IV. INVESTIGATION OF C. DIPHTHERIAE
101
FIG. 16. Additional routine phage typing scheme. 0 , lytic usual pattern; (O),
inconsistent lytic activity.
selected phage samples mentioned above. Phage types were labelled with
capital letters as follows: A, B, C, D, D1, E, F, G, H, I, J, K, K1, L.
Thereafter a new routine assay with the additional scheme was carried out
on about 7000-8000 C . diphtheriae strains.
(c) Characters of the additional phage typing scheme. The following points
have to be stressed:
The additional phage types were stable as proved in repeated tests,
irrespective of the means used to store the strains. This was proved during
the approximately 3 years’ surveillance of closed children’s communities,
showing high carriage percentages of non-toxigenic diphtheria bacilli. The
same phage type was identified throughout the whole period.
While the original phage typing scheme is at present almost complete
and further changes may be limited as it has proved its value on about
35 000 C . d$htheriae wild strains from Romania and approximately