Bergmann J S, Woods G L
Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555-0740, USA.
J Clin Microbiol. 1998 Oct;36(10):2940-3. doi: 10.1128/JCM.36.10.2940-2943.1998.
The reliability of the ESP Culture System II (herein referred to as ESP II) for testing susceptibilities of Mycobacterium tuberculosis isolates to isoniazid, rifampin, ethambutol, and streptomycin was evaluated by comparing results to those of the method of proportion (MOP), which was considered the reference method, for 20 clinical isolates and 30 challenge strains provided by the Centers for Disease Control and Prevention (CDC). Clinical isolates also were tested with the BACTEC TB 460 system; these results agreed with those obtained by the MOP for all isolates and all drugs, except the high concentration of isoniazid, for which agreement was 95%. After resolution of discrepancies, levels of agreement between ESP II and MOP for the clinical isolates were 95 and 100%, respectively, for the low and high concentrations of isoniazid, 100% for rifampin and ethambutol, and 95% for streptomycin. For the 30 challenge isolates, ESP II results for both concentrations of isoniazid agreed with the expected results in all cases, whereas agreement was 93% for both rifampin and streptomycin and 90% for ethambutol. All discrepancies with the CDC isolates were due to failure of ESP II to correctly classify resistant strains. By testing isolates yielding discrepant ethambutol and streptomycin results with a lower concentration of both drugs in the ESP II system, agreement increased to 93% for ethambutol and 100% for streptomycin. For the clinical isolates, the times to an ESP II result of susceptible (means +/- standard errors of the means) were 8.47 +/- 0.12 days (range, 7 to 10 days) and 8.73 +/- 0.29 days (range, 5 to 11 days) when the inoculum was prepared from a McFarland equivalent and from a seed bottle, respectively. The time to an ESP II result of resistant varied by drug and method of inoculum preparation, ranging from 5.50 +/- 0.22 days for ethambutol with the inoculum prepared from a McFarland standard to 8. 0 days for ethambutol with the inoculum prepared from a seed bottle. These data suggest that the ESP II system is a rapid and reliable method for testing susceptibilities of M. tuberculosis isolates to isoniazid and rifampin. Performance, however, may be suboptimal for ethambutol and streptomycin. Testing additional ethambutol-resistant and streptomycin-resistant strains with two concentrations of both drugs is necessary.
通过将结果与比例法（MOP）（被视为参考方法）进行比较，评估了ESP Culture System II（以下简称ESP II）检测结核分枝杆菌分离株对异烟肼、利福平、乙胺丁醇和链霉素敏感性的可靠性，该比较针对疾病控制与预防中心（CDC）提供的20株临床分离株和30株挑战菌株。临床分离株还用BACTEC TB 460系统进行了检测；除高浓度异烟肼外，所有分离株和所有药物的这些结果与MOP获得的结果一致，高浓度异烟肼的一致性为95%。在解决差异后，ESP II与MOP之间对于临床分离株，低浓度和高浓度异烟肼的一致性水平分别为95%和100%，利福平和乙胺丁醇为100%，链霉素为95%。对于30株挑战分离株，两种浓度异烟肼的ESP II结果在所有情况下均与预期结果一致，而利福平和链霉素的一致性为93%，乙胺丁醇为90%。与CDC分离株的所有差异均是由于ESP II未能正确分类耐药菌株。通过在ESP II系统中用较低浓度的两种药物检测产生乙胺丁醇和链霉素结果不一致的分离株，乙胺丁醇的一致性提高到93%，链霉素提高到100%。对于临床分离株，当接种物分别由麦氏浊度标准液和种子瓶制备时，ESP II得出敏感结果的时间（平均值±平均值的标准误）分别为8.47±0.12天（范围为7至10天）和8.73±0.29天（范围为5至11天）。ESP II得出耐药结果的时间因药物和接种物制备方法而异，从用麦氏标准液制备接种物时乙胺丁醇的5.50±0.22天到用种子瓶制备接种物时乙胺丁醇的8.0天不等。这些数据表明，ESP II系统是检测结核分枝杆菌分离株对异烟肼和利福平敏感性的快速且可靠的方法。然而，对于乙胺丁醇和链霉素，其性能可能欠佳。有必要用两种浓度的这两种药物检测更多的乙胺丁醇耐药和链霉素耐药菌株。
