The Integrative and Conjugative Element ICECspPOL2 Contributes to the Outbreak of Multi-Antibiotic-Resistant Bacteria for Chryseobacterium Spp. and Elizabethkingia Spp.

Antibiotic resistance genes (ARGs) and horizontal transfer of ARGs among bacterial species in the environment can have serious clinical implications as such transfers can lead to disease outbreaks from multidrug-resistant (MDR) bacteria. Infections due to antibiotic-resistant Chryseobacterium and Elizabethkingia in intensive care units have been increasing in recent years. In this study, the multi-antibiotic-resistant strain Chryseobacterium sp. POL2 was isolated from the wastewater of a livestock farm. Whole-genome sequencing and annotation revealed that the POL2 genome encodes dozens of ARGs. The integrative and conjugative element (ICE) ICECspPOL2, which encodes ARGs associated with four types of antibiotics, including carbapenem, was identified in the POL2 genome, and phylogenetic affiliation analysis suggested that ICECspPOL2 evolved from related ICEEas of Elizabethkingia spp. Conjugation assays verified that ICECspPOL2 can horizontally transfer to Elizabethkingia species, suggesting that ICECspPOL2 contributes to the dissemination of multiple ARGs among Chryseobacterium spp. and Elizabethkingia spp. Because Elizabethkingia spp. is associated with clinically significant infections and high mortality, there would be challenges to clinical treatment if these bacteria acquire ICECspPOL2 with its multiple ARGs, especially the carbapenem resistance gene. Therefore, the results of this study support the need for monitoring the dissemination of this type of ICE in Chryseobacterium and Elizabethkingia strains to prevent further outbreaks of MDR bacteria. IMPORTANCE Infections with multiple antibiotic-resistant Chryseobacterium and Elizabethkingia in intensive care units have been increasing in recent years. In this study, the mobile integrative and conjugative element ICECspPOL2, which was associated with the transmission of a carbapenem resistance gene, was identified in the genome of the multi-antibiotic-resistant strain Chryseobacterium sp. POL2. ICECspPOL2 is closely related to the ICEEas from Elizabethkingia species, and ICECspPOL2 can horizontally transfer to Elizabethkingia species with the tRNA-Glu-TTC gene as the insertion site. Because Elizabethkingia species are associated with clinically significant infections and high mortality, the ability of ICECspPOL2 to transfer carbapenem resistance from environmental strains of Chryseobacterium to Elizabethkingia is of clinical concern.

Automated summary

This study identified a multi-antibiotic-resistant strain Chryseobacterium sp. POL2 from livestock wastewater carrying multiple ARGs and the integrative conjugative element ICECspPOL2 associated with four types of antibiotics. ICECspPOL2 can horizontally transfer to Elizabethkingia species, contributing to the dissemination of ARGs between Chryseobacterium and Elizabethkingia species, posing a clinical concern due to their association with significant infections and high mortality. Monitoring the spread of ICECspPOL2 in these bacterial strains is essential to prevent outbreaks of multidrug-resistant bacteria.