Molecular and evolutionary bases of within-patient genotypic and phenotypic diversity in Escherichia coli extraintestinal infections.

Although polymicrobial infections, caused by combinations of viruses, bacteria, fungi and parasites, are being recognised with increasing frequency, little is known about the occurrence of within-species diversity in bacterial infections and the molecular and evolutionary bases of this diversity. We used multiple approaches to study the genomic and phenotypic diversity among 226 Escherichia coli isolates from deep and closed visceral infections occurring in 19 patients. We observed genomic variability among isolates from the same site within 11 patients.

Multiple acquisitions of CTX-M plasmids in the rare D2 genotype of Escherichia coli provide evidence for convergent evolution.

Over the last decade, CTX-M enzymes have become the most prevalent extended-spectrum beta-lactamases (ESBLs) worldwide, mostly in Escherichia coli, causing a major health problem. An epidemiological relationship has been established between a rare genotype of E. coli, the D(2) genotype, and the presence of CTX-M genes.