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首页> 外文期刊>Applied Microbiology >Modeling the Infection Dynamics of Bacteriophages in Enteric Escherichia coli: Estimating the Contribution of Transduction to Antimicrobial Gene Spread
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Modeling the Infection Dynamics of Bacteriophages in Enteric Escherichia coli: Estimating the Contribution of Transduction to Antimicrobial Gene Spread

机译：建模在大肠杆菌中噬菌体的感染动力学：估计转导对抗菌素基因传播的贡献。

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Animal-associated bacterial communities are infected by bacteriophages, although the dynamics of these infections are poorly understood. Transduction by bacteriophages may contribute to transfer of antimicrobial resistance genes, but the relative importance of transduction among other gene transfer mechanisms is unknown. We therefore developed a candidate deterministic mathematical model of the infection dynamics of enteric coliphages in commensal Escherichia coli in the large intestine of cattle. We assumed the phages were associated with the intestine and were predominantly temperate. Model simulations demonstrated how, given the bacterial ecology and infection dynamics, most (>90%) commensal enteric E. coli bacteria may become lysogens of enteric coliphages during intestinal transit. Using the model and the most liberal assumptions about transduction efficiency and resistance gene frequency, we approximated the upper numerical limits (“worst-case scenario”) of gene transfer through specialized and generalized transduction in E. coli by enteric coliphages when the transduced genetic segment is picked at random. The estimates were consistent with a relatively small contribution of transduction to lateral gene spread; for example, generalized transduction delivered the chromosomal resistance gene to up to 8 E. coli bacteria/hour within the population of 1.47 × 10~(8) E. coli bacteria/liter luminal contents. In comparison, the plasmidic bla _(CMY-2) gene carried by ～2% of enteric E. coli was transferred by conjugation at a rate at least 1.4 × 10~(3) times greater than our generalized transduction estimate. The estimated numbers of transductants varied nonlinearly depending on the ecology of bacteria available for phages to infect, that is, on the assumed rates of turnover and replication of enteric E. coli .
机译：与动物相关的细菌群落被噬菌体感染，尽管对这些感染的动力学了解甚少。噬菌体的转导可能有助于抗菌素耐药基因的转移，但是在其他基因转移机制中转导的相对重要性尚不清楚。因此，我们开发了一种候选确定性数学模型，用于确定牛大肠内共生大肠杆菌中肠杆菌的感染动力学。我们假设噬菌体与肠有关，并且主要是温带的。模型仿真表明，鉴于细菌的生态学和感染动态，大多数（> 90％）普通肠道大肠杆菌在肠道运输过程中可能会变成肠巨噬细胞的溶原菌。使用有关转导效率和抗性基因频率的模型和最宽松的假设，我们估算了当转导的基因片段通过肠噬菌体在大肠杆菌中进行专门和广义的转导时，基因转移的数值上限（“最坏情况”）随机选择。估计与转导对侧向基因扩散的贡献相对较小;例如，在1.47×10〜（8）大肠埃希菌/升管腔内，一般转导将染色体抗性基因传递至每小时最多8个大肠埃希菌。相比之下，约2％的肠大肠杆菌携带的质粒bla _（CMY-2）基因通过缀合转移的速率比我们的一般转导估计值高至少1.4×10〜（3）倍。估计的转导子数量非线性变化，这取决于可用于噬菌体感染的细菌的生态学，即取决于肠大肠菌的周转率和复制率。

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