IV. INVESTIGATION OF C. DIPHTHERIAE
89
different epidemics on the basis of their lysogeny; Ortalli et al. (1956)
obtained a phage sample displaying a wide lytic activity against all three
diphtheria biotypes and C. ulcerans; Gabrilovitch (1966), using ten phage
preparations, was able to class 73% of gravis strains into nine phage types
and observed a close relationship with the biotype and serological properties.
Endemann (1960) with the help of two lysogenic phages, and later Rische
and Endemann (1962) with three more temperate phages classified a group
of 389 gravis strains into four phage types. They found only one intermedius and no mitis phage types.
Starting from studies on the frequency of naturally occurring lysogeny,
among about 10000 C. diphtheriae strains, a remarkable number of
lysogenic phage preparations were isolated in Romania. They were
subsequently selected and grouped with respect to their lytic activity,
against a large number of wild C. diphtheriue strains belonging to all 3
biotypes. Seventeen lysogenic (endogenous) phages were selected and
grouped together with two reference phages (25 Warshaw and Freeman’s
B phage) (1956-1959). The set was completed in 1962 by five German
phage preparations. A group of 24 lysogenic phage preparations, representing the basic set of typing phages, was thus established and has, to date,
been used in the classification of about 35 000 C. diphtheriue strains in
Romania.
The phage typing scheme established was named at first “Provisional
Phage Typing Scheme for C. diphtheriae” (Saragea and Maximescu, 1964).
The scheme was improved in 1969 (Fig. 8) and called by the authors
(Saragea and Maximescu, 1969) the “original” phage typing scheme for
C. diphtheriae. Two of the 24 phage preparations, i.e. nos. 23 and 24,
were discarded, as they were not biotype specific. Two new phage types
were identified by the same set. At present, by means of 22 lysogenic
phages, the three classical biotypes may be classified into 21 phage types,
namely four mitis, three intermedius, and 14 gravis types irrespective of the
charactets of lytic reactions (Figs 9-11). The “original” phage types are
stable and specifically correlated to biotype and toxinogenicity.
This scheme has proved its efficiency during the entire epidemic period
of diphtheria in Romania (Saragea et ul., 1966a, b, 1967a) b, 1968, 1973;
Gabrilovitch, 1966; Hajderi et al., 1967; Ejowa, 1967; Saragea and
Maximescu, 1969). It has also been used successfully to analyse different
epidemic outbreaks in other countries (Saragea and Maximescu, 1966;
Saragea et al., 1966b, 1972a; Gibson et ul., 1970; McCloskey et al., 1972;
Zamiri et al., 1972). During the period 1956-1969, 99-100% of the
C. diphtheriae type gravis tox+ strains and 75% of the total number of
C. diphtheriae strains isolated in Romania proved typable. Everywhere
abroad where C. dzjJhtheriae type gravis tax+ strains were prevalent and
89
different epidemics on the basis of their lysogeny; Ortalli et al. (1956)
obtained a phage sample displaying a wide lytic activity against all three
diphtheria biotypes and C. ulcerans; Gabrilovitch (1966), using ten phage
preparations, was able to class 73% of gravis strains into nine phage types
and observed a close relationship with the biotype and serological properties.
Endemann (1960) with the help of two lysogenic phages, and later Rische
and Endemann (1962) with three more temperate phages classified a group
of 389 gravis strains into four phage types. They found only one intermedius and no mitis phage types.
Starting from studies on the frequency of naturally occurring lysogeny,
among about 10000 C. diphtheriae strains, a remarkable number of
lysogenic phage preparations were isolated in Romania. They were
subsequently selected and grouped with respect to their lytic activity,
against a large number of wild C. diphtheriue strains belonging to all 3
biotypes. Seventeen lysogenic (endogenous) phages were selected and
grouped together with two reference phages (25 Warshaw and Freeman’s
B phage) (1956-1959). The set was completed in 1962 by five German
phage preparations. A group of 24 lysogenic phage preparations, representing the basic set of typing phages, was thus established and has, to date,
been used in the classification of about 35 000 C. diphtheriue strains in
Romania.
The phage typing scheme established was named at first “Provisional
Phage Typing Scheme for C. diphtheriae” (Saragea and Maximescu, 1964).
The scheme was improved in 1969 (Fig. 8) and called by the authors
(Saragea and Maximescu, 1969) the “original” phage typing scheme for
C. diphtheriae. Two of the 24 phage preparations, i.e. nos. 23 and 24,
were discarded, as they were not biotype specific. Two new phage types
were identified by the same set. At present, by means of 22 lysogenic
phages, the three classical biotypes may be classified into 21 phage types,
namely four mitis, three intermedius, and 14 gravis types irrespective of the
charactets of lytic reactions (Figs 9-11). The “original” phage types are
stable and specifically correlated to biotype and toxinogenicity.
This scheme has proved its efficiency during the entire epidemic period
of diphtheria in Romania (Saragea et ul., 1966a, b, 1967a) b, 1968, 1973;
Gabrilovitch, 1966; Hajderi et al., 1967; Ejowa, 1967; Saragea and
Maximescu, 1969). It has also been used successfully to analyse different
epidemic outbreaks in other countries (Saragea and Maximescu, 1966;
Saragea et al., 1966b, 1972a; Gibson et ul., 1970; McCloskey et al., 1972;
Zamiri et al., 1972). During the period 1956-1969, 99-100% of the
C. diphtheriae type gravis tox+ strains and 75% of the total number of
C. diphtheriae strains isolated in Romania proved typable. Everywhere
abroad where C. dzjJhtheriae type gravis tax+ strains were prevalent and