Characterization of Tularemia Cases in Slovenia with Multiple-Locus Variable-Number Tandem Repeat Analysis.

is the etiologic agent of tularemia, a bacterial zoonotic disease. The genome of shows a recent evolutionary change, especially in reservoirs. Variable number of tandem repeats (VNTR) is described as a high-speed molecular clock and can thus be used as a high-resolution typing system. The main objective of our study was to investigate the molecular diversity of strains and reveal possible sources of infection. Using real-time PCR targeting the IS2 region, we successfully amplified targeted DNA in 13/31 Slovenian patients with a clinical diagnosis of tularemia, and with PCR targeting the gene, we obtained 11/13 PCR products. Sequencing revealed that all samples were identified as subsp. . We successfully obtained one isolate from a lymph node aspirate by culture on chocolate agar. Our isolate was clustered into major clade B12 (subclade B43). We optimized VNTR typing to be used directly on clinical samples. Multiple-locus VNTR analysis (MLVA) revealed five unique MLVA types; 45.5% samples had the same MLVA type, another 27.3% shared a different MLVA type, and each of the remaining had a unique MLVA type. Most samples differed at only two VNTR markers (Ft-M03 and Ft-M06). Additionally, we investigated samples from small mammals ( = 532) and ticks ( = 232) captured in the same geographical area in which patients with tularemia were found. No DNA was detected in samples of small mammals or ticks. The diversity of MLVA types in Slovenia was high, despite the small region, but most of the samples from the same region shared the same MLVA type. Our results suggest that MLVA is a useful tool for quick molecular characterization of directly from patient samples, especially when investigating geographically localized outbreaks.