INTRODUCTION
The global emergence and rapid dissemination of mobile
phosphoethanolamine transferase mcr genes, responsible for
transferable colistin resistance in Enterobacterales, is a public health
concern (El-Sayed Ahmed et al., 2020; Wang et al., 2020). In this
regard, since the first report of the mcr-1 gene, in 2016, novel
alleles including mcr-2 , mcr-3 , mcr-4 ,mcr-5 , mcr-6 , mcr-7 , mcr-8 , mcr-9 andmcr-10 have been globally identified (El-Sayed Ahmed et al.,
2020; Liu et al., 2016; Wang et al., 2020). Worryingly, the occurrence
of mcr genes has been documented in critical-priority
extended-spectrum β-lactamase (ESBL)-producing pathogens, most isolated
from humans and food-producing animals (El-Sayed Ahmed et al., 2020; Liu
et al., 2016; Wang et al., 2020). In this study, we report the emergence
of mcr-9.1 in an ESBL-producing Enterobacter kobeiinfecting a free-living Franciscana dolphin (Pontoporia
blainvillei ), threatened with extinction, in Brazil. Additionally, an
epidemiological landscape on global distribution of MCR-9-producing
Enterobacterales circulating at human-animal interface is presented.