MLVA typing and antibiotic susceptibility of Brucella human isolates from Liaoning, China.

We have characterized clinical isolates of Brucella melitensis from Liaoning, China, using multiple-locus variable-number repeat analysis of 16 loci (MLVA-16) and evaluated the antimicrobial susceptibilities in vitro. All 31 isolates shared the panel 1 genotype 42 profile suggesting that they belong to the 'East Mediterranean' group. In vitro antibiotic susceptibility was determined by the broth microdilution testing. All isolates were sensitive to tested antibiotics (rifampin, doxycycline, ciprofloxacin, levofloxacin, moxifloxacin, norfloxacin, ofloxacin, ceftriaxone, streptomycin and trimethoprim-sulfamethoxazole) in addition to azithromycin and clarithromycin. Partial nucleotide sequences of the 23SrRNA gene were analyzed for all isolates and single nucleotide polymorphism alterations of 2632 T/C were found. The MLVA-16 assay can be applied to the long-term surveillance and investigation of strain relatedness in regions of endemicity.