V. BACTERIOPHAGE TYPING OF SHIGELLA
281
latter may be useful to break down larger groups of strains with the same
lytic type.
Phage typing of Shigella is recommended only for national, or regional
reference laboratories of several collaborating nations.
X. FUTURE TRENDS
The work of the international panels studying the phage typing of S.
JEexneri and S . sonnei is approaching definition of suitable typing sets for
both species. When agreement is reached, the situation should be followed
closely to detect changes in the bacterial population. Such changes may
conceivably be observed over the years and may require addition to or
exclusion from the typing sets. Computers are useful in such continuous
surveillance and in evaluating the discriminatory ability of the typing
phages.
Computers are also useful aids in discrimination between patterns.
Further development may give additional support to the proposal (vide
supra) that phage typing patterns should be reported instead of using the
rigid system of phage types.
Areas that need scientific elaboration are :
Reproducibility of the reactions of individual phages.
Evaluation of how many phage reactions may be tolerated as acceptable
Validation of the techniques used, such as propagation and temperatures
for source identity of epidemiologically related strains.
of incubation.
The global impact of Sh%ella infections will continue on a high scale for
the unforeseeable future. Shigellosis is under the constant surveillance of
the World Health Organisation (WHO). In many countries, S. dysenteriae
is a more severe health problem due to the high frequency and the gravity
of the disease as compared with industrialised areas, Consequently, carefully standardised and internationally studied typing sets for s. dysenteyiae
need to be developed.
ACKNOIVLEDGEMENTS
I would like to thank Dr L.-0. Kallings, Stockholm, Sweden, and Dr S. Slopek
Wroclaw, Poland, for generously having made several figures available for this
Chapter. Dr Kallings has also contributed valuable pieces of information and has
been available for discussions for which I am grateful.
281
latter may be useful to break down larger groups of strains with the same
lytic type.
Phage typing of Shigella is recommended only for national, or regional
reference laboratories of several collaborating nations.
X. FUTURE TRENDS
The work of the international panels studying the phage typing of S.
JEexneri and S . sonnei is approaching definition of suitable typing sets for
both species. When agreement is reached, the situation should be followed
closely to detect changes in the bacterial population. Such changes may
conceivably be observed over the years and may require addition to or
exclusion from the typing sets. Computers are useful in such continuous
surveillance and in evaluating the discriminatory ability of the typing
phages.
Computers are also useful aids in discrimination between patterns.
Further development may give additional support to the proposal (vide
supra) that phage typing patterns should be reported instead of using the
rigid system of phage types.
Areas that need scientific elaboration are :
Reproducibility of the reactions of individual phages.
Evaluation of how many phage reactions may be tolerated as acceptable
Validation of the techniques used, such as propagation and temperatures
for source identity of epidemiologically related strains.
of incubation.
The global impact of Sh%ella infections will continue on a high scale for
the unforeseeable future. Shigellosis is under the constant surveillance of
the World Health Organisation (WHO). In many countries, S. dysenteriae
is a more severe health problem due to the high frequency and the gravity
of the disease as compared with industrialised areas, Consequently, carefully standardised and internationally studied typing sets for s. dysenteyiae
need to be developed.
ACKNOIVLEDGEMENTS
I would like to thank Dr L.-0. Kallings, Stockholm, Sweden, and Dr S. Slopek
Wroclaw, Poland, for generously having made several figures available for this
Chapter. Dr Kallings has also contributed valuable pieces of information and has
been available for discussions for which I am grateful.