“French case study shows evolution of colistin-resistant bacteria”

“French researchers tracked the evolution of a Klebsiella pneumoniae carbapenemase (KPC) strain of bacteria for more than 4.5 years in a patient who ultimately died from sepsis. The case study, published in Clinical Infectious Diseases, shows the bacteria is capable of several genomic and phenotypic diversifications and mutations in a relatively short period, even from drug resistance to susceptibility.

The patient contracted the bacterium via a contaminated endoscope at a French tertiary care hospital in 2009. The patient was seeking treatment from chronic infection in the liver’s bile ducts.

Researchers collected 17 isolates until the patient died in 2014. All 17 isolates were subjected to whole-genome sequencing. During the study period, a total of 98 genetic events occurred, and the average evolutionary rate of the KPC strain was 7.5 single nucleotide polymorphisms per year per genome.

Most interestingly, the researchers reported, “The contaminating strain was colistin resistant but after two years of carriage, all isolates became susceptible to colistin.”

Source: CIDRAP