This study investigated the prevalence of IncX plasmid subtypes in commensal and pathogenic Escherichia coli isolates and the biological features of the IncX4 subtype. Two hundred and twenty-five E. coli isolates from multiple sources (47 chickens, 41 pigs, 30 cattle and 107 humans) obtained during the period 2006–2012 were tested for the presence of IncX1 to IncX5. Overall, the prevalence of IncX plasmids in chicken, pig, cattle and human isolates were 21.2 % (10/47), 19.5 % (8/41), 3.3 % (1/30) and 4.8 % (5/107), respectively. IncX4 was the most common subtype, followed by IncX1 and IncX3, while no IncX2 or IncX5 were found. Seven out of 16 (43.8 %) IncX4 plasmids were found to carry blaCTX-M genes and six of them originating from different host sources (four chickens, one pig and one human) had identical or highly similar RFLP patterns. Three IncX4 plasmids carrying blaCTX-M from different host sources were investigated further. It was found that the IncX4 plasmids had little effect on bacterial host growth parameters after their introduction to J53 recipients. Conjugation experiments demonstrated that the IncX4 plasmids could be efficiently transferred at 30–42 °C at rates which were generally 102–105-fold higher than those for the epidemic IncFII plasmid carrying blaCTX-M (pHK01). In conclusion, the IncX plasmids are more common than previously recognized. The efficient transfer of IncX4 plasmid at different temperatures and the lack of fitness burden on bacterial hosts highlight the ability of this plasmid replicon to be an important vehicle for dissemination of antimicrobial resistance.
BurmølleM., BahlM. I., JensenL. B., SørensenS. J., HansenL. H.2008; Type 3 fimbriae, encoded by the conjugative plasmid pOLA52, enhance biofilm formation and transfer frequencies in Enterobacteriaceae strains. Microbiology 154:187–195 [View Article][PubMed]
ChenL., ChavdaK. D., FraimowH. S., MediavillaJ. R., MelanoR. G., JacobsM. R., BonomoR. A., KreiswirthB. N.2013; Complete nucleotide sequences of blaKPC-4- and blaKPC-5-harboring IncN and IncX plasmids from Klebsiella pneumoniae strains isolated in New Jersey. Antimicrob Agents Chemother 57:269–276 [View Article][PubMed]
ClermontO., ChristensonJ. K., DenamurE., GordonD. M.2013; The Clermont Escherichia coli phylo-typing method revisited: improvement of specificity and detection of new phylo-groups. Environ Microbiol Rep 5:58–65 [View Article][PubMed]
GrudniakA. M., Kraczkiewicz-DowjatA., WolskaK. I., WildJ.2007; Conjugal transfer of plasmid R6K γ ori minireplicon derivatives from Escherichia coli to various genera of pathogenic bacteria. Curr Microbiol 55:549–553 [View Article][PubMed]
HoP. L., YipK. S., ChowK. H., LoJ. Y., QueT. L., YuenK. Y.2010; Antimicrobial resistance among uropathogens that cause acute uncomplicated cystitis in women in Hong Kong: a prospective multicenter study in 2006 to 2008. Diagn Microbiol Infect Dis 66:87–93 [View Article][PubMed]
HoP.-L., LiZ., LoW.-U., CheungY.-Y., LinC.-H., ShamP.-C., ChengV. C.-C., NgT.-K., QueT.-L., ChowK.-H.2012a; Identification and characterization of a novel incompatibility group X3 plasmid carrying blaNDM-1 in Enterobacteriaceae isolates with epidemiological links to multiple geographical areas in China. Emerg Micro Infect 1:e39 [View Article]
HoP. L., LoW. U., YeungM. K., LiZ., ChanJ., ChowK. H., YamW. C., TongA. H., BaoJ. Y.& other authors (2012b; Dissemination of pHK01-like incompatibility group IncFII plasmids encoding CTX-M-14 in Escherichia coli from human and animal sources. Vet Microbiol 158:172–179 [View Article][PubMed]
JohnsonT. J., BielakE. M., FortiniD., HansenL. H., HasmanH., DebroyC., NolanL. K., CarattoliA.2012; Expansion of the IncX plasmid family for improved identification and typing of novel plasmids in drug-resistant Enterobacteriaceae. Plasmid 68:43–50 [View Article][PubMed]
Leverstein-van HallM. A., DierikxC. M., Cohen StuartJ., VoetsG. M., van den MunckhofM. P., van Essen-ZandbergenA., PlatteelT., FluitA. C., van de Sande-BruinsmaN.& other authors (2011; Dutch patients, retail chicken meat and poultry share the same ESBL genes, plasmids and strains. Clin Microbiol Infect 17:873–880 [View Article][PubMed]
LiterakI., DolejskaM., JanoszowskaD., HrusakovaJ., MeissnerW., RzyskaH., BzomaS., CizekA.2010; Antibiotic-resistant Escherichia coli bacteria, including strains with genes encoding the extended-spectrum beta-lactamase and QnrS, in waterbirds on the Baltic Sea coast of Poland. Appl Environ Microbiol 76:8126–8134 [View Article][PubMed]
NhuN. T. K., VinhH., NgaT. V. T., StablerR., DuyP. T., Thi Minh VienL., van DoornH. R., Cerdeño-TárragaA., ThomsonN.& other authors (2010; The sudden dominance of blaCTX-M harbouring plasmids in Shigella spp. circulating in Southern Vietnam. PLoS Negl Trop Dis 4:e702 [View Article][PubMed]
WilliamsL. E., WiremanJ., HilliardV. C., SummersA. O.2013; Large plasmids of Escherichia coli and Salmonella encode highly diverse arrays of accessory genes on common replicon families. Plasmid 69:36–48 [View Article][PubMed]
ZhongX., DroeschJ., FoxR., TopE. M., KroneS. M.2012; On the meaning and estimation of plasmid transfer rates for surface-associated and well-mixed bacterial populations. J Theor Biol 294:144–152 [View Article][PubMed]