Towards Clinical Phage Microbiology for Biofilm Infections: A Comparative Study and a Suggested Protocol

Non-resolving bacterial infections involve biofilm formation and are often complicating treatments. Utilizing lytic bacteriophages with antibiotics holds promise in biofilm eradication. Accurately matching phage-antibiotic combinations against target bacteria, termed Clinical Phage Microbiology (CPM), is crucial in effective phage therapy treatments. However, compared to planktonic cultures, performing CPM on biofilm infections poses a significant challenge due to the lack of effective methods and a standard protocol. This study compared various CPM approaches in biofilms. To this end, the activity of five phages was assessed against Pseudomonas aeruginosa biofilms using nine methods and multiple approaches. Here, we discuss various aspects of each technique, including sensitivity, duration, ease of implementation in diagnostic labs, and labor. Finally, we offer a preliminary protocol for testing phage-sensitivity in biofilm, which was tested on various bacteria species, and may serve as a basis for comprehensive CPM in biofilm.