Poster Presentation BACPATH 2022

Isolation of bacteriophage with lytic activity against Acinetobacter baumannii (#119)

Daniel R Laucirica 1 2 , Jack S Canning 1 3 , Rohan Flint 1 3 , Renee N Ng 1 3 , Stephen M Stick 1 2 4 , Anthony Kicic 1 2 4 5 , AREST CF 1 4 6 7 , WAERP 1 4 8
  1. Wal-yan Respiratory Research Centre, Telethon Kids Institute, Nedlands, WA, Australia
  2. Faculty of Health and Medical Sciences, University of Western Australia, Nedlands, WA, Australia
  3. School of Biomedical Sciences, University of Western Australia, Nedlands, WA, Australia
  4. Dept of Respiratory and Sleep Medicine, Perth Children's Hospital, Nedlands, WA, Australia
  5. School of Population Health, Curtin University, Bentley, WA, Australia
  6. Murdoch Children's Research Institute, Melbourne, VIC, Australia
  7. Dept of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
  8. St. John of God Hospital, Subiaco, WA, Australia

Introduction: Acinetobacter baumannii is a gram-negative aerobe that is a major cause of nosocomial infections, including ventilator-associated pneumonia, bacteraemia, and urinary tract infections1. As one of the ESKAPE pathogens2, A. baumannii has been flagged as a bacterium of concern due to growing multidrug resistance (MDR), with MDR acquisition associated with increased mortality3. The increased prevalence of MDR infections and lack of novel antibiotic development have led to exploration of bacteriophage or phage, viruses that infect bacteria, as an alternative antimicrobial therapy. To address the lack of new therapies for MDR A. baumannii infections, we screened wastewater for bacteriophage with lytic activity against this pathogen.

Methods: Wastewater was sampled monthly from the Subiaco Wastewater Treatment Plant in Shenton Park, Western Australia, from February to June 2022. Water samples were assessed for phage activity by whole-plate double agar overlay, with a panel of fourteen A. baumannii clinical isolates serving as hosts for phage isolation. Zones of clearing indicative of bacterial lysis, or plaques, were picked and filtered to isolate phage. Isolated phages were further purified by replating over three rounds of whole plate overlays.

Results: Over 300 phages were isolated across all five samples of wastewater over the collection period, with each sample yielding an average of fifty phage. Lytic activity was observed against thirteen clinical isolates. Phages were pH and temperature stable, and formed plaques that varied in size and morphology, indicating diversity of phage species.

Conclusion: In summary, phages with lytic activity against A. baumannii can be successfully isolated from wastewater. Ongoing work seeks to characterise phage genomes, host range activity, as well as susceptibility and resistance in the propagating hosts. This information will be used to further assess capacity of isolated bacteriophages as antimicrobials for A. baumannii infections.

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  2. Rice LB. Federal funding for the study of antimicrobial resistance in nosocomial pathogens: no ESKAPE. J Infect Dis. 2008 Apr 15;197(8):1079-81. doi: 10.1086/533452.
  3. da Silva KE, Maciel WG, Croda J, Cayô R, Ramos AC, de Sales RO, Kurihara MNL, Vasconcelos NG, Gales AC, Simionatto S. A high mortality rate associated with multidrug-resistant Acinetobacter baumannii ST79 and ST25 carrying OXA-23 in a Brazilian intensive care unit. PLoS One. 2018 Dec 28;13(12):e0209367. doi: 10.1371/journal.pone.0209367.