Multiple-Locus Variable-Number Tandem-Repeat Analysis Genotyping of Human Brucella Isolates from Turkey

A multiple-locus variable-number tandem-repeat analysis (MLVA) was applied to investigate the epidemiological relationship and genetic diversity among 162 human Brucella isolates collected from all geographic regions of Turkey in an 8-year period (2001 to 2008). The isolates were genotyped by using an MLVA assay developed in Orsay, France (MLVA-16(Orsay)) including eight minisatellite (panel 1) and eight microsatellite (panel 2, subdivided into 2A and 2B) markers. Panels 1 and 2A distinguish 14 genotypes; two of these represented 85% of the strains. Panel 2B displayed a very high discriminatory power. Three loci from panel 2B had diversity index values higher than 0.74. MLVA-16(Orsay) yielded 105 genotypes; 73 were represented by a unique isolate, and 32 included two to eight isolates. The isolates from different patients within the same outbreak or from the same patient before first-line therapy and after relapse showed identical genotypes. A number of MLVA genotypes appeared to be partially restricted to some geographic areas and displayed no annual variation, possibly reflecting persistence of genotypes in certain areas for a time span of at least a decade. This study, representing the first molecular typing results of human Brucella isolates from Turkey, indicated that Turkish human Brucella melitensis isolates were most closely related to the neighboring countries' isolates included in the East Mediterranean group.