HiMedia – M1600 HiCrome™ Universal Differential Medium

Principle and Interpretation
HiCrome™ Universal Differential Medium is a modification of the medium　formulated on basis of the work carried out by Pezzlo (4), Wilkie et al (6), Friedman et al (1), Murray et al (3), Soriano and Ponte (5) and Merlinoet al (2). HiCrome™ Universal Differential Medium is recommended for the presumptive identification of microorganisms from clinical and non-clinical specimens where the medium has broader application as a general nutrient agar for isolation of various microorganisms. This medium helps in the identification of some gram-positive bacteria and gram-negative bacteria on the basis of different colony colours exhibited by them. These colours are formed due to the reactions of genus or species specific enzymes with the two chromogenic substrates incorporated in the medium. Enterococcus species, Escherichia coli and coliforms produce enzymes which specifically cleave these chromogenic substrates to give characteristically distinctive colony colours. Peptone in the medium serve as sources of amino acids like phenylalanine and tryptophan which aids in indicating tryptophan deaminase activity, thereby facilitating the identification of Proteus species, Morganella species and Providencia species. One of the chromogenic substrate is cleaved by b-glucosidase enzyme possessed by Enterococci resulting in the formation of bluish green colonies. Escherichia coli possesses the enzyme b-galactosidase which specifically cleaves the other chromogenic substrate resulting in the formation of purple coloured colonies. Escherichia coli can be differentiated and confirmed from other similar coloured colonies, by performing the indole test. Coliforms cleave both the chromogenic substrates forming blue to purple coloured colonies. Colonies of Proteus, Morganella and Providencia species appear brown due to tryptophan deaminase activity. Peptone and Tryptone provide nitrogenous and carbonaceous compounds, essential growth nutrients and also serve as a source of amino acids.

原理與解釋
HiCrome™通用差示介質是根據Pezzlo（4），Wilkie等人（6），Friedman等人（1），Murray等人（3），Soriano和Ponte（ 5）和Merlinoet al（2）。 HiCrome™通用差異培養基推薦用於推定鑑定來自臨床和非臨床樣本的微生物，其中培養基作為用於分離各種微生物的一般營養瓊脂具有更廣泛的應用。該培養基有助於根據它們表現出的不同菌落顏色鑑定一些革蘭氏陽性細菌和革蘭氏陰性細菌。這些顏色是由於屬或物種特異性酶與摻入培養基中的兩種生色底物的反應而形成的。腸球菌屬物種，大腸桿菌和大腸桿菌產生特異性切割這些生色底物的酶，以產生特徵性的菌落顏色。蛋白腖 在培養基中充當氨基酸如苯丙氨酸和色氨酸的來源，其有助於指示色氨酸脫氨酶活性，從而有助於鑑定變形桿菌屬物種，摩根氏菌屬物種和普羅威登斯菌種。其中一個生色底物被腸球菌所具有的β-葡糖苷酶切割，導致形成藍綠色菌落。大腸桿菌具有酶b-半乳糖苷酶，其特異性切割其他生色底物，導致紫色菌落的形成。通過進行吲哚試驗，可以從其他相似的有色菌落中區分和確認大腸桿菌。 大腸桿菌切割兩種生色底物，形成藍色至紫色的菌落。 Proteus，Morganella和Providencia物種的菌落由於色氨酸脫氨酶活性而呈棕色。蛋白腖和胰蛋白腖提供含氮和含碳化合物，必需的生長營養素，也可作為其來源氨基酸。