Data from: Effects of antibiotic resistance alleles on bacterial evolutionary responses to viral parasites

Antibiotic resistance has wide-ranging effects on bacterial phenotypes and evolution. However, the influence of antibiotic resistance on bacterial responses to parasitic viruses remains unclear, despite the ubiquity of such viruses in nature and current interest in therapeutic applications. We experimentally investigated this by exposing various Escherichia coli genotypes, including eight antibiotic-resistant genotypes and a mutator, to different viruses (lytic bacteriophages). Across 960 populations, we measured changes in population density and sensitivity to viruses, and tested whether variation among bacterial genotypes was explained by their relative growth in the absence of parasites, or mutation rate towards phage resistance measured by fluctuation tests for each phage. We found that antibiotic resistance had relatively weak effects on adaptation to phages, although some antibiotic-resistance alleles impeded the evolution of resistance to phages via growth costs. By contrast, a mutator allele, often found in antibiotic-resistant lineages in pathogenic populations, had a relatively large positive effect on phage-resistance evolution and population density under parasitism. This suggests costs of antibiotic resistance may modify the outcome of phage therapy against pathogenic populations previously exposed to antibiotics, but the effects of any co-occurring mutator alleles are likely to be stronger.

抗生素耐药性对细菌表型与进化具有广泛影响。然而，尽管这类病毒在自然界中无处不在且在治疗应用领域备受关注，抗生素耐药性对细菌应对寄生性病毒的响应所产生的影响仍不明朗。本研究通过将多种大肠杆菌（Escherichia coli）基因型（涵盖8株抗生素耐药性基因型与1株突变株（mutator））暴露于不同病毒（裂解性噬菌体（lytic bacteriophages））中，对该问题开展了实验探究。我们在960个种群中测定了种群密度与病毒敏感性的变化，并验证了细菌基因型间的表型差异是否可通过其在无寄生虫条件下的相对生长速率，或是针对每种噬菌体通过波动试验（fluctuation test）测得的噬菌体抗性突变率来解释。研究结果表明，尽管部分抗生素耐药性等位基因（allele）会通过生长代价阻碍噬菌体抗性的进化，但抗生素耐药性对细菌适应噬菌体的影响整体相对较弱。与之形成对比的是，常于致病种群的抗生素耐药性谱系中被检出的突变株等位基因，对寄生条件下的噬菌体抗性进化与种群密度均具有显著的正向影响。这提示，抗生素耐药性的生长代价或许会改变针对既往暴露于抗生素环境的致病种群的噬菌体疗法（phage therapy）效果，而共存的突变株等位基因所产生的影响可能更为显著。