title: Genomics of KPC-producing Klebsiella pneumoniae sequence type 512 clone highlights the role of RamR and ribosomal S10 protein mutations in conferring tigecycline resistance.
abstract: Full genome sequences were determined for five Klebsiella pneumoniae strains belonging to the sequence type 512 (ST512) clone, producing KPC-3. Three strains were resistant to tigecycline, one showed an intermediate phenotype, and one was susceptible. Comparative analysis performed using the genome of the susceptible strain as a reference sequence identified genetic differences possibly associated with resistance to tigecycline. Results demonstrated that mutations in the ramR gene occurred in two of the three sequenced strains. Mutations in RamR were previously demonstrated to cause overexpression of the AcrAB-TolC efflux system and were implicated in tigecycline resistance in K. pneumoniae. The third strain showed a mutation located at the vertex of a very well conserved loop in the S10 ribosomal protein, which is located in close proximity to the tigecycline target site in the 30S ribosomal subunit. This mutation was previously shown to be associated with tetracycline resistance in Neisseria gonorrhoeae. A PCR-based approach was devised to amplify the potential resistance mechanisms identified by genomics and applied to two additional ST512 strains showing resistance to tigecycline, allowing us to identify mutations in the ramR gene.
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Villa
authors.forename: Claudia
authors.initials: C
authors.lastname: Feudi
authors.forename: Daniela
authors.initials: D
authors.lastname: Fortini
authors.forename: Aurora
authors.initials: A
authors.lastname: García-Fernández
authors.forename: Alessandra
authors.initials: A
authors.lastname: Carattoli
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001483:Base Sequence; D024881:Drug Resistance, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D016680:Genome, Bacterial / Q000235:genetics; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics*; D000078304:Tigecycline
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D012269:Ribosomal Proteins; C029537:ribosomal protein S10; D000078304:Tigecycline; D008911:Minocycline