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Francisella tularensis is the cause of the zoonotic disease tularemia and is classified 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 identification. Phenotypic identification 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 flight mass spectrometry (MALDI-TOF MS) was recently evaluated as a useful tool for the rapid identification of a variety of microorganisms. In this study, we evaluated the use of MALDI-TOF MS for the rapid identification of Francisella tularensis and differentiation 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-specific polymerase chain reaction (PCR) test and MALDI-TOF MS. All isolates were originally identified as F. tularensis subsp. holarctica according to region of difference 1 (RD1) subspecies-specific PCR results. For all isolates MALDI-TOF MS provided results in concordance with subspecies-specific PCR analysis. Although PCR-based methods are effective 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-effective identification technique for Francisella spp. Shorter analysis time and low cost make this an appealing new option in microbiology laboratories.

Abstract The main aim of this study was to improve the mechanical properties of the recycled poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate) (r-PET/PEN) blends by enhancing the miscibility between PET and PEN with the usage of chain extenders. This idea was novel for the recycled PET-based r-PET/PEN blends, as investigation of the effects of the chain extender usage on the properties of r-PET/PEN blends has not been studied in the literature, according to our knowledge. 1,4-Phenylene-bis-oxazoline (PBO), 1,4-phenylene-di-isocyanate (PDI), and triphenyl phosphite (TPP) were selected as chain extenders. The maximum tensile strength value was observed for the 1.0PDI sample. Moreover, PDI-based blends exhibited better Izod impact strength when compared with all other samples. The miscibility and degree of crystallinity values of all blends were discussed by means of thermal analysis. 1H-nuclear magnetic resonance (1H-NMR) analysis was carried out to determine transesterification reaction levels. According to 1H-NMR results, the increase in the level of transesterification was around 40% with the usage of PDI. The optimum loading level for selected chain extenders was determined as 1 wt.%, and PDI-based blends exhibited better properties when compared with those of the blends based on PBO and TPP at this loading level.

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