AUTHOR=Kang Yao-Xia , Li Xu-Ming , Piao Dong-Ri , Tian Guo-Zhong , Jiang Hai , Jia En-Hou , Lin Liang , Cui Bu-Yun , Chang Yung-Fu , Guo Xiao-Kui , Zhu Yong-Zhang 

TITLE=Typing Discrepancy Between Phenotypic and Molecular Characterization Revealing an Emerging Biovar 9 Variant of Smooth Phage-Resistant B. abortus Strain 8416 in China

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.01375

DOI=10.3389/fmicb.2015.01375

ISSN=1664-302X

ABSTRACT=<p>A newly isolated smooth colony morphology phage-resistant strain 8416 isolated from a 45-year-old cattle farm cleaner with clinical features of brucellosis in China was reported. The most unusual phenotype was its resistance to two <italic>Brucella</italic> phages Tbilisi and Weybridge, but sensitive to Berkeley 2, a pattern similar to that of <italic>Brucella melitensis</italic> biovar 1. VITEK 2 biochemical identification system found that both strain 8416 and <italic>B. melitensis</italic> strains shared positive ILATk, but negative in other <italic>B. abortus</italic> strains. However, routine biochemical and phenotypic characteristics of strain 8416 were most similar to that of <italic>B. abortus</italic> biovar 9 except CO<sub>2</sub> requirement. In addition, multiple PCR molecular typing assays including AMOS-PCR, <italic>B. abortus</italic> special PCR (B-ab PCR) and a novel sub-biovar typing PCR, indicated that strain 8416 may belong to either biovar 3b or 9 of <italic>B. abortus</italic>. Surprisingly, further MLVA typing results showed that strain 8416 was most closely related to <italic>B. abortus</italic> biovar 3 in the <italic>Brucella</italic> MLVA database, primarily differing in 4 out of 16 screened loci. Therefore, due to the unusual discrepancy between phenotypic (biochemical reactions and particular phage lysis profile) and molecular typing characteristics, strain 8416 could not be exactly classified to any of the existing <italic>B. abortus</italic> biovars and might be a new variant of <italic>B. abortus</italic> biovar 9. The present study also indicates that the present phage typing scheme for <italic>Brucella sp.</italic> is subject to variation and the routine <italic>Brucella</italic> biovar typing needs further studies.</p>