Changes in the Eradication Efficacy of Fluoroquinolone-containing Triple Therapy for Helicobacter pylori Infection in Korea

Background/Aims@#Fluoroquinolone-containing triple eradication therapy could be considered an alternative regimen for the second- line treatment of Helicobacter pylori infection. This study aimed to investigate the changes in the eradication efficacy of fluoroquinolone- containing triple therapy from 2003 to 2018 in Korea. @*Materials and Methods@#Patients with a history of first-line eradication therapy failure were consecutively enrolled at Seoul National University Bundang Hospital from 2003 to 2018. All patients took moxifloxacin-containing triple therapy as the second-line eradication therapy. The treatment regimen comprised a three-drug combination comprising a proton pump inhibitor, amoxicillin, and moxifloxacin. Data on age, sex, endoscopic diagnosis, eradication results, compliance, and adverse outcomes were acquired and analyzed. @*Results@#In total, 824 participants were enrolled during the study period, of whom, 46 were lost to follow-up. Finally, 778 participants were included in the per-protocol (PP) analysis, of whom, 72.1% received moxifloxacin-containing triple therapy for 14 days. The eradication rate of moxifloxacin-containing triple therapy was 72.1% (594/824) in the intention-to-treat analysis and 76.3% (594/778) in the PP analysis. A decline in eradication efficacy was observed, especially in the PP analysis (P=0.046). Diarrhea was the most commonly observed adverse event, accounting for 19.6% (41/209) of recorded adverse events. @*Conclusions@#Moxifloxacin-containing triple therapy has shown suboptimal eradication efficacy as the second-line eradication therapy. In addition, there is a concern that eradication rate will decrease due to increase in antimicrobial resistance.

Development and Verification of Nested PCR Assay for Detection of Tobacco rattle virus in Plant Quarantine

Tobacco rattle virus (TRV) is a plant pathogen belonging to the Group IV positive-sense single-stranded RNA viruses. TRV causes disease in various plants (e.g., potato, tomato and tobacco), for which it was classified as a controlled quarantine virus in Korea. This study aimed to develop specific primer sets for the rapid detection of TRV. Two RT-PCR primer sets were developed for specific detection of TRV. Furthermore, nested primer sets were also developed, which is required for high sensitivity detection in plant quarantine. The RT-PCR and nested PCR products had the following sizes: set 5 (1,096-->540 bp), and set 7 (878-->756 bp), respectively. In addition, a modified positive-control plasmid was also developed for use as a positive control in TRV quarantine. The diagnostic system for TRV detection was verified using samples from Korean quarantine sites for the last five years (2009-2014). A total of 83 cases were detected among various import crops. This system for detection of TRV will continuously contribute to plant quarantine in the future.

Phylogeny of Flavobacteria Group Isolated from Freshwater Using Multilocus Sequencing Analysis

Sequence analysis of the 16S rRNA gene has been widely used for the classification of microorganisms. However, we have been unable to clearly identify five Flavobacterium species isolated from a freshwater by using the gene as a single marker, because the evolutionary history is incomplete and the pace of DNA substitutions is relatively rapid in the bacteria. In this study, we tried to classify Flavobacterium species through multilocus sequence analysis (MLSA), which is a practical and reliable technique for the identification or classification of bacteria. The five Flavobacterium species isolated from freshwater and 37 other strains were classified based on six housekeeping genes: gyrB, dnaK, tuf, murG, atpA, and glyA. The genes were amplified by PCR and subjected to DNA sequencing. Based on the combined DNA sequence (4,412 bp) of the six housekeeping genes, we analyzed the phylogenetic relationship among the Flavobacterium species. The results indicated that MLSA, based on the six housekeeping genes, is a trustworthy method for the identification of closely related Flavobacterium species.