Antimicrobial blue light inactivation of international clones of multidrug-resistant Escherichia coli ST10, ST131 and ST648.

ABSTRACT

BACKGROUND: International clones of multidrug-resistant Escherichia coli have been a leading cause of human and animal infections worldwide. Microbial inactivation by blue light has been proposed as an effective treatment for superficial infections and surface contamination. AIM: To evaluate the inactivation efficacy of blue light irradiation against high-risk multidrug-resistant strains of E. coli. METHODS: Blue LED light (λ = 410 nm) was used to inactivate in vitro suspensions of colistin- broad-spectrum cephalosporin-, or carbapenem-resistant E. coli strains belonging to sequence types (STs) ST10, ST131 and ST648, carrying mcr-1, blaCTX-M or blaKPC-2 genes. RESULTS: Our results showed that all E. coli strains were susceptible to blue light irradiation, independently of antibiotic resistance and virulence profiles. In addition, blue light irradiation induced a strain-specific and dose-dependent bacterial effect. CONCLUSION: Our results support use of blue light as a promising antimicrobial option against MDR pathogens, including high-risk clones of E. coli displaying resistance to polymyxins or broad-spectrum ß-lactam antibiotics.