HiMedia – M1580 HiCrome™ Enterococcus faecium Agar Base

Principle and Interpretation
HiCrome™ Enterococcus faecium Agar Base is recommended for the chromogenic detection of Enterococcus faecium from urine, faeces, soil, food, water, plants and animals. E. faecium is commonly found in the gastrointestinal tracts of humans (1). The resistance exhibited by Enterococcus species to various antimicrobials has led them to being a major cause of human infections including nosocomial infections (2). E. faecalis causes 80-90% of infection while E. faecium causes the majority of the remainder (3). The use of selective media for the isolation of Enterococci has been previously reviewed, including those containing chromogenic substrates (4) and media containing cephalexin-aztreonam supplements. Enterococcus species possess the enzyme glucosidase, which specifically cleaves the chromogenic substrate to produce blue coloured colonies. E. faecium ferment arabinose; and cleaves the chromogenic substrate present in the media to produce green coloured colonies along with yellow colouration to the medium. E. faecalis does not ferment arabinose and therefore retains the blue colour. Peptone special serves as a source of carbon, nitrogen and essential growth nutrients. Corn starch neutralizes the toxic metabolites while sodium chloride maintains the osmotic equilibrium. Phenol red serves as a pH indicator with arabinose being the fermentable carbohydrate.

原理與解釋
HiCrome™屎腸球菌瓊脂基質推薦用於從尿液，糞便，土壤，食物，水，植物和動物中檢測屎腸球菌。屎腸球菌常見於人類的胃腸道（1）。腸球菌對各種抗菌藥物的耐藥性使其成為包括醫院感染在內的人類感染的主要原因（2）。 E. faecalis引起80-90％的感染，而E. faecium引起其餘大部分（3）。先前已經綜述了選擇性培養基用於分離腸球菌的用途，包括含有生色底物（4）和含有頭孢氨芐 - 氨曲南補充劑的培養基。腸球菌屬有 酶葡糖苷酶，其特異性切割生色底物以產生藍色菌落。 E. faecium ferment阿拉伯糖;並切割培養基中存在的生色底物，以產生綠色菌落，同時將黃色著色到培養基中。 E. faecalis不發酵阿拉伯糖，因此保持藍色。 蛋白腖特殊作為碳，氮和必需生長營養素的來源。玉米澱粉中和有毒代謝物，而氯化鈉保持滲透平衡。酚紅作為pH指示劑，阿拉伯糖是可發酵的碳水化合物。