Saito H
Hiroshima Environment and Health Association, Japan.
Kekkaku. 1998 May;73(5):329-37.
A variety of different media for the cultivation of mycobacteria have been described but a few of them are in use today. Those currently used can be characterized by three basic types. The first is egg-based media represented by Ogawa and Löwenstein-Jensen. The second type is agar-based media; the most common one are Middlebrook 7H10 and 7H11. The third type is liquid media such as Middlebrook 7H9. Several weeks of incubation may be required for the isolation of M. tuberculosis on solid media. Substantial improvement in the time to detection and the recovery rate was realized by using broth-based culture system such as the BACTEC 460TB, Septi-Chek AFB, MGIT and BACTEC 9000. In the BACTEC 460TB system, the mycobacteria is detected radiometrically. The processed specimen is added to a modified 7H9 medium (BACTEC 12B) containing 14C-labeled palmitic acid and an antibiotic complex, PANTA. Mycobacterial growth can be ascertained by the liberation of 14CO2 and detected by BACTEC 460TB instrument. The Septi-Chek AFB is a biphasic medium which combines broth and solid media. The liquid medium is a modified Middlebrook 7H9 in a carbon-dioxide-enriched culture bottle. After inoculation of the sample, the bottle is capped with a slide consisting of three solid media; a non-selective Middlebrook 7H11 agar, an egg-based medium, and chocolate agar. A novel system is the MGIT, which is a nonradiometric broth method for the detection of mycobacteria from clinical specimens. The MGIT consists of a modified Middlebrook 7H9 broth and a sensor embedded in silicone on the bottom of a tube. The appearance of orange-colored fluorescence in the sensor when excited indicates the growth of mycobacteria. MB Redox is a modified, serum-supplemented Kirchner medium containing p-indonitrotetrazolium violet (INT) as an indicator of microbial growth. The INT is reduced by the redox system of the mycobacteria to deep violet-colored formazan. This substance is water insoluble and is reduced to the cell surface, by which bacterial clamps can be easily detected by their violet color. At present, the egg-based media are the first choice for the culture of clinical samples. However, there are advantages to each type of medium and not all strains of mycobacteria can be recovered on a single medium. Therefore, it is recommended that one representative of each type of medium be used for primary isolation; one example in Japan may be Ogawa egg medium in combination with Middlebrook 7H11 and MGIT.
人们已经描述了多种用于培养分枝杆菌的不同培养基，但如今仍在使用的只有少数几种。目前使用的培养基可分为三种基本类型。第一种是以小川培养基和罗-琴培养基为代表的基于鸡蛋的培养基。第二种类型是基于琼脂的培养基；最常见的是Middlebrook 7H10和7H11。第三种类型是液体培养基，如Middlebrook 7H9。在固体培养基上分离结核分枝杆菌可能需要数周的培养时间。通过使用基于肉汤的培养系统，如BACTEC 460TB、Septi-Chek AFB、MGIT和BACTEC 9000，检测时间和回收率有了显著提高。在BACTEC 460TB系统中，分枝杆菌通过放射性检测。将处理后的标本加入含有14C标记的棕榈酸和抗生素复合物PANTA的改良7H9培养基（BACTEC 12B）中。分枝杆菌的生长可以通过14CO2的释放来确定，并由BACTEC 460TB仪器检测。Septi-Chek AFB是一种双相培养基，它结合了肉汤和固体培养基。液体培养基是在富含二氧化碳的培养瓶中的改良Middlebrook 7H9。接种样品后，瓶子用一个由三种固体培养基组成的载玻片覆盖；一种非选择性的Middlebrook 7H11琼脂、一种基于鸡蛋的培养基和巧克力琼脂。一种新型系统是MGIT，它是一种用于从临床标本中检测分枝杆菌的非放射性肉汤法。MGIT由改良的Middlebrook 7H9肉汤和嵌入管底部硅胶中的传感器组成。传感器在激发时出现橙色荧光表明分枝杆菌生长。MB Redox是一种改良的、添加血清的基尔希纳培养基，含有对硝基四氮唑紫（INT）作为微生物生长的指示剂。INT被分枝杆菌的氧化还原系统还原为深紫色的甲臜。这种物质不溶于水，并还原到细胞表面，通过其紫色可以很容易地检测到细菌菌落。目前，基于鸡蛋的培养基是临床样本培养的首选。然而，每种类型的培养基都有其优点，并非所有分枝杆菌菌株都能在单一培养基上生长。因此，建议在初次分离时使用每种类型培养基的一种代表；在日本，一个例子可能是小川鸡蛋培养基与Middlebrook 7H11和MGIT联合使用。
