacterium were never lysed by the C. diphtheriae phages representing this
basic set. Exceptions were C. ulcerans and C. ovis species which may be
lysed by some C. diphtheriae phages and even induced to synthesise
diphtherial toxin (Maximescu, 1968; Maximescu et al., 1968, 1974a, b).
This property was taken as an argument for considering them to be
closely related to C. diphtheriae (Carne, 1968).
(c) Diversity of phage types in most cases is due to the lysogenic state of the
receptive strain and expressed in the large number of phage types
determined by this scheme capable of subdividing the three classical
biotypes.
A. SARAGEA ET AL.
The species must be divisible into as many types as possible.
The types and reactions, should be stable.
The technique must be simple, easy to perform and interpret and
reproducible.
The method must be standardisable.
The value of the classification must be verified through intensive field
applications, i.e. the incidence of types should be interpreted on a
sufficiently representative sample of biological material.
Due to its stability, diversity and specificity, the “original” phage-typing
scheme meets all of these criteria.
(a) Stability of the C. diphtheriae original phage-typing scheme has been
proven both in vitro and in vivo. Strains stored in vitro (irrespective of
storage method, i.e. freeze-dried, or by monthly subcultures) retained their
lytic pattern for about 20 years (the period of our observation) and did not
change after passage in experimental animals. The phage type stability
could also be fully demonstrated in epidemic situations. During an outbreak the same type could be isolated from patients and from their contacts.
Bearing this in mind, the whole area of an outbreak could be determined
from the spread of the prevalent epidemic phage type and could readily be
cleared up, until the last healthy carrier or contact was identified and
treated.
In a certain geographical area, the same phage type could persist for a
long time if all healthy carriers were not treated.
The same phage type was found over a long period of time in healthy
carriers showing pathological modifications of the rhinopharynx.
(b) The specijicity of phage ty’pe is demonstrated by the fact that each
biotype is specifically lysed by groups of phages and that other bacterial
genera, pseudodiphtheric species or other members of the genus Corynebacterium were never lysed by the C. diphtheriae phages representing this
basic set. Exceptions were C. ulcerans and C. ovis species which may be
lysed by some C. diphtheriae phages and even induced to synthesise
diphtherial toxin (Maximescu, 1968; Maximescu et al., 1968, 1974a, b).
This property was taken as an argument for considering them to be
closely related to C. diphtheriae (Carne, 1968).
(c) Diversity of phage types in most cases is due to the lysogenic state of the
receptive strain and expressed in the large number of phage types
determined by this scheme capable of subdividing the three classical
biotypes.