Data from: Evolutionary dynamics of separate and combined exposure of Pseudomonas fluorescens SBW25 to antibiotics and bacteriophage

The use of bacteriophages against pathogenic bacteria in health care and in the food industry is now being advocated as an alternative to the use of antibiotics. But what is the evolutionary response for a bacterial population if both antibiotics and phages are used in combination? We employ an experimental evolution approach to address these questions and exposed Pseudomonas fluorescens SBW25 and a related hypermutator strain (mutS-) to the action of the antibiotic rifampicin and the lytic bacteriophage SBW25φ2. We then compared the densities, growth rates, and the mutations at the rpoB locus leading to rifampicin resistance of the evolved bacterial populations. We observed that the evolutionary response of populations under different treatments varied depending on the order in which the antimicrobials were added and whether the bacterium was a hypermutator. We found that wild type rifampicin-resistant populations involved in biofilm formation often reverted to rifampicin sensitivity when stresses were added sequentially. In contrast, when the mortality agents were added simultaneously, phage populations frequently went extinct and the bacteria evolved antibiotic resistance. Finally, populations of the hypermutator mutS- converged to a single genotype at the rpoB locus. Future investigation on other bacteria and using different antibiotics and bacteriophage are needed to evaluate the generality of our findings.

在医疗保健与食品工业领域，利用噬菌体对抗致病细菌现已被倡导为抗生素的替代方案。但当抗生素与噬菌体联合使用时，细菌种群会产生怎样的进化响应？本研究采用实验进化方法解答上述问题，将荧光假单胞菌SBW25（Pseudomonas fluorescens SBW25）及其相关的高突变株（mutS-）暴露于抗生素利福平（rifampicin）与裂解性噬菌体SBW25φ2的作用之下。随后，我们对进化后的细菌种群的密度、生长速率，以及携带利福平抗性的rpoB位点突变情况进行了比较分析。研究发现，不同处理组下种群的进化响应因抗菌剂的添加顺序以及细菌是否为高突变株而异。我们观察到，当胁迫因素按序添加时，参与生物被膜形成的野生型利福平抗性种群常会恢复为利福平敏感型。与之相对，当两种致死因子同时施加时，噬菌体会大量灭绝，而细菌则进化出抗生素抗性。此外，高突变株mutS-的种群最终收敛至rpoB位点的单一基因型。未来仍需针对其他细菌、采用不同抗生素与噬菌体开展研究，以评估本研究发现的普适性。