Association of pth Variants with Elevated Persister Fractions in Clinical Escherichia coli Isolates

Persister cells pose severe threats and serve as the primary drivers of chronic and recurrent infections. Nevertheless, clinical laboratories rarely quantify persister fractions of pathogenic bacteria due to the limited number of detection approaches and scarce available detection biomarkers. In our prior study, we identified a transposon insertion mutant of the essential gene pth. The growth curve, lag time and persister fraction measurements indicated that the pth-Tn strain exhibited slow growth with a markedly elevated persister cell proportion. Transcriptomic and metabolomic analyses revealed that the pth-Tn strain exhibited typical persister phenotypic characteristics, including reduced energy metabolism, membrane biogenesis, substrate transport and translational activity, among others. The pth mutations in host-transmitted E. coli could serve as indicators of persister levels, as also demonstrated in vitro. Thus, we identified seven point mutations in pth among clinical isolates. Compared with clinical isolates harboring the wild-type pth gene, the G109S mutants displayed higher persister fractions. Multiple linear regression models revealed that the G109S mutation was independently associated with elevated persister levels. Collectively, these findings reveal an association between the pth G109S mutation and elevated persister levels in clinical isolates.