CRE bacteria - CDC image

Unrelated Bacterial Strains Can Transfer Antibiotic Resistance Genes To Each Other Interview with:

CRE bacteria - CDC image

CRE bacteria – CDC image

Richard Stanton, PhD
Health Scientist, Division of Healthcare Quality Promotion
Centers for Disease Control and Prevention What is the background for this study?

Response: We used whole genome sequencing (WGS) to investigate an outbreak of carbapenem-resistant Enterobacteriaceae (CRE) that occurred in an acute care hospital in Kentucky over a six month period in late 2016. The outbreak included 18 cases of CRE. What are the main findings?

Response: After analyzing the 18 clinical isolates associated with the outbreak using whole genome sequencing, we determined that the infections had been caused by bacteria carrying one of two different antimicrobial resistance (AMR) plasmids with different carbapenemases that were circulating among unrelated bacteria.

These findings show that horizontal transfer of antimicrobial resistance genes can occur between otherwise unrelated strains and species of CRE. What should readers take away from your report?

Response: Although a reservoir was not identified, the WGS revealed that there was not a single source of the CRE and the outbreak represented several importations with subsequent transmission. This reinforces the need for facilities to be vigilant for patients returning from high risk areas and consider screening (e.g., healthcare outside the US in last 6 months). The transmission was controlled following reinstitution of recommended infection control practices, such as implementation of contact precautions and the use of screening for high risk patients.

Additionally, this investigation highlights that environmental cleaning is a critical component in infection control efforts, as plasmid exchange can occur in areas of dense bacterial growth, such as in biofilms. What recommendations do you have for future research as a result of this work?

Response: With the development of long-read next generation sequencing technology, we now have the ability to detect plasmid-mediated outbreaks spanning multiple bacterial species.  Traditional laboratory methods would not identify these outbreaks. Due to these advances and our outbreak response experiences, we now recognize two types of healthcare-associated outbreaks: those due to a single pathogen and those due to mobile AMR-plasmids spreading antibiotic resistance across pathogens. If a plasmid-mediated antimicrobial resistance outbreak is suspected, the appropriate tools, such as long-read sequencing platforms, are selected for laboratory analysis of isolates associated with the outbreak investigation. Clinicians should be aware that infections due to rare resistance genes in unrelated bacteria may indicate a single AMR plasmid-mediated outbreak 

No disclosures


Abstract presented at the American Society for Microbiology, June 2018 Atlanta, Georgia.
Genetic Analysis of Multi-Species, Plasmid-Mediated Carbapenem-Resistant Enterobacteriaceae Hosp. Outbreak  

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Last Updated on June 22, 2018 by Marie Benz MD FAAD