In profile: Dewa A.P. Rasmika Dewi, PhD student

Over the last two decades, antibiotic resistance has been a growing issue for many health professionals, and the focus of extensive scientific research. Antibiotic resistant bacteria can cause considerable harm to humans and animals as the effects of antibiotics, prescribed to treat infections, are reduced or halted altogether.

For Dewa A.P. Rasmika Dewi (‘Mika’), her interest in antibiotic resistant bacteria stemmed from her work as a Junior Lecturer and Research Assistant in Bali, where her office was located within a hospital. Mika, who has a Master of Science in Environmental Microbiology from Gadjah Mada University, Indonesia, was regularly involved in routine microbiological assessments of hospital wastewater. This prompted her to think about the potential for antibiotic resistance to spread outside the hospital environment.

I was intrigued by the heavy use of antibiotics in our hospital and wondered whether they could be released through wastewater into our environment

Dewa A.P. Rasmika Dewi, PhD student

“I was intrigued by the heavy use of antibiotics in our hospital and wondered whether they could be released through wastewater into our environment, resulting in antibiotic resistance outside of the hospital setting,” said Mika.

Her interest focused a specific type of antibiotic named carbapenem. Commonly called a ‘last-resort’ antibiotic, it is used to treat severe or multi-drug bacterial infections which are resistant to other beta-lactam antibiotics.

While past studies have generated a wealth of information on carbapenem resistance in human and clinical settings, in contrast, little is known about carbapenem resistance in natural ecosystems or in marine bacteria specifically.

Through her PhD, Mika is exploring the issue of carbapenem resistance in marine environments and identifying potential sources of this resistance. As part of her project, Mika isolated Carbapenem Resistant Bacteria (CRB) from seawater samples along the eastern Sydney coast, and looked at other aquatic samples taken from wastewater, storm water, and terrestrial run-offs close to seawater collection sites.

“My study revealed a surprising abundance and phylogenetic diversity of CRB in the marine environment, including those that have not been previously identified as containing carbapenem resistance,” said Mika.

“This highlights the fact that a substantial reservoir of resistance to this antibiotic exists outside the clinical setting.”

Mika is now investigating if these environmental bacteria have new mechanisms of resistance, and whether they acquired their resistance from human enteric bacteria and can potentially transfer their resistance to other pathogenic bacteria.

This will suggest whether CRB in the marine environment could enter the human body through accidental consumption or open wounds and pose a threat to human health—something Mika is interested in studying further after completing her PhD

“In the future, I would like to be involved in further research exploring more about antibiotic resistance in nature and its significance to human health,” said Mika.

Mika was afforded the opportunity to complete her PhD at UNSW through an Australian Awards grant, awarded by the Australian Department of Foreign Affairs and Trade. During her time with the UNSW Centre for Marine Bio-Innovation (CMB), she has learnt a lot about how to collaborate with colleagues from different backgrounds and how to work as a team.

“My PhD has given me precious experience, networking opportunities, and the chance to update my technical skills,” said Mika.

“My supervisor, Professor Torsten Thomas, has given me valuable guidance—and all the other people from CMB are incredibly helpful and always willing to discuss my research. I am really grateful to have such helpful support during my PhD journey.”