Kichan Lee

First detection of the mcr-1 gene in Escherichia coli isolated from livestock between 2013 and 2015 in South Korea

Abstract The plasmid-mediated colistin resistance gene mcr-1 was first reported in China in 2013, and has since been identified in both humans and livestock from many other countries (1-3,5).….

Immunoproteomics of Brucella abortus RB51 as candidate antigens in serological diagnosis of brucellosis.

The current brucellosis serodiagnostic assays are chiefly based on detecting anti-LPS (lipopolysaccharide) antibodies. However, cross-reaction with some gram-negative bacteria can occasionally induce due to similar O-polysaccharide (OPS) structure. Therefore, the aim of the present study was to identify new candidate antigens from Brucella abortus RB51, a mutant strain lacking the LPS portion, which might be valuable in brucellosis diagnosis. To detect potential antigens, immobilized pH gradients (IPG) strips with three ranges (pH 3-5.6, 4-7 and 6-11) were applied. After separating the insoluble proteins of B. abortus RB51 using two-dimensional electrophoresis (2-DE), their immunogenicity was evaluated by western blotting using four types of antisera - B. abortus, Yersinia enterocolitica O:9 and Escherichia coli O157:H7-positive, and B. abortus-negative bovine sera. Among the several immunogenic spots, the spots showing specific reactivity with only the B. abortus-positive antisera, were considered as candidate antigens. Overall, eleven immuno-reactive proteins were identified, as follows: Cu/Zn superoxide dismutase, histidinol dehydrogenase, chaperonin DnaK, chaperonin GroES, beta-ketoadipyl CoA thiolase, two-component response regulator, the cell-division protein FtsZ, aldehyde dehydrogenase, 50s ribosomal protein L10 and invasion protein B. These selected highly immunogenic protein spots might be useful as alternative antigens for brucellosis and helpful in reducing the cross-reactivity.

Epidemiologic relatedness between Brucella abortus isolates from livestock and wildlife in South Korea.

To investigate the epidemiologic relatedness of Brucella abortus isolates from Chinese water deer (Hydropotes inermis) and goral (Naemorhedus goral raddeanus) in 2010–2011, 22l isolates from livestock (including domestic elk, Cervus canadensis) were analyzed using the multilocus variable-number tandem repeats analysis. In the clustering analysis, Korean B. abortus isolates were divided into 40 genotypes by 18 markers, and 2 B. abortus isolates from wildlife were clustered with those of domestic cattle. Based on the minimum spanning tree, B. abortus isolates from wildlife were closely related to or had originated from livestock. Control measures are necessary to be able to block the transmission of Brucella between domestic and wild animals, and continuous monitoring of wildlife will be necessary to eradicate brucellosis in South Korea.

Rapid and specific identification of Brucella abortus using the loop-mediated isothermal amplification (LAMP) assay

A rapid and accurate diagnosis of brucellosis is required to reduce and prevent the spread of disease among animals and the risk of transfer to humans. In this study, a Brucella abortus-specific (Ba) LAMP assay was developed, that had six primers designed from the BruAb2_0168 region of chromosome I. The specificity of this LAMP assay was confirmed with Brucella reference strains, B. abortus vaccine strains, B. abortus isolates and phylogenetically or serologically related strains. The detection limit of target DNA was up to 20 fg/μl within 60 min. The sensitivity of the new LAMP assay was equal to or slightly higher than other PCR based assays. Moreover, this Ba-LAMP assay could specifically amplify all B. abortus biovars compared to previous PCR assays. To our knowledge, this is the first report of specific detection of B. abortus using a LAMP assay. The Ba-LAMP assay can offer a rapid, sensitive and accurate diagnosis of bovine brucellosis in the field.

Brucellosis among ruminants in some districts of Bangladesh using four conventional serological assays

Brucellosis causes a great economic loss to the livestock industries through abortion, infertility, birth of weak and dead offspring, increased calving interval and reduction of milk yield and it is endemic in Bangladesh. The present study was performed to know the seroprevalence of brucellosis for 1000 ruminants (135 Buffaloes, 465 cattle, 230 goats and 170 sheep) in five different districts of Bangladesh by four conventional serological tests such as: Rose Bengal Plate Test (RBT), tube agglutination test (TAT), competitive enzyme-linked immunosorbent assay (C-ELISA), and Fluorescent polarization assay (FPA). Sheep has the highest prevalence (8.24%) of brucellosis. The seroprevalence of brucellosis was significantly higher in animals with previous abortion record in case of buffaloes, cattle, goats and sheep than that with no abortion record. C-ELISA can be the most suitable choice for extensive use in many kinds of livestocks and accurate estimation of Brucella antibodies in ruminants in Bangladesh.

A new Brucella canis species-specific PCR assay for the diagnosis of canine brucellosis

Brucellosis is a zoonotic disease that is transmitted from animals to humans, and the development of a rapid, accurate, and widely available identification method is essential for diagnosing this disease. In this study, we developed a new Brucella canis species-specific (BcSS) PCR assay and evaluated its specificity and sensitivity. A specific PCR primer set was designed based on the BCAN_B0548-0549 region in chromosome II of B. canis. The PCR detection for B. canis included amplification of a 300-bp product that is, not found on other Brucella species or, genetically or serologically related bacteria. The detection limit of BcSS-PCR assay was 6pg/μl by DNA dilution, or 3×10(3) colony-forming units (CFU) in the buffy coats separated from whole blood experimentally inoculated with B. canis. Using the buffy coat in this PCR assay resulted in approximately 100-times higher sensitivity for B. canis as compared to detect directly from whole blood. This is the first report of a species-specific PCR assay to detect B. canis, and the new assay will provide a valuable tool for the diagnosis of B. canis infection.