Distribution of class 1 integrons with IS26-mediated deletions in their 3'-conserved segments in Escherichia coli of human and animal origin.
Class 1 integrons play a role in the emergence of multi-resistant bacteria by facilitating the recruitment of gene cassettes encoding antibiotic resistance genes. 512 E. coli strains sourced from humans (n = 202), animals (n = 304) and the environment (n = 6) were screened for the presence of the intI1 gene. In 31/79 integron positive E. coli strains, the gene cassette regions could not be PCR amplified using standard primers. DNA sequence analysis of 6 serologically diverse strains revealed atypical integrons harboured the dfrA5 cassette gene and only 24 bp of the integron 3'-conserved segment (CS) remained, due to the insertion of IS26. PCR targeting intI1 and IS26 followed by restriction fragment length polymorphism (RFLP) analysis identified the integron-dfrA5-IS26 element in 27 E. coli strains of bovine origin and 4 strains of human origin. Southern hybridization and transformation studies revealed the integron-dfrA5-IS26 gene arrangement was either chromosomally located or plasmid borne. Plasmid location in 4/9 E. coli strains and PCR linkage of Tn21 transposition genes with the intI1 gene in 20/31 strains, suggests this element is readily disseminated by horizontal transfer.
Life Sciences Commons, Physical Sciences and Mathematics Commons, Social and Behavioral Sciences Commons
Dawes, F. E., Kuzevski, A., Bettelheim, K., Hornitzky, M., Djordjevic, S. & Walker, M. J. (2010). Distribution of class 1 integrons with IS26-mediated deletions in their 3'-conserved segments in Escherichia coli of human and animal origin.. PloS one, 5 (9), 1-6.