264
T. BERGAN
T A B L E X V I
Critical dilutions (CD) and routine test dilutions (RTD) of
S. sonnei typing phages
Ten-fold dilution of freshly
prepared phage suspension
commonly yielding
Relative dilution
Phage
of C D suspension
designations
C D
R T D
to give R T D
I
I1
111
IV
IVA
V
VI
VII
VIII
VIIIA
I X
X
XI
XI1
F12
766
10-3
10-3
10-4
10-2
10-3
10-3
10-4
10-3
10-4
10-4
10-2
10-4
10-6
10-2
10-2
10-1
10-3
10-3
10-2
10-2
10-3
10-3
10-4
10-3
10-4
10-1
10-6
10-1
x 10-1
Undiluted
x 10-1
x 10-1
x 10-1
x 10-1
x 10-1
Undiluted
Undiluted
x 10-1
x 10-1
Undiluted
Undiluted
x 10-1
culture is made from each colony type. The tubes are incubated overnight
at 37°C.
On the second day, the colonies are thoroughly mixed. Then, 9 ml
diameter plates are flooded, excess fluid taken off, and the plates dried at
37°C for 10-15 min with the lids off.
The RTD bacteriophage preparations are applied with, for example,
the semi-automatic phage applicator of Lidwell (1959) (Fig. 2).
T A B L E X V I I
Plaque count giving plaques of size compatible with routine
test dilution (Hammarstrorn, 1949)
Plaque number per drop zone
Plaque
size (mm)
Lower limit
Upper limit
0.05
0.1
0.2
>0.3
1000
100
50
20
6000
1500
400
150