152
A. SARAGEA ET AL.
test. The excess fluid is removed by vacuum and the plate left to dry for
45-50 min at 37°C with the lid half open. A drop of 100 RTD of each
preparation from the basic set of typing’ phages is then placed (at predetermined positions) on the agar surface over the dried film of the culture.
The plates are then incubated overnight at 35°C. Lytic reactions are
recorded the following day and compared with the known phage type
patterns.
C. Notation of results
marked in the following manner:
Any degree of lytic reaction is taken into consideration. Results are
CL = confluent clear lysis
OL = confluent opaque lysis due to a film of fine growth on the area
of the dropped phage
LCL = clear lysis with irregular margins of the lytic area
LOL = opaque lysis with irregular margins of the lytic area
SCL = semiconfluent clear lysis
SOL = semiconfluent opaque lysis
& = 5-10 lytic plaques
1+ = 10-20 lytic plaques
2+ = 20-50 lytic plaques
3 + = 50 or more plaques.
According to the size of plaques we add for normal sized plaques “n”
(normal plaques) or “s” (small plaques) for instance: 1 +n, 2 + n or
l+s, 2+s.
The notation of lytic reactions is performed according to the position of
phages in the basic set; the whole group of lytic reactions of a strain
represents its lytic pattern, i.e. its phage type, which is recorded in the
original phage typing scheme by a Roman numeral (Fig. 8) and in the
additional phage typing scheme (Fig. 16) by capital letters.
D. Preparation of phage stocks
1. Original phage typing scheme
(a) Propagating strains. Each of the 22 typing phages has its specific
propagating (indicator) strain. The first five typing phages of the basic
set (nos. 1-5) are propagated on a mitis tox- strain no. 1180 (Freeman);
phage no. 6 on another mitis tox- strain no. 15.872 (Romania); phages
nos. 7-9 on an intermedius tox- strain no. 4465 (Romania); phages 10-13
A. SARAGEA ET AL.
test. The excess fluid is removed by vacuum and the plate left to dry for
45-50 min at 37°C with the lid half open. A drop of 100 RTD of each
preparation from the basic set of typing’ phages is then placed (at predetermined positions) on the agar surface over the dried film of the culture.
The plates are then incubated overnight at 35°C. Lytic reactions are
recorded the following day and compared with the known phage type
patterns.
C. Notation of results
marked in the following manner:
Any degree of lytic reaction is taken into consideration. Results are
CL = confluent clear lysis
OL = confluent opaque lysis due to a film of fine growth on the area
of the dropped phage
LCL = clear lysis with irregular margins of the lytic area
LOL = opaque lysis with irregular margins of the lytic area
SCL = semiconfluent clear lysis
SOL = semiconfluent opaque lysis
& = 5-10 lytic plaques
1+ = 10-20 lytic plaques
2+ = 20-50 lytic plaques
3 + = 50 or more plaques.
According to the size of plaques we add for normal sized plaques “n”
(normal plaques) or “s” (small plaques) for instance: 1 +n, 2 + n or
l+s, 2+s.
The notation of lytic reactions is performed according to the position of
phages in the basic set; the whole group of lytic reactions of a strain
represents its lytic pattern, i.e. its phage type, which is recorded in the
original phage typing scheme by a Roman numeral (Fig. 8) and in the
additional phage typing scheme (Fig. 16) by capital letters.
D. Preparation of phage stocks
1. Original phage typing scheme
(a) Propagating strains. Each of the 22 typing phages has its specific
propagating (indicator) strain. The first five typing phages of the basic
set (nos. 1-5) are propagated on a mitis tox- strain no. 1180 (Freeman);
phage no. 6 on another mitis tox- strain no. 15.872 (Romania); phages
nos. 7-9 on an intermedius tox- strain no. 4465 (Romania); phages 10-13