88
A. SARAGEA ET AL.
bacteriological research. Among the first were attempts to utilise phage for
bacterial classification.
The well-known classification of C. dz’phtheriae into three biotypes
gravis, mitis and intermedius (Anderson et al., 1931) is based on biochemical
and cultural differentiation. This classification established by the medical
staff of Leeds (Anderson et al., 1931) during the big diphtheria epidemics
which occurred in Great Britain in 193 1 represented remarkable progress,
and has since led to considerable advances in the epidemiological study of
diphtheria.
However, the experience of those responsible for the surveillance of the
epidemiological process in diphtheria subsequently showed that this first
classification was not satisfactory for thorough epidemiological investigations. The persistence over a long period and over large geographical
areas, of only one biotype as, for instance, the gravis type throughout
Europe in the severe diphtheria epidemic during the Second World War
(Tasman and Lansberg, 1957), that of mitis in the U.S.A. (National Communicable Diseases Center Surveillance Rept., 1968), that of intermedius in
Madagascar and India (Saragea and Maximescu, 1966) and the wide distribution of gravis-type strains for about 15 years in Romania (Saragea,
1965; Saragea et al., 1965, 1967a, b, 1968) supports this statement. The
differences in clinical severity in various areas contaminated by the same
biotype suggested the existence of some biological differences between
the strains. This indicated that further subdivision of the biotypes was
needed (McLeod, 1943).
Even one of the authors of this first classification, McLeod (1943), foresaw
that: “A more analytical research is necessary in order to evidence a series
of complex relations and subdivisions not yet discovered”.
B. History of research on phage typing
The first attempts to investigate phage sensitivity in C. diphtheriae were
made in Australia (Keogh et al., 1938). These authors used two phages and
were able to characterise a group of strains belonging to the gravis and
intermedius types. They found a close correlation between phage sensitivity
and serological type. Toshach (1950), by isolating and adapting three
lysogenic phages (one of which, C/13, was subsequently used by Freeman
under the name of B phage) succeeded in typing some C. diphtheriae
strains from Canada, but no definite “pattern” related to type or source
was established. Fahey (1952) proposed and discussed a tentative typing
scheme, but did not find any correlation between biotype and phage
sensitivity.
Thibaut and FrCdCricq (1956a, b) found nine phage types among gravis
strains. Christensen (1957) was able to differentiate strains from two
A. SARAGEA ET AL.
bacteriological research. Among the first were attempts to utilise phage for
bacterial classification.
The well-known classification of C. dz’phtheriae into three biotypes
gravis, mitis and intermedius (Anderson et al., 1931) is based on biochemical
and cultural differentiation. This classification established by the medical
staff of Leeds (Anderson et al., 1931) during the big diphtheria epidemics
which occurred in Great Britain in 193 1 represented remarkable progress,
and has since led to considerable advances in the epidemiological study of
diphtheria.
However, the experience of those responsible for the surveillance of the
epidemiological process in diphtheria subsequently showed that this first
classification was not satisfactory for thorough epidemiological investigations. The persistence over a long period and over large geographical
areas, of only one biotype as, for instance, the gravis type throughout
Europe in the severe diphtheria epidemic during the Second World War
(Tasman and Lansberg, 1957), that of mitis in the U.S.A. (National Communicable Diseases Center Surveillance Rept., 1968), that of intermedius in
Madagascar and India (Saragea and Maximescu, 1966) and the wide distribution of gravis-type strains for about 15 years in Romania (Saragea,
1965; Saragea et al., 1965, 1967a, b, 1968) supports this statement. The
differences in clinical severity in various areas contaminated by the same
biotype suggested the existence of some biological differences between
the strains. This indicated that further subdivision of the biotypes was
needed (McLeod, 1943).
Even one of the authors of this first classification, McLeod (1943), foresaw
that: “A more analytical research is necessary in order to evidence a series
of complex relations and subdivisions not yet discovered”.
B. History of research on phage typing
The first attempts to investigate phage sensitivity in C. diphtheriae were
made in Australia (Keogh et al., 1938). These authors used two phages and
were able to characterise a group of strains belonging to the gravis and
intermedius types. They found a close correlation between phage sensitivity
and serological type. Toshach (1950), by isolating and adapting three
lysogenic phages (one of which, C/13, was subsequently used by Freeman
under the name of B phage) succeeded in typing some C. diphtheriae
strains from Canada, but no definite “pattern” related to type or source
was established. Fahey (1952) proposed and discussed a tentative typing
scheme, but did not find any correlation between biotype and phage
sensitivity.
Thibaut and FrCdCricq (1956a, b) found nine phage types among gravis
strains. Christensen (1957) was able to differentiate strains from two