Photoinactivation of mcr-1 positive Escherichia coli

• Published in: Laser physics letters Vol. 15; no. 1; pp. 15601 - 15605
• Main Authors: Caires, C S A, Leal, C R B, Rodrigues, A C S, Lima, A R, Silva, C M, Ramos, C A N, Chang, M R, Arruda, E J, Oliveira, S L, Nascimento, V A, Caires, A R L
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.01.2018
• Subjects: eosin methylene-blue; gene; photoinactivation; plasmid-mediated colistin resistance
• ISSN: 1612-2011; 1612-202X
• DOI: 10.1088/1612-202X/aa86e0

The emergence of plasmid-mediated colistin resistance in Enterobacteriaceae, mostly in Escherichia coli due to the mcr-1 gene, has revealed the need to develop alternative approaches in treating mcr-1 positive bacterial infections. This is because colistin is a broad-spectrum antibiotic and one of the 'last-resort' antibiotics for multidrug resistant bacteria. The present study evaluated for the first time, to the best of our knowledge, the efficacy of photoinactivation processes to kill a known mcr-1 positive E. coli strain. Eosin methylene-blue (EMB) was investigated as a photoantimicrobial agent for inhibiting the growth of a mcr-1 positive E. coli strain obtained from a patient with a diabetic foot infection. The photoantimicrobial activity of EMB was also tested in a non-multidrug resistant E. coli strain. The photoinactivation process was tested using light doses in the 30-45 J cm−2 range provided by a LED device emitting at 625 nm. Our findings demonstrate that a mcr-1 positive E. coli strain is susceptible to photoinactivation. The results show that the EMB was successfully photoactivated, regardless of the bacterial multidrug resistance; inactivating the bacterial growth by oxidizing the cells in accordance with the generation of the oxygen reactive species. Our results suggest that bacterial photoinactivation is an alternative and effective approach to kill mcr-1 positive bacteria.