%0 Journal Article %A Woodward, M. J. %A Wray, C. %A Ridha, G. A. %A Walton, J. R. %T Plasmid and chromosomal related toxin polymorphism of Escherichia coli serogroup O138; plasmid transfer and co-integration with pRP4 %D 1990 %J Journal of Medical Microbiology, %V 31 %N 4 %P 241-249 %@ 1473-5644 %R https://doi.org/10.1099/00222615-31-4-241 %I Microbiology Society, %X Summary. DNA-DNA hybridisation was used to examine 89 isolates of Escherichia coli serogroup O138 for toxin gene content and location. Sixty-six isolates encoded toxin genes; 29 were STpa STpb VT2, 24 were VT2, four were STpa STpb, three wereSTpb VT2, three were STpb VT2 LT and one was STpa. None were K88-, K99- or F41-positive. The VT toxin gene was chromosomally located in all VT+ isolates tested whereas STpa, STpb and LT were plasmid borne. In co-transfer experiments with pRP4 as the mobilising plasmid, VT2 genes were not transferred to recipient E. coli K12 whereas STpa, STpb and LT genes were. Two VT2-positive isolates inhibited pRP4 transfer to K12 by a factor of 106 and rare transconjugants harboured a cointegrate plasmid comprising pRP4 (54kb) and a cryptic host plasmid (145 kb). In a K12 background, the co-integrate had transfer and incompatibility properties of pRP4 whereas in both progenitor E. coli O138 backgrounds the co-integrate was transfer inhibited and in one case resolved to give original plasmids. %U https://www.microbiologyresearch.org/content/journal/jmm/10.1099/00222615-31-4-241