Baird Parker 琼脂上金黄色葡萄球菌的检测与鉴别

Jvo Siegrist

微生物学产品经理,

AnalytiX 第10卷 第4篇

ivo.siegrist@sial.com

Baird Parker 琼脂可按 Baird Parker 方法用于食品和药品中凝固酶阳性葡萄球菌的分离和鉴别。

酪蛋白胨和肉提取物作为生物体的氮源被添加到培养基中。酵母提取物提供氮以及其他重要的营养物质,如维生素 B12 复合物。培养基中含有锂和亚碲酸盐,能抑制大部分污染菌群,而甘氨酸和丙酮酸能增强葡萄球菌的生长。葡萄球菌可将亚碲酸盐还原成碲化物,导致菌落呈灰色至黑色。加入蛋黄后,培养基变成黄色,稍不透明。凝固酶阳性的金黄色葡萄球菌在菌落周围形成明显的晕圈,进一步培养后可能由于蛋黄卵磷脂酶反应(脂解活性)而产生不透明区。由于凝固酶试验和脂溶活性之间存在高度相关性,因此推测该培养基上的灰黑色菌落和晕圈是凝固酶阳性葡萄球菌的指示。金黄色葡萄球菌和腐生葡萄球菌的某些菌株(Shaw 等人 [5])可能表现出这两种特征,但很容易通过晕发生的不同时间来区分它们。

含兔血浆纤维蛋白原的Baird Parker 琼脂可用于凝固酶活性的检测。由于亚碲酸盐的减少和不透明的晕圈,由于凝固酶从纤维蛋白原转化为纤维蛋白,凝固酶阳性生物体呈现为灰色至黑色的菌落。只有少于 100 个特征菌落的平板才应计数。使用这种培养基无需进行额外的凝固酶试验。

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