Abstract
Raoultella planticola is an emerging pathogen causing several infections in humans, and its roles in the propagation of antibiotic resistance genes (ARGs) remain uncharacterized. In this study, a carbapenem and tigecycline-resistant R. planticola isolate was recovered from hospital sewage. It carried nine plasmids, bearing 30 ARGs, including one blaKPC-2 and two blaNDM-1. It also contained a plasmid-borne efflux pump gene cluster, tmexCD1-toprJ, conferring resistance to tigecycline. Analysis of plasmid sequences revealed that both blaNDM-1-carrying plasmids were highly similar to those recovered from humans, reinforcing the close relatedness of environmental and clinical isolates. We also identified that plasmid bearing blaNDM-1 or tmexCD1-toprJ1 was transferable, and can be stabilized in the host bacteria, indicating that the R. planticola isolate has a considerable potential in the dissemination of ARGs. Besides, we found that this isolate could produce biofilm and was virulent in a Galleria mellonella infection model. In conclusion, our study shows the convergence of virulence and multidrug resistance in a R. planticola isolate. This potentially virulent superbug may disseminate into its receiving rivers, and finally to humans through cross-contamination during recreation activities or daily use of water, which poses a risk to public health.
Highlights
Raoultella planticola is an emerging pathogen causing several infections in humans, and its roles in the propagation of antibiotic resistance genes (ARGs) remain uncharacterized
R. planticola SCLZS62 was isolated during a study for the presence of carbapenemresistant Enterobacteriaceae strains in hospital sewage. 5 ml of water sample was collected from the influx mainstream of hospital sewage at the affiliated hospital of Southwest Medical University, Luzhou in western China, in November 2019
SCLZS62 belongs to R. planticola as it had 99.02% identity (89.81% query coverage) to the R. planticola reference strain FDAARGOS_64 by average nucleotide identity (ANI) analysis, and the Digital DNADNA hybridization (dDDH) value between them was 93.10%, both above the suggested cut-off for defining a bacterial species
Summary
Raoultella planticola is an emerging pathogen causing several infections in humans, and its roles in the propagation of antibiotic resistance genes (ARGs) remain uncharacterized. A carbapenem and tigecycline-resistant R. planticola isolate was recovered from hospital sewage It carried nine plasmids, bearing 30 ARGs, including one blaKPC-2 and two blaNDM-1. The widespread of carbapenem- and colistin-resistant Enterobacterales represents a major challenge due to limited treatment options[3,4] In this scenario, tigecycline, classified as a critically important antimicrobial by the WHO (World Health Organization), was considered as one of the last therapeutic options against infections caused by these bacteria[5]. Raoultella planticola, belonging to the Enterobacteriaceae family, is a Gram-negative, non-motile, rod-shaped anaerobic bacterium[15] It was first found by Freney et al in 1984 in a patient with sepsis, and was originally classified as the Klebsiella spp., while it was reclassified as a member of the Raoultella genus based on 16S rRNA and rpoB gene analysis in 200116–18. The combination of MDR and hypervirulence would significantly limit options for treating severe infections, causing a particular threat for human health
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