Specific phenotypic, genomic, and fitness evolutionary trajectories toward streptomycin resistance induced by pesticide co-stressors in Escherichia coli

Abstract

To explore how co-occurring non-antibiotic environmental stressors affect evolutionary trajectories toward antibiotic resistance, we exposed susceptible Escherichia coli K-12 populations to environmentally relevant levels of pesticides and streptomycin for 500 generations. The coexposure substantially changed the phenotypic, genotypic, and fitness evolutionary trajectories, resulting in much stronger streptomycin resistance (>15-fold increase) of the populations. Antibiotic target modification mutations in rpsL and rsmG, which emerged and dominated at late stages of evolution, conferred the strong resistance even with less than 1% abundance, while the off-target mutations in nuoG, nuoL, glnE, and yaiW dominated at early stages only led to mild resistance (2.5–6-fold increase). Moreover, the strongly resistant mutants exhibited lower fitness costs even without the selective pressure and had lower minimal selection concentrations than the mildly resistant ones. Removal of the selective pressure did not reverse the strong resistance of coexposed populations at a later evolutionary stage. The findings suggest higher risks of the selection and propagation of strong antibiotic resistance in environments potentially impacted by antibiotics and pesticides.

Low-Level Cefepime Exposure Induces High-Level Resistance in Environmental Bacteria: Molecular Mechanism and Evolutionary Dynamics

“…Highly resistant cells with an MIC > 100 μg/mL were detected starting from day 28 and represented 10 –5 of the total population on day 40 (Figure B, Table S3). Despite the late appearance and extremely low frequency, the MICs of strongly resistant mutants were close to the ultimate MIC of the overall population . It was confirmed that tolerance was not the survival strategy of the resistant subpopulations on day 40 in response to environmental concentrations of cefepime (Figure S5).…”

“…Despite the late appearance and extremely low frequency, the MICs of strongly resistant mutants were close to the ultimate MIC of the overall population. 10 It was confirmed that tolerance was not the survival strategy of the resistant subpopulations on day 40 in response to environmental concentrations of cefepime (Figure S5). As a result, it is essential to predict the emergence of high- level resistant mutants in a population and estimate their resistance levels.…”

“…Intriguingly, a few highly resistant mutants can contribute to the strong phenotypic resistance of a population or community. Xing et al suggested that strongly resistant mutants representing only 10 –5 of the population can significantly increase streptomycin resistance . How environmental level antibiotics select diversified mutations and whether the evolution of antibiotic resistance can be predicted are key questions to be addressed for mitigating ARB/ARG transmissions from the environment to humans.…”

Development of Resistance to Clarithromycin and Amoxicillin-Clavulanic Acid in Lactiplantibacillus plantarum In Vitro Is Followed by Genomic Rearrangements and Evolution of Virulence

“…However, none of the mutations identified by us in the genome of L. plantarum 8p-a3-Clr-Amx were previously described as the root cause, that is, obligately determining the occurrence of resistance to appropriate antibiotics in lactobacilli. In principle, the results of the active application of genomic profiling to determine the molecular scenarios of antibiotic resistance in different bacteria in vitro and in vivo in the last decade have made it possible to verify that the genetic signatures of antibiotic resistance are not always valid; phenotypic resistance in bacteria is not always accompanied by mutations in the genes of antimicrobial targets ( 8 , 31 , 32 ). Our results indicate that L. plantarum can complement the list of similar cases.…”

“…Studies have shown that the length of the lag time can reflect the strain’s ability to respond to the new environment ( 43 ). High maximum growth rates generally present a positive correlation with virulence factors and pathogenicity ( 31 ). However, in the case of the strains studied by us, such a pattern was not traced.…”