Kluyvera ascorbata Strain from Hospital Sewage Carrying the mcr-1 Colistin Resistance Gene

Area of Science:

• Microbiology
• Genetics
• Public Health

Background:

• The plasmid-borne colistin resistance gene, mcr-1, is a significant global health concern.
• Colistin is a critical last-resort antibiotic for treating multidrug-resistant Gram-negative infections.

Purpose of the Study:

• To report the identification and characterization of the mcr-1 gene in a novel bacterial species.
• To investigate the genetic context and plasmid carriage of mcr-1 in a clinical environmental isolate.

Main Methods:

• Bacterial isolation and identification from hospital sewage.
• Plasmid DNA extraction, sequencing, and characterization.
• Analysis of the genetic environment surrounding the mcr-1 gene.

Main Results:

• The mcr-1 gene was identified in a Kluyvera ascorbata isolate from Chinese hospital sewage.
• The mcr-1 gene was located on a 57-kb self-transmissible IncI2 plasmid.
• Unlike previous findings, mcr-1 was not associated with ISApl1 and was inserted into a gene encoding a putative membrane protein via an unknown mechanism.

Conclusions:

• This finding demonstrates the spread of mcr-1 to additional bacterial species beyond Enterobacteriaceae.
• The presence of mcr-1 in environmental samples like hospital sewage highlights potential transmission routes.
• Further surveillance is crucial to monitor the dissemination of plasmid-mediated colistin resistance.