Study explores hospital bacteria's ability to change

Flinders University researchers are exploring how bacterial cells adapt and resist antimicrobial medications — focusing on hospital strain of Acinetobacter baumannii and its cellular response to important antibiotic colistin.

The WHO has already named antibiotic resistance as one of the biggest threats to global health, food security, and development with a growing number of infections — including pneumonia, tuberculosis, gonorrhoea and salmonellosis — becoming harder to treat as antibiotics used to treat them become less effective.

Antibiotic resistance leads to 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,” said Flinders microbial researcher Dr Sarah Giles.

“If we can understand the bacterial mechanisms, such as this, we can potentially apply new therapies to treat patients — particularly those with multi-drug-resistant bacterial infections.”

“We noted that the A baumannii bacterial strain had a two-part signal system which altered its potential response to antibiotic treatment,” Giles observed in the course of the NHMRC-Flinders University graduate scholarship study.

This ‘two-component signal transduction’ involves a response regulator protein in the StkR/S system acting as a repressor; when it is genetically removed, hundreds of transcriptional changes are seen.

The transcriptional changes affect the bacterial cell’s outer membrane composition, leading to colistin resistance.

“Colistin is known as a ‘last resort’ antibiotic and therefore identifying and understanding the mechanisms contributing to bacterial antibiotic-resistance is critical,” said senior researcher Professor Melissa Brown.

Image caption: Bacteria resistance researcher Dr Sarah Giles. Image courtesy of Flinders University.