RT Journal Article SR Electronic(1) A1 Woodward, M. J. A1 Wray, C. A1 Ridha, G. A. A1 Walton, J. R.YR 1990 T1 Plasmid and chromosomal related toxin polymorphism of Escherichia coli serogroup O138; plasmid transfer and co-integration with pRP4 JF Journal of Medical Microbiology, VO 31 IS 4 SP 241 OP 249 DO https://doi.org/10.1099/00222615-31-4-241 PB Microbiology Society, SN 1473-5644, AB 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., UL https://www.microbiologyresearch.org/content/journal/jmm/10.1099/00222615-31-4-241