Characterization of IncA/C conjugative plasmid harboring bla TEM-52 and bla CTX-M-15 extended-spectrum β-lactamases in clinical isolates of Escherichia coli in Tunisia.

To characterize the extended-spectrum β-lactamases (ESBLs) as well as their genetic environment in different isolates of Escherichia coli from patients with repeated urinary tract infections, large multidrug resistance (MDR) plasmids have been found. Definitive evidence for the presence of an A/C incompatibility complex (IncA/C) plasmid in the MDR isolates was provided by the probing of plasmids extracted from the clinical isolates. Conjugation experiments showed that bla genes were transferred by conjugation from the ten E. coli clinical isolates to E. coli XL1-Blue recipient. A comparative restriction fragment length polymorphism (RFLP) analysis of these plasmids showed that they are genetically similar, while the overall similarity of these plasmids supports the likelihood of recent movements among these E. coli isolates. Polymerase chain reaction (PCR) amplification and sequencing of the amplicons showed that the IncA/C plasmids harbor two ESBLs, identified as TEM-52 and CTX-M-15. Analysis of the plasmid DNA surrounding the bla (CTX-M-15) gene in the clinical isolates under study revealed a partially truncated fragment of ISEcp1 tnpA transposase. This result indicates the variety of genetic events that have enabled associations between ISEcp1 sequences and bla (CTX-M-15) genes in these clinical isolates.