Department of Microbiology, Nil Ratan Sircar Medical College, Kolkata, India.
Indian J Med Res. 2009 Nov;130(5):561-6.
BACKGROUND & OBJECTIVE: There is resurgence of tuberculosis in recent years in spite of availability of comprehensive multidrug therapy. Conventional culture media require a long time for the appearance of growth of Mycobacterium tuberculosis, while the other methods are expensive. Hence, a rapid low cost and safe bilayered medium was developed for early growth and sensitivity testing of M. tuberculosis and the results were compared with those on Lowenstein Jensen medium, Middlebrook 7H10 and Kirchner's liquid media.
A specially designed bilayered medium, consisting of a lower layer of Lowenstein Jensen medium without malachite green and a top layer of Middlebrook 7H 10 medium with added antibiotics and antifungal agents was prepared. Sputum from clinically suspected cases of tuberculosis, pleural fluid and pus samples were inoculated on the bilayered medium along with the inoculation on other conventional media after proper decontamination and concentration of the samples. Antibiotic sensitivity pattern was determined against a few rapidly growing control and test strains by disc diffusion technique and the results could be recorded by 3 to 7 days.
Statistically significant (P< 0.001) isolation rate was obtained on this bilayered medium when compared with the other three media, being 81.7 per cent growth by 7 days. Antibiotic sensitivity test could be recorded by 3 days in case of the rapidly growing strains on this medium, and by 7 days in case of M. tuberculosis strains.
INTERPRETATION & CONCLUSION: Bilayered medium produced rapid growth earliest by 48 h, higher isolation rates were achieved as compared to the other conventional media and drug sensitivity testing could also be carried out successfully. Thus, the bilayered medium can be used for obtaining early culture report.
尽管有综合多药疗法，但近年来结核病的发病率又出现了回升。传统的培养基需要很长时间才能出现结核分枝杆菌的生长，而其他方法则比较昂贵。因此，开发了一种快速、低成本、安全的双层培养基，用于早期生长和结核分枝杆菌的药敏试验，并将结果与 Lowenstein Jensen 培养基、Middlebrook 7H10 培养基和 Kirchner 液体培养基进行了比较。
设计了一种特殊的双层培养基，由下一层不含孔雀绿的 Lowenstein Jensen 培养基和上一层添加抗生素和抗真菌剂的 Middlebrook 7H10 培养基组成。将来自临床疑似肺结核的痰液、胸腔积液和脓液样本接种在双层培养基上，并在适当的去污和浓缩样本后接种在其他常规培养基上。通过纸片扩散技术对抗生素快速生长的对照和测试菌株进行药敏模式测定，并可在 3 至 7 天内记录结果。
与其他三种培养基相比，该双层培养基的分离率具有统计学意义（P<0.001），在第 7 天达到 81.7%的生长。在这种培养基上，快速生长的菌株在 3 天内可进行药敏试验，而结核分枝杆菌则需 7 天。
双层培养基最早在 48 小时内产生快速生长，与其他常规培养基相比，其分离率更高，并且可以成功进行药敏试验。因此，双层培养基可用于获得早期培养报告。
