MALDI-TOF MS as a tick identification tool in a tertiary hospital in Spain

In Spain, as in other countries, the spectrum of tick-borne diseases and their number have increased in recent years. The tick identification, at species level, can be challenging outside research centers although this infor-mation is very usufull for decisions making. The performance of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in tick identification of specimens collected from patients have been seldomly reported. The aim of the present study was to desing a protein-extraction protocol and build a tick-legs reference spectra. This protocol was then validated using specimens from both patients and non-patient sources. Nine species of ticks that usually bites humans in Spain were included: Dermacentor marginatus, Der-macentor reticulatus, Haemaphysalis punctata, Hyalomma lusitanicum, Hyalomma marginatum, Ixodes ricinus, Rhi-picephalus bursa, Rhipicephalus pusillus and Rhipicephalus sanguineus sensu lato. Other less-frequent biting species were also included: Haemaphysalis inermis, Haemaphysalis concinna, Hyalomma scupense, Ixodes frontalis, Ixodes hexagonus, and Argas sp. specimens were identified by PCR and sequencing of a fragment of the 16S rRNA gene of ticks. In the tests performed with non-patient collected specimens, a 100% correlation was observed between molecular methods and MS, while in the tests performed with ticks collected from patients a 92.59% correlation was observed. Misidentification was observed only in two of I. ricinus nymphs (identified as Ctenocephalides felis). Therefore, mass-spectrometry can be confidently used as a tick identification tool in a hospital setting for the rapid identification of tick vectors.

Automated summary

In recent years, there has been an increase in the number and spectrum of tick-borne diseases in Spain. However, tick identification at the species level can be challenging outside research centers. This study aimed to develop a protein-extraction protocol and create a tick-legs reference spectra for accurate identification using mass spectrometry. The results showed that mass-spectrometry can be confidently used in a hospital setting for the rapid identification of tick vectors.