Plasmid-mediated mcr-1 in carbapenem-susceptible Escherichia coli ST156 causing a blood infection: an unnoticeable spread of colistin resistance in Brazil?

• Main Authors: Flavia Rossi, Raquel Girardello, Carlos Morais, Ana Paula Cury, Layla Farage Martins, Aline Maria da Silva, Edson Abdala, João Carlos Setubal, Alberto José da Silva Duarte
• Format: Article
• Language: English
• Published: Faculdade de Medicina / USP
• Series: Clinics
• Subjects: Colistin Resistance; Polymyxin Resistance; Escherichia Coli; Carbapenem-Susceptible; ST156
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1807-59322017001000642&lng=en&tlng=en
• ISSN: 1980-5322

OBJECTIVE: We describe an IncX4 pHC891/16mcr plasmid carrying mcr-1 in a colistin-resistant and carbapenem-susceptible E. coli isolate (HC891/16), ST156, which caused a blood infection in a Brazilian patient with gallbladder adenocarcinoma. METHODS: Strain HC891/16 was subjected to whole genome sequencing using the MiSeq Platform (Illumina, Inc., USA). Assembly was performed using Mira and ABACAS. RESULTS: The isolates showed resistance only to ciprofloxacin, ampicillin and cefoxitin, and whole-genome sequencing revealed the presence of aac(6’)Ib-cr and blaTEM1. CONCLUSION: Our findings warn of the possible silent dissemination of colistin resistance by carbapenem-susceptible mcr-1 producers, as colistin susceptibility is commonly tested only among carbapenem-resistant isolates.