Transfer of an Escherichia coli ST131 multiresistance cassette has created a Klebsiella pneumoniae-specific plasmid associated with a major nosocomial outbreak

• Published in: Journal of antimicrobial chemotherapy 2012-01, Vol.67 (1), p.74-83
• Main Authors: Sandegren, Linus, Linkevicius, Marius, Lytsy, Birgitta, Melhus, Åsa, Andersson, Dan I.
• Format: Article
• Language: English
• Subjects: Antibiotics. Antiinfectious agents. Antiparasitic agents; Antimicrobial agents; beta-Lactamases - genetics; Biological and medical sciences; Conjugation, Genetic; Cross Infection - epidemiology; Cross Infection - microbiology; CTX-M-15; Disease Outbreaks; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Drug resistance; Drug Resistance, Multiple, Bacterial; E coli; Electrophoresis, Gel, Pulsed-Field; Epidemics; ESBL; Escherichia coli; Escherichia coli - genetics; evolution; fitness-cost; Gene Transfer, Horizontal; General aspects; horizontal transfer; Host Specificity; Human infectious diseases. Experimental studies and models; Humans; Infectious diseases; Klebsiella Infections - epidemiology; Klebsiella Infections - microbiology; Klebsiella pneumoniae; Klebsiella pneumoniae - drug effects; Klebsiella pneumoniae - genetics; Klebsiella pneumoniae - isolation & purification; Medical sciences; Microbiology; Mikrobiologi; Molecular Sequence Data; Molecular Typing; Multiplex Polymerase Chain Reaction; Nosocomial infections; O25:H4-ST131; outbreak; Pharmacology. Drug treatments; Plasmids; Polymorphism, Restriction Fragment Length; Sequence Analysis, DNA
• ISSN: 0305-7453; 1460-2091; 1460-2091
• DOI: 10.1093/jac/dkr405

Objectives To characterize the complete sequence, horizontal spread and stability of the CTX-M-15-encoding multiresistance plasmid of a Klebsiella pneumoniae strain involved in a large nosocomial outbreak. Methods The 220 kbp plasmid pUUH239.2 was completely sequenced using 454 technology. The conjugational host range, conjugation frequencies, plasmid stability and fitness cost of plasmid carriage were studied in vitro. Conjugational spread during the outbreak was assessed retrospectively by multiplex PCR screening, restriction fragment length polymorphism and PFGE. Results Plasmid pUUH239.2 encodes resistance to β-lactams (bla CTX-M-15, bla TEM-1 and bla OXA-1), aminoglycosides [aac-(6′)-1b-cr and aadA2], tetracyclines [tet(A) and tetR], trimethoprim (dhfrXII), sulphonamides (sul1), quaternary ammonium compounds (qacEΔ1), macrolides [mph(A)-mxr-mphR(A)] and heavy metal ions (silver, copper and arsenic). The plasmid consists of a backbone, highly similar to the K. pneumoniae plasmid pKPN3, and a 41 kbp resistance region, highly similar to the resistance regions of plasmids pEK499 and pC15-1a previously isolated from Escherichia coli strains belonging to the outbreak lineage ST131 (where ST stands for sequence type). The pUUH239.2 plasmid is stable in K. pneumoniae but unstable in E. coli and confers a fitness cost when introduced into a naive host cell. Transfer of pUUH239.2 from the outbreak K. pneumoniae clone to the E. coli of the patients' intestinal floras has occurred on multiple occasions during the outbreak. Conclusions The plasmid pUUH239.2 is a composite of the pKPN3 K. pneumoniae plasmid backbone and the bla CTX-M-15-encoding multiresistance cassette associated with the internationally recognized outbreak strain E. coli ST131. The resulting plasmid differs in stability between K. pneumoniae and E. coli, and this has probably limited the spread of this plasmid during the outbreak.