Detection and genomic characterization of mcr-9 in Enterobacter hormaechei recovered from a pediatric patient in Lebanon.
Infect Genet Evol, 2021/10;94:105014.
Khodor R[1], Salloum T[1], El Jisr T[2], El Chaar M[3], Tokajian S[4]
Affiliations
PMID: 34325053DOI: 10.1016/j.meegid.2021.105014
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Abstract
background: The emergence and spread of mobilized colistin resistance (mcr) genes are a global health concern.
objectives: In this study, we report the detection and genomic characterization of mcr-9 in a colistin-susceptible Enterobacter hormaechei (EH23) recovered from a pediatric patient in Lebanon.
results: EH23 was susceptible to colistin with a minimal inhibitory concentration (MIC) of 0.25 mg/L. Studying the mcr-9 genetic environment revealed that it was chromosomal and was bracketed by IS903 and IS26. QseCB, a two-component regulatory system, mediating the inducible expression of mcr-9 gene was not detected within the mcr-9 cassette but elsewhere on the genome. EH23 was 99.96% similar based on average nucleotide identity (ANI) to another mcr-negative E. hormaechei OIPH-N069 isolate recovered from Japan. wgSNP-based phylogenetic analysis divided all mcr-9 positive E. hormaechei isolates into five clades (I to V), with isolates from the same ST being clustered together.
conclusion: The silent spread of mcr-9, particularly in the globally successful ST-78 Enterobacter lineage, is worrisome and requires close monitoring in humans and animals.
Keywords: Colistin; Enterobacter hormaechei; mcr-9; qseB; qseC
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