MALDI-TOF mass spectrometry applied as new diagnostic tool in parasitology and virology

Background: At present, MALDI-TOF MS is considered the holy grail of rapid microbial identification despite only being introduced for use in routine laboratories less than 10 year ago. The diagnostic applications cover bacteria and fungi. However, very few reports are available about its application in parasitology and virology. In this study we report the application developed in these fields. Materials/methods: In this study one reference strain for each parasite and 21 Trichomonas vaginalis, 6 Entamoeba histolytica, 8 E. dispar and 13 Dientamoeba fragilis clinical isolates, respectively, were used. Likewise, one reference strain for each respiratory virus included in the study (human influenza A and B, type 2 and 5 adenovirus C species, parainfluenza virus type 1, 2 and 3, respiratory syncytial virus, human echovirus type 30, human cytomegalovirus and human metapneumovirus) and Poliovirus type 1, 2 and 3 was used. In addition, a total of fifty-eight respiratory viruses and 5 polioviruses isolated from as many biological samples were included. Results: In a first approach, the commercial database of the spectrometer used in our laboratory (Maldi Biotyper database Bruker Daltonics) was supplemented with additional spectra of T. vaginalis reference strain and a new respiratory viruses infected cells database was created, extensively modifying the parameters commonly set for the routine identification of bacteria and fungi. After implementation, the protein spectra of T. vaginalis clinical isolates were correctly identify as well as those of respiratory viruses clinical isolates, when compared with the specific newly created database. In a second approach protein biomarkers were picked out to identify and differentiate E. histolytica and E. dispar and to identify D. fragilis, and poliovirus at serotype level. For each parasite and for each virus specific biomarkers were found that allowed to properly identify clinical strains. Conclusions: Although the massive number of entries in the available commercial database, the absence of reference spectra of parasites and viruses does not allow their identification. In this study, the versatility of the system was demonstrated, allowing us to identify them using different approaches such as the creation of specific database modifying parameter setting and by biomarkers research.