摘要
      耐多药细菌在环境中的生存能力对抗微生物耐药性的传播至关重要。在本研究中，使用两种大肠杆菌菌株，MDR LM13和易感ATCC25922，来阐明它们对六价铬（Cr（VI））胁迫的生存能力和转录反应的差异。结果表明，在2–20 mg/L Cr（VI）暴露下，LM13的活力显著高于ATCC25922，LM13和ATCC2592的抑菌率分别为3.1%–57%和0.9%–93.1%。在Cr（VI）暴露下，ATCC25922的活性氧和超氧化物歧化酶水平远高于LM13。此外，从两株菌株的转录组中鉴定出514个和765个差异表达基因（log2|FC|>1，p<0.05）。其中，134个上调基因在LM13中富集以响应外部压力，但只有48个基因在ATCC25922中注释。此外，LM13中抗生素抗性基因、插入序列、DNA和RNA甲基转移酶以及毒素抗毒素系统的表达水平通常高于ATCC25922。这项工作表明，MDR LM13在Cr（VI）胁迫下具有更强的生存能力，因此可能促进MDR细菌在环境中的传播。
Abstract
The viability of multidrug resistant (MDR) bacteria in environment is critical for the spread of antimicrobial resistance. In this study, two Escherichia coli strains, MDR LM13 and susceptible ATCC25922, were used to elucidate differences in their viability and transcriptional responses to hexavalent chromium (Cr(VI)) stress. The results show that the viability of LM13 was notably higher than that of ATCC25922 under 2–20 mg/L Cr(VI) exposure with bacteriostatic rates of 3.1%–57%, respectively, for LM13 and 0.9%–93.1%, respectively, for ATCC25922. The levels of reactive oxygen species and superoxide dismutase in ATCC25922 were much higher than those in LM13 under Cr(VI) exposure. Additionally, 514 and 765 differentially expressed genes were identified from the transcriptomes of the two strains (log2|FC| > 1, p < 0.05). Among them, 134 up-regulated genes were enriched in LM13 in response to external pressure, but only 48 genes were annotated in ATCC25922. Furthermore, the expression levels of antibiotic resistance genes, insertion sequences, DNA and RNA methyltransferases, and toxin-antitoxin systems were generally higher in LM13 than in ATCC25922. This work shows that MDR LM13 has a stronger viability under Cr(VI) stress, and therefore may promote the dissemination of MDR bacteria in environment.

https://www.sciencedirect.com/science/article/abs/pii/S0269749123003482