Details

Autor(en) / Beteiligte

• Ambrose, Stephanie J.
• Harmer, Christopher J.
• Hall, Ruth M.

Titel

Evolution and typing of IncC plasmids contributing to antibiotic resistance in Gram-negative bacteria

Ist Teil von

• Plasmid, 2018-09, Vol.99, p.40-55

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2018

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The large, broad host range IncC plasmids are important contributors to the spread of key antibiotic resistance genes and over 200 complete sequences of IncC plasmids have been reported. To track the spread of these plasmids accurate typing to identify the closest relatives is needed. However, typing can be complicated by the high variability in resistance gene content and various typing methods that rely on features of the conserved backbone have been developed. Plasmids can be broadly typed into two groups, type 1 and type 2, using four features that differentiate the otherwise closely related backbones. These types are found in many different countries in bacteria from humans and animals. However, hybrids of type 1 and type 2 are also occasionally seen, and two further types, each represented by a single plasmid, were distinguished. Generally, the antibiotic resistance genes are located within a small number of resistance islands, only one of which, ARI-B, is found in both type 1 and type 2. The introduction of each resistance island generates a new lineage and, though they are continuously evolving via the loss of resistance genes or introduction of new ones, the island positions serve as valuable lineage-specific markers. A current type 2 lineage of plasmids is derived from an early type 2 plasmid but the sequences of early type 1 plasmids include features not seen in more recent type 1 plasmids, indicating a shared ancestor rather than a direct lineal relationship. Some features, including ones essential for maintenance or for conjugation, have been examined experimentally. •Typing of IncC plasmids using key backbone features provides clear discrimination of two main types and two novel types.•Plasmids with hybrid backbones indicate recombination between types is extensive.•Typing of IncC plasmids using the location of resistance islands discriminates many sub-lineages.•Large resistance islands have variable resistance gene content indicating ongoing evolution in situ.•GIsul2 is found in early type 1 plasmids, revealing the origin of the ARI-B resistance island.