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（antibiotic resistance）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，且其治疗应用当前备受关注，但抗生素耐药性对细菌应对寄生病毒的响应机制仍尚未明确。 本研究通过将多种大肠杆菌（Escherichia coli）基因型——包括8株抗生素耐药基因型与1株突变型菌株——暴露于不同裂解性噬菌体（lytic bacteriophages）中，对该问题开展了实验探究。在共计960个种群中，我们测定了种群密度与病毒敏感性的变化，并检验了不同细菌基因型间的表型差异，是否可由其在无寄生虫胁迫时的相对生长速率，或是针对每种噬菌体的波动试验（fluctuation test）测得的噬菌体耐药突变率加以解释。 我们发现，抗生素耐药性对细菌适应噬菌体的整体影响相对较弱，不过部分抗生素耐药等位基因会通过生长成本阻碍细菌的噬菌体耐药性进化。与之形成鲜明对比的是，常在致病菌群的抗生素耐药谱系中被检出的突变型等位基因，对寄生条件下的细菌噬菌体耐药性进化与种群密度均具有较强的正向影响。这表明，抗生素耐药性的成本或许会改变此前经抗生素暴露的致病菌群的噬菌体疗法效果，而同时存在的突变型等位基因的影响可能更为显著。