Fig. 1.

Experiment overview: Evolution experiment with HGT from multidrug-resistant strains of H. pylori. The antibiotic-sensitive HGT recipient strain, P12, was propagated with HGT from one of two antibiotic-resistant H. pylori clinical donor strains (CH426 and CH428) in 96-well plates (A). HGT and non-HGT treatment populations were subjected to four different growth conditions: media without antibiotics, media supplemented with the antibiotic clarithromycin, media supplemented with the antibiotic metronidazole, and media supplemented with both clarithromycin and metronidazole. The detailed workflow of the HGT and antibiotic treatments are shown in SI Appendix, Fig. S1. The outcomes of evolution with HGT were analyzed using whole-genome sequencing and growth assays (B). The fitness effects of the genetic variants that evolved in four HGT treatment populations were measured using DNA sequence–based fitness assays (C).