​Diagnostic Sensitivity Test Agar (DST Agar)

[所属分类:培养基配方] [发布时间:2020-6-16] [发布人:] [阅读次数:] [返回]

山东拓普生物工程有限公司

Shandong Tuopu Biol-Engineering Co.,Ltd

Diagnostic Sensitivity Test Agar
(DST Agar)

培养基配方
Composition per liter:
Agar........................................................................12.0g
Proteose peptone............................................................10.0g
Veal infusion solids........................................................10.0g
NaCl.........................................................................3.0g
Na2HPO4 .....................................................................2.0g
Glucose......................................................................2.0g
Sodium acetate...............................................................1.0g
Adenine sulfate.............................................................0.01g
Guanine·HCl................................................................0.01g
Uracil .....................................................................0.01g
Xanthine....................................................................0.01g
Thiamine...................................................................0.02mg
Horse blood, defibrinated .................................................70.0mL
pH 7.4 ± 0.2 at 25°C
Source:  This medium is available as a premixed powder from Oxoid
Unipath.
Preparation of Medium: Add components, except horse blood, to
distilled/deionized water and bring volume to 930.0mL. Mix thorough-
ly. Gently heat and bring to boiling. Autoclave for 15 min at 15 psi
pressure–121°C. Cool to 45°–50°C. Aseptically add sterile horse
blood. Mix thoroughly. Pour into sterile Petri dishes or distribute into
sterile tubes.
Use:  For antimicrobial testing of various pathogenic microorganisms.
DSTA is primarily used for susceptibility tests rather than the primary
isolation of organisms from clinical samples. An essential requirement
for satisfactory antimicrobial susceptibility media is that the reactive
levels of thymidine and thymine must be sufficiently reduced to avoid
antagonism of trimethoprim and sulphonamides. DSTA meets this
requirement and in the presence of lysed horse blood (or defibrinated
horse blood if the plates are stored long enough to allow some lysis of
the erythrocytes) the level of thymidine will be further reduced. This is
caused by the action of the enzyme thymidine phosphorylase which is
released from lysed horse erythrocytes. Thymidine is an essential
growth factor for thymidine-dependent organisms and they will not
grow in its absence or they will grow poorly in media containing
reduced levels.