Objective

To compare the performance of agar dilution and broth microdilution by commercial and in-house prepared plates for the Bacteroides fragilis group. The cost analysis was performed to demonstrate that in-house prepared BMD plates were a suitable alternative to agar dilution given the high cost and low feasibility of incorporating commercial BMD plates in routine, particularly in the tertiary care institutes of many low- and middle-income countries.

Methods

Thirty B. fragilis group isolates were tested against six antibiotics, frequently used as empirical therapy for anaerobic infections including metronidazole, clindamycin, imipenem, piperacillin-tazobactam, cefoxitin, and chloramphenicol. The running consumable expenditure for all methodologies was calculated.

Results

The results demonstrated essential and categorical agreement of >90% for all antibiotics except cefoxitin, which showed <90% categorical agreement. No major or very major errors were observed. We observed a high agreement and strong concordance for MIC values between both methods and inter-rate reliability of >0.9 by Cohen's kappa analysis, indicating almost perfect agreement between both methods using either of the plates. In contrast to agar dilution, a 20.5 fold cost reduction was seen in BMD using in-house plates and a 5.8 fold reduction using commercial plates to test a single isolate. However, when testing 30 isolates concurrently the cost significantly increased for commercial BMD plates by 8.4 folds, and only 1.03 fold cost reduction was seen with in-house BMD plates.

Conclusion

BMD gives comparable results to agar dilution and can be considered a method of choice to test a small number of samples. The technique is an economical option when plates are standardized in-house and could be employed for susceptibility testing of the B. fragilis group.

中文翻译：

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商业和内部平板对脆弱拟杆菌群的琼脂稀释和肉汤微量稀释的比较评估：资源有限环境的经济快速方法

客观的

比较脆弱拟杆菌组的商业和内部制备板的琼脂稀释和肉汤微量稀释性能。进行成本分析以证明内部制备的 BMD 板是琼脂稀释的合适替代品，因为将商业 BMD 板纳入常规，特别是在许多低收入和中等收入的三级护理机构中成本高且可行性低国家。

方法

对30株脆弱拟杆菌群分离株进行了针对六种抗生素的测试，这些抗生素经常用作厌氧菌感染的经验性治疗，包括甲硝唑、克林霉素、亚胺培南、哌拉西林-他唑巴坦、头孢西丁和氯霉素。计算了所有方法的运行消耗品支出。

结果

结果表明，除头孢西丁外，所有抗生素的基本一致性和分类一致性均大于 90%，头孢西丁的分类一致性小于 90%。没有观察到重大或非常重大的错误。通过 Cohen 的 kappa 分析，我们观察到两种方法之间的 MIC 值高度一致且高度一致，速率间可靠性 > 0.9，表明使用任一板的两种方法之间几乎完全一致。与琼脂稀释相比，使用内部板检测 BMD 成本降低了 20.5 倍，使用商业板测试单个分离物降低了 5.8 倍。然而，当同时测试 30 个分离株时，商业 BMD 板的成本显着增加了 8.4 倍，而内部 BMD 板的成本仅降低了 1.03 倍。

结论

BMD 提供与琼脂稀释相当的结果，可以被认为是测试少量样品的首选方法。当板在内部标准化时，该技术是一种经济的选择，可用于脆弱拟杆菌群的敏感性测试。