Background

This study aims to investigate the antimicrobial ability and mechanism analysis of Lactobacillus species against carbapenemase-producing Enterobacteriaceae (CPE).

Methods

Five Lactobacillus spp. strains and 18 CPE clinical isolates were collected. Their anti-CPE effects were assessed by agar well diffusion and broth microdilution assay, as well as time-kill test. Finally, the specific anti-CPE mechanism, especially for the effect of organic acids was determined using broth microdilution method.

Results

All of five Lactobacilli isolates displayed the potent activity against most CPE isolates with mean zones of inhibition ranging 10.2–21.1 mm. The anti-CPE activity was not affected by heating, catalase, and proteinase treatment. Under the concentration of 50% LUC0180 cell-free supernatant (CFS), lactic acid, and mix acid could totally inhibit the growth of carbapenem-resistant Klebsiella pneumoniae (CPE0011), and acetic acid could inhibit 67.8%. In contrast, succinic acid and citric acid could not inhibit the growth of CPE0011. While we decreased the concentration to 25%, only lactic acid and mix acid displayed 100% inhibition. In contrast, succinic acid, citric acid and acetic acid did not show any inhibitory effect.

Conclusions

Lactobacillus strains exhibit potent anti-CPE activity, and lactic acid produced by Lactobacillus strains is the major antimicrobial mechanism.

中文翻译：

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乳酸菌对产碳青霉烯酶肠杆菌科细菌的抑菌能力及机制分析

背景

本研究旨在探讨乳酸菌对产碳青霉烯酶肠杆菌科(CPE)的抗菌能力和机制分析。

方法

五种乳酸菌。收集到 18 个 CPE 临床分离株。它们的抗 CPE 效果通过琼脂孔扩散和肉汤微量稀释测定以及时间杀伤试验进行评估。最后，使用肉汤微量稀释法确定了特定的抗CPE机制，特别是有机酸的作用。

结果

所有五种乳杆菌分离株均显示出对大多数 CPE 分离株的有效活性，平均抑菌圈范围为 10.2-21.1 mm。抗CPE活性不受加热、过氧化氢酶和蛋白酶处理的影响。在50% LUC0180无细胞上清液（CFS）、乳酸和混合酸浓度下，对耐碳青霉烯类肺炎克雷伯菌（CPE0011）的生长有完全抑制作用，醋酸抑制率为67.8%。相反，琥珀酸和柠檬酸不能抑制CPE0011的生长。虽然我们将浓度降低到 25%，但只有乳酸和混合酸显示出 100% 的抑制作用。相比之下，琥珀酸、柠檬酸和乙酸没有表现出任何抑制作用。

结论

乳酸杆菌菌株表现出强大的抗 CPE 活性，乳酸杆菌菌株产生的乳酸是主要的抗菌机制。