Dissemination and persistence of blaCTX-M-9 are linked to class 1 integrons containing CR1 associated with defective transposon derivatives from Tn402 located in early antibiotic resistance plasmids of IncHI2, IncP1-alpha, and IncFI groups.
This study analyzes the diversity of In60, a class 1 integron bearing CR1 and containing bla(CTX-M-9), and its association with Tn402, Tn21, and classical conjugative plasmids among 45 CTX-M-9-producing clinical strains (41 Escherichia coli strains, 2 Klebsiella pneumoniae strains, 1 Salmonella enterica strain, and 1 Enterobacter cloacae strain). Forty-five patients in a Spanish tertiary care hospital were studied (1996 to 2003). The diversity of In60 and association of In60 with Tn402 or mercury resistance transposons were investigated by overlapping PCR assays and/or hybridization. Plasmid characterization included comparison of restriction fragment length polymorphism patterns and determination of incompatibility group by PCR-based replicon typing, sequencing, and hybridization. CTX-M-9 plasmids belonged to IncHI2 (n = 26), IncP-1alpha (n = 10), IncFI (n = 4), and IncI (n = 1) groups. Genetic platforms containing bla(CTX-M-9) were classified in six types in relation to the In60 backbone and in eight subtypes in relation to Tn402 derivatives. They were associated with Tn21 sequences when located in IncP-1alpha or IncHI2 plasmids. Our study identified bla(CTX-M-9) in a high diversity of CR1-bearing class 1 integrons linked to different Tn402 derivatives, often to Tn21, highlighting the role of recombination events in the evolution of antibiotic resistance plasmids. The presence of bla(CTX-M-9) on broad-host-range IncP-1alpha plasmids might contribute to its dissemination to hosts that were not members of the family Enterobacteriaceae.
Novais
Angela
A
Hospital Universitario Ramón y Cajal, IMSALUD, Madrid 28034, Spain.
Cantón
Rafael
R
Valverde
Aránzazu
A
Machado
Elisabete
E
Galán
Juan-Carlos
JC
Peixe
Luísa
L
Carattoli
Alessandra
A
Baquero
Fernando
F
Coque
Teresa M
TM
D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000032:analysis; D016972:Enterobacter cloacae / Q000201:enzymology / Q000302:isolation & purification; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D014644:Genetic Variation; D006761:Hospitals; D006801:Humans; D032023:Integrons / Q000235:genetics*; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000302:isolation & purification; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012189:Retrospective Studies; D019779:Salmonella enterica / Q000201:enzymology / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D013030:Spain / Q000453:epidemiology; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics*
D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D001618:beta-Lactamases