Determining the Sequence of Two Colibactin Genes, clbN and clbB, in Some Clinical Isolates of E. coli

Background: Escherichia coli is a widespread human-infecting bacterium that can produce the genotoxin colibactin, which is encoded by the pks pathogenicity island and has been reported as a determinant of bacterial virulence. Objective: This study aimed to determine the presence of two colibactin markers in some isolates of E. coli . Materials and Methods: Seven of nine pk-positive E. coli samples were chosen to determine the genetic variants in the sequence of two specific polymerase chain reaction (PCR) fragments partially covering the clbN and clbB genes. Results: The results indicated the presence of only one nucleic acid variant in both clbN and clbB compared to their reference sequences (GenBank acc. no. CP109929.1). Concerning the clbN gene, the identified variant was 243C>T, which was suitable for position 1113 of the entire clbN gene-encoded colibactin nonribosomal peptide synthetase. In the clbB gene, the identified variant was 62C>T, which was located at position 1790 in the entire clbB-encoded colibactin hybrid nonribosomal peptide synthetase/type I polyketide synthase. Both variants were synonymous, namely, p.Thr1113= and p.F1790=. Conclusion: This study detected that variants in both genes did not affect colibactin production because they were silent mutations. These PCR products can be efficiently used to detect the biological diversity of a wider spectrum of E. coli sequences. Nevertheless, these PCR products can also be explored to discover further details of the identified bacterial sequences in various infections.