Bacteriophages (phages) are characterized for their high specificity being able to discriminate their
host up to the strain level. This feature is largely dependent on specific structural proteins encoded
on the phages genomes. These proteins recognize specific receptors on the bacterial cell surface
and are known as phage receptor binding proteins (RBP). The ability to specifically recognize and
bind to certain bacteria make RBP valuable biorecognition elements with high potential for the development
of new diagnosis methods.
Considering the slow turnover of the conventional culture methods and the limitations of the immune
and molecular assays, it is crucial and urgent the development of new diagnostic methodologies
able to rapidly and accurately detect and identify the etiological agent of important bacterial
infections. This is exacerbated in COVID-19 patients for which a high rate of deaths was attributed
to secondary bacterial infections (SBI).
Through bioinformatics and functional analysis we identified RBP encoded in the genome of two
lytic phages. These two RBP were able to specifically recognize and bind to 2 of the most important
bacteria responsible for SBI associated with COVID-19: Pseudomonas aeruginosa and
Staphylococcus aureus. By fusing the RBP to different fluorescent proteins we developed a method
to detect and identify these bacteria in multiplex through epifluorescent microscopy and spectrofluorimetry.
Fusion of the RBP to the NanoLuc luciferase improved the limit of detection 100 times
when compared with the fluorescent proteins.
This new methodology was tested against more than 200 bacteria isolated from COVID-19 patients
with a specificity of 100% and 90%, and a sensitivity of 44% and 96%, against P. aeruginosa and S.
aureus respectively.
In conclusion, we developed here a new methodology based on viral proteins able to fast and accurately
detect P. aeruginosa and S. aureus that will improve diagnosis of SBI associated with COVID-
19.info:eu-repo/semantics/publishedVersio
