Antimicrobial resistance imposes an ever-increasing burden on public health via its detrimental influence on patient mortality and morbidity. Most prevalent in immunocompromised patients, antimicrobial-resistant infections are associated with 5 million deaths annually, which the WHO predicted to double by 2050.
The rise of multi-antimicrobial-resistant bacteria has created a dire need for new alternative therapies. Bacteriophages (phages) are viruses that infect and kill bacteria and are present in every microbiome. Phage therapy can augment current antibiotic treatment and specifically target problematic bacterial species. Phage therapy can prevent mortality and improve quality of life.
Stenotrophomonas maltophila is an emerging multi-antimicrobial-resistant opportunistic pathogen with an associated 30-day mortality rate of 30–51%. In addition, S. maltophila exacerbates polymicrobial respiratory infections by forming well-integrated, protective biofilms that may allow the growth of cystic fibrosis pathogens, such as Pseudomonas aeruginosa.
We isolated and characterised lytic phages against clinical S. maltophila samples from South Australian patients. Our phage pipeline starts with isolating phages from environmental samples, like sewage, and then we purify them and sequence their genomes to characterise whether they are candidates for phage therapy. Next, we visualise phages with TEM and use MS/MS to identify the structural proteins.
We have isolated four unique novel lytic Caudovirales from environmental samples. Cross-infectivity against 30 S. maltophila clinical strains indicated they were broad host range phages. Additionally, genomic analysis of the phages suggests their viability for phage therapy. We compare the genomes of the phages and the hosts they can and can not infect to identify what limits their host range.
Our broad host range, lytic S. maltophila phages, are excellent candidates for phage therapy.