Relationships between Efflux Pumps and Emergence of Heteroresistance: A Comprehensive Study on the Current Findings

Figure 1

The difference between HR, resistance, persistence, and susceptibility and influential factors in the emergence of HR. (a) In the presence of antibiotic agents, heteroresistant cells can survive and grow in the presence of the antibiotic. Since the HR phenotype is unstable, cells return to the susceptible cell phenotype without antibiotic agents. On the other hand, resistant cells grow in the presence of antibiotics and remain resistant in their absence because genetic changes in resistance are stable, unlike HR. Persistence and HR are both subpopulation-mediate resistance; however, although persister cells can survive antibiotic treatment, they do not grow or grow slowly in the presence of antibiotic agents. In the absence of the antibiotic treatment, persister cells also switch back to the susceptible cell phenotype. (b) Several factors have been identified and hypothesized to be influential in HR emergence: antibiotic exposure, mutation susceptibility in some strains, environmental changes such as decreasing specific ions, and changes in expression of the EPs.

(a)

(b)