ionization-time of fl ight mass spectrometry in the identifi cation of Francisella tularensis

Francisella tularensis is the cause of the zoonotic disease tularemia and is classifi ed among highly pathogenic bacteria (HPB) due to its low infection dose and potential for airborne transmission. In the case of HBP, there is a pressing need for rapid, accurate and reliable identifi cation. Phenotypic identifi cation of Francisella species is inappropriate for clinical microbiology laboratories because it is time-consuming, hazardous and subject to variable interpretation. Matrix-assisted laser desorption ionization-time of fl ight mass spectrometry (MALDI-TOF MS) was recently evaluated as a useful tool for the rapid identifi cation of a variety of microorganisms. In this study, we evaluated the use of MALDI-TOF MS for the rapid identifi cation of Francisella tularensis and diff erentiation of its subspecies. Using national collection of Francisella isolates from the National Tularemia Reference Laboratory (Public Health Institution of Turkey, Ankara), a total of 75 clinical isolates were investigated by species and subspecies-specifi c polymerase chain reaction (PCR) test and MALDI-TOF MS. All isolates were originally identifi ed as F. tularensis subsp. holarctica according to region of diff erence 1 (RD1) subspecies-specifi c PCR results. For all isolates MALDI-TOF MS provided results in concordance with subspecies-specifi c PCR analysis. Although PCR-based methods are eff ective in identifying Francisella species, they are labor-intensive and take longer periods of time to obtain the results when compared with MALDI-TOF MS. MALDI-TOF MS appeared to be a rapid, reliable and cost-eff ective identifi cation technique for Francisella spp. Shorter analysis time and low cost make this an appealing new option in microbiology laboratories.