|EMD Cat. No. 1.01347.0500|
|Selective agar proposed by HOLT-HARRIS and TEAGUE (1916) for the detection and isolation of pathogenic Enterobacteriaceae.|
|Mode of Action||Preparation|
|Experimental Procedure and Evaluation||Quality Control|
|Typical Composition (g/liter)||Literature|
Mode of Action The lactose and sucrose contained in this medium allow lactose- and sucrose-negative salmonellae and shigellae to be distinguished from lactose-positive coliform organisms and lactose-negative, sucrose-positive, accompanying flora (e.g. Proteus vulgaris, Citrobacter, Aeromonas hydrophila). The growth of undesired accompanying microorganisms, particularly Gram-positive bacteria, is largely inhibited by the dyes present in the medium.
Typical Composition (g/liter) Peptones 10.0; di-potassium hydrogen phosphate 2.0; lactose 5.0; sucrose 5.0; eosin Y, yellowish 0.4; methylene blue 0.07; agar-agar 13.5.
Preparation Suspend 36 g in 1 liter of purified water. Autoclave (15 min at 121°C), pour plates. pH: 7.1 ± 0.2 at 25°C. The plates are clear and reddish-brown to violet-brown.
Experimental Procedure and Evaluation Inoculate by spreading the sample material thinly on the surface of the plates. Incubation: 24 hours at 35°C aerobically.
|Appearance of Colonies||Microorganisms|
|Translucent, amber colored||Salmonella, Shigella|
|Greenish, metallic sheen in reflected light, blue-black centre in transmitted light||Escherichia coli|
|Colonies are larger than those of E. coli, mucoid, confluent, gray-brown centre in transmitted light||Enterobacter, Klebsiella and others|
|Test strains||Growth||Colony color||Metallic sheen|
|Escherichia coli ATCC 25922||good / very good||violet||+|
|Escherichia coli ATC 11775||good / very good||violet||+|
|Escherichia coli 194||good / very good||violet||+|
|Escherichia coli ATCC 23716||good / very good||violet||+|
|Escherichia coli ATCC 8739||good / very good||violet||+|
|Enterobacter cloacae ATCC 13047||fair / very good||pink, dark centre||+ / -|
|Salmonella typhimurium ATCC 14028||good / very good||colorless, transparent||-|
|Shigella flexneri ATCC 12022||good / very good||colorless, transparent||-|
|Bacillus cereus ATCC 11778||none / poor|| ||-|
HOLT-HARRIS, J.E., a. TEAGUE, O.A.: A new culture medium for the isolation of Bacillus typhosus from stools. - J. Infect. Dis., 18; 596-600 (1916).