BACKGROUND: Conjugative plasmids play a major role in the dissemination of antibiotic resistance genes. Knowledge of the plasmid characteristics and behaviour can allow development of control strategies. Here we focus on the IncX group of plasmids carrying genes conferring quinolone resistance (PMQR), reporting their transfer and persistence within host bacteria of various genotypes under distinct conditions and levels of induced stress in form of temperature change and various concentrations of ciprofloxacin supplementation. METHODS: Complete nucleotide sequences were determined for eight qnr-carrying IncX-type plasmids, of IncX1 (3), IncX2 (3) and a hybrid IncX1-2 (2) types, recovered from Escherichia coli of various origins. This data was compared with further complete sequences of IncX1 and IncX2 plasmids carrying qnr genes (n = 41) retrieved from GenBank and phylogenetic tree was constructed. Representatives of IncX1 (pHP2) and IncX2 (p194) and their qnrS knockout mutants, were studied for influence of induced stress and genetic background on conjugative transfer and maintenance. RESULTS: A high level of IncX core-genome similarity was found in plasmids of animal, environmental and clinical origin. Significant differences were found between the individual IncX plasmids, with IncX1 subgroup plasmids showing higher conjugative transfer rates than IncX2 plasmids. Knockout of qnr modified transfer frequency of both plasmids. Two stresses applied simultaneously were needed to affect transfer rate of wildtype plasmids, whereas a single stress was sufficient to affect the IncX ΔqnrS plasmids. The conjugative transfer was shown to be biased towards the host phylogenetic proximity. A long-term cultivation experiment pointed out the persistence of IncX plasmids in the antibiotic-free environment. CONCLUSIONS: The study indicated the stimulating effect of ciprofloxacin supplementation on the plasmid transfer that can be nullified by the carriage of a single PMQR gene. The findings present the significant properties and behaviour of IncX plasmids carrying antibiotic resistance genes that are likely to play a role in their dissemination and stability in bacterial populations.

• Klíčová slova
• Bacterial background, Escherichia coli, IS26, IncX, Induced stress, PMQR, Plasmid conjugation, Plasmid persistence, Qnr, Transfer rate,
• MeSH
• antibakteriální látky farmakologie   MeSH
• bakteriální léková rezistence genetika   MeSH
• ciprofloxacin farmakologie   MeSH
• Escherichia coli * genetika   MeSH
• fylogeneze MeSH
• genomika MeSH
• konjugace genetická MeSH
• plazmidy genetika   MeSH
• proteiny z Escherichia coli * genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antibakteriální látky MeSH
• ciprofloxacin MeSH
• proteiny z Escherichia coli * MeSH
• Qnr protein, E coli MeSH Prohlížeč

A total of 18 Enterobacteriaceae (17 from gulls and 1 from a clinical sample) collected from Australia, carrying IncA/C plasmids with the IMP-encoding In809-like integrons, were studied. Seven plasmids, being representatives of different origins, plasmid sizes, replicon combinations, and resistance genes, were completely sequenced. Plasmid pEc158, identified in a clinical Escherichia coli ST752 isolate, showed extensive similarity to type 2 IncA/C2 plasmids. pEc158 carried none of the blaCMY-2-like region or ARI-B and ARI-A regions, while it contained a hybrid transposon structure. The six remaining plasmids, which were of wildlife origin, were highly similar to each other and probably were fusion derivatives of type 1 and type 2 A/C2 plasmids. The latter plasmids contained an ARI-B region and hybrid transposon structures. In all plasmids, hybrid transposon structures containing In809-like integrons were inserted 3,434 bp downstream of the rhs2 start codon. In all cases, the one outermost 38-bp inverted repeat (IR) of the transposon was associated with the Tn1696 tnp module, while the other outermost 38-bp IR of the transposon was associated with either a Tn6317-like module or a Tn21 mer module. However, the internal structure of the transposon and the resistance genes were different in each plasmid. These findings indicated that, for the specific periods of time and settings, different IncA/C2 plasmid types carrying In809-like elements circulated among isolates of wildlife and clinical origins. Additionally, they provided the basis for speculations regarding the reshuffling of IncA/C2 plasmids with In809-like integrons and confirmed the rapid evolution of IncA/C2 plasmid lineages.

• Klíčová slova
• Citrobacter freundii, Escherichia coli, IMP, Klebsiella pneumoniae, PMLST, metallo-β-lactamases,
• MeSH
• antibakteriální látky farmakologie   MeSH
• beta-laktamasy genetika   MeSH
• Charadriiformes mikrobiologie   MeSH
• Citrobacter freundii genetika   izolace a purifikace   MeSH
• Escherichia coli genetika   izolace a purifikace   MeSH
• Klebsiella pneumoniae genetika   izolace a purifikace   MeSH
• lidé MeSH
• mikrobiální testy citlivosti MeSH
• mnohočetná bakteriální léková rezistence genetika   MeSH
• obrácené repetice genetika   MeSH
• plazmidy genetika   MeSH
• sekvence nukleotidů MeSH
• sekvenční analýza DNA MeSH
• transpozibilní elementy DNA genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Austrálie MeSH
• Názvy látek
• antibakteriální látky MeSH
• beta-laktamasy MeSH
• transpozibilní elementy DNA MeSH