This makes it harder to treat as antibiotics used to treat them become less effective, resulting in longer hospital stays, higher medical costs, and increased mortality, researchers warn.
“Around the world, there are fewer and fewer new antibiotics being identified and produced for medical use – and this is compounded by the ever-increasing antibiotic resistance seen in bacterial strains causing infections,” says Flinders microbial researcher Dr. Sarah Giles.
This is the first study to describe the novel TCS StkSR identified in an A. baumannii strain isolated from an Australian hospital.
Resistance to Colistin by Superbug
The team has demonstrated that the observed increase in colistin resistance seen for the ΔstkR derivative of this isolate is not due to the loss of lipid A but correlates to the increased transcription of the pmrCAB operon which is linked to the modification of lipid A.
“We noted that the A baumannii bacterial strain had a two-part signal system which altered its potential response to antibiotic treatment,” says Dr. Sarah Giles, NHMRC-Flinders University.
This modification decreases the overall membrane electronegativity and therefore decreases the cells affinity to the colistin compound.
Colistin represents a “last resort” antibiotic used for the treatment of severe A. baumannii infections, and understanding the resistance mechanisms to this clinically important compound is vital for its continued application in new therapies to treat multi-drug-resistant bacterial infections.