How Does a Fatty Acid Protect Pathogenic Bacteria Against Antibiotics?

A recent study published online in Nature Communications provides new insight on how fatty acids known as oxylipins play a key role in forming the biofilm shield that helps protect disease-causing bacteria against antibiotics.

“We show that two oxylipins, 10-HOME and 7,10-DiHOME, derived from a diol synthase activity of [Pseudomonas] aeruginosa oleic acid are directly involved in this process,” wrote Eriel Martinez, PhD, and Javier Campos-Gomez, PhD, both from Southern Research, Birmingham, Alabama.

“These oxylipins seem to play a critical role in the initial stages of biofilm formation by inducing a microcolony organization of attached bacteria.”

Biofilm is a complex association of bacteria in which microbial cells adhere to each other within a matrix that safeguards them against antibiotics and other environmental stressors. Therefore, formation of biofilm represents a survival strategy for bacteria as they adapt to their environment.

Although the biological functions of oxylipins have been well studied in animals, plants, algae, and fungi, less is known about their role in bacteria.

Therefore, the researchers conducted a study in Pseudomonas aeruginosa, an antibiotic-resistant bacterium that causes disease in plants and animals. They wanted to examine how oxylipins are involved in organizing bacterial colonies into biofilm. They investigated this using in vitro studies as well as in vivo studies in Drosophila flies.

Dr. Martinez and Dr. Campos-Gomez found that oxylipin production blocks flagellum-driven motility and promotes type IV pilus-dependent twitching motility of P. aeruginosa. In this way, the bacteria switch from a free-swimming state to a more fixed state, which enables them to organize into colonies, and thus, form biofilms. Two oxylipins, 10-HOME and 7,10-DiHOME, appear to be especially important in this process.

The researchers also showed that oxylipins produced by P. aeruginosa play a key role in the organism’s virulence in both Drosophila flies and in lettuce.

In a press release from Southern Research, Dr. Campos-Gomez concluded that these findings have significant implications for understanding the formation of biofilms of those bacteria with multiple antibiotic resistance mechanisms that cause opportunistic infections in immunocompromised individuals.

This increased understanding of how bacteria use oxylipin production to develop protective biofilms could allow scientists to identify ways in which to block these biofilm shields in antibiotic-resistant bacteria. As a next step, Dr. Martinez and Dr. Campos-Gomez plan to investigate agents that could block bacterial oxylipin production and potentially save lives.

Dr. Parry graduated from the University of Liverpool, England in 1997 and is a board-certified veterinary pathologist. After 13 years working in academia, she founded Midwest Veterinary Pathology, LLC where she now works as a private consultant. She is passionate about veterinary education and serves on the Indiana Veterinary Medical Association’s Continuing Education Committee. She regularly writes continuing education articles for veterinary organizations and journals, and has also served on the American College of Veterinary Pathologists’ Examination Committee and Education Committee.