 This study found that the prevalence of colistin resistance in E. coli and K. Pneumoniae in Ecuador is high, despite a low prevalence of phenotypic resistance. The authors recommend that Ecuador's ban on the use of colistin in animal husbandry be strictly enforced, and that continuous monitoring of the situation be conducted. This article was authored by Carlos Bastitas-Caldes, Salome Guerrero-Ferri, Nimor-Ortunogutieres, and others.