IV. INVESTIGATION OF C. DIPHTHERIAE
97
5. The genetic basis of the original C. diphtheriae phage typing scheme
The three properties mentioned above which ascertain the value of this
scheme have recently been verified (Saragea et al., unpublished data).
There were indications that the lytic pattern of the phage types is genetically determined as a result of their lysogenic state. The stability of the
lysogenic state determines the phage type stability. The world-wide distribution of gravis phage type XVI and the fact that most gravis types
may be obtained by its lysogenisation with appropriate phages, support the
hypothesis (Saragea et al., unpublished).
A “genetic structural formula” was thus established for almost all
original phage types. It indicates the stability, specificity and diversity of
the original C. diphtheriae phage types, and consequently the good reproducibility of the results.
6. Serological relationship of the typing phages
During our routine work on C. diphtheriae phage typing the differences
in lytic activity of various groups of phages were repeatedly correlated with
the biotype of the host cell. This raised the question of possible serological
differences among typing phages. Saragea and Maximescu (1969) found
three principal serological groups among the typing phages closely linked
to their host-range activities.
7. Practical results of the C. diphtheriae original phage typing scheme
The original phage-typing scheme proved its epidemiological efficiency
in the surveillance programme of the causative agent in Romania over the
whole epidemic period as well as in a number of other countries (Canada,
unpublished data; Australia, Gibson et al., 1970; Iran, Zamiri et al., 1972;
France, Saragea et al., 1972a; Great Britain, unpublished data; Soviet
Union, Krilova et al., 1969; Berezkina and Kravcenko 1970; Albania,
Hajderi et al., 1967; U.S.A., McCloskey et al., 1972; Madagascar, Hungary,
Jugoslavia, Italy, unpublished data).
By phage typing the origin and geographical spread of epidemics, the
role of healthy carriers, the means of transmission and the relationships
among different outbreaks may be determined. Yearly geographical maps
of the incidence and distribution of phage types in Romania have enabled
us to follow the filiation of epidemics, the alternation of phage types, or the
penetration of a new type in a region, and to establish possible links with
visitors from abroad.
8. Distribution of the original phage types
During the first period studied in Romania (1956-1964) the most
97
5. The genetic basis of the original C. diphtheriae phage typing scheme
The three properties mentioned above which ascertain the value of this
scheme have recently been verified (Saragea et al., unpublished data).
There were indications that the lytic pattern of the phage types is genetically determined as a result of their lysogenic state. The stability of the
lysogenic state determines the phage type stability. The world-wide distribution of gravis phage type XVI and the fact that most gravis types
may be obtained by its lysogenisation with appropriate phages, support the
hypothesis (Saragea et al., unpublished).
A “genetic structural formula” was thus established for almost all
original phage types. It indicates the stability, specificity and diversity of
the original C. diphtheriae phage types, and consequently the good reproducibility of the results.
6. Serological relationship of the typing phages
During our routine work on C. diphtheriae phage typing the differences
in lytic activity of various groups of phages were repeatedly correlated with
the biotype of the host cell. This raised the question of possible serological
differences among typing phages. Saragea and Maximescu (1969) found
three principal serological groups among the typing phages closely linked
to their host-range activities.
7. Practical results of the C. diphtheriae original phage typing scheme
The original phage-typing scheme proved its epidemiological efficiency
in the surveillance programme of the causative agent in Romania over the
whole epidemic period as well as in a number of other countries (Canada,
unpublished data; Australia, Gibson et al., 1970; Iran, Zamiri et al., 1972;
France, Saragea et al., 1972a; Great Britain, unpublished data; Soviet
Union, Krilova et al., 1969; Berezkina and Kravcenko 1970; Albania,
Hajderi et al., 1967; U.S.A., McCloskey et al., 1972; Madagascar, Hungary,
Jugoslavia, Italy, unpublished data).
By phage typing the origin and geographical spread of epidemics, the
role of healthy carriers, the means of transmission and the relationships
among different outbreaks may be determined. Yearly geographical maps
of the incidence and distribution of phage types in Romania have enabled
us to follow the filiation of epidemics, the alternation of phage types, or the
penetration of a new type in a region, and to establish possible links with
visitors from abroad.
8. Distribution of the original phage types
During the first period studied in Romania (1956-1964) the most