F74 plasmids are major vectors of virulence genes in bovine NTEC2. (1st August 2022)

• Record Type: Journal Article
• Authors: Valat, C.; Haenni, M.; Arnaout, Y.; Drapeau, A.; Hirchaud, E.; Touzain, F.; Boyer, T.; Delannoy, S.; Vorimore, F.; Fach, P.; Madec, J.‐Y.
• Is Part Of: Letters in applied microbiology. Volume 75:Number 2(2022)
• Page Start: 355
• Page End: 362
• Publication Date: 2022-08-01
• Subjects: cnf2 -- E. coli -- F74 -- IncF -- virulence; Microbiology -- Periodicals; 660.62
• DOI: 10.1111/lam.13733
• Languages: English
• ISSNs: 0266-8254

Abstract

Abstract: Necrotoxigenic Escherichia coli 2 (NTEC2) are defined as E. coli producing the toxin known as cytotoxic necrotizing factor 2 (CNF2), a potent toxin primarily found in bovine but also in humans. NTEC2 are mostly associated with bovine, and cnf2 is known to be carried by pVir‐like plasmids. In this study, we looked for NTEC2 in a collection of E. coli collected between 2011 and 2018 in French bovine. Thirty‐two isolates, collected from both sick (n = 19) and healthy (n = 13) animals, were identified and characterized using whole‐genome sequencing. One F74 plasmid of this bacterial collection was long‐read sequenced: its size was 138 121 bp and it carried the cnf2, F17cA‐eG, cdtB, iutA, iucC and ompP virulence factors (VFs), but no resistance gene. A large variety of genetic backgrounds was observed, but all cnf2‐carrying plasmids belonged to the IncF family, and most of them (78·1%) were of the F74 group. Similar F74 plasmids were also reported from bovine in the United Kingdom and the United States, as identified in the publically available databases. Consequently, these F74 plasmids, which are widely disseminated among E. coli from cattle in the French territory, are vectors of virulence determinants that largely went unnoticed until now. Abstract: Significance and Impact of the Study: Successful plasmids, that is geographically widespread and present in different hosts or matrices, carrying resistance determinants have been widely characterized, several of them belonging to the IncF family. Plasmids encoding specific virulence factors (VFs) are much less reported. In this study, we characterized 32 NTEC2 isolates collected from French sick and healthy calves and identified the occurrence of highly similar F74 plasmids carrying the cnf2 gene, most likely associated with cdtIII, ompP and F17 variants when present in the isolates. These F74 plasmids are thus successful vectors of VFs in bovine in France, but also in the United Kingdom and United States as found in the publically available databases. This is of One Health significance since NTEC2 is found in bovine but also in derived foodstuff and in humans.